WO2021258166A1 - Procédé de conversion de déchets organiques et installation associée - Google Patents

Procédé de conversion de déchets organiques et installation associée Download PDF

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Publication number
WO2021258166A1
WO2021258166A1 PCT/BG2020/050003 BG2020050003W WO2021258166A1 WO 2021258166 A1 WO2021258166 A1 WO 2021258166A1 BG 2020050003 W BG2020050003 W BG 2020050003W WO 2021258166 A1 WO2021258166 A1 WO 2021258166A1
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Prior art keywords
unit
alkaline
catalyst
decarboxylation
hydrothermal liquefaction
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PCT/BG2020/050003
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English (en)
Inventor
Riccardo RAINONE
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Rba Ood
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Priority to PCT/BG2020/050003 priority Critical patent/WO2021258166A1/fr
Publication of WO2021258166A1 publication Critical patent/WO2021258166A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G3/00—Production of liquid hydrocarbon mixtures from oxygen-containing organic materials, e.g. fatty oils, fatty acids
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
    • C10L2290/02—Combustion or pyrolysis
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
    • C10L2290/14—Injection, e.g. in a reactor or a fuel stream during fuel production
    • C10L2290/141—Injection, e.g. in a reactor or a fuel stream during fuel production of additive or catalyst
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
    • C10L2290/14—Injection, e.g. in a reactor or a fuel stream during fuel production
    • C10L2290/146—Injection, e.g. in a reactor or a fuel stream during fuel production of water
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E50/00—Technologies for the production of fuel of non-fossil origin
    • Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P30/00—Technologies relating to oil refining and petrochemical industry
    • Y02P30/20—Technologies relating to oil refining and petrochemical industry using bio-feedstock

Definitions

  • the present invention concerns a process for the conversion of organic wastes and biomass into fuel.
  • the invention concerns a process to convert organic wastes and biomass into valuable high-energy gaseous fuel, through solvothermal liquefaction followed by an alkaline decarboxylation of the remaining solid fraction.
  • the proposed methodology is outlined in the context of organic waste and biomass valorization, precisely in regards to the conversion of these latter into higher-value fuels, other sources of energy and valuable chemical compounds.
  • the process described hereinafter interfaces with the organic waste recovery chain, providing a broad spectrum of exploitable wastes including municipal solid wastes (MSW), agricultural wastes such as animal manure and vegetable biomass, exhausted digestate fraction derived from end-stage biomethanation processes.
  • MSW municipal solid wastes
  • agricultural wastes such as animal manure and vegetable biomass
  • exhausted digestate fraction derived from end-stage biomethanation processes exhausted digestate fraction derived from end-stage biomethanation processes.
  • Organic matrixes can be renewed into highly valuable fuels and/or general chemicals mainly by means of three known conversion methodologies: i) thermal conversion, ii) chemical conversion and iii) biochemical conversion.
  • electrochemical conversion is also applied by means of direct carbon fuel cell technology.
  • the optimal renovation pathway is highly dependent on the feedstock availability and composition, as well as the associated warehousing and general disposal costs.
  • Thermal conversion processes are based on heat as the main agent for the degradation and transformation of the original molecules into more practical fuels.
  • the most known technologies belonging to this category are torrefaction, pyrolysis, and gasification.
  • Torrefaction is a thermochemical treatment performed at temperature ranging from 200 to 320 °C, which requires absence of oxygen to avoid undesired partial oxidation of the valuable components.
  • the water contained in the biomass and a large fraction of volatile compounds are released, with subsequent controlled degradation of biopolymers (cellulose, hemicellulose and lignin) to obtain a char like final product in the form of a blackened mass that is often referred to as bio coal.
  • Pyrolysis relies on heating the organic substrate above its decomposition temperature with consequent disruption of the original molecular structure. Oxygen, water and other substances may be present during the process to promote occurrence of side reactions such as combustion, hydrolysis and different thermochemical transformations; on the other hand, harsh dehydration is needed to exclusively carry out the pyrolytic process. Most of the common organic molecules breakdown between 100 °C and 500 °C, with the decomposition output being defined as a mixture of water, carbon monoxide and carbon dioxide, and a plethora of different volatiles. The remaining solid mass is composed of non-volatile residues that, at the end of the process, are greatly enriched in carbon (carbonized matter).
  • gasification is a process that transforms organic materials into a mixture of carbon monoxide, hydrogen and carbon dioxide (namely syngas). This is usually achieved by reacting the material at high temperatures (>700 °C) within a controlled environment with specific amount of oxygen and/or steam. Syngas is readily burned in gas engines, used to produce methanol and hydrogen, or converted via the Fischer-Tropsch process into synthetic fuel.
  • Chemical conversion processes are represented by a range of chemical transformations for the conversion of biomasses into renewable fuels and chemical precursors, including technologies with high similarity with coal-based processes, such as the Fischer-Tropsch synthesis and the Sabatier reaction, and/or any other process that envisions the biomass feedstock conversion into multiple commodity chemicals through the action of specific reagents (e.g. hydrogenation).
  • specific reagents e.g. hydrogenation
  • Biochemical conversion is referred to as the breakdown of biomass and other organic matrixes through the action of microbial activity, usually to convert them into ethanol and other alcohols (fermentation) or into biogas fuel (anaerobic digestion).
  • Glycoside hydrolases are the enzymes involved in the degradation of the most abundant biomass fraction, such as polysaccharides and lignocellulose.
  • a problem of the known thermal processes is that they output products with limited calorific value.
  • torrefaction and pyrolysis are associated with the production of bio coal or general char-like materials with a calorific value of 15 to 35 MJ.kg 1 , which is lower with respect to that of other known fuel, such as for example methane or LPG-like gaseous mixtures (48 to 55 MJ.kg 1 ).
  • biomass conversion following pyrolysis and gasification processes occurs at very high temperature (> 500 °C) reducing the overall cost efficiency of the process itself.
  • Chemical conversion of biomass into valuable organic compounds is applied through a broad spectrum of catalyzed reactions depending on the biomass feedstock composition and availability.
  • chemical conversion processes are referred to as technologies with high similarity with coal-based processes, such as the Fischer-Tropsch synthesis and the Sabatier reaction, and/or any other process that envisions the biomass feedstock conversion into multiple commodity chemicals through the action of specific reagents in presence of selected catalysts (e.g. hydrogenation).
  • biochemical processes can be summarized into two major categories, namely anaerobic digestion (production of biogas with high content of methane) and fermentation (production of alcohols and other chemicals).
  • the known plants are subject to pollution directly related to sludge leaking from the anaerobic digestion and fermentation basins or tanks which leads to as well as improper handling of effluent sludge (mainly the exhaust digestate fraction) or dumping procedure that envisages the offload of the given effluent streams into rivers, lakes and plots of land.
  • effluent sludge mainly the exhaust digestate fraction
  • Another disadvantage of the known biochemical process is the process time, which extends from few days to months in the case of biological biomass degradation, depending on the microorganisms concentration and typology, as well as the composition and degradability of the active organic substrate.
  • a scope of the invention is that of providing a process for converting organic wastes and biomass which chemicals of high value and/or biofuel with higher calorific power with respect to the original biomass.
  • Another scope of the present invention is that of providing a process with higher yields with respect to the known processes.
  • a further scope of the present invention is that of providing a process that is simpler and faster with respect to the known processes.
  • Another scope of the present invention is that of providing a plant wherein the process can be carried out efficiently.
  • the Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.
  • the present invention concerns a process for the conversion of organic wastes or biomass.
  • the present invention relies on a process carried out in presence of water (either derived from the humidity of the biomass or retrieved from external sources). In particular, it provides a two-step conversion of the biomass into chemicals with high calorific power or with high value as precursors for synthesis of more complex substances, or as end-user products.
  • the process takes benefit of the synergic action of both thermal and chemical biomass degradation routes.
  • the process comprises a first step of hydrothermal liquefaction of the organic wastes, or biomass, in presence of sub-critical water in a gas-tight vessel at a first temperature equal to or above 100°C.
  • the sub-critical water plays the role of a strong oxidizing agent within the reaction environment.
  • the hydrothermal liquefaction reaction fosters the degradative oxidation of the organic macromolecules composing the biomass (e.g. cellulose, hemicellulose, lignin, proteins and peptides) transforming them into a range of chemicals with lower molecular weight, with the major product fraction being populated by short chain organic acids such as formic acid, acetic acid, lactic acid and propionic acid. These latter are readily reacted with the sodium hydroxide forming the derivative alkaline sodium salts.
  • the biomass e.g. cellulose, hemicellulose, lignin, proteins and peptides
  • the product of this primary stage is a crude bio-oil containing the respective alkaline salts, any other organic molecule that has been partially degraded via oxidative reactions and/or any inorganic component, which being present in the original organic matrix, has not undergone any significant degradation process and is found in the crude bio-oil in its pristine or semi-pristine form.
  • the yield of organic compounds (reported as the weight percentage of the compounds generated from the oxidative degradation of the biomass macromolecules in respect to the dry biomass weight), is comprised between 10% and 90%.
  • the first temperature, at which the hydrothermal liquefaction is carried out ranges between 100°C and 500°C, more preferably between 100°C and 400°C, even more preferably between 100°C and 374°C.
  • the quantity of water present during the first step, in the gas- tight vessel ranges between 2% and 90% by volume with respect to the total volume of the vessel. More advantageously such quantity of water is present at any time during the hydrothermal liquefaction step.
  • the water may be readily available as derived from the natural humidity of the biomass, or can be supplied from any suitable external source.
  • the pressure generated by the water vapor is comprised between 0.1 to 40 MPa.
  • the treatment time varies from 1 minute to 24 hours once the set point temperature is reached.
  • the reaction is carried out in presence of one or more specific reagents, and optionally one or more catalysts, at pH equal to or higher than 7 (alkaline environment).
  • the reagent is a strong oxidizing agent chosen in the group consisting in sodium oxide, ammonia, organic compounds containing nitrogen, hydroxides of alkaline metals and alkaline earth metals and their respective salts, peroxide compounds and metal oxides.
  • the at least one reagent is at a first concentration
  • the at least one catalyst is at a second concentration.
  • concentrations independently from each other, are comprised between 0.001% and 100% by weight with respect to the weight of the dry organic wastes.
  • the reagent is sodium hydroxide NaOH. It is possible to provide the presence of a catalyst that is calcium oxide CaO.
  • the process also comprises a second step of alkaline decarboxylation of the bio- oil obtained from the hydrothermal liquefaction step, in order to produce methane and carbon dioxide.
  • Such species are mainly derived from selective decarboxylation of sodium acetate as the most abundant specie dissolved into the bio-oil mixture
  • the alkaline decarboxylation step is carried out in presence of a stoichiometric excess of a basic reagent.
  • a basic reagent is sodium hydroxide or potassium hydroxide. This leads to release of carbon dioxide immediately followed by the sequestration of this latter as it reacts with the alkaline hydroxide. Following these reactions, sodium carbonate (NaiCO ) is formed as the main by-product of the process.
  • the alkaline decarboxylation step is carried out at a temperature equal to or above 100°C, more preferably comprised between 100°C and 600°C, even more preferably comprised between 100°C and 450°C.
  • the alkaline decarboxylation step is carried out at atmospheric pressure or at a pressure comprised between 0.1 and 10 MPa.
  • the reaction time may vary from 1 minute to 24 hours depending on the composition, concentration and product distribution of the crude bio-oil as well as its humidity, pH and electrical conductivity, the catalysts and the reagents in use, the heating rate and the reaction temperature.
  • a step of separation of the product of the reaction i.e. the bio-oil, from the solvent, i.e. water.
  • Such separation is preferably made via evaporation of water at a second temperature equal to or above 100°C.
  • the second temperature is equal to or lower than the first temperature.
  • the released water steam is then condensed into liquid through direct cooling of the stream and collected elsewhere. Some volatile compounds are present in this liquid fraction (albeit in minimal concentration) and could be retrieved for different purposes depending on their nature.
  • the collected liquid portion is recirculated within the system should that be needed to ensure the presence of a sufficient amount of water to perform the first stage of the process.
  • a plant which comprises a first reservoir wherein organic wastes are stored.
  • the plant comprises a hydrothermal unit for the conversion of said organic wastes, said hydrothermal liquefaction unit comprising a sealable gas-tight vessel suitable to withstand temperatures above 100°C for periods of time ranging from 1 minute to 24 hours and at a pressure comprised between 0.1 and 40 MPa.
  • the hydrothermal liquefaction unit is connected to the first reservoir so as to receive the organic wastes therefrom.
  • the plant also comprises a decarboxylation unit connected to the exit of the hydrothermal liquefaction unit and comprising a container suitable to withstand temperatures above 100°C for periods of time ranging from 1 minute to 24 hours.
  • the plant also comprises a homogenization unit connected to the first reservoir so as to receive therefrom the organic wastes, and suitable to perform a homogenization step of the organic wastes before feeding these latter to the hydrothermal liquefaction unit.
  • the plant comprises a catalyst reservoir suitable to contain at least one catalyst, and connected to the hydrothermal liquefaction unit or to the homogenization unit so that the catalyst can be fed into the hydrothermal liquefaction unit or into the homogenization unit (30).
  • the plant advantageously comprises a catalyst recovery unit connected to the decarboxylation unit and to the catalyst reservoir, and suitable to recover the catalyst from the reaction product exiting from the decarboxylation unit, and to feed the recovered catalyst into the catalyst reservoir.
  • the decarboxylation unit is connected to the first reservoir and/or to the homogenization unit) so that a liquefied fraction of water resulting from the decarboxylation reaction carried out in the decarboxylation unit is recirculated towards the first reservoir and/or the homogenization unit.
  • Fig. 1 is a schematic representation of a plant suitable for carrying out the process.
  • the same reference numbers have been used, where possible, to identify identical common elements in the figures. It is understood that elements and characteristics of one embodiment can conveniently be incorporated into other embodiments without further clarifications.
  • the plant 10 comprises a first reservoir 20 to contain the biomass feedstock.
  • This latter may comprise any form of organic waste such as municipal solid wastes (MSW), paper and cardboard and/or any cellulose-based material, lignin and lignocellulose, animal manure of any source, agricultural and food industry by- products and wastes, exhaust digestate fraction from biomethanation processes, sewage effluents and city mowing.
  • the exit of the reservoir 20 is connected directly to a homogenization unit 30, configured to homogenize the biomass, which will be the substrate of the subsequent steps of the process.
  • the homogenization unit 30 can comprise a mixer suitable to mix and/or grind the substrate.
  • the homogenization unit 30 is also suitable to perform a pre-heating of the substrate prior to the previous steps of the process.
  • the homogenization unit 30 is optional in the plant 10.
  • a catalyst reservoir 40 Connected to the homogenization unit 30 is a catalyst reservoir 40, intended as any container/reservoir where the catalyst is loaded (either in its solid form or as a solution in water with specific concentration) and dosed into the homogenization unit 30.
  • the catalysts species provided for in the process are chosen in the group consisting in any metal oxide and/or transition metal oxide, strong oxidizing agents, such as peroxide components (e.g. hydrogen peroxides), and any alkaline metal and alkaline earth metal oxide.
  • the catalyst is calcium oxide CaO.
  • the plant 10 also comprises a hydrothermal liquefaction unit 50, connected to the exit of the homogenization unit 30 or, if this latter is not present, of the first reservoir 20.
  • the hydrothermal liquefaction unit 50 comprises a gas-tight vessel of any type, provided it can withstand a temperature equal to or above 100°C, autogenous pressure between 0.1 to 40 MPa, and is chemically resistant to any of the reagents, catalysts and reaction products involved in the present invention within a pH range between 0.1 to 20.
  • the hydrothermal liquefaction reaction is preferably carried out in presence of at least one reagent chosen in the group consisting in sodium oxide, ammonia, organic compounds containing nitrogen, hydroxides of alkaline metals and alkaline earth metals and their respective salts, peroxide compounds and metal oxides. More preferably the reagent is sodium hydroxide NaOH.
  • the substrate treated in the hydrothermal liquefaction unit 50 is transformed into a digestible crude bio-oil. It is noted that, alternatively to what indicated above, the catalyst reservoir 40 can be connected directly to the hydrothermal liquefaction unit 50, should the homogenization step be conducted in the absence of the catalyst itself or be skipped as a whole.
  • the plant 10 At the exit of the hydrothermal liquefaction unit 50, the plant 10 provides a decarboxylation unit 60, wherein the bio-oil exiting from the hydrothermal liquefaction unit 50 is to be transferred so as to undergo an alkaline decarboxylation step.
  • the decarboxylation unit 60 comprises preferably a container wherein such reaction can be carried out.
  • the container can withstand temperatures above 100°C for a reaction time varying from 1 minute to 24 hours, depending on the composition, concentration and product distribution of the bio-oil as well as its humidity, pH and electrical conductivity, the catalysts and reagents in use, the heating rate and the reaction temperature.
  • the alkaline decarboxylation is preferably carried out after removal of the liquid portion of the crude bio-oil, i.e. on a remaining solid mixture of alkaline salts formed upon reaction with the reagent, i.e. sodium hydroxide NaOH, forming mainly sodium formiate, sodium acetate, sodium lactate and sodium propionate.
  • the reagent i.e. sodium hydroxide NaOH, forming mainly sodium formiate, sodium acetate, sodium lactate and sodium propionate.
  • Such separation step is preferably carried out in the decarboxylation unit 60, more preferably through evaporation of the liquid fraction.
  • the liquid fraction mainly comprises water
  • the evaporation step is conducted at a temperature equal to or above 100°C.
  • Such alkaline decarboxylation step implies the decarboxylation of specific alkaline organic salts, formed by the reaction of NaOH (or any other alkaline compound that could be used instead, according to the aforementioned array of catalysts/reagents) with the low-weight organic acids produced through the degradation of the biomass the sub-critical water liquefaction and extraction step. It yields a gaseous biofuel 61 mainly comprising volatile hydrocarbons.
  • the respective volatile hydrocarbons (comprising between 60 and 90% of methane) are released in stoichiometric concentration, together with carbon dioxide molecules that are sequestrated by the unreacted reagent (sodium hydroxide or any other alkaline compounds that could be used instead), leading to formation of sodium carbonate NaiCCb as the main by-product, or any other carbonate salt depending on the reactant that has been selected for the process.
  • the unreacted reagent sodium hydroxide or any other alkaline compounds that could be used instead
  • the liquid fraction 62 of the bio-oil which has been separated from the solid fraction which has been decarboxylated.
  • the liquid fraction mainly comprises the solvent used in the hydrothermal liquefaction step, i.e. water.
  • the released water steam is then condensed into liquid 62 through direct cooling of the steam.
  • the collected liquid portion 62 is recirculated within the system should that be needed to ensure the presence of a sufficient amount of water to perform the first stage of the process.
  • the decarboxylation unit 60 is advantageously connected to the first reservoir 20 and, if present, to the homogenization unit 30, so that the water steam 62 can be recirculated thereto.
  • the plant 10 also comprises a catalyst recovery unit 70 wherein the catalyst, if used, is extracted from the solid salts mixture and re-used in the hydrothermal liquefactions unit 50 to perform another cycle of reactions.
  • the extracted catalyst is then recovered as will be explained in the following, and fed towards the catalyst reservoir 40, to which the catalyst recovery unit 70 is connected.
  • the plant 10 advantageously comprises heating means configured to heat at least the hydrothermal liquefaction unit 50, the decarboxylation unit 60 and, if present, the homogenization unit 30.
  • the conversion process of the invention carried out in a plant as described above and illustrate in fig. 1, is performed on an organic substrate or organic precursor, as mentioned above.
  • Such organic substrate is transferred from the first reservoir 20 to the homogenization unit 30, if provided, wherein it undergoes a homogenization step.
  • the homogenization step can comprise, for example, mixing and/or grinding, as well as a pre-heating.
  • the homogenization step can be avoided. In such case, the substrate is directly sent to the hydrothermal liquefaction unit 50.
  • the homogenization step it is preferably provided to add the catalyst to the substrate, at the homogenization unit 30.
  • the catalyst e.g. acetic acid
  • the hydrothermal liquefaction step such species exert catalytic function increasing the overall yield of organic acids (e.g. acetic acid) within the resulting crude bio-oil.
  • the catalyst is chosen between the metal oxides and/or transition metal oxides that can be used in combination with the aforementioned reagents and are not necessarily associated to alkaline behavior (e.g. titanium(II) oxide, Zinc(II) oxide...); the strong oxidizing agents, such as peroxide components (e.g. hydrogen peroxides), that are associated to release of elemental oxygen and/or oxygen radical species upon contact with water and other chemicals within the crude bio-oil or upon heating; and any alkaline metal and alkaline earth metal oxide with particular mention to calcium oxide (CaO).
  • peroxide components e.g. hydrogen peroxides
  • the catalyst can be added to the organic substrate directly into the hydrothermal liquefaction unit 50.
  • hydrothermal liquefaction step which can be described as a combination of sub-critical water extraction and selective hydrothermal liquefaction of the organic substrate, is carried out.
  • the original biomass is converted in a mixture of water and organic compounds, referred to a black crude bio-oil, which will be further processed in the secondary degradation stage.
  • the organic substrate is heated at temperature equal or higher than the water boiling point (100 °C, up to 374 °C) while kept enclosed within a confined environment (in the gas-tight vessel) in presence of water in any of its forms.
  • This latter is either derived from the natural humidity of the original organic matter, or can be added to the reaction ambient being supplied via any suitable external sources.
  • organic wastes and biomass have intrinsic humidity ranging between 20% - 90% depending on their nature, origin and storage condition.
  • the generated pressure can range between 0.1 - 40 MPa.
  • the autogenous pressure is directly related to the temperature of the reaction environment and the degree of filling of the pressure vessel. It is possible to provide that an external pressure is applied to increase overall reaction pressure in the vessel. External pressure is applied to the system by feeding compressed air before the heating process. Compressed air preferably accounts for up to 10 MPa of the total system pressure (at cold temperature).
  • water must not be lower than 1% of the total gas-tight vessel volume.
  • the maximal water volume that is allowed is equal to 100% of the total pressure vessel volume.
  • Heating intended as raise of the temperature until the set point temperature for the reaction, is performed with the substrate inside the vessel, together with the reagent and the catalyst, if provided, at a predetermined heating rate.
  • the resulting output is manipulated in regards to the bio-oil composition and products distribution, as well as the phase distribution that is defined as the variation in the ratio of solid, liquid and gaseous products generated upon degradation of the original organic matter.
  • Phase streams are strongly related to heating rate rather than temperature itself, due to the prevalence of secondary reactions at non-optimum heating rates and the likelihood of formation of char-like products, especially in conjunction with milder alkalinity or even neutral/acidic pH ranges.
  • the process is designed with an optimal heating rate no lower than 0.5 °C/min and neither higher than 20°C/min, more preferably not higher than 10 °C/min, which is observed to be related to high yields of highly carbon- and hydrogen- enriched compounds in the liquid phase and minimal formation of char-like by products, as well as very low release of gaseous species (which accounts for less than 1% of the total pressure vessel volume).
  • the residence time varies from 1 minute to 24 hours once the set point temperature is achieved. Short residence time (usually equal or lower than 1 hour) increases yields of liquid components in the form of low-weight organic acids, which are formed as a direct consequence of the strong oxidizing action of subcritical water and airborne oxygen onto biochemical polymers components such as cellulose, hemicellulose and lignocellulose composing the major fraction of the biomass.
  • the original molecules are broken down through a series of low- temperature thermochemical oxidation processes in presence of both airborne oxygen gas and sub-critical water, which in this case exerts the function of main oxidizing agent.
  • the dissociation constant Kw increases from 10 14 to 10 11 within a temperature range between 100°C and 350°C, which favors basic and acid catalysis mechanisms of hydrolysis due to the greater amount of free ions (H 3 0 + , OH ) derived from water dissociation.
  • the dielectric constant (e) of water, as well as other parameters such as viscosity and surface tension decrease with increasing temperature. Therefore, the solubility of organic compounds with more hydrophobic behavior increases in subcritical water compared to standard conditions, with significant variation at temperature higher than 200 °C.
  • NaOH plays the role of coadjuvant oxidizing agent, leading to a much higher degree of oxidation that would not be achievable with subcritical water alone.
  • a preferred embodiment of the process envisages the use of sodium hydroxide, other reagents can be applied as well to perform such reaction.
  • Such reagents are chosen in the group consisting in any other alkaline metals hydroxides, such as KOH, in any available form; any alkaline earth hydroxides, such as calcium hydroxide, in any available form; any alkaline salts derived from the salification of hydroxide molecules with organic acids (or other weak acids), such as acetate and carbonate salts of sodium, potassium and any given alkaline metal or alkaline earth metal, in any available form; ammonia and organic compounds containing nitrogen and having alkaline behavior, such as amines and amides, in any available form; in general, any compounds that, when solubilized in water, can increase the pH value thus providing alkaline environment.
  • any other alkaline metals hydroxides such as KOH, in any available form
  • any alkaline earth hydroxides such as calcium hydroxide, in any available form
  • one or more catalysts as mentioned above can be added.
  • Presence of oxidizing agents and occurrence of the reaction at alkaline pH promotes the multi-step oxidation of partially degraded molecules and formation of low molecular weight compounds such as short organic acids (e.g. formic acid, lactic acid, acetic acid) and their relative structural isomers.
  • Other components that are found in the resulting bio-oil are ketones, aldehydes, aromatics, alcohols, partially degraded fatty acids and compounds derived from protein degradation, such as amino-acids and by-products of their oxidation and/or condensation.
  • Hydrolytic depolymerization of macromolecules such as peptides, proteins, polysaccharides and others may lead to occurrence of medium- to low- molecular- weight fragments in the bio-oil mixture.
  • Transition metals and other oligo-elements that were originally present within the biomass are not oxidized due to the low temperature at which the treatment is carried out. As such, those components are found in the bio-oil and consequently in the solid residue that is remaining at the end of the overall process in conjunction with sodium carbonate and possibly traces of char-like materials.
  • the catalysts that remain unreacted in the final solid fraction upon degradation of the alkaline organic salts into methane and other hydrocarbons can be recovered in the catalyst recovery unit 70. Catalysts recirculation can be carried out, as the recovered NaOH is eligible for its use as primary catalysts/reagent in the hydrothermal liquefaction process.
  • reaction product biological-oil
  • decarboxylation unit 60 the reaction product (bio-oil) is transferred to the decarboxylation unit 60 to undergo the alkaline decarboxylation step.
  • Such step is performed on the solid residue of the crude bio-oil upon removal of the liquid fraction via evaporation or any other suitable mean.
  • Such solid residue is composed of alkaline salts, resulting from the reaction of short chain organic acids (derived from biomass degradation and oxidation) and sodium hydroxide. This leads to the formation of sodium formiate, sodium lactate, sodium acetate, sodium propionate and sodium butanoate with sodium acetate being the most abundant species (70 - 95%).
  • the decarboxylation process permits the cleavage of the organic moiety of the salts, releasing carbon dioxide and the resulting volatile hydrocarbon, defined as methane from sodium acetate, ethane from sodium propionate and propane from sodium butanoate.
  • the selective alkaline decarboxylation of sodium formiate and sodium lactate respectively leads to release of hydrogen gas and ethanol.
  • the main gaseous output of the process is methane.
  • this process stage provides the in-situ capture of this component via its reaction with free sodium hydroxide resulting in the formation of sodium carbonate (NaiCO ) as the main by-product, independently on the identity and concentration of the produced hydrocarbons (or any other chemicals that is produced via this process).
  • the crude bio-oil is firstly dehydrated through any suitable methodology (e.g. evaporation, filtration, freeze-drying) and the remaining solid fraction is then heated up at a temperature preferably comprised between 250°C and 450°C at a pressure ranging preferably between atmospheric pressure and 5 MPa.
  • the time of reaction is varied leading to much faster formation of volatile hydrocarbons at higher temperature and heating rate.
  • the product distribution (in terms of the overall gas concentration) is only dependent on the original distribution of the different alkaline salts and, therefore, on the parameters used to perform the hydrothermal liquefaction process.
  • This step is performed with an optimal heating rate ranging from 0.5 °C/min to 20 °C/min.
  • the content of sodium hydroxide is advantageously comprised between 5% - 100% in weight with respect to the original wet waste weight.
  • this decarboxylation step may lead to formation of char-like materials either remaining as by-products of the preceding hydrothermal liquefaction step or being formed through collateral carbonization processes occurring during the selective alkaline decarboxylation step.
  • the char-like materials fraction would better not be higher than 10% of the total mass of the solid residue left from the bio-oil dehydration.
  • Higher reaction temperature above 350°C is associated with combustion of char-like materials that may have been formed during the preceding thermochemical process, and depending on the concentration of these latter can lead to release of combustion products such as carbon dioxide, carbon monoxide and smoke.
  • the fraction of reagent (NaOH) that remains unreacted in the final solid fraction upon degradation of the alkaline organic salts into methane and other hydrocarbons can be recovered in the catalyst recovery unit 70.
  • Catalysts recirculation is carried out, as the recovered reagent (NaOH) is eligible for its use as primary catalysts/reagent in the hydrothermal liquefaction step.
  • the recovered reagent NaOH
  • any other component that is added to the process such as calcium oxide, can be easily separated from the sodium carbonate mass at the end of the process due to differences in their solubility.
  • Sodium hydroxide may be totally or partially converted into carbonate derivatives due to reaction with carbon dioxide produced in-situ. This observation applies as well to any hydroxide compound, being either formed with alkaline metals or alkaline earth metals, giving the respective carbonate salt upon reaction with free carbon dioxide.
  • Sedimentation refers to any physical water treatment process using gravity to remove suspended solids from water.
  • Clarifiers refer to any settling tanks/basins built with mechanical machineries committed to the continuous removal of solids deposited by sedimentation.
  • coagulation and flocculation reagents e.g. polyelectrolytes and/or ferric sulfate
  • floes e.g. polyelectrolytes and/or ferric sulfate
  • Filtration is referred to as any physical operation that separates solid matter and fluid from a mixture by means of a filter medium.
  • Precipitation is referred to as any process where a solid is generated from a solution, which occurs as the concentration of a compound exceeds its solubility, or where parameters such as temperature and pH are modified or where different solvents are mixed together.
  • Reverse osmosis is referred to as any water purification process that uses a partially permeable membrane to remove ions, unwanted molecules and larger particles from water.
  • potassium hydroxide KOH is used instead of sodium hydroxide NaOH as reagent in the hydrothermal liquefaction step, leading to production of different components at the end of the process.
  • NDIR analysis reports the following gas composition (in respect to wet biomass weight): 45.6 - 78.9 L.kg 1 (methane); 12.3 - 28.3 L.kg 1 (hydrogen); 2.1 - 6.5 L.kg 1 (propane/butane mixture).
  • NDIR analysis reports the following gas composition (in respect to wet biomass weight): 35.9 - 58.9 L.kg-1 (methane); 16.2 - 25.1 L.kg-1 (hydrogen); 5.6 - 10.4 L.kg-1 (propane/butane mixture).
  • NDIR analysis reports the following gas composition (in respect to wet biomass weight): 65.0 - 98.2 L.kg 1 (methane); 14.0 - 31.6 L.kg 1 (hydrogen); 5.7 - 14.7 L.kg 1 (propane/butane mixture).
  • NDIR analysis reports the following gas composition (in respect to wet biomass weight): 105.4 - 164.5 L.kg 1 (methane); 24.6 - 46.8 L.kg 1 (hydrogen); 12.3 - 25.8 L.kg 1 (propane/butane mixture).
  • NDIR analysis reports the following gas composition (in respect to wet biomass weight): 74.3 - 80.8 L.kg 1 (methane); 10.2 - 34.3 L.kg 1 (hydrogen); 2.5 - 15.4 L.kg 1 (propane/butane mixture).

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  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Processing Of Solid Wastes (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

Abstract

La présente invention concerne une installation (10) pour la conversion de déchets organiques qui comprend un premier réservoir (20), les déchets organiques étant stockés, et une unité (50) de liquéfaction hydrothermale pour la conversion des déchets organiques en biocarburant gazeux, ladite unité (50) de liquéfaction hydrothermale comprenant un récipient étanche au gaz pouvant être scellé relié au premier réservoir (20) de manière à recevoir les déchets organiques de celui-ci.
PCT/BG2020/050003 2020-06-24 2020-06-24 Procédé de conversion de déchets organiques et installation associée WO2021258166A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130276361A1 (en) * 2011-01-05 2013-10-24 Licella Pty Ltd Processing of organic matter
US20140275299A1 (en) * 2013-03-14 2014-09-18 Algae Systems, LLC Systems and Methods for Hydrothermal Conversion of Biomass
US20200155885A1 (en) * 2018-11-20 2020-05-21 Colorado School Of Mines Hydrothermal Technology for Decontamination and Mineralization of Perfluoro- and Polyfluoroalkyl Substance (PFAS) in Wastes, Concentrate Solutions, and Chemical Stockpiles

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130276361A1 (en) * 2011-01-05 2013-10-24 Licella Pty Ltd Processing of organic matter
US20140275299A1 (en) * 2013-03-14 2014-09-18 Algae Systems, LLC Systems and Methods for Hydrothermal Conversion of Biomass
US20200155885A1 (en) * 2018-11-20 2020-05-21 Colorado School Of Mines Hydrothermal Technology for Decontamination and Mineralization of Perfluoro- and Polyfluoroalkyl Substance (PFAS) in Wastes, Concentrate Solutions, and Chemical Stockpiles

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SAQIB SOHAIL TOOR ET AL: "Hydrothermal liquefaction of biomass: A review of subcritical water technologies", ENERGY, ELSEVIER, AMSTERDAM, NL, vol. 36, no. 5, 6 March 2011 (2011-03-06), pages 2328 - 2342, XP028204307, ISSN: 0360-5442, [retrieved on 20110315], DOI: 10.1016/J.ENERGY.2011.03.013 *

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