Hydrothermal purification process

Abstract

A process and system for reducing contaminants contained within a contaminated feedstock includes mixing the contaminated feedstock with water and at least one of a metal scavenger or reactant to form a feedstock-water-reactant mixture; feeding the mixture under pressure into a hydrothermal purification reactor, where the mixture is exposed to heat, pressure, and turbulent flow conditions to cause rapid reaction of the inorganic contaminants with the metal scavenger or reactant to form inorganic salts that separate into the aqueous phase; maintaining the temperature, pressure, and turbulent flow conditions of the feedstock-water-reactant mixture for a predetermined space-time to prevent the organic portion of the feedstock in the mixture from undergoing conversion reactions and form a hydrothermal reactor effluent; and separating the effluent into an aqueous phase containing salts of the inorganic contaminants and an organic phase containing a lower concentration of inorganic contaminants than the contaminated feedstock.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 064,234, filed on August 11, 2020, and U.S. Patent Application No. 17 / 398,082, filed on August 10, 2021, which are hereby incorporated by reference in their entirety.

[0002] (Field of the Invention) The present invention is directed to rapid metal reduction of renewable feedstocks in combination with a hydrothermal purification (HTP) process and system for reducing inorganic and organic contaminants such as salts, minerals, metals, and coke precursors in renewable oils. The process includes combining the feedstock with at least one of a metal scavenger and / or a reactant prior to or during feeding the feedstock to the hydrothermal purification reactor, wherein the metal scavenger or reactant comprises a salt or an acid solution. The conditions within the reactor are maintained to cause a reaction between the inorganic contaminants and the acid and / or salt scavenger while preventing the organic portion of the feedstock from undergoing conversion reactions such as polymerization or pyrolysis. The process and system are characterized by a very short residence time under turbulent flow and a temperature and pressure controlled to maintain hydrothermal (saturated water) conditions.

Background Art

[0003] (Background of the Invention) The ever-increasing demand for renewable fuels and chemicals is forcing refineries to focus on alternative hydrocarbon sources and ways to upgrade these sources or raw materials into viable products. In particular, refineries need processes to upgrade renewable raw materials such as vegetable oils, algal and microbial oils, waste vegetable oils, yellow and brown greases, animal fats, soap raw materials, and pyrolysis oils from cellulose into high-value light and middle distillate hydrocarbon products. Renewable waste and low-cost raw materials often contain contaminants that must be collectively removed before they can be upgraded into clean hydrocarbon fuels or chemicals through conventional refining processes.

[0004] Renewable oils and greases typically contain phospholipid compounds or complexes, referred herein as phospholipids. The phosphorus in phospholipids presents two major problems with the operation of conventional refining equipment. First, phosphorus acts as a nucleating site and catalyst for coke formation. Renewable feedstocks high in phosphorus cause coking in calcination furnaces and heat exchangers, which significantly increases downtime for coke removal and other maintenance operations. Second, phosphorus irreversibly contaminates and inactivates catalysts used in hydrotreatment, hydrocracking, and hydroisomerization, leading to more frequent and costly downtime and catalyst replacement. Catalysts may be protected using guard beds containing alumina or similar high-surface-area materials that can absorb low concentrations of metal and phosphorus compounds; however, this method is prohibitively expensive for renewable oils containing high levels of phospholipids.

[0005] Renewable oils containing phospholipids can be chemically degummed to remove phosphorus. Phospholipids consist of diglycerides (two fatty acid chains covalently bonded to a glycerol molecule through an ester bond) and phosphate groups (PO4 3- ) contains, typically choline (C5H 14It forms complexes with various organic molecules such as NO, ethanolamine, serine, inositol, and equivalents. Conventional chemical degumming uses phosphoric acid or citrate to remove phospholipids as phosphatidic acid. Phosphatidic acid contains two fatty acids and a glycerol backbone from the original phospholipid. Therefore, conventional chemical degumming of plant or algal oils that are rich in phospholipids results in significant yield loss because the entire phospholipid diglyceride is removed from the oil after processing.

[0006] The process for converting renewable oil into renewable hydrocarbon fuels (as opposed to fatty acid methyl esters or FAME biodiesel) typically involves hydrogenating triglyceride feedstocks, which result in the hydrogenation of the glycerol backbone. Partly due to the hydrogen required to hydrogenate the glycerol backbone, which produces propane, this process requires up to 100% more hydrogen than is required for the deoxygenation reaction of fatty acids alone. Hydrolysis or "lipolysis" processes may be used to produce glycerol and free fatty acids, which are used for renewable fuel or chemical production. A widely adopted hydrolysis process is the Colgate-Emery process.

[0007] The Colgate-Emery process is a continuous counter-flow process that typically operates at 250-260°C and 725 psig. Oil is fed to the bottom of the cracking column, and desalinated water is fed to the top of the column. Fatty acids are released from the top of the column, and the water-glycerin solution (sweet water) is removed from the bottom of the column. The processing time is 2-3 hours, which requires very large heated pressure vessels for large-scale commercial applications. Several factors limit the performance of the Colgate-Emery process: 1) The need to operate below the glycerin cracking temperature, which is about 290°C. 2) The need to provide a long residence time for hydrolysis and allow for gravity separation of free fatty acids and the glycerin-aqueous phase. 3) The need to use relatively clean degumming raw materials to prevent emulsion formation. 4) Economic trade-offs between operating temperature, pressure, and residence time. Operating the corrugated emery process at higher temperatures requires higher pressures and carries the risk of glycerin degradation due to the long residence times at temperatures around 290°C. The large equipment required, due to the large volume of oil that must be processed to achieve economic viability, makes this process prohibitively expensive for alternative fuel production. Sweetwater (diluted glycerin solution) can form emulsions due to the presence of residual free fatty acids and partially hydrolyzed triglycerides. To recover the diluted glycerin product, the sweetwater must typically be allowed to settle for up to 24 hours with a deemulsifier at 80-90°C. Vacuum distillation can also be used to further separate long-chain and short-chain fatty acids.

[0008] Soap raw materials are formed during the refining of edible oils, where sodium hydroxide is used to remove free fatty acids from vegetable oil as sodium soap. Soap raw materials contain sodium soap and phospholipids. Large quantities of soap raw materials are produced globally. Because the clean free fatty acids have a much higher value as raw materials for biofuel production and non-soap applications, acidification using strong acids such as sulfuric acid is used to reverse the reaction at 90°C and recover the free fatty acids and sodium salts. In addition to the need for and use of strong acids, the process results in the production of acidic wastewater containing phospholipids and other compounds.

[0009] Vegetable oils, algal and microbial oils, waste vegetable oils, yellow and brown greases, animal fats, and other lipids contain metals in the form of sodium, potassium, calcium, magnesium, iron, and other cations in the form of soaps. These metals must be reduced to less than a few ppm to prevent coke formation and catalyst adhesion in biofuel production processes. It should be understood that waste oils, fats, greases, phospholipid gums, soaps, and mixtures thereof can be in the form of mixtures and emulsions that interfere with or prevent conventional pretreatment operations. [Overview of the initiative] [Means for solving the problem]

[0010] (Summary of the invention) The present invention relates to hydrothermal purification processes and systems for renewable raw materials such as vegetable oils, algal and microbial oils, waste vegetable oils, brown grease, yellow grease, animal fat, chicken fat, distillers, corn oil, soap raw materials, tall oil, and bio(pyrolytic) oils from cellulosic materials. The present invention has several advantages over other purification processes such as chemical degumming, desalination processes, or other chemical, extraction, filtration, or thermal processes. The advantages include, but are not limited to, the following: 1) Equipment with a small footprint that can be installed alongside conventional petroleum refineries, waste oil collectors, or oilseed grinding facilities. 2) Ability to recover glycerin, fatty acids, or mono, di, and triglycerides. 3) Reduction of phosphorus, metals, and chlorine to less than 2 ppm. 4) Reduction of polyethylene. 5) Reduction of silicon. 6) Elimination of solid waste and associated increase in clean product yield due to the recovery of fatty acids from phospholipids and metal soaps. This system is particularly desirable for use in processing unrefined or waste oils, oils, and greases, including algal oils and animal fats. Under the turbulent, high Reynolds number conditions employed during hydrothermal refining, the recyclable oil and water are tightly mixed, resulting in rapid mass transfer and conversion of soaps and other contaminants into salts, which rapidly separate into the aqueous phase during oil-water separation. The addition of metal scavengers and / or reactants prior to or during the feeding of feedstocks into the hydrothermal refining reactor, with the metal scavengers and reactants providing salt or acid solutions along with water, accelerates the reduction of metal contaminants to very low ppm levels. The conditions within the reactor are maintained to induce the reaction of inorganic contaminants with the acid and / or salt scavengers, while preventing the organic parts of the feedstocks from undergoing conversion reactions such as polymerization or thermal decomposition.

[0011] When used for metal reduction, such as for soap raw materials or lipids containing metal soaps, the present invention achieves rapid acidification without the need for strong mineral acids. Since phospholipids are completely hydrolyzed during hydrothermal purification, clean lipid products are recovered. The diglyceride residue produced by the hydrolysis of phospholipids is not only recovered into the oil phase to improve yield, but the oil and aqueous phases can then be easily separated without the formation of a lag layer or the generation of residual waste liquid caused by the presence of phospholipids.

[0012] According to one embodiment of the present disclosure, a process for reducing contaminants contained in renewable raw materials comprises providing at least one of a metal scavenger or a reactant, the metal scavenger or reactant comprising an acid or salt solution, or a combination of an acid and a salt solution. The process comprises mixing the metal scavenger or reactant with water and raw materials to form a raw material-water-reactant mixture, and feeding the raw material-water-reactant mixture into a hydrothermal purification reactor, the mixture being subjected to heat, pressure, and turbulent conditions. The process further comprises maintaining temperature, pressure, and turbulent conditions of the raw material-water-reactant mixture in the hydrothermal purification reactor in such a manner that it causes a rapid reaction between inorganic contaminants and the metal scavenger or reactant, forming an inorganic salt that separates into an aqueous phase. The process further includes maintaining temperature, pressure, and turbulence conditions of the feedstock-water-reactant mixture in a hydrothermal purification reactor to prevent the organic portion of the feedstock in the mixture from undergoing thermal decomposition of the carbon-carbon bonds of lipids into low molecular weight fragments, from polymerization into high molecular weight hydrocarbons, and / or from isomerization of unsaturated compounds from "cis" isomers to "trans" isomers. The process then includes separating the hydrothermal purification reactor waste into an aqueous phase containing salts of inorganic contaminants and an organic phase, or the resulting product stream, containing inorganic contaminants at lower concentrations than the contaminated feedstocks.

[0013] Contaminated renewable oils may consist of lipid-type oils, including, but are not limited to, virgin vegetable oils, tri, di, and monoglycerides, free fatty acids, lecithin, gum, and phospholipids, fatty acid soaps, deodorized distillates, acidic oils, crude tall oil and its derivatives, used edible oils, yellow grease, brown grease, chicken fat, and animal fat, as well as distilled corn oil, algal oil, microbial oil, bio-oil, or mixtures thereof or aqueous emulsions. When the raw materials consist of renewable lipid-based oils, the organic phase after separation will consist of lipids with low metal content. It should be understood that different raw materials may be mixed in proportions that will improve processability, performance, and economics.

[0014] The raw materials and metal scavengers or reactants, comprising salt or acid solutions, or mixtures thereof, can be mixed by combining flows using tee connections, static mixers, pumps, and equivalents, while the mixture is maintained in turbulence to form a raw material-water-reactant mixture. The metal scavengers and / or reactants can be added to the water flow before mixing with the raw materials, or added to the raw material-water mixture before entering the hydrothermal purification reactor, or added at any point along the process, including a point after processing within the hydrothermal purification reactor.

[0015] It should be understood that metal scavengers or reactants may include strong acids, weak acids including carbonic acid, organic acids, salts, and mixtures thereof.

[0016] A hydrothermal purification reactor may be equipped with a tubular plug-flow reactor (PFR) designed to maintain turbulent conditions equal to or greater than a Reynolds number of 2,000. The feedstock-water-reactant mixture may be heated to a reaction temperature in the range of 150°C to 350°C. The pressure within the hydrothermal purification reactor may be maintained in the range of 100 psig to 2,500 psig and controlled to keep the mixture in a liquid hydrothermal phase. Under these conditions, the space time of the feedstock-water-reactant mixture within the hydrothermal reactor may range from approximately 10 seconds to 15 minutes, 10 seconds to 10 minutes, or 10 seconds to 5 minutes. Alternatively, the hydrothermal reactor may operate at a pressure in the range of 500 to 1,000 psig, a temperature in the range of 200 to 300°C, and a space time (or surface residence time) of 2 minutes or less. It should be understood that the pressure, temperature, and residence time used in a hydrothermal purification reactor can be determined based on several variables, including the specific raw materials being processed, the type of contaminants in the raw materials, and specific metal scavengers or reactants, including acid or salt solutions mixed with water and the raw materials. It should also be understood that specific pressures, temperatures, and residence times may be outside the parameters outlined above, depending on the variables listed above and the required level of contaminant reduction. It should be understood that space time is synonymous with "supercritical residence time" and is generally used in relation to flow reactors where the reaction, fluid density, or phase changes within the reactor. Space time is defined as the time required to process one reactor volume of fluid based on entry conditions (standard temperature and pressure). Because hydrothermal (liquid phase) conditions are maintained, the density of the fluid mixture at operating temperatures of 200–300°C decreases to approximately 87%–72% of the density at entry conditions, respectively. This means that the actual residence time is approximately 87%–72% of the space time at these operating temperatures.

[0017] The raw material-water-reactant mixture may exist as a single-phase solution or as a two-phase raw material-water mixture, depending on the operating temperature and the solubility of the raw materials in water at that temperature. The water concentration in the raw material-water-reactant mixture is controlled to ensure complete dissolution of inorganic salt contaminants into the aqueous wastewater. The process of separating the reactor wastewater into an aqueous stream and an organic product stream includes steps of cooling, depressurization, and separation to produce clean lipid and aqueous streams. Separation of the oil phase from the aqueous phase can be carried out using at least one of a gravity separator, hydrocyclone, centrifuge, and / or any combination thereof, including an electrostatic or coalescer element, and may be accelerated by the use of a deemulsifier. Separation may be carried out before and after cooling and pressure drop.

[0018] The present invention also includes a hydrothermal purification system for decontaminating renewable oil, comprising: a hydrothermal purification reactor system operated under temperature, pressure, and turbulent conditions to maintain a liquid hydrothermal phase that results in rapid hydrolysis of phospholipids without causing thermal decomposition, polymerization, or isomerization of the raw material carbon-carbon bonded lipids; and a separation system for removing clean oil product streams and water streams containing inorganic contaminants from the wastewater of the hydrothermal purification reactor system. The hydrothermal purification reactor system can be operated under turbulent conditions having a Reynolds number (Re) of at least 2,000. The hydrothermal purification reactor system can be operated at pressures in the range of 100 psig to 2,500 psig and temperatures in the range of 150°C to 350°C, and oil purification occurs with a spatial time (or surface residence time) of about 10 seconds to 15 minutes, 10 seconds to 10 minutes, or 10 seconds to 5 minutes. Alternatively, hydrothermal purification reactors can be operated at pressures in the range of 500–1,000 psig, temperatures in the range of 200–300°C, and space times of up to 2 minutes or less. The water-to-oil ratio, pressure, temperature, and residence time of a hydrothermal purification reactor system can be determined based on several variables, including the specific raw materials being processed, the type of contaminants in the raw materials, the degree of hydrolysis, and specific metal scavengers and / or reagents, which should be understood to include an acid or salt solution mixed with water and raw materials. It should also be understood that specific pressures, temperatures, and space times may be outside the parameters outlined above, depending on the variables listed above and the required level of contaminant reduction. The present invention provides, for example, the following: (Item 1) A process for reducing contaminants contained in contaminated raw materials, The contaminated raw material is mixed with water and at least one of a metal scavenger or reactant, wherein the metal scavenger or reactant comprises an acid or salt solution, or a combination of an acid and a salt solution, forming a raw material-water-reactant mixture. The process involves feeding the aforementioned raw material-water-reactant mixture under pressure into a hydrothermal purification reactor, wherein the mixture is exposed to heat, pressure, and turbulent conditions. Maintaining the temperature, pressure, and turbulence conditions of the raw material-water-reactant mixture in a manner that causes a rapid reaction between the inorganic contaminant and at least one of the metal scavenger or reactant, separating into an aqueous phase to form an inorganic salt, and preventing the organic portion of the raw material in the mixture from undergoing thermal decomposition of carbon-carbon bonds into low molecular weight fragments, preventing the compounds in the organic fraction from polymerization, and / or preventing the compounds in the organic fraction from isomerizing from a "cis" isomer to a "trans" isomer, and in a manner that forms hydrothermal reactor wastewater, maintaining the temperature, pressure, and turbulence conditions of the raw material-water-reactant mixture over a predetermined spatial time, The hydrothermal reactor wastewater is separated into an aqueous phase containing salts of inorganic contaminants and an organic phase containing inorganic contaminants at a lower concentration than the contaminated raw material. A process that includes this. (Item 2) The process according to item 1, wherein at least one of the metal scavenger or reactant is mixed with the water prior to mixing with the raw materials, or is added to the oil-water mixture at any point throughout the hydrothermal purification process. (Item 3) The process described in item 1 comprises recycled oils and greases, including waste oils, oils and greases, distilled corn oil, algal oil, microbial oil, degreased oils and greases from wastewater treatment, pyrolysis oils, or mixtures thereof or aqueous emulsions, with the contaminated raw materials including virgin vegetable oil, tri, di, and monoglycerides, free fatty acids, lecithin, gum and phospholipids, soap raw materials and fatty acid soaps, deodorized distillates, acidic oils, used edible oils, yellow grease, brown grease and animal fat, distilled corn oil, algal oil, microbial oil, degreased oils and greases from wastewater treatment, pyrolysis oils, or mixtures thereof or aqueous emulsions. (Item 4) The process described in item 1 may involve the mixing of different raw materials in proportions that would improve the processability of the raw materials, system performance, and / or process economics. (Item 5) The process according to item 1, wherein the raw materials and at least one of the metal scavenger or reactant are mixed by combining the flows using a tee connection, static mixer, pump, or mixing valve while the mixture is maintained in turbulence, in order to form a raw material-water-reactant mixture. (Item 6) The process according to item 1, wherein at least one of the metal scavengers or reactants comprises at least one of a strong acid, a weak acid, an organic acid, a salt, and a mixture thereof. (Item 7) The hydrothermal purification reactor comprises a tubular plug-flow reactor (PFR) designed to maintain a turbulent state at a Reynolds number (Re) of at least 2,000, as described in item 1, for the process described in item 1. (Item 8) The process according to item 1, wherein the raw material-water-reactant mixture is heated to a reaction temperature in the range of 150°C to 350°C. (Item 9) The process according to item 1, wherein the pressure in the hydrothermal purification reactor is maintained within the range of 100 psig to 2,500 psig and controlled to maintain the mixture in the liquid hydrothermal phase. (Item 10) The process according to item 1, wherein the raw material-water-reactant mixture may exist as a single-phase solution or as a two-phase raw material-water mixture. (Item 11) The process according to item 1, wherein the operating pressure is in the range of 100 psig to 2,500 psig and the operating temperature is in the range of 150°C to 350°C, and the space time of the raw material-water-reactant mixture in the hydrothermal purification reactor is in the range of approximately 10 seconds to 15 minutes. (Item 12) The hydrothermal purification reactor may operate as an isothermal or adiabatic reactor in the process described in item 1. (Item 13) The process according to item 1, wherein the water concentration in the raw material-water-reactant mixture is controlled to result in the dissolution of inorganic salt contaminants into the aqueous phase. (Item 14) The process according to item 1, wherein the separation of the reactor wastewater into the aqueous stream and the product stream comprises the steps of cooling, reducing the pressure, and separating to produce a clean oil stream and an aqueous stream. (Item 15) The separation of the clean oil and water stream is carried out by using at least one of a gravity separator, an electrostatically assisted gravity separator, a coalescer, a hydrocyclone, a centrifuge, the addition of a deemulsifier or water clarifier, or any combination thereof, as described in item 14. (Item 16) A hydrothermal purification system for decontaminating renewable oil, A hydrothermal purification reactor system operated under temperature, pressure, and turbulence conditions to maintain a liquid hydrothermal phase that brings about a rapid reaction between inorganic contaminants and acids and salt scavengers in a raw material-water-reactant mixture without causing the decomposition of carbon-carbon bonds of lipids or isomerization of the raw materials, A separation system for removing the purified oil product stream and the water stream containing inorganic contaminants from the wastewater of the hydrothermal purification reactor system, A system equipped with these features. (Item 17) The hydrothermal purification reactor system is the system described in item 16, which operates in turbulence having at least 2,000 Reynolds numbers (Re). (Item 18) The hydrothermal reactor system is operated at a pressure in the range of 100 psig to 2,500 psig and a temperature in the range of 150°C to 350°C, and the purification of the oil occurs with a residence time in the range of approximately 10 seconds to 15 minutes, as described in item 16. (Item 19) A process for reducing contaminants in renewable raw materials / water emulsions and for breaking down emulsions, The process involves mixing an oil / water emulsion with water and at least one of a metal scavenger or reactant, wherein the metal scavenger or reactant comprises an acid or salt solution, or a combination of an acid and a salt solution, to form a raw material-water-emulsion mixture. The process involves feeding the aforementioned raw material-water-emulsion mixture under pressure into a hydrothermal purification reactor, wherein the mixture is exposed to heat, pressure, and turbulent conditions. Maintaining temperature, pressure, and turbulence conditions of the raw material-water-emulsion mixture in a manner that causes a rapid reaction between the inorganic contaminant and at least one of the metal scavenger or reactant, which separates into an aqueous phase and forms an inorganic salt, In a manner that prevents the organic portion of the raw materials in the mixture from undergoing thermal decomposition of carbon-carbon bonds into low molecular weight fragments, prevents the compounds in the organic fraction from polymerization, and / or prevents the compounds in the organic fraction from isomerizing from a "cis" isomer to a "trans" isomer, and maintains the temperature, pressure, and turbulence conditions of the raw materials-water-reactant mixture over a predetermined spatial time, in a manner that forms hydrothermal reactor wastewater, The hydrothermal reactor wastewater is separated into an aqueous phase containing salts of inorganic contaminants. Methods that include... (Item 20) The process according to item 19, wherein the raw material-water-emulsion mixture in the hydrothermal purification reactor is maintained at an operating pressure in the range of about 100 psig to 2,500 psig and heated to an operating temperature in the range of 150°C to 350°C over a space time in the range of about 10 seconds to 15 minutes. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 is a schematic diagram of an acidification-based hydrothermal purification (HTP) system according to an embodiment of the present disclosure for reducing contaminants contained in renewable raw materials, incorporating a plug-flow reactor and an oil-water separator for the recovery of refined renewable oil. [Modes for carrying out the invention]

[0020] (Description of the invention) As used herein, unless otherwise expressly provided, all numbers, including values, ranges, quantities, or percentages, may be read as being preceded by the word “about,” even if the term does not appear expressly. Any numerical ranges described herein are intended to include all subranges to which they belong. The plural forms encompass the singular forms, and vice versa. When ranges are given, any endpoints of those ranges and / or numbers within those ranges may be combined with the scope of the invention. The terms “including,” “e.g.,” “for example,” and their equivalents mean “not limited to, but including / e.g. / for example, is.”

[0021] For the purposes of this specification, the terms “upper,” “lower,” “right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” “lateral,” “vertical,” and their derivatives shall be used in relation to the present invention as oriented in the drawings. However, it should be understood that the present invention may envision various alternative modifications unless otherwise expressly provided. It should also be understood that the specific devices illustrated in the accompanying drawings and described in the following specification are merely exemplary embodiments of the present invention. Therefore, the specific dimensions and other physical characteristics relating to the embodiments disclosed herein should not be considered limiting. Similar reference numerals refer to similar elements.

[0022] It should be understood that any numerical range described herein is intended to include all subranges to which they belong. For example, the range "1 to 10" is intended to include the stated minimum value of 1 and the stated maximum value of 10 and all subranges between them, i.e., all subranges starting from the minimum value equal to or greater than 1 and ending with the maximum value equal to or less than 10, and all subranges in between, for example, 1 to 6.3, or 5.5 to 10, or 2.7 to 6.1.

[0023] This invention relates to continuous flow processes and systems for the hydrothermal purification of renewable raw materials such as vegetable oils, algal and microbial oils, waste vegetable oils, brown grease, animal fats, tall oils, acidic oils, and bio-oils. The processes of this invention separate undesirable contaminants such as minerals, metals, and salts from the raw materials to produce clean, refined oil. "Clean" means that the amount of contaminants in the product is reduced by more than 95%, such as more than 99%, often resulting in trace amounts of contaminants (near or below the detection limit of typical analytical methods) compared to the raw materials. The level of contaminants in the clean oil is minimized, significantly reducing precipitation, polymerization, and coking in downstream conversion equipment, as well as inactivation or adhesion of downstream conversion catalysts. The purification process is carried out by hydrolysis, solvation, acidification, and concentration of contaminants in the water wastewater stream. The HTP process does not involve raw material conversion. "Conversion" means molecular rearrangement of lipids or FFAs, such as that occurring in decarboxylation, pyrolysis, isomerization, cyclization, polymerization, hydrogenation, or dehydrogenation. These conversion processes can be carried out downstream of the system of the present invention, thereby benefiting from the conversion of clean raw materials and reducing or eliminating problems associated with the conversion of contaminated raw materials.

[0024] Contaminated raw materials may be renewable raw materials such as vegetable oils. Suitable vegetable oils for processing according to the present invention may include canola, carinata, castor, jatropha, palm, pongamia, soybean, tan, and / or corn (such as those obtained from distilled grains) oils, soap raw materials, waste vegetable oils, yellow grease (from edible oils), brown grease (from grease traps and wastewater treatment), strongly acidic oils (also called acidic oils), animal fats, algal oils, microbial oils, other pine-related by-products from terpenes and tall oils, or other biosynthetic oils (such as those obtained from pyrolysis, esterification, oligomerization, or polymerization), and mixtures thereof. It should be understood that waste oils, fats, oils, greases, phospholipid gums, soaps, and mixtures thereof may be in the form of mixtures and emulsions that interfere with or prevent conventional pretreatment operations. The contaminants that can be removed include inorganic elements such as halides (e.g., Cl, Br, I), phosphorus and phosphorus-containing species, alkali metals and metalloids (e.g., B, Si, As), other metals (e.g., Na, K, Ca, Fe, Mg, Ni, V, Zn, Cr, Al, Sn, Pb, etc.), and organic compounds (proteins, polymers such as polyethylene). The process and system yields clean oil by achieving a reduction of more than 95% (e.g., more than 99%) in phosphorus, salt, mineral, and metal content. HTP process conditions can be controlled in a manner that will retain triglycerides in the triglyceride-containing raw material, or the process conditions can be adjusted to achieve rapid hydrolysis of triglycerides to free fatty acids. In phospholipid-containing raw materials, HTP process conditions can be controlled in a manner that reduces the phosphorus content to less than 2 parts per million (ppm), with minimal yield loss, as associated with conventional degumming. The system of the present invention includes a hydrothermal purification reactor system coupled with high temperature, high pressure, and the addition of an acid, salt, or metal scavenger, without other operations or additions in between, and components for the separation and / or recovery of a clean oil product. The integrated reactor and separation system is based on the HTP process.

[0025] Referring here to Figure 1, this shows a schematic diagram of an HTP process and system, generally shown as 110, according to an embodiment of the present disclosure, for the purification of recyclable oils, oils, and greases, including waste oils, oils, and greases such as brown grease and yellow grease, from which clean oil and water products are recovered by a conventional oil-water separation process. The process and system includes providing recyclable contaminated raw material 132. The contaminated raw material 132 can be fed into a equalization tank 134. Generally, the equalization tank acts as a holding tank that allows for the equalization of the flow of the raw material. The equalization tank can also act as a regulating operation, where the temperature of the raw material is controlled to maintain desired flow characteristics. The contaminated raw material is present in the equalization tank 136 and enters a pump 138 to form a pressurized feed flow 140. The pressurized feed flow 140 can be preheated by a heating device such as a heat exchanger 142 to form a heated feed flow 144.

[0026] The water supply flow 112 is supplied to the equalization tank 116 and can be fed to the pump 120 at 118 to form a pressurized water flow 122. The pressurized water flow 122 can be heated by a heating device such as a heat exchanger 124 to form a heated water flow 126. It should be understood that flows 126 and 144 can be heated by any known process or device, and that heat recovery from other process flows is also included to optimize the overall thermal efficiency. A salt or solution of the reactant and / or metal scavenger is added at 114. It should be understood that flow 114 can be added at any point throughout the HTP process, such as in the equalization tank 116 and / or in flows 118, 122, 126, etc. It should also be understood that the reactant and / or metal scavenger can be added at multiple of these points simultaneously.

[0027] The heated organic feed stream 144 and the heated water stream 126 are mixed in a mixing device 150 to form a high-pressure mixed stream 152. Sufficient pressure is required to maintain the feed and water streams in the liquid phase under the conditions necessary to carry out metal reduction and phospholipid hydrolysis, based on the feed contaminants. Renewable feed can be miscible with water at a low temperature of 300°C and a low pressure of 1,250 psig. It should be understood that the mixing device 150 may be a combination of two flows via a tee connection, or may include one or more conventional static mixers, mixing valves, or pumps. The type of mixing device and the degree of mixing depend on the feed, the fluidity of the feed, and the miscibility of the feed with water. As shown in Figure 1, a salt 114 of the reactant and / or metal scavenger may also be added to the stream 152. The high-pressure mixed stream 152 is heated in a feed-waste heat exchanger 154 to form a heated stream 156. It should be understood that the feed-waste liquid heat exchanger 154 can be any combination of heat exchangers configured throughout the process to maximize overall thermal efficiency. The flow 156 is fed to heater 158, which can be any type of heater or heat exchanger, which heats the oil-water mixture in the flow 160 to a target processing temperature, such as in the range of 150°C to 350°C, before entering the hydrothermal purification reactor 162.

[0028] The hydrothermal purification reactor 162 operates at a high Reynolds number (at least 2,000 or higher), creating turbulent dynamics to achieve rapid mixing, mass transfer, and heat transfer. This allows the hydrothermal purification reactor to operate at much shorter space times and higher operating temperatures than prior art systems for desalination (100°C to 150°C) or for lipolysis via the Colgate-Emery process (250°C to 260°C). Under these conditions, the hydrothermal purification reactor 162 achieves a significantly reduced reactor size compared to prior art systems. The operating conditions of the hydrothermal purification reactor 162 may be selected based on the contaminants in the raw materials and the purification requirements. The weight ratio of water to oil in the hydrothermal purification reactor 162 may be 1:10 to 1:1, 1:100 to 3:1, etc. The hydrothermal purification reactor 162 is operated at sufficient pressure to maintain a liquid phase, such as in the range of 250–3,000 psig or 500–1,500 psig. The hydrothermal purification reactor 162 is configured to operate under turbulent conditions that optimize mixing and maximize mass and heat transfer. At operating temperature and pressure, the space time can range from a maximum of 15 minutes to less than 10 seconds, depending on specific raw material and contaminant reduction requirements. As used herein, the space time is calculated under standard conditions (temperature of 20°C and pressure of 1 atm) based on the reactor volume and raw material volume. Actual hydrodynamic residence times may be calculated based on operating conditions (temperature and pressure) as well as the weight ratio of water to oil. The hydrothermal purification reactor 162 may be a tubular plug flow reactor (PFR). It should be understood that the hydrothermal purification reactor can be operated as an adiabatic reactor or as an isothermal reactor due to very short space times. Different reactor conditions provide a range of mixing, heat transfer, space-time, and product quality scenarios suitable for different feedstock types and contaminant reduction requirements. Generally, PFR systems will exhibit a Reynolds number (Re) of at least 2,000, in the range of 2,000–4,000, or above 4,000, and will show turbulence, close mixing, and high heat and mass transfer rates.According to one embodiment, the present invention can employ a combination of a space time of up to 15 minutes or less and a Reynolds number (Re) greater than 4,000 throughout the entire hydrothermal reaction zone. One example of a hydrothermal purification reactor 162 that may be used is the high-proportion reactor disclosed in U.S. Patent No. 10,071,322 (the disclosure thereof is incorporated herein by reference as a whole).

[0029] Therefore, the hydrothermal refining reactor is operated under conditions where no conversion reaction occurs and no coke is formed, which would affect performance. Instead, inorganic contaminants are liberated under hydrothermal operating conditions and removed by an integrated hydrothermal refining reactor and oil-water separation system.

[0030] The waste liquid 164 from the hydrothermal purification reactor 162 is cooled in a feed-waste heat exchanger 154, yielding a partially cooled product 166, which then passes through a pressure control valve 168 that maintains the system pressure. Reactant and / or metal scavenging salts 114 may also be added to the flow 164 after it has exited the hydrothermal purification reactor 162. The depressurized product flow 170 is further cooled by a cooling heat exchanger 172, if necessary. The cooled product flow 170 is then fed to an oil-water separator 176. Separation of the oil phase from the aqueous phase can be carried out using at least one of a gravity separator, hydrocyclone, centrifuge, and / or any combination thereof, including an electrostatic or coalescer element, and may be accelerated by the use of a deemulsifier to reduce the water content of the product. It should be understood that the separation can be carried out before or after the pressure drop, depending on the subsequent treatment of the clean product oil. After partial cooling, a high-pressure separator may be employed to produce pressurized clean product oil for subsequent processing, eliminating the need for additional pump operation. The clean product oil 178 and process water flow 180 are removed from the separator 176. Operating as described above, the hydrothermal system 110 rapidly dissociates inorganic contaminants (e.g., salts, minerals, and / or metals) that separate into the process water flow 180, and more than 95% (more than 99%, etc.) of the contaminants are removed from the contaminated raw material 132.

[0031] The clean oil 178 may be further processed into chemicals or fuels (not shown), depending on the type of raw material being processed and the purpose of the product. The renewable raw material may be hydrothermally cracked into synthetic crude oil via a high-ratio hydrothermal reactor system (as described above), and then hydrogenated into transport fuels or chemicals. Alternatively, the clean renewable oil product 178 may be converted to biodiesel via esterification, or to renewable fuels and chemicals via hydrotreatment, hydroisomerization, and hydrocracking or other conventional refining processes.

[0032] The process water stream 180 may be treated, reused, further treated to recover by-products, applied to land, dewatered and used as an animal feed supplement, or treated in a conventional wastewater treatment process (not shown). The fate of the process water stream 180 depends, at least in part, on the components of the raw materials and the purpose of recovering and reusing the water. For example, when the hydrothermal system 110 is used to desalinate the raw materials, the process water stream 180 may contain both inorganic and trace organic contaminants and may be sent directly to wastewater treatment.

[0033] The system 110 depicted in Figure 1 can be used for rapid hydrolysis. Rapid hydrolysis is most effectively carried out in liquid or hydrothermal operation. During the rapid hydrolysis of triglyceride oil, the clean oil 178 consists mainly of FFA, and the process water stream 180 contains water and glycerin. Pure glycerin can be recovered from the process water stream 180 by a conventional distillation process.

[0034] Alternatively, system 110 may be used for degumming or dephosphorization. Rapid dephosphorization is most effectively carried out in a liquid phase where temperature and pressure are controlled to maintain water in the saturated phase. Rapid hydrolysis of phospholipids in the hydrothermal purification reactor 162 is achieved by cleaving the phosphate groups from the glycerol backbone of the phospholipids, as well as by cleaving groups that may contain fatty acids and other organic components from the phospholipids, such as choline, ethanolamine, serine, or the inositol component of the phospholipids. Phosphates are removed in the aqueous phase of the reaction mixture, while fatty acids, typically appearing in amounts exceeding 70% by weight of the phospholipids, are reserved for subsequent processing into chemicals or fuels. The phosphorus content of the clean oil 178 from high-phospholipid content raw materials can be reduced from over 500 ppm to less than 2 ppm, and the total metal content can be reduced to less than 10 ppm. The yield of low-phosphorus oil from high-phospholipid oil is significantly increased compared to conventional degumming processes. For example, in the case of algal oil containing 6,000 ppm of phosphorus, the process of the present invention can increase the yield of low-phosphorus oil by more than 10%, thereby the clean oil 178 contains clean FFA with a low phosphorus content. The process water stream 180 contains water and phosphate ions (PO4 3- ) are included and can be recovered and reused as a nutrient source for growing crops or algae.

[0035] The advantages of the hydrothermal purification process and system of the present invention are that the physically small footprint of system 110 requires low capital and operating costs. The hydrothermal process can operate in very short spatial time, such as less than 2 minutes. This results in relatively small equipment and low capital costs. When used for degumming, the operating costs for HTP are lower than conventional chemical degumming because degumming acids are not required, products and by-products are easily separated and recovered using conventional oil-water separation techniques, high-quality water can be recovered and reused without additional treatment, other valuable by-products such as glycerin can be recovered, and no other liquid or solid waste products are generated. The present invention performs rapid acidification without requiring strong mineral acids to obtain clean lipid products without the formation of residual waste streams caused by the presence of phospholipids, as phospholipids are hydrolyzed during hydrothermal purification. Diglyceride residues produced by the hydrolysis of phospholipids are not only recovered to improve yield, but the oil and aqueous phases can then be easily separated without the formation of a lag layer or the generation of residual wastewater. When used for rapid acidification of soap raw materials or lipids containing metal soaps, strong mineral acids such as sulfuric acid are not required, and weaker acids such as citric acid, acetic acid, phosphoric acid, and carbonic acid can be employed to obtain clean lipid products without the formation of a lag layer. The use of weaker acids allows for the use of low-cost structural materials, which reduces capital costs.

[0036] It should be understood that the optimal operating conditions depend on the quality of the raw materials, and that these operating conditions can be varied to achieve the required product quality. Operating conditions can be varied to maximize desalting (e.g., waste vegetable oil), acidification, phospholipid hydrolysis, or glyceride hydrolysis and glycerin recovery. It should also be understood that hydrothermal processes can be operated in a manner that reduces metals in highly contaminated raw materials such as brown grease, producing clean lipid products and wastewater containing inorganic contaminants.

[0037] The following embodiments are presented to demonstrate the general principle of reducing contaminants in raw materials using HTP. All quantities listed are given in parts by weight unless otherwise indicated. The invention should not be considered limited to the specific embodiments presented. While specific embodiments of the invention are described above for illustrative purposes, it will be apparent to those skilled in the art that various detailed modifications of the invention can be made without departing from the invention as defined in the appended claims.

[0038] (Examples) Example 1: Distilled corn oil and used cooking oil A 50:50 mixture of distilled corn oil (DCO) and used edible oil (UCO) was used as the feedstock for a pilot-scale hydrothermal purification system configured as shown in Figure 1. The tubular plug-flow reactor was designed to achieve a space time of 2 minutes and maintain a Reynolds number > 4,000 based on the combination of volume fluxes of water and oil. The operating conditions are shown in Figure 1. The pressure was controlled to 1,000 psig, which ensured that liquid-phase hydrothermal conditions were maintained. A small amount of phosphoric acid was added to the feedwater to achieve an acid dosing rate equal to 2.6 mmol of phosphoric acid per liter of feedwater. The oil and water were separated by gravity at 80°C in a product separator. [Table 1]

[0039] Table 2 compares the feed and product properties. Total metals were reduced to less than 1 ppm, and phosphorus was reduced by 98%. The total acid number (TAN) increased slightly from 25.6 to 34.5, indicating that a small amount of hydrolysis occurred. [Table 2]

[0040] Example 2: Brown Grease Brown grease was used as the raw material for a pilot-scale hydrothermal purification system configured as shown in Figure 1. The tubular plug-flow reactor was designed to achieve a space time of 2 minutes and maintain a Reynolds number > 4,000 based on the volumetric flux combination of water and oil. The operating conditions are shown in Table 3. The pressure was controlled to 1,000 psig, which ensured that liquid-phase hydrothermal conditions were maintained. Citric acid was added to the feedwater to achieve an acid dosing rate equal to 30 mmol of citric acid per liter of feedwater. The oil and water were separated by gravity at 80°C in a product separator. [Table 3]

[0041] Table 4 compares the feed and product properties. Phosphorus content was reduced from 23.5 to less than 2 ppm. Total metal content was reduced from over 96% to less than 15 ppm. The brown grease feedstock had an increased high TAN of 18, indicating that some hydrolysis occurred. [Table 4]

[0042] Example 3: Coarse soybean oil Crude soybean oil is typically refined, bleached, and deodorized through a multi-stage process to achieve low phosphorus and metallic products. The crude soybean oil used in this embodiment was unrefined and contained over 500 ppm of phosphorus and over 260 ppm of other metals. The crude soybean oil was fed to a pilot-scale hydrothermal refining system configured as shown in Figure 1. The tubular plug-flow reactor was designed to achieve a space time of 2 minutes and maintain a Reynolds number > 4,000 based on the volume flux combination of water and oil. The operating conditions are shown in Table 5. The pressure was controlled to 1,000 psig, which ensured that liquid-phase hydrothermal conditions were maintained. Citric acid was added to the feed water to achieve an acid dosing rate equal to 11.4 mmol of citric acid per liter of feed oil. The oil and water were separated by gravity at 80°C in a product separator. [Table 5]

[0043] Table 6 compares the feed and product properties. Phosphorus content was reduced by 99.5%, from 510 to 2.9 ppm. Metal content was reduced to less than 1 ppm. TAN increased only slightly, indicating that nearly complete hydrolysis of phospholipids was achieved essentially without hydrolysis of triglycerides or the organic backbone of the phospholipids. [Table 6]

[0044] Example 4: Crude Tall Oil Tall oil is a viscous, yellowish-black, odorous liquid obtained primarily as a by-product of the wood pulpmaking kraft process when softwoods are pulped. It consists of a mixture of rosinic acid, fatty acids, alcohols, sterols, and other alkyl hydrocarbon derivatives. Crude tall oil was fed into a pilot-scale hydrothermal purification system configured as shown in Figure 1. The tubular plug-flow reactor was designed to achieve a space time of 2 minutes and maintain a Reynolds number > 2,000 based on the volumetric flux combination of water and oil. The operating conditions are shown in Table 7. The pressure was controlled to 2,000 psig, which ensured that liquid-phase hydrothermal conditions were maintained. In this example, phosphoric acid was added to the water feed stream. The oil and water were separated by gravity at 80°C in a product separator. [Table 7]

[0045] Table 8 compares the feed and product properties. Phosphorus was reduced from 13.4 ppm to less than 1 ppm. Total metals were reduced to 98% of their original level, to less than 3 ppm. The total acid number (TAN) in the product oil remained unchanged at 169. [Table 8]

[0046] While the present invention has been described in detail based on what is considered to be the most practical and preferred embodiments at present for illustrative purposes, it should be understood that such details are solely for that purpose, and the present invention is not limited to the disclosed embodiments, but rather intended to cover an array of modifications and equivalents that fall within the spirit and scope of this description. For example, it should be understood that, wherever possible, one or more features of any embodiment may be combined with one or more features of any other embodiment.

Claims

1. A process for reducing contaminants contained in contaminated renewable raw materials, The process involves mixing the contaminated renewable raw material with water and at least one of a metal scavenger or reactant to form a raw material-water-reactant mixture, wherein the metal scavenger or reactant comprises an acid or salt solution, or a combination of an acid and a salt solution. The process involves feeding the aforementioned raw material-water-reactant mixture under pressure into a hydrothermal purification reactor, wherein the raw material-water-reactant mixture is exposed to heat, pressure, and turbulent conditions at at least 2,000 Reynolds numbers. Maintaining the temperature, pressure, and turbulence conditions of the raw material-water-reactant mixture in a manner that causes a rapid reaction between an inorganic contaminant and water and at least one of the metal scavenger or reactant to form an inorganic salt that separates into an aqueous phase, and preventing the organic portion of the raw material in the raw material-water-reactant mixture from undergoing thermal decomposition of carbon-carbon bonds into low molecular weight fragments, preventing the polymerization of compounds in the organic portion, and / or preventing the isomerization of compounds in the organic portion from a "cis" isomer to a "trans" isomer, thereby forming hydrothermal reactor wastewater, wherein the temperature, pressure, and turbulence conditions of the raw material-water-reactant mixture are maintained for a space time of less than 10 seconds or a maximum of 10 seconds to less than 10 minutes, wherein the space time of the raw material-water-reactant mixture in the hydrothermal purification reactor at an operating pressure in the range of 100 psig to 2,500 psig and an operating temperature in the range of 150°C to 350°C is in the range of 10 seconds to less than 10 minutes. The hydrothermal reactor wastewater is separated into an aqueous phase containing salts of the inorganic contaminants and an organic phase containing the inorganic contaminants at a lower concentration than the contaminated renewable raw materials. A process that includes this.

2. The process according to claim 1, wherein at least one of the metal scavenger or reactant is mixed with the water prior to mixing with the raw materials, or is added to the raw material-water mixture at any point throughout the process.

3. The process according to claim 1, wherein the contaminated renewable raw materials consist of renewable oils and greases, including virgin vegetable oil; tri, di, monoglycerides; free fatty acids; lecithin, gum, phospholipids; soap raw materials and fatty acid soaps; deodorized distillates; acidic oils; waste oils and greases including used cooking oil and yellow grease and brown grease and animal fat; distilled corn oil; algal oil; microbial oil; degreased oils and greases from wastewater treatment; pyrolysis oils; or mixtures thereof or aqueous emulsions.

4. The process according to claim 1, wherein the raw materials and at least one of the metal scavenger or reactant are mixed by mixing the raw materials with water using a tee connection, a static mixer, a pump, or a mixing valve while the mixture is maintained in turbulence, in order to form the raw materials-water-reactant mixture.

5. The process according to claim 1, wherein at least one of the metal scavenger or reactant comprises at least one of a strong acid, a weak acid, an organic acid, a salt, or a mixture thereof.

6. The process according to claim 1, wherein the pressure in the hydrothermal purification reactor is controlled to maintain the mixture in a liquid hydrothermal phase.

7. The process according to claim 1, wherein the raw material-water-reactant mixture may exist as a single-phase solution or as a two-phase raw material-water mixture.

8. The process according to claim 1, wherein the hydrothermal purification reactor may operate as an isothermal reactor or an adiabatic reactor.

9. The process according to claim 1, wherein the water concentration of the raw material-water-reactant mixture is controlled to result in the dissolution of inorganic salt contaminants into the aqueous phase.

10. The process according to claim 1, wherein the separation of the reactor waste liquid into the aqueous phase and the organic phase includes the steps of cooling, reducing the pressure, and separating to produce a clean oil stream and a water stream.

11. The process according to claim 1, wherein the separation of the aqueous phase and the organic phase is carried out by using at least one of a gravity separator, an electrostatically assisted gravity separator, a coalescer, a hydrocyclone, a centrifuge, the addition of a deemulsifier or water clarifier, or any combination thereof.

12. A process for reducing contaminants in renewable raw materials / water emulsions and for breaking down emulsions, The process involves mixing an oil / water emulsion with water and at least one of a metal scavenger or reactant, wherein the metal scavenger or reactant comprises an acid or salt solution, or a combination of an acid and a salt solution, forming a raw material-water-emulsion mixture. The process involves feeding the aforementioned raw material-water-emulsion mixture under pressure into a hydrothermal purification reactor, wherein the raw material-water-emulsion mixture is exposed to heat, pressure, and turbulent conditions at at least 2,000 Reynolds numbers. In a manner that causes a rapid reaction between an inorganic contaminant and water and at least one of the metal scavenger or reactant, forming an inorganic salt that separates into an aqueous phase, the temperature, pressure and turbulence conditions of the raw material-water-emulsion mixture are maintained, Maintaining the temperature, pressure, and turbulence conditions of the raw material-water-reactant mixture for a space time of less than 10 seconds or a maximum of 10 seconds to less than 10 minutes, such that the organic portion of the raw material in the raw material-water-emulsion mixture is prevented from undergoing thermal decomposition of the carbon-carbon bonds of lipids into low molecular weight fragments, the unsaturated compounds in the organic portion are prevented from polymerization, and / or the unsaturated lipid compounds in the organic portion are prevented from isomerizing from "cis" isomers to "trans" isomers, and that the space time of the raw material-water-emulsion mixture in the hydrothermal purification reactor at an operating pressure in the range of 100 psig to 2,500 psig and an operating temperature in the range of 150°C to 350°C is in the range of 10 seconds to less than 10 minutes, and that The hydrothermal reactor wastewater is separated into the aqueous phase containing the salt of the inorganic contaminant. A process that includes this.

13. The process according to claim 1, wherein the hydrothermal purification reactor operates at at least 4,000 Reynolds numbers.

14. The process according to claim 1, wherein the amounts of phosphorus, metal, and chlorine in the organic phase are reduced to less than 2 parts per million.

15. The process according to claim 1, wherein the amount of minerals, metals, and salts in the organic phase is reduced by more than 95% compared to the amount of minerals, metals, and salts in the contaminated renewable raw materials.

16. The process according to claim 1, wherein the phosphorus content of the organic phase from the contaminated renewable raw material is reduced from more than 500 parts per million to less than 2 parts per million, and the total metal content is reduced to less than 10 parts per million.

17. The process according to claim 1, wherein the hydrothermal purification reactor is operated at a pressure in the range of 3.4 MPag (500 psig) to 6.9 MPag (1000 psig) and at a temperature in the range of 200°C to 300°C, and the space time of the raw material-water-reactant mixture in the hydrothermal purification reactor is less than 2 minutes.

18. The process according to claim 12, wherein the hydrothermal purification reactor is operated at a pressure in the range of 3.4 MPag (500 psig) to 6.9 MPag (1000 psig) and at a temperature in the range of 200°C to 300°C, and the space time of the raw material-water-emulsion mixture in the hydrothermal purification reactor is less than 2 minutes.

19. The process according to claim 12, wherein at least one of the metal scavenger or reactant comprises at least one of a weak acid, an organic acid, a salt, or a mixture thereof.

20. The process according to claim 12, wherein the separation of the hydrothermal reactor wastewater into the aqueous phase comprises the steps of cooling, reducing the pressure, and separating to produce a clean oil stream and an aqueous stream, the separation of the aqueous phase being carried out by using at least one of a gravity separator, an electrostatically assisted gravity separator, a coalescer, a hydrocyclone, a centrifuge, the addition of a deemulsifier or water clarifier, or any combination thereof.

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