Method for hydrothermal liquefaction of an organic feedstock

Abstract

The invention relates to a method for the hydrothermal liquefaction of organic matter, comprising: (a) a step of preparing a suspension in aqueous solution of organic matter of biomass and / or plastic type; (b) an optional step of preheating the suspension from step (a) to a preheating temperature and a pressure of at least 220 barg; (c) a step of hydrothermal liquefaction in which the suspension leaving step (a) or (b) is introduced into a single tubular reactor at a pressure of at least 220 barg, heated by ohmic heating to a temperature of at least 350°C at a rate of at least 10°C per minute, and held at the temperature of at least 350°C and at the pressure of at least 220 barg for at least one minute to produce a predominantly liquid effluent containing oil and an aqueous phase; (d) a step of recovering the liquid phases from the effluent produced by step (c).

Description

[0001] PROCESS FOR HYDROTHERMAL LIQUEFACTION OF AN ORGANIC FEED

[0002] Field of invention

[0003] The present invention relates to a process for the hydrothermal liquefaction of an organic feedstock. The process according to the invention makes it possible in particular to heat the feedstock rapidly and uniformly to the liquefaction temperature of the organic compounds in the feedstock.

[0004] State of the art

[0005] Hydrothermal liquefaction is one of the promising recovery processes for liquefying organic loads such as biomass or plastic and then producing fuels and chemical compounds.

[0006] These organic feedstocks can be converted into liquid by pyrolysis or hydrothermal liquefaction (HTL), or by gasification into synthesis gas followed by Fischer-Tropsch or methanol synthesis. The implementation of pyrolysis and gasification processes has the disadvantage of requiring the evaporation of excess water contained in the organic feedstock to be treated by heating, which considerably increases the energy cost of the treatment.

[0007] HTL was born out of the need to convert wet biomass resources without the energy-intensive step of drying. Essentially, HTL replicates and enhances the extreme environmental conditions that transformed old biomass into crude oil. HTL is typically performed at elevated temperatures, between 250 and 450°C, with appropriate pressures to maintain the wet slurry in a single liquid state, between 100 and 350 barg, eliminating the liquid-to-gas phase change and resulting in significant energy savings.

[0008] The most widely used liquid heating techniques rely on heat transfer: energy is delivered to the product by conduction and convection from a hot surface. Until now, the HTL process generally involves heating a suspension of the organic feedstock placed inside a reactor from the reactor surface. The ratio between the heat exchange surface area and the volume therefore determines the heating rate, while the metal surface of the reactor must be at a significantly higher temperature to force heat into the suspension (temperature gradient to transfer heat). This high surface area / volume ratio makes it expensive to scale up to large industrial capacity, and hot surfaces can lead to fouling due to the instability of the feedstock at the high temperature applied.

[0009] The technical disadvantage of existing solutions is the difficulty of heating the organic feedstock to be liquefied throughout its volume to the required temperature, as the feedstock is heated only by the reactor walls. Excessively high reactor wall temperatures can produce water vapor and lead to local gasification and a reduction in the liquefaction efficiency of biomass and / or plastics. Excessively low feedstock temperatures inside the reactor, which are not in contact with the reactor walls, can influence the reduction of liquefaction efficiency and an increase in the volume of coal produced.

[0010] Patent EP2872598 describes the use of microwave radiation to reach the temperature required for biomass liquefaction in a very short time and to heat the biomass evenly throughout its volume. The biomass, at a pressure of 220 - 250 atm, is preheated in a heat exchanger to a temperature of at least 150 °C to 250 °C, then introduced into a reactor in which it is heated in a very short time using microwave radiation. The power of the radiation is adjusted to maintain the biomass inside the reactor at a temperature of 374 °C to 400 °C. However, secondary reactions of degradation of the material then occur from the preheating, which increases the total reaction time with the risk of increasing the production of gas by secondary cracking and therefore reducing the liquid yield.Furthermore, microwave heating of materials is highly dependent on the dielectric properties (presence of a dipole moment) of the material to be heated (a conductor does not absorb microwaves and an insulator allows microwaves to pass through) and thus, if the material to be heated is heterogeneous in composition, hot spots may occur due to selective heating. Although microwave heating can be done rapidly, microwave penetration drops rapidly (the intensity of the electromagnetic field decreases) with the depth of the material to be heated. In addition, the conversion of electricity into microwaves is done at an efficiency between 50 and 85% depending on the applied frequency.

[0011] Patent AU2011274308 describes a rapid ballistic heating concept where organic matter is mixed with a superheated fluid to quickly achieve a hot mixture. It thus describes a method for producing a bio-oil from organic matter comprising the steps of: (i) generating a supercritical aqueous solvent before contacting the supercritical aqueous solvent with the organic matter; (ii) contacting the organic matter to be treated with a supercritical aqueous solvent to form a reaction mixture, this contacting causing a supercritical to subcritical phase change in the aqueous solvent. The reaction mixture is then maintained at a temperature of 250°C - 400°C and a pressure of 100 to 300 bar for a period of one to sixty minutes to produce bio-oil.This method involves higher energy consumption because the water must be superheated beyond the critical point to then bring it into contact with the organic matter, and finally maintain the typical HTL operating conditions. WO2017 / 178626 describes a process for producing a fuel product in which the organic feedstock or biomass is mixed with an alkaline material and then heated by ohmic heating to a temperature of 280°C to 320°C and a pressure of 6.6 to 11.6 MPa under subcritical water conditions. The resulting fuel product is essentially in solid form, with a particle size small enough to be able to make a stable fuel dispersion. It is therefore a hydrothermal carbonization (HTC) process and not a hydrothermal liquefaction process.The reaction is carried out in a tubular reactor or a continuous tubular reactor (“plug flow reactor” in English).

[0012] MJ Mohr, in his thesis "Hydrothermal Processing of Aqueous Biomass: Process Development and Integration of a Novel Heating Technique" of July 2013 tested a setup for the treatment of algal biomass, in which the feedstock is pressurized by a pump, then preheated by ohmic heating in a tubular heater before entering a continuously stirred tank reaction vessel (CSTR reactor) in which it is heated and maintained at the reaction temperature. The reaction products are then cooled and separated. The setup described has the disadvantage of implementing high-temperature heating before entering the reactor: under these conditions, the decomposition reactions begin at this preheating, so that fouling phenomena can be observed in the pipes connecting the preheating tubular reactor and the CSTR reactor.Furthermore, the residence time of molecules in a CSTR reactor can have a relatively wide distribution due to the reactor's operating mode, favoring side reactions for species that have remained there too long and conversions of biological macromolecules that are not advanced enough for species that have remained there for too short a time. Finally, under supercritical conditions, given the complexity of the mixtures and the products formed, it is difficult to determine where the products formed are located in a CSTR reactor, so that carrying out their withdrawal can be complex and the residence time can be extended. Thus, the industrialization of the process described by MJ Mohr raises many problems.

[0013] There is a need for a hydrothermal liquefaction process for an organic feedstock that limits the formation of gases and solids. There is also a need for a hydrothermal liquefaction process for an organic feedstock that can be industrialized and limits side reactions.

[0014] Summary of the invention

[0015] The invention aims to propose a process for the hydrothermal liquefaction of organic matter, comprising:

[0016] (a) a step of preparing a suspension of the organic matter in an aqueous solution, the organic matter being chosen from biomass and plastics, alone or as a mixture, (b) an optional step of preheating the suspension prepared in step (a) at a pressure of at least 220 barg and at a preheating temperature at least 10°C lower than a decomposition temperature of the organic matter at the pressure in question,

[0017] (c) a hydrothermal liquefaction step in which the suspension leaving step (a), optionally from step (b), is introduced into a single tubular reactor at a pressure of at least 220 barg, heated by ohmic heating to a temperature of at least 350°C and at most 450°C at a heating rate of at least 10°C per minute, and maintained at the temperature of at least 350°C and at most 450°C and at the pressure of at least 220 barg for at least one minute to produce a predominantly liquid effluent containing oil and an aqueous phase,

[0018] (d) a step of recovering the liquid phases of the effluent produced in step (c), and optionally, the conductivity of the suspension is adjusted before implementing step (c) of hydrothermal liquefaction, in particular to a value of at least 0.01 S / m.

[0019] By heating the feedstock to be liquefied very quickly in step (c) using ohmic heating, it is possible to achieve favorable conditions for hydrothermal liquefaction very quickly without forming, or by forming small amounts of, coke or char. It is thus possible to maximize the formation of liquid products and minimize the amount of solid products by crossing the cracking zone (going from the temperature of step (a), or optionally step (b), to the liquefaction temperature) as quickly as possible. Side reactions are then minimized, as is the reaction time, favoring the formation of liquid products.

[0020] Furthermore, the use of a single tubular reactor (also called a piston reactor), namely the implementation of step (c) in this single tubular reactor, and thus the elimination of product transfer lines between several reactors, it is possible to limit fouling of these lines. The use of a single tubular reactor also allows better management of the products formed, even under supercritical conditions, which makes it possible to control the distribution of the residence time inside the reactor, to limit secondary reactions and to achieve the narrowest possible distribution of the transformation rates of the biological species.

[0021] The tubular reactor may be recirculating or non-recirculating. When it is not recirculating, the residence time distribution may be narrow, which can further reduce side reactions and achieve the same conversion rate of biological species. When it is recirculating, at least one of the products formed at the end of the hydrothermal liquefaction step is returned to the inlet of the single tubular reactor. In this case, the residence time distribution is broader than in the case of a tubular reactor without recirculation, but mixing the feedstock to be treated with at least one of the reaction products can promote the solubilization of the feedstock and its treatment. Typically, 10 to 50% by mass of at least one of the products formed or of the mixture formed at the end of the hydrothermal liquefaction reaction can be recycled.

[0022] Advantageously, when the optional preheating step (b) is present, steps (b) and (c) follow one another without stopping the heating between the two steps.

[0023] The method according to the invention has the advantage of being able to be implemented in batch or continuously, preferably continuously.

[0024] Step (a) may comprise at least one of the following features:

[0025] - the suspension contains from 5 to 50% by mass of solid in the aqueous solution,

[0026] - at least part of the organic matter is in solid form and is previously ground to form particles whose size is less than 5mm, optionally less than 500pm.

[0027] The implementation of the optional step (b) makes it possible to preheat the suspension without degrading it, since the temperature used is too low for the hydrothermal liquefaction reactions to begin. This makes it possible to limit the amount of heating to be provided in step (c) without risking the formation of degradation products upstream of the tubular reactor.

[0028] The preheated suspension in step (b), when present, can be introduced immediately (directly) into the single tubular reactor of step (c).

[0029] Step (b), when present, may include at least one of the following features:

[0030] - the pressure is 220 barg to 350 barg,

[0031] - preheating temperature of not more than 220°C, preferably not more than 180°C, more preferably not more than 150°C,

[0032] - preheating is carried out in a heat exchanger.

[0033] Step (c) may comprise at least one of the following features:

[0034] - the pressure is 220 barg to 350 barg,

[0035] - the suspension is heated and maintained at a temperature of 350°C to 420°C,

[0036] - the heating rate is at least 60°C per minute,

[0037] - the suspension is maintained at a temperature of at least 350°C and at most 450°C, preferably 350°C to 420°C, and at a pressure of at least 220 barg for 1 to 60 minutes, preferably for 5 to 60 minutes or for 10 to 40 minutes, - the suspension has a conductivity of at least 0.01 S / m.

[0038] The temperature conditions can advantageously be adapted to the nature of the organic matter treated.

[0039] Thus, in one embodiment, step (c) may comprise at least one of the following characteristics: the organic matter comprises, or consists of, mainly biomass, and the suspension is heated and maintained at a temperature of 350 to 380°C, in particular at the pressure used, the organic matter comprises, or consists of, mainly plastics, and the suspension is heated and maintained at a temperature of 350 to 420°C, in particular at the pressure used.

[0040] Depending on the composition of the organic filler in conductive species, such as alkali or alkaline earth metal salts, the electrical conductivity of the suspension may be sufficient, for example at least 0.01 S / m, to allow ohmic heating. Typically, organic matter such as biomass contains conductive species that are soluble in aqueous solution and contribute to the necessary conductivity of the suspension. Organic fillers such as plastic waste generally do not contain these types of conductive species that are soluble in aqueous solution.

[0041] When the conductivity of the suspension is too low, it can be adjusted before implementing step (c), by adding one or more conductive species to the suspension, either by adding one or more electrically conductive species, advantageously soluble in the aqueous solution of step (a), or by adding at least part of the aqueous solution recovered downstream of step (c).

[0042] Thus, advantageously, in order to adjust the electrical conductivity of the suspension, in particular so that it reaches a target value, it is possible to add to the suspension, upstream of step (c), preferably during step (a), at least one soluble species, in particular in the aqueous solution of step (a), electrically conductive chosen from alkali or alkaline earth metal halides, alkali or alkaline earth metal oxyhalides, alkali or alkaline earth metal bicarbonates, alkali or alkaline earth metal carbonates, organic carboxylates (e.g. formic, acetic, propionic, lactic, etc.) of alkali or alkaline earth metals, alkali or alkaline earth metal sulfates, including monohydrogenated sulfates, alkali or alkaline earth metal phosphates, including monohydrogenated and bihydrogenated phosphates.

[0043] Advantageously, the electrical conductivity can be adjusted by adding at least one electrically conductive soluble species having a hydrothermal liquefaction catalysis function. Thus, in one embodiment, the at least one electrically conductive soluble species is chosen from species having catalytic activity for hydrothermal liquefaction.

[0044] Advantageously, the recovery step (d) may comprise (e) a step of cooling the effluent recovered in step (d). This cooling is typically a quenching cooling, very rapid, for example from 100°C / minute to 6000°C / minute, in order to stop the reactions in progress.

[0045] This cooling can be carried out in one or more stages. When it is carried out in several stages, the first stage is typically a quench, very rapid, as described above, typically to a temperature above 0 °C, the second cooling stage can then be a condensation stage at a lower temperature. Advantageously, the first cooling stage can consist of cooling the effluent from stage (d) in a first heat exchanger using liquid water which vaporizes to create water vapor and the second cooling stage can consist of further cooling the effluent in a second heat exchanger by heat exchange with the suspension from stage (a).

[0046] Alternatively, the cooling step may be carried out by means of a single heat exchanger using liquid water or by heat exchange with the suspension from step (a).

[0047] The method according to the invention may further comprise: (e) a step of separating the liquid phases recovered in step (d), into an oily phase and an aqueous phase. The aqueous phase separated in step (e) may be at least partly returned to step (a) of preparing the suspension in order to reduce the quantity of fresh aqueous solution used to prepare the suspension, and optionally adjust the conductivity of the suspension.

[0048] The invention also relates to a hydrothermal liquefaction unit, in particular adapted to the implementation of the method according to the invention, comprising a section (A) for preparing a suspension, an optional preheating section (B), a hydrothermal liquefaction section (C) consisting of a single tubular reactor comprising at least two electrodes, an optional section (E) for separating the liquid phases of an effluent produced by the hydrothermal liquefaction section, optionally a system for injecting at least one conductive species upstream of the section (C), in which the different sections are fluidically connected to implement the method according to the invention.

[0049] Definitions

[0050] The terms "comprising" and "comprises" as used herein are synonymous with "including," "includes," or "contains," "containing," and are inclusive or unbounded and do not exclude unspecified additional features, elements, or method steps. The specification of a numeric domain without decimals includes all whole numbers and, where appropriate, fractions thereof (e.g., 1 to 5 may include 1, 2, 3, 4, and 5 when referring to a number of elements, and may also include 1.5, 2, 2.75, and 3.80, when referring to, for example, a measurement.).

[0051] The specification of a decimal also includes the decimal itself (e.g., "from 1.0 to 5.0" includes 1.0 and 5.0). Any range of numeric values ​​recited here also includes any subrange of numeric values ​​mentioned above.

[0052] The expressions % by weight and % by mass have an equivalent meaning and refer to the proportion of the mass in grams of a product relative to 100 g of a composition comprising it.

[0053] "barg" refers to "bar gauge" and expresses the deviation from normal atmospheric pressure (0 barg is 101,325 Pa).

[0054] Detailed description of the invention

[0055] In the following description, the different embodiments described, and in particular the preferred embodiments of each step, can be combined according to the desired objective.

[0056] Description of organic matter subjected to the hydrothermal liquefaction process

[0057] This organic material is chosen from biomass and plastics, alone or in a mixture.

[0058] Biomass can be defined as an organic plant or animal product. Biomass thus includes (i) biomass produced from surplus agricultural land, preferably not used for human or animal food: dedicated crops, called energy crops; (ii) biomass produced by deforestation (forest maintenance) or clearing of agricultural land; (iii) agricultural residues from crops, in particular cereal crops, vines, orchards, olive trees, fruits and vegetables, agri-food residues, etc.; (iv) forest residues from forestry and wood processing; (v) agricultural residues from livestock farming (manure, slurry, bedding, droppings, etc.); (vi) household organic waste (paper, cardboard, green waste, etc.); (vii) industrial organic waste (paper, cardboard, wood, putrescible waste, etc.)); (viii) algal biomass, namely biomass formed from algae, for example microalgae (the algal biomass may be an algal suspension obtained by harvesting algae from, for example, a bioreactor, or an algal residue obtained by dehydrating an algal suspension) or macroalgae; alone or in a mixture.

[0059] Plastic can be of any type, including any type of new or used plastic, included in household (post-consumer) or industrial waste. Plastics means materials made of polymers, including thermoplastic polymers, thermosetting polymers and / or elastomers, alone or in mixtures, and optionally auxiliary components such as plasticizers, fillers, colorants, catalysts, flame retardants, stabilizers, etc.For example, these polymers can be polyethylene, halogenated polyethylene (Cl, F), polypropylene, polystyrene, polybutadiene, polyisoprene, poly(ethylene terephthalate) (PET), polylactic acid (PLA), acrylonitrile-butadiene-styrene (ABS), polybutylene, poly(butylene terephthalate) (PBT), polyvinyl chloride (PVC), polyvinylidene chloride, polyester, polyamide, polycarbonate, polyether, epoxy polymer, polyacetal, polyimide, polyesteramide, silicone etc.

[0060] Elastomers include natural rubbers (including latex, possibly vulcanized) or synthetic rubbers (linear or branched polymers transformed by vulcanization into a weakly crosslinked, infusible and insoluble three-dimensional network). Elastomers may be part of tire-type waste or any other household or industrial waste containing elastomers, natural and / or synthetic rubber, whether or not mixed with other components, such as plastics, plasticizers, fillers, vulcanizing agents, vulcanization accelerators, additives, etc.Examples of elastomeric polymers include ethylene-propylene copolymers, ethylene-propylene-diene terpolymer (EPDM), polyisoprene (natural or synthetic), polybutadiene, styrene-butadiene copolymers, isobutene-based polymers, isobutylene-isoprene copolymers, chlorinated or brominated, butadiene-acrylonitrile copolymers (NBR), and polychloroprenes (CR), polyurethanes, silicone elastomers, etc.

[0061] Thus, plastics include thermoplastic polymers, thermosetting polymers, elastomers, and waste containing one or more of these polymers, alone or in a mixture.

[0062] Generally speaking, any polymer or mixture of polymers capable of producing hydrocarbons by hydrothermal liquefaction can be used.

[0063] The different types of biomass and plastics previously described can be used alone or in a mixture in any proportion to form an organic material to be treated by the process according to the invention.

[0064] Step (a) of preparing a suspension

[0065] This step consists of preparing a suspension of the organic matter to be treated in an aqueous solution.

[0066] The implementation of this step depends in particular on the initial water content of the organic matter. Depending on its origin, the organic matter can be dry (e.g. plastics, forest residues, etc.), or moist (case of algal biomass, agricultural residues from livestock farming, etc.). Thus, depending on the water content of the organic matter used, it may be necessary to add a sufficient quantity of aqueous solution to the organic matter to obtain a suspension, and possibly to grind the organic matter before preparing the suspension.

[0067] The prepared suspension typically contains 5 to 50% by mass of solids. In particular, the aqueous solution content of the suspension is sufficient to allow pumping of the suspension and / or suspension of the organic matter particles it contains.

[0068] Optionally, water and / or organic components (such as alcohols, carbonyls, etc.) that are soluble in water may be added to the organic matter to prepare this suspension. For example, C1-C4 alcohols (methanol, ethanol, propanol, and butanol), acetone, hydroxyacetin, or acetaldehyde may be added.

[0069] In other words, the aqueous solution may be a water / organic solvent solution, the organic solvent being soluble in water. Preferably, the aqueous solution contains at most 10% by mass of organic solvent.

[0070] When part or all of the organic matter to be liquefied is solid, a preliminary grinding step may be provided to form particles whose size is less than 5 mm, preferably less than 1 mm, more preferably less than 500 μm, particularly advantageously less than 300 μm. This grinding step may be carried out by any grinding technique appropriate to the organic matter to be ground (grinding by crushing, by percussion, by shearing, etc.).

[0071] This suspension step may be carried out in a mixing chamber, or include a mixing chamber, in order to prepare a homogeneous suspension of the organic matter in the aqueous solution.

[0072] Optional preheating step (b)

[0073] In this step, the suspension prepared in step (a) is heated to a preheating temperature at a pressure of at least 220 barg.

[0074] Typically, the preheating temperature is 20°C, preferably 10°C below a decomposition temperature of the organic matter at the pressure considered.

[0075] The degradation temperature is defined as the temperature at which 10% by mass of the material has volatilized during a thermogravimetric analysis (TGA) under nitrogen. This TGA analysis includes the following steps: a drying step of the organic material: heating ramp of 20°C / min from room temperature to 120°C and holding for 60 min at 120°C (under nitrogen), followed by a volatiles measurement step: heating ramp 20°C / min from 120°C to 350°C (under nitrogen).

[0076] The degradation temperature corresponds to the temperature at which 10% by mass of the material has volatilized during the measurement step.

[0077] For example, a temperature of at most 220°C, preferably at most 180°C, more preferably at most 150°C, at the pressure in question may be chosen. Typically, this temperature is at least 50°C.

[0078] The chosen pressure typically corresponds to the implementation pressure of step (c). It is at least 220 barg, for example from 220 barg to 350 barg.

[0079] Preheating is typically implemented in a heat exchanger.

[0080] When a heat exchanger is used, the effluent produced in step (c), (d) or (e) can be used to preheat the suspension.

[0081] When a heat exchanger is used, high pressure steam, produced for example by cooling the effluent exiting step (c) or (d) as described with reference to step (d), may be used to preheat the slurry.

[0082] Advantageously, the preheating can be carried out by the exchanger supplied by the effluent produced during step (c), (d) or (e) or by the exchanger supplied by steam alone or in combination with several exchangers supplied by several heat sources.

[0083] Stage (c) of hydrothermal liquefaction

[0084] This step allows the organic matter contained in the suspension to be liquefied in order to produce a predominantly (more than 50% by mass) liquid effluent containing liquid hydrocarbon compounds forming a liquefaction oil.

[0085] For this purpose, the suspension, optionally preheated, leaving step (a) or (b) is introduced into a single tubular reactor at a pressure of at least 220 barg, heated by ohmic heating to a temperature of at least 350°C and at most 450°C, at a heating rate of at least 10°C per minute, and maintained at the temperature of at least 350°C and at most 450°C and at the pressure of at least 220 barg for at least one minute to produce a predominantly (more than 50% by mass) liquid effluent containing oil and an aqueous phase.

[0086] The operating conditions, and in particular the temperature, are chosen to maintain the water in the liquid (subcritical) or supercritical state. This step is thus carried out under conditions close to the critical point of water (374°C at 22 MPa), generally under subcritical conditions. Under conditions close to its critical point, water has a low viscosity and its dielectric constant is lower than under normal temperature and pressure conditions, which makes it less polar and increases the solubility of organic compounds. These conditions thus favor the reactions carried out.

[0087] Step (c) may be carried out in the presence of a homogeneous or heterogeneous catalyst. Examples of homogeneous catalysts include alkali metal salts (e.g. Na2CO3, KHCO3, K2CO3), acids (e.g. HCOOH, H2SO4) or strong bases (e.g. NaOH, KOH). Examples of heterogeneous catalysts include:

[0088] • acid catalysts, such as zeolites, aluminas, aluminosilicates, silicas and clays,

[0089] • basic catalysts, such as alkaline earth oxides, lanthanides or mixtures, hydrotalcites, or alkali or alkaline earth or rare earth oxides / hydroxides supported on carbons (activated carbon, graphite, petcoke or biochar), aluminas or silicas,

[0090] • metal catalysts, such as palladium, platinum, ruthenium, nickel, cobalt, molybdenum or mixtures, unsupported or supported on carbon, aluminas or silicas, aluminosilicates or zeolites or Raney nickel.

[0091] The suspension can advantageously be heated and maintained at a temperature of 350°C to 450°C, preferably 350°C to 420°C, in particular at the pressure used.

[0092] The temperature at which step (c) is implemented may vary depending on the organic material to be treated.

[0093] When the organic matter comprises, or consists of, mainly biomass (e.g. 50% by mass to 100% by mass of biomass), the suspension can advantageously be heated and maintained at a temperature of 350 to 380°C, in particular at the pressure used.

[0094] When the organic matter comprises, or is made up of, mainly plastics (e.g. 50% by mass to 100% by mass of biomass), the suspension can advantageously be heated and maintained at a temperature of 350 to 420°C, in particular at the pressure used.

[0095] The pressure used in step (c) may be from 220 barg to 350 barg, preferably from 225 to 300 barg. The heating rate will preferably be as high as possible, at least 10°C per minute, preferably at least 60°C per minute, more preferably at least 100°C, or even at least 150°C / minute.

[0096] The suspension may be maintained at a temperature of at least 350°C and at most 450°C, and at a pressure of at least 220 barg (or the other temperature and pressure ranges mentioned above) for 1 to 60 minutes, preferably for 5 to 60 minutes or for 10 to 40 minutes.

[0097] According to the invention, the suspension is heated and maintained at temperature by ohmic heating. Ohmic heating is based on the Joule effect: the circulation of an electric current through a solution produces heat by the Joule effect, the electrical resistance of the solution transforming the electrical energy into heat.

[0098] Advantageously, the suspension may have an electrical conductivity of at least 0.01 S / m, preferably at least 0.05 S / m, more preferably at least 0.1 S / m. Typically, the electrical conductivity is from 0.01 to 10 S / m or in any range defined by two of the aforementioned limits.

[0099] In order to increase the electrical conductivity of the suspension, provision may be made to add to the suspension at least one soluble electrically conductive species chosen from alkali or alkaline-earth metal halides, alkali or alkaline-earth metal oxyhalides, alkali or alkaline-earth metal bicarbonates, alkali or alkaline-earth metal carbonates, alkali or alkaline-earth metal hydroxides, alkali and alkaline-earth metal oxides, organic carboxylates (formic, acetic, propionic, lactic, etc.) of alkali or alkaline-earth metals, alkali or alkaline-earth metal sulfates, including monohydrogen sulfates, alkali or alkaline-earth metal phosphates, including monohydrogen and bihydrogen phosphates. This addition can be made during step (c) or before it, preferably in step (a).

[0100] The above species have the additional advantage of catalyzing the hydrothermal liquefaction reaction.

[0101] Advantageously, a recirculating tubular reactor makes it possible to recycle at least part of the soluble electrically conductive species among the species exhibiting catalytic activity.

[0102] Advantageously, at least a portion of the aqueous phase, containing conductive species, separated from the effluent from step (d), may be recycled to step (a) to suspend the organic matter and enrich it with conductive species. It may thus be possible to control the electrical conductivity of the suspension by means of an appropriate sensor in order to add to the solution a quantity of soluble species sufficient to achieve a target electrical conductivity.

[0103] Step (c) is carried out using a single tubular reactor into which the suspension is introduced and containing at least two electrodes immersed in the suspension. The electrodes are connected to a current generator for applying a voltage between the electrodes and generating an electric current within the suspension. An alternating electric current with a frequency of 50 to 10,000 Hz may be used.

[0104] A tubular reactor (or piston reactor) is typically equipped with a suspension injection system at the inlet and a withdrawal system to recover the hydrothermal treatment products at the outlet.

[0105] The tubular reactor used in the present invention may be with or without recirculation of at least one of the products of the hydrothermal treatment.

[0106] When it is recirculating, one or more of the products of the hydrothermal liquefaction are returned at least in part to the inlet of the tubular reactor. A loop reactor may then be used, equipped with a suspension recirculation system, a suspension injection system and a withdrawal system to recover the products of the hydrothermal treatment. At least one of the products of the hydrothermal treatment, in particular the mixture obtained at the end of the hydrothermal treatment, may be returned to the inlet of the reactor from 10 to 50% by mass.

[0107] The tubular reactor used in the present invention does not include an ohmic preheating device: the heating of the organic material to be treated to the reaction temperature is carried out only inside the single tubular reactor.

[0108] The single tubular reactor may also comprise at least two zones, each comprising at least two electrodes. Different voltages may then be applied to the electrodes of each zone in order to maintain the second zone at a different temperature from the temperature of the first zone. The temperatures of these two zones may, for example, differ by at least 20°C. The advantage of two zones, each with at least two electrodes, makes it possible to produce different thermal energy depending on the requirements of the reactions carried out.

[0109] Step (c) produces a predominantly liquid effluent (more than 50% by mass, typically more than 60% by mass) containing oil and an aqueous phase. Gas and solids (such as coal or coke) are also produced during this step, but in smaller quantities (less than 50% by mass, typically less than 40% by mass). The oil present in the effluent advantageously contains at least 65% by mass of carbon. It can be subjected to purification and subsequent treatment treatments to produce polymers or hydrocarbons, in particular fuels. It can thus be subjected to one or more of the following treatments: hydrotreatment, purification and fractionation into usable streams whose cut points are typically chosen according to the subsequent treatment.This fractionation can be carried out according to distillation temperature ranges, for example, to separate streams of the LPG, gasoline, diesel, heavy fuel oil, kerosene type, which can then be treated in a gasifier and / or a steam cracker and / or in a catalytic cracker and / or in a hydrocracker (then possibly in a steam cracker) and / or in a hydrotreatment reactor and / or used as such for the preparation of fuels, combustibles, lubricants or base oils. The person skilled in the art knows how to select the most suitable cuts for the subsequent treatment units depending on the desired objective.

[0110] The aqueous phase of the effluent may contain organic compounds, inorganic compounds and / or dissolved gases.

[0111] The gas produced during step (d) typically comprises one or more of the following gases: CO2, CO, C1-C4 hydrocarbons (notably CH4), H2, NH3, H2S.

[0112] The quantity of solids produced is low, advantageously less than 30% by mass, or even 20% by mass relative to the totality of the products of step (c).

[0113] Step (d) of recovery

[0114] At the end of step (c), a recovery step (d) makes it possible to recover the liquid phases of the effluent produced in step (c).

[0115] This recovery step is typically a separation step allowing the elimination of the gas phase, essentially C1-C4 hydrocarbons and the solid phase (typically char) to recover only the liquid effluent.

[0116] Advantageously, the recovery step (d) may comprise a step of cooling the effluent from step (c), for example by means of one or more heat exchangers, and optionally a step of separating the gases and / or a step of separating the solid particles.

[0117] This recovery step (d) typically consists of:

[0118] • Cool the effluent from step (c) from the temperature of step (c) to at least a temperature below 250°C, preferably below 180°C, while maintaining a pressure close to the pressure used in step (c). • Separate the gases present by flashing (gas blowing) at a pressure close to the pressure used in step (c).

[0119] • Recover the liquid phases, in particular the aqueous phase and the oily phase.

[0120] • Optionally, separation of solid particles in the effluent from step (d) from the liquid phases, by filtration, hydrocyclone, sedimentation, centrifugation or combinations.

[0121] Typically, cooling is carried out very rapidly, by quenching, with a cooling rate of 100°C / minute to 6000°C / minute.

[0122] Advantageously, the cooling of the effluent from step (c) can be carried out via a heat exchanger which is used to produce high pressure steam.

[0123] Advantageously, the cooling of the effluent from step (c) can be carried out via a heat exchanger which is used to preheat the suspension during step (b).

[0124] Advantageously, the liquid phases of step (d), after separation of the gases and solids, in particular the aqueous phase and the oily phase, can be cooled via a heat exchanger located downstream of the recovery step (d) which is used to produce high-pressure steam.

[0125] Advantageously, the liquid phases of step (d), after separation of the gases and solids, in particular the aqueous phase and the oily phase, can be cooled via a heat exchanger located downstream of the recovery step (d) which is used for preheating the suspension during step (b).

[0126] Optionally, the exchangers for cooling producing high pressure steam and the exchangers for preheating the suspension during step (b) can be used alone or in combination.

[0127] Optional step (e) of separation of the liquid phases recovered in step (d)

[0128] During this step, the aqueous phase present in the liquid phases recovered in step (d) is advantageously separated from the oil.

[0129] Advantageously, the aqueous phase of step (e) is cooled to produce high pressure steam via a heat exchanger located downstream of step (e).

[0130] Advantageously, the aqueous phase of step (e) is used to preheat the suspension during step (b) via a heat exchanger located downstream of step (e).

[0131] Advantageously, the oily phase of step (e) is cooled to produce high pressure steam via a heat exchanger located downstream of step (e). Advantageously, the oily phase of step (e) is used to preheat the suspension during step (b) via a heat exchanger located downstream of step (e).

[0132] Optionally, the exchangers for cooling producing high pressure steam and the exchangers for preheating the suspension during step (b) can be used alone or in combination.

[0133] The recovered oil can then undergo further processing to produce fuels, combustibles, lubricants or base oils.

[0134] The aqueous phase separated in step (e) can then be at least partly returned to step (a) of preparing the suspension.

[0135] The aqueous phase present in the effluent from step (c) and recovered in step (e) can in fact be enriched in soluble and conductive species, originating in particular from the organic matter and / or added to the suspension to adjust the conductivity of the latter, and can thus be advantageously used during step (a) to produce a suspension of organic matter having sufficient conductivity for the implementation of step (c).

[0136] This liquid / liquid separation step (e) can be carried out by (i) centrifugation, (ii) decantation, (iii) hydrocyclone or (iv) by the combination of two or three of these steps.

[0137] Description of figures

[0138] Figure 1 schematically represents a hydrothermal liquefaction unit according to one embodiment of the invention.

[0139] Figure 1 represents a hydrothermal liquefaction unit 1 comprising a section (A) for preparing a suspension, an optional preheating section (B), a hydrothermal liquefaction section (C) consisting of a tubular reactor 2 comprising at least two electrodes 21, 22; 21', 22', an optional section (E) for separating the liquid phases of an effluent produced by the hydrothermal liquefaction section, optionally an injection system (I) of at least one conductive species upstream of the section (C), in which the different sections are fluidically connected to implement the method according to the invention.

[0140] In the example shown, organic matter to be liquefied MHs which is made up of, or which comprises, solid matter (plastics, wood residues, etc.) is brought via a pipe 3 into an optional grinding section (01) which may comprise one or more grinding units, for example by crushing, by percussion, by shearing or any other technique suitable for reducing the size of the solid particles, as previously described with reference to the preliminary grinding step. The ground organic matter MHp which leaves this section (01) via the pipe 4 is then sent into the section (A) for preparing a suspension.

[0141] The organic matter can also be a wet organic matter MHIiq, containing suspended solid matter which can be sent directly to the section (A) for preparing a suspension via a pipe 5. This section (A) can thus receive the ground organic matter MHp and the wet organic matter MHIiq, or only one of the two types of organic matter.

[0142] In the preparation section (A), which may be a mixing chamber, a suspension containing the organic matter SMH is prepared. Depending on the solid content of the incoming organic matter (MHs and / or MHIiq), an aqueous solution may optionally be added via line 6 in order to prepare the suspension and obtain a solid content of 5 to 50% by mass.

[0143] Depending on the electrical conductivity of the suspension, provision may be made to add at least one conductive species via a line 7 of the injection system (I), as described with reference to the method. This injection system (I) may thus comprise a reservoir containing the conductive species(s) connected to the line 7, typically via a valve (not shown). The organic matter suspension SMH may then be transferred to the preheating section (B) via a line 8. In this preheating section, the SMH suspension is preheated to the preheating temperature previously described under a pressure of at least 220 barg. The pressurization of the suspension may for example be carried out by using a suitable pump (not shown). Section (B) may be a heat exchanger, as in the example shown. Alternatively, the SMH suspension could be sent directly to the hydrothermal liquefaction section (C).

[0144] The preheated SMHISO suspension is then brought via a pipe 9 into the hydrothermal liquefaction section (C) to be heated there by ohmic heating to a temperature of at least 350°C and at most 450°C at a heating rate of at least 10°C per minute, preferably at least 60°C per minute, and maintained at the temperature of at least 350°C and at most 450°C and at a pressure of at least 220 barg for at least 1 minute. At the outlet of the hydrothermal liquefaction section (C), an effluent EL is recovered via a pipe 10. The operational conditions used make it possible to recover a predominantly liquid effluent EL.

[0145] The hydrothermal liquefaction section (C) here comprises a single tubular reactor 2 comprising at least two electrodes, here 4 (21, 22; 21', 22'), immersed in the suspension of organic matter, and connected to an electric generator 11, typically an alternating current generator. In the example, the reactor comprises two zones 2A and 2B each comprising at least two electrodes (here two), each connected to the generator 11, the latter being able to apply different voltages to each group of electrodes: it is thus possible to control the temperature of the suspension differently in each zone. In particular, a temperature sensor of the reactor may be provided connected to a control system of the liquefaction unit configured to control the temperature of the section (C), optionally of each of the zones of the section (C). It is thus possible to control the temperature of the zone 2B so that it is higher than the temperature of the zone 2A.This temperature control can be achieved by controlling the voltage applied between the electrodes.

[0146] The invention is of course not limited by this embodiment, and the single reactor could comprise a single ohmic heating zone.

[0147] Reactor 2 is a tubular reactor or may be a tubular reactor with recirculation such as a loop reactor.

[0148] The electrodes can be arranged in different configurations described below. Different configurations may be provided inside the reactor, particularly when two different zones are planned.

[0149] For a reactor operating continuously, it will be possible to distribute the electrodes along the entire length of the reactor, possibly in one or two zones.

[0150] For example, the following electrode configurations can be used:

[0151] (i) parallel plate electrodes extending parallel to the fluid flow inside the reactor,

[0152] (ii) coaxial cylindrical electrodes whose axis is parallel to the flow of fluid inside the reactor,

[0153] (iii) rod-shaped electrodes parallel to each other and to the flow of fluid inside the reactor,

[0154] (iv) a cylindrical electrode and a rod-shaped electrode extending inside the cylindrical electrode, along its axis,

[0155] (v) electrodes positioned so that the fluid flow inside the reactor is parallel to the electric field. The electrodes may be positioned in the fluid flow or as collars around a pipe that forms a completely free flow channel,

[0156] (vi) rod-shaped electrodes arranged in a staggered pattern, with the rods perpendicular to the direction of fluid flow.

[0157] In configurations (i) and (ii), the electric field extends in a direction perpendicular to the fluid flow, which improves its homogeneity and enhances heating. Configurations (i) and (ii) are particularly suitable for fluids with low conductivity and are advantageous when large solid particles are present in the fluid because shear forces remain minimal due to the flow channel being left free. The uniformity of the electric field is also optimized in this geometry, which allows for uniform heating.

[0158] Configuration (iii) has the advantage of being inexpensive to construct but provides less uniform heating. This problem can be circumvented by mixing during and / or after heating to uniform the fluid temperature.

[0159] In configuration (iv), the fluid advantageously flows inside the cylindrical electrode.

[0160] Configuration (v) is particularly suitable for a fluid with high electrical conductivity. For most applications, this configuration requires a higher voltage than configurations (i) or (ii). However, the current distribution may be less regular and areas of high current density may be found at the leading edges of the electrodes.

[0161] Configuration (vi) can provide more uniform heating than configuration (iii) with parallel rods.

[0162] Regardless of the configuration, the electrodes should be made of a suitable material, for example, titanium, stainless steel, platinum-plated titanium, aluminum, and graphite. Carbon electrodes are often used for corrosive environments. In the case of stainless steel electrodes, the power supply frequency can be increased to prevent corrosion and apparent dissolution of the metal.

[0163] In the example shown, at the outlet of the hydrothermal liquefaction section (C), the predominantly liquid effluent EL enters a recovery section (D) via the pipe 10. This recovery section (D) makes it possible to recover the liquid phases PL contained in the effluent EL. Typically, this recovery section comprises one or more heat exchangers, optionally a flash evaporator to separate any gases G that may be present, optionally a separation unit (by filtration, by hydrocyclone, by sedimentation and / or by centrifugation), to separate any solids S that may be present.

[0164] The liquid phases PL recovered in section (D) are then brought to the separation section (E) via a pipe 12, in which they are separated into an oily phase H recovered by a pipe 13 and an aqueous phase Aq recovered by a pipe 14. This separation section (E) may comprise one or more centrifugation and / or decantation chambers, and / or one or more hydrocyclones. The aqueous phase Aq may then be returned at least in part to the preparation section (A) via the pipe 14. In the example shown, the pipe 14 passes through the heat exchanger of section (B) for preheating the suspension, which makes it possible to cool the aqueous phase before returning it to the preparation section (A).Alternatively, one of lines 10 or 12 could pass through the heat exchanger of section (B) for preheating the suspension, or one of the heat exchangers of section (D) could be used for preheating the suspension. Alternatively, preheating may be accomplished by heat exchangers supplied with high-pressure steam generated by heat exchangers of section (D) and / or located on lines 10, 12, or 14.

Claims

AMENDED CLAIMS received by the International Bureau on May 15, 2024 (15.05.2024) 1. Process for the hydrothermal liquefaction of an organic material, in particular continuously, comprising: (a) a step of preparing a suspension of the organic matter in an aqueous solution, the organic matter being chosen from biomass and plastics, alone or as a mixture, (c) a hydrothermal liquefaction step in which the suspension leaving step (a) is introduced into a single tubular reactor at a pressure of at least 220 barg, heated by ohmic heating to a temperature of at least 350°C and at most 450°C at a heating rate of at least 10°C per minute, and maintained at the temperature of at least 350°C and at most 450°C and at the pressure of at least 220 barg for at least one minute to produce a predominantly liquid effluent containing oil and an aqueous phase, (d) a step of recovering the liquid phases of the effluent produced by step (c), and optionally, the conductivity of the suspension is adjusted before implementing step (c) of hydrothermal liquefaction.

2. Method according to claim 1, in which step (c) is carried out with recirculation of at least one of the products formed at the end of the hydrothermal liquefaction step at the inlet of the single tubular reactor.

3. The method of claim 1 or 2, wherein step (a) comprises at least one of the following features: - the suspension contains from 5 to 50% by mass of solid in the aqueous solution, - at least part of the organic matter is in solid form and is previously ground to form particles whose size is less than 5mm, optionally less than 500pm.

4. Method according to any one of claims 1 to 3, further comprising, between step (a) and (c), a step (b) of preheating the suspension prepared in step (a) at a pressure of at least 220 barg and at a preheating temperature at least 10°C lower than a decomposition temperature of the organic matter at the pressure in question.

5. The method of claim 4, wherein step (b) comprises at least one of the following features: - the pressure is 220 barg to 350 barg, - preheating temperature of no more than 220°C, - preheating is implemented in a heat exchanger.

6. Method according to any one of claims 1 to 5, in which step (c) comprises at least one of the following characteristics: 5 - the pressure is 220 barg to 350 barg, - the suspension is heated and maintained at a temperature of 350°C to 420°C, - the heating rate is at least 60°C per minute, - the suspension is maintained at a temperature of at least 350°C and at most 450°C, preferably from 350°C to 420°C, and at a pressure of at least 220 barg for 1 to 60 10 minutes, preferably for 5 to 60 minutes or for 10 to 40 minutes, - the suspension has a conductivity of at least 0.01 S / m.

7. Method according to any one of claims 1 to 6, in which step (c) comprises at least one of the following characteristics: - organic matter comprises, or is made up of, mainly biomass, and the 15 suspension is heated and maintained at a temperature of 350 to 380°C, in particular at the pressure used, - the organic matter comprises, or is made up of, mainly plastics, and the suspension is heated and maintained at a temperature of 350 to 420°C, in particular at the pressure used. 20 8. Method according to any one of claims 1 to 7, in which at least one soluble electrically conductive species chosen from alkali or alkaline-earth metal halides, alkali or alkaline-earth metal oxyhalides, alkali or alkaline-earth metal bicarbonates, alkali metal hydroxides is added to the suspension during step (c) or upstream of step (c). 25 or alkaline earth metals, alkali and alkaline earth metal oxides, alkali or alkaline earth metal carbonates, organic alkali or alkaline earth metal carboxylates, alkali or alkaline earth metal sulfates, including monohydrogen sulfates, alkali or alkaline earth metal phosphates, including monohydrogen and dihydrogen phosphates. 30 9. Method according to any one of claims 1 to 8, characterized in that step (d) comprises a step of cooling the effluent leaving step (c).

10. A method according to any one of claims 1 to 9, further comprising: (e) a step of separating the liquid phases recovered in step (d) into an oily phase and an aqueous phase.

11. The method of claim 10, further comprising: - the aqueous phase separated in step (e) is at least partly returned to step (a) of preparation of the suspension.

12. Method according to any one of claims 1 to 11, comprising at least one of the following characteristics: - the biomass is chosen from (i) biomass produced from surplus agricultural land, (ii) biomass produced from deforestation or clearing of agricultural land, (iii) agricultural residues from crops, (iv) forest residues from forestry and wood processing; (v) agricultural residues from livestock farming, (vi) organic household waste; (vii) industrial organic waste; (viii) algal biomass, alone or in a mixture, - plastics include thermoplastic polymers, thermosetting polymers, elastomers, and waste containing these polymers, alone or in mixtures.

13. Hydrothermal liquefaction unit comprising a section (A) for preparing a suspension, an optional preheating section (B), a hydrothermal liquefaction section (C) consisting of a single tubular reactor comprising at least two electrodes, a recovery section (D), an optional section (E) for separating the liquid phases of an effluent produced by the hydrothermal liquefaction section, optionally an injection system (I) of at least one conductive species upstream of the section (C), in which the different sections are fluidically connected to implement the method according to any one of the preceding claims.

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