Hydrothermal purification process

Abstract

To provide a hydrothermal purification process.SOLUTION: A process and system for reducing contaminants contained in a contaminated feedstock comprises: mixing the contaminated feedstock with water and at least one of metal scavengers or reactants, to form a feedstock-water-reactant mixture; feeding the mixture under pressure into a hydrothermal purification reactor, wherein the mixture is subject to heat, pressure, and turbulent flow conditions to cause rapid reaction of the inorganic contaminants with the metal scavengers or reactants to form inorganic salts that partition into an aqueous phase; and 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 a conversion reaction and to form a hydrothermal reactor effluent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 064,234, filed August 11, 2020, and U.S. Patent Application No. 17 / 398,082, filed August 10, 2021, which are incorporated by reference in their entireties.

[0002] FIELD OF THE INVENTION The present invention is directed to rapid metal reduction of renewable feedstocks in combination with a hydrothermal refining (HTP) process and system for the reduction of inorganic and organic contaminants, such as salts, minerals, metals, and coke precursors, in renewable oils. The process involves combining the feedstock with at least one metal scavenger and / or reactant prior to or during the feedstock's delivery to a hydrothermal refining reactor, where the metal scavenger or reactant comprises a salt or acid solution. Conditions within the reactor are maintained to induce reaction of inorganic contaminants with 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 very short residence times under turbulent flow and controlled temperature and pressure to maintain hydrothermal (water-saturated) conditions. [Background technology]

[0003] BACKGROUND OF THE INVENTION The ever-increasing demand for renewable fuels and chemicals is forcing refineries to look to alternative hydrocarbon sources and methods for upgrading and converting these sources or feedstocks into viable products. In particular, refineries need processes to upgrade renewable feedstocks such as vegetable oils, algae and microbial oils, waste vegetable oils, yellow and brown grease, tallow, soapstock, and pyrolysis oils from cellulose into high-value light and middle distillate hydrocarbon products. Renewable waste and low-cost feedstocks often contain contaminants that must collectively be removed prior to being upgraded to clean hydrocarbon fuels or chemicals by conventional refining processes.

[0004] Renewable oils and greases typically contain phospholipid compounds or complexes, referred to herein as phospholipids. The phosphorus in phospholipids poses two major problems for conventional refinery operation. First, phosphorus serves as a nucleation site and catalyst for coke formation. High-phosphorus renewable feedstocks cause coking in calciners and heat exchangers, significantly increasing downtime for coke removal and other maintenance operations. Second, phosphorus irreversibly fouls and deactivates catalysts used in hydrotreating, hydrocracking, and hydroisomerization, leading to more frequent and costly downtime and catalyst replacement. While catalysts may be protected using guard beds containing alumina or similar high-surface-area materials capable of absorbing low concentrations of metal and phosphorus compounds, this approach is cost-prohibitive for renewable oils containing high levels of phospholipids.

[0005] Renewable oils containing phospholipids can be chemically degummed to eliminate phosphorus. Phospholipids consist of a diglyceride (two fatty acid chains covalently attached to a glycerol molecule through an ester bond), a phosphate group (PO4 3- ), typically containing choline (CH 14They are complexed with various organic molecules such as NO, ethanolamine, serine, inositol, and the like. Traditional chemical degumming uses phosphoric acid or citric acid to remove phospholipids as phosphatidic acid, which contains two fatty acids and a glycerol backbone from the original phospholipid. Therefore, traditional chemical degumming of phospholipid-rich plant or algal oils results in significant yield losses because the entire phospholipid diglyceride is removed from the processed oil.

[0006] Processes for converting renewable oils into renewable hydrocarbon fuels (as opposed to fatty acid methyl esters, or FAME, biodiesel) typically hydrotreat triglyceride feedstocks, resulting in hydrogenolysis of the glycerin backbone. Due in part to the hydrogen required to hydrotreat the glycerin backbone to produce propane, this process requires up to 100% more hydrogen than is required for fatty acid deoxygenation alone. Hydrolysis or "lipolysis" processes may be used to produce glycerin and free fatty acids, which can be used for renewable fuel or chemical generation. A widely adopted hydrolysis process is the Colgate-Emery process.

[0007] The Colgate-Emery process is a continuous countercurrent process typically operating at 250–260°C and 725 psig. Oil is fed to the bottom of the cracking tower, and demineralized water is fed to the top of the tower. Fatty acids are discharged from the top of the tower, and a water-glycerin solution (sweet water) is removed from the bottom. 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 approximately 290°C; 2) the need to provide a long residence time for hydrolysis and allow gravity separation of the free fatty acids and glycerin-water phases; 3) the need to use a relatively clean degummed feedstock to prevent emulsion formation; and 4) the economic tradeoff between operating temperature, pressure, and residence time. Operating the Colgate-Emery process at higher temperatures requires higher pressures and risks glycerin decomposition due to the long residence time at temperatures around 290 °C. The large equipment required makes this process cost-prohibitive for alternative fuel production due to the large amount of oil that must be processed to achieve economic viability. Sweet water (a dilute solution of glycerin) can form emulsions due to the presence of residual free fatty acids and partially hydrolyzed triglycerides. To recover the dilute glycerin product, sweet water must typically be settled with a demulsifier at 80–90 °C for up to 24 hours. Vacuum distillation can also be used to further separate long- and short-chain fatty acids.

[0008] Soapstock is formed during edible oil refining, where sodium hydroxide is used to remove free fatty acids from vegetable oils as sodium soap. Soapstock contains sodium soap as well as phospholipids. Large quantities of soapstock are produced worldwide. Because clean free fatty acids are much more valuable as feedstocks for biofuel production and other uses, acidification using a strong acid, 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 and use of strong acids, the process results in the production of an acidic waste liquor containing phospholipids and other compounds.

[0009] Vegetable oils, algae 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 cationic soaps. These metals must be reduced to below a few ppm to prevent coke formation and catalyst fouling in biofuel production processes. It should be understood that waste fats, oils, greases, phospholipid gums, soaps, and mixtures thereof can form mixtures and emulsions that interfere with or prevent conventional pretreatment operations. Summary of the Invention [Means for solving the problem]

[0010] (Summary of the Invention) The present invention is directed to a hydrothermal purification process and system for renewable feedstocks, such as vegetable oils, algae and microbial oils, waste vegetable oils, brown grease, yellow grease, animal fat, chicken fat, distiller's oil, corn oil, soapstock, tall oil, and bio-(pyrolysis) oils from cellulosic materials. The present invention has various advantages over other purification processes, such as chemical degumming, desalting processes, or other chemical, extraction, filtration, or thermal processes. Advantages include, but are not limited to: 1) Equipment exhibiting a small footprint that can be integrated with conventional oil refineries, waste oil collectors, or oilseed crushing 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) Polyethylene reduction; 5) Silicon reduction; and 6) Elimination of solid waste and associated increase in clean product yield due to recovery of fatty acids from phospholipids and metal soaps. The system is particularly desirable for use in processing crude or waste greases, oils, and greases, including algae oils and tallow. Under the turbulent, high-Reynolds-number conditions employed during hydrothermal refining, renewable oil and water become intimately mixed, resulting in rapid mass transfer and conversion of soaps and other contaminants to salts, which rapidly partition into the aqueous phase during oil-water separation. Addition of metal scavengers and / or reactants prior to or during feedstock delivery to the hydrothermal refining reactor accelerates metal contaminant reduction to very low ppm levels, with the metal scavengers and reactants comprising a salt or acid solution along with water. Conditions within the reactor are maintained to allow reaction of inorganic contaminants with the acid and / or salt scavengers while preventing the organic portion of the feedstock from undergoing conversion reactions such as polymerization or pyrolysis.

[0011] When used for metal reduction, such as for soapstock or lipids containing metal soaps, the present invention achieves rapid acidification without the need for strong mineral acids. Because phospholipids are completely hydrolyzed during hydrothermal refining, a clean lipid product is recovered. Not only are diglyceride residues produced by phospholipid hydrolysis recovered within the oil phase to improve yield, but the oil and water phases can then be easily separated without the formation of a rag layer or residual waste generated by the presence of phospholipids.

[0012] According to one embodiment of the present disclosure, a process for reducing contaminants contained in renewable feedstocks includes providing at least one metal scavenger or reactant, where the metal scavenger or reactant comprises an acid or salt solution, or a combination of an acid and a salt solution. The process includes mixing the metal scavenger or reactant with water and a feedstock to form a feedstock-water-reactant mixture, and feeding the feedstock-water-reactant mixture into a hydrothermal purification reactor, where the mixture is exposed to heat, pressure, and turbulent flow conditions. The process further includes maintaining the temperature, pressure, and turbulent flow conditions of the feedstock-water-reactant mixture in the hydrothermal purification reactor in a manner that causes the inorganic contaminants to rapidly react with the metal scavenger or reactant to form inorganic salts that partition into the aqueous phase. The process further includes maintaining the temperature, pressure, and turbulent flow conditions of the feedstock-water-reagent mixture in the hydrothermal purification reactor to prevent the organic portion of the feedstock in the mixture from undergoing thermal decomposition of lipid carbon-carbon bonds into lower molecular weight fragments and polymerization into higher molecular weight hydrocarbons, and / or preventing unsaturated compounds from isomerizing from "cis" to "trans" isomers. The process then includes separating the hydrothermal purification reactor effluent into an aqueous phase containing salts of inorganic contaminants and an organic phase, or resultant product stream, containing inorganic contaminants at a lower concentration than the contaminated feedstock.

[0013] The contaminated renewable oil may be comprised of lipid-type oils, including, but not limited to, virgin vegetable oils, tri-, di-, and monoglycerides, free fatty acids, lecithins, gums, and phospholipids, fatty acid soaps, deodorized distillates, acid oils, crude tall oil and its derivatives, used cooking oils, waste fats, oils, and greases, including yellow grease, brown grease, chicken fat, and animal fat, distilled corn oil, algal oil, microbial oil, bio-oil, or mixtures or water emulsions thereof. When the feedstock comprises renewable lipid-based oils, the organic phase after separation comprises lipids with low metal content. It is understood that different feedstocks may be blended in proportions that will improve processability, performance, and economics.

[0014] The feedstock and metal scavenger or reactant, comprising a salt or acid solution, or mixtures thereof, can be mixed by combining the streams using a Tee connection, static mixer, pump, and the like, while the mixture is maintained in turbulent flow to form a feedstock-water-reactant mixture. The metal scavenger and / or reactant can be added to the water stream before mixing with the feedstock, or can be added to the feedstock-water mixture before entering the hydrothermal purification reactor, or can be added at any point along the process, including after treatment in the hydrothermal purification reactor.

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

[0016] The hydrothermal purification reactor can comprise a tubular plug flow reactor (PFR) designed to maintain turbulent flow conditions equal to or exceeding a Reynolds number of 2,000. The feed-water-reactant mixture can be heated to a reaction temperature ranging from 150°C to 350°C. The pressure within the hydrothermal purification reactor can be maintained within a range of 100 psig to 2,500 psig and controlled to maintain the mixture in the liquid hydrothermal phase. Under these conditions, the space time of the feed-water-reactant mixture within the hydrothermal reactor can range from about 10 seconds to 15 minutes, 10 seconds to 10 minutes, or 10 seconds to 5 minutes. Alternatively, the hydrothermal reactor can be operated at a pressure ranging from 500 to 1,000 psig, a temperature ranging from 200 to 300°C, and a space time (or superficial residence time) of up to 2 minutes or less. It should be understood that the pressure, temperature, and residence time used within a hydrothermal purification reactor can be determined based on several variables, including the specific feedstock being processed, the type of contaminants in the feedstock, and the specific metal scavenger or reactant, including acid or salt solution, mixed with the water and feedstock. It should also be understood that the specific pressure, temperature, and residence time may be outside the parameters outlined above, depending on the variables listed above and the desired level of contaminant reduction. It should be understood that space time is synonymous with "supercritical residence time" and is generally used in connection with flow reactors where reaction, fluid density, or phase changes occur 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%, respectively, of the density at the entry conditions. This means that the actual residence time is approximately 87%-72% of the space time at these operating temperatures.

[0017] The feedstock-water-reactant mixture can exist as a single-phase solution or as a two-phase feedstock-water mixture, depending on the operating temperature and the solubility of the feedstock in water at the operating temperature. The water concentration of the feedstock-water-reactant mixture is controlled to result in complete dissolution of inorganic salt contaminants in the aqueous effluent. The process of separating the reactor effluent into an aqueous stream and an organic product stream includes the steps of cooling, depressurizing, and separating to produce a clean lipid stream and an aqueous stream. Separation of the oil phase from the aqueous phase can be carried out using at least one of a gravity separator, a hydrocyclone, a centrifuge, and / or any combination thereof, including a gravity separator, electrostatic or coalescing element, and can be accelerated by the use of a demulsifier. Separation can be carried out before or after cooling and pressure reduction.

[0018] The present invention also includes a hydrothermal purification system for decontaminating renewable oils, comprising a hydrothermal purification reactor system operated at temperature, pressure, and turbulent flow conditions to maintain a liquid hydrothermal phase that results in rapid phospholipid hydrolysis without causing pyrolysis, polymerization, or isomerization of the carbon-carbon bonded lipids of the feedstock, and a separation system for removing a clean oil product stream and a water stream containing inorganic contaminants from the effluent of the hydrothermal purification reactor system. The hydrothermal purification reactor system can be operated at a turbulent flow rate having a Reynolds number (Re) of at least 2,000. The hydrothermal purification reactor system can be 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, with oil purification occurring in a space time (or superficial residence time) of about 10 seconds to 15 minutes, 10 seconds to 10 minutes, or 10 seconds to 5 minutes. Alternatively, the hydrothermal refining reactor can be operated at a pressure in the range of 500-1,000 psig, a temperature in the range of 200-300°C, and a space time of up to 2 minutes or less. It is understood that the water-to-oil ratio, pressure, temperature, and residence time of the hydrothermal refining reactor system can be determined based on several variables, including the particular feedstock being processed, the type of contaminants in the feedstock, the degree of hydrolysis, and the particular metal scavenger and / or reactant, which may comprise an acid or salt solution mixed with the water and feedstock. It is also understood that the particular pressure, temperature, and space time may be outside the parameters outlined above, depending on the variables listed above and the level of contaminant reduction desired. The present invention provides, for example, the following. (Item 1) 1. A process for reducing contaminants contained in a contaminated feedstock, comprising: mixing the contaminated feedstock with water and at least one of a metal scavenger or a reactant, the metal scavenger or reactant comprising an acid or a salt solution, or a combination of an acid and a salt solution, to form a feedstock-water-reactant mixture; conveying the feed-water-reactant mixture under pressure into a hydrothermal purification reactor, wherein the mixture is subjected to heat, pressure, and turbulent flow conditions; maintaining the temperature, pressure, and turbulent flow conditions of the feed-water-reactant mixture in a manner that causes a rapid reaction of the inorganic contaminants with at least one of the metal scavenger or reactant to form an inorganic salt that partitions into an aqueous phase; and maintaining the temperature, pressure, and turbulent flow conditions of the feed-water-reactant mixture for a predetermined space-time period in a manner that prevents the organic portion of the feedstock in the mixture from undergoing thermal decomposition of carbon-carbon bonds into lower molecular weight fragments, prevents compounds in the organic fraction from polymerizing, and / or prevents compounds in the organic fraction from isomerizing from "cis" to "trans" isomers, forming a hydrothermal reactor effluent; separating the hydrothermal reactor effluent into an aqueous phase containing salts of inorganic contaminants and an organic phase containing inorganic contaminants at a lower concentration than the contaminated feedstock; The process includes: (Item 2) 2. The process of claim 1, wherein at least one of the metal scavenger or reactant is mixed with the water prior to mixing with the feedstock or is added to the oil-water mixture at any time throughout the hydrothermal refining process. (Item 3) 2. The process of claim 1, wherein the contaminated feedstock consists of virgin vegetable oils, tri-, di-, and monoglycerides, free fatty acids, lecithin, gums, and phospholipids, soapstock and fatty acid soaps, deodorized distillates, acid oils, used cooking oils, waste greases, oils and greases including yellow grease, brown grease, and tallow, renewable oils and greases including distilled corn oil, algae oil, microbial oil, defatted oils and greases from wastewater treatment, pyrolysis oil, or mixtures or water emulsions thereof. (Item 4) 10. The process of claim 1, wherein different feedstocks may be blended in proportions that will improve feedstock processability, system performance, and / or process economics. (Item 5) 2. The process of claim 1, wherein the feedstock and at least one of the metal scavenger or reactant are mixed by combining the streams using a Tee connection, static mixer, pump, or mixing valve while maintaining turbulent flow of the mixture to form a feedstock-water-reactant mixture. (Item 6) 2. The process of 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, and mixtures thereof. (Item 7) Item 1. The process of item 1, wherein the hydrothermal purification reactor comprises a tubular plug flow reactor (PFR) designed to maintain turbulent flow conditions at a Reynolds number (Re) of at least 2,000. (Item 8) Item 1. 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) 2. The process of claim 1, wherein the pressure in the hydrothermal purification reactor is maintained within a range of 100 psig to 2,500 psig and controlled to maintain the mixture in the liquid hydrothermal phase. (Item 10) 2. The process of claim 1, wherein the feed-water-reactant mixture can exist as a single-phase solution or can exist as a two-phase feed-water mixture. (Item 11) 2. The process of claim 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 feed-water-reactant mixture in the hydrothermal purification reactor is in the range of about 10 seconds to 15 minutes. (Item 12) 2. The process of claim 1, wherein the hydrothermal purification reactor may be operated as an isothermal reactor or an adiabatic reactor. (Item 13) 2. The process of claim 1, wherein the water concentration of the feed-water-reactant mixture is controlled to result in dissolution of inorganic salt contaminants into the aqueous phase. (Item 14) 2. The process of claim 1, wherein separating the reactor effluent into the aqueous stream and the product stream comprises cooling, depressurizing, and separating to produce a clean oil stream and a water stream. (Item 15) 15. The process of claim 14, wherein separation of the clean oil and water streams is accomplished by using at least one of a gravity separator, an electrostatically assisted gravity separator, a coalescer, a hydrocyclone, a centrifuge, the addition of a demulsifier or a water clarifier, or any combination thereof. (Item 16) 1. A hydrothermal purification system for decontaminating renewable oil, comprising: a hydrothermal purification reactor system operated under temperature, pressure, and turbulence conditions to maintain a liquid hydrothermal phase that results in rapid reaction of inorganic contaminants with the acid and salt scavengers in the feedstock-water-reactant mixture without causing degradation of lipid carbon-carbon bonds or isomerization of the feedstock; a separation system for removing a clean oil product stream and a water stream containing inorganic contaminants from the effluent of said hydrothermal refining reactor system; A system comprising: (Item 17) Item 17. The system of item 16, wherein the hydrothermal purification reactor system is operated in turbulence having a Reynolds number (Re) of at least 2,000. (Item 18) Item 17. The system of item 16, wherein 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 oil purification occurs at a residence time in the range of about 10 seconds to 15 minutes. (Item 19) 1. A process for reducing contaminants in renewable raw material / water emulsions and breaking the emulsions, comprising: mixing the oil / water emulsion with water and at least one of a metal scavenger or reactant, the metal scavenger or reactant comprising an acid or salt solution, or a combination of an acid and a salt solution, to form a feedstock-water-emulsion mixture; feeding the feed-water-emulsion mixture under pressure into a hydrothermal purification reactor, wherein the mixture is exposed to heat, pressure, and turbulent flow conditions; maintaining temperature, pressure, and turbulent flow conditions of the feedstock-water-emulsion mixture in a manner that causes rapid reaction of the inorganic contaminants with at least one of the metal scavenger or reactant to form inorganic salts that partition into the aqueous phase; maintaining temperature, pressure, and turbulent flow conditions of said feed-water-reactant mixture for a predetermined space-time period in a manner that prevents the organic portion of the feed in said mixture from undergoing thermal decomposition of carbon-carbon bonds into lower molecular weight fragments, prevents compounds in said organic fraction from polymerizing, and / or prevents compounds in said organic fraction from isomerizing from "cis" to "trans" isomers, and forms a hydrothermal reactor effluent; separating the hydrothermal reactor effluent into an aqueous phase containing salts of inorganic contaminants; A method comprising: (Item 20) 20. The process of claim 19, wherein the feed-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 for a space time in the range of about 10 seconds to 15 minutes. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of a hydrothermal refining (HTP) system using acidification for reducing contaminants contained within renewable feedstocks, according to an embodiment of the present disclosure, incorporating a plug flow reactor and an oil-water separator for the recovery of refined renewable oil. DETAILED DESCRIPTION OF THE INVENTION

[0020] Description of the Invention As used herein, unless expressly stated otherwise, all numbers, such as those specifying values, ranges, amounts, or percentages, can be read as if preceded by the word "about," even if the term does not explicitly appear. Any numerical ranges stated herein are intended to include all subranges therebetween. Plural forms include the singular, and vice versa. When ranges are given, any endpoints of those ranges and / or numbers within those ranges can be combined to form the scope of the invention. The terms "including," "e.g.," "for example," and equivalents mean "including, but not limited to, such as, for example."

[0021] For purposes of the remainder of this specification, the terms "upper," "lower," "right," "left," "vertical," "horizontal," "top," "bottom," "lateral," "longitudinal," and derivatives thereof, shall refer to the present invention as oriented in the drawing figures. However, it should be understood that the present invention may contemplate various alternative modifications, except where expressly specified to the contrary. 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. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered limiting. Like reference numerals refer to like elements.

[0022] It should be understood that any numerical ranges stated herein are intended to include all subranges subsumed therein. For example, a range of "1 to 10" is intended to include the stated minimum value of 1 and the stated maximum value of 10, as well as all subranges therebetween, i.e., all subranges beginning with a minimum value equal to or greater than 1 and ending with a maximum value equal to or less than 10, and all subranges therebetween, for example, 1 to 6.3, or 5.5 to 10, or 2.7 to 6.1.

[0023] The present invention is directed to a continuous-flow process and system for the hydrothermal refining of renewable feedstocks, such as vegetable oils, algae and microbial oils, waste vegetable oils, brown grease, tallow, tall oil, acid oils, and bio-oils. The process separates undesirable contaminants, such as minerals, metals, and salts, from the feedstock to produce a clean refined oil. By "clean," we mean that contaminants in the product are 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 feedstock. Contaminant levels in clean oil are minimized, significantly reducing precipitation, polymerization, and coking in downstream conversion equipment and deactivation or fouling of downstream conversion catalysts. The refining process is accomplished by hydrolysis, solvation, acidification, and concentration of contaminants in an aqueous waste stream. HTP processes do not involve feedstock conversion. By "conversion," we mean molecular rearrangements of lipids or FFAs, such as those that occur 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 feedstocks and reducing or eliminating the problems associated with the conversion of contaminated feedstocks.

[0024] The contaminated feedstock may be a renewable feedstock, such as vegetable oil. Vegetable oils suitable for treatment according to the present invention may include canola, carinata, castor, jatropha, palm, pongamia, soybean, tallow, and / or corn (such as obtained from distillers grains) oils, soapstock, waste vegetable oils, yellow grease (from cooking oils), brown grease (from grease traps and wastewater treatment), highly acidic oils (also referred to as acidic oils), animal tallow, algal oils, microbial oils, terpene and other pine-related by-products from tall oil, or other biosynthetic oils (such as obtained from pyrolysis, esterification, oligomerization, or polymerization), and mixtures thereof. It should be understood that waste 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. 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 greater than 95% (e.g., greater than 99%) reduction of phosphorus, salt, mineral, and metal content. HTP process conditions can be controlled in a manner that will retain triglycerides in triglyceride-containing feedstocks, or process conditions can be adjusted to achieve rapid hydrolysis of triglycerides to free fatty acids. In phospholipid-containing feedstocks, HTP process conditions can be controlled in a manner that reduces the phosphorus content to less than 2 parts per million (ppm), with little yield loss. The system of the present invention includes a hydrothermal refining reactor system coupled with high temperature, high pressure, acid, salt, or metal scavenger addition, with no other operations or additions in between, and components for separation and / or recovery of a clean oil product. The integrated reactor and separation system is based on the HTP process.

[0025] Referring now to FIG. 1 , this illustrates a schematic diagram of an HTP process and system, generally designated as 110, according to an embodiment of the present disclosure for the refining of renewable oils, including waste greases, oils, and greases, such as brown grease and yellow grease, from which clean oil and water products are recovered by conventional oil-water separation processes. The process and system includes providing a renewable contaminated feedstock 132. The contaminated feedstock 132 may be fed into an equalization tank 134. Generally, the equalization tank acts as a holding tank, allowing for equalization of the feedstock flow. The equalization tank may also act as a regulating operation, where the temperature of the feedstock is controlled to maintain desired flow characteristics. The contaminated feedstock exits the equalization tank 134 at 136 and enters a pump 138 to form a pressurized feed stream 140. The pressurized feed stream 140 may be preheated by a heating device, such as a heat exchanger 142, to form a heated feed stream 144.

[0026] Water feed stream 112 is fed to equalization vessel 116 and can be pumped at 118 to pump 120 to form pressurized water stream 122. Pressurized water stream 122 can be heated by a heating device, such as heat exchanger 124, to form heated water stream 126. It should be understood that streams 126 and 144 can be heated by any known process or device, including heat recovery from other process streams, to optimize overall thermal efficiency. Salts or solutions of reactants and / or metal scavenger are added at 114. It should be understood that stream 114 can be added at any location throughout the HTP process, such as in equalization vessel 116 and / or to streams 118, 122, and 126. It should also be understood that reactants and / or metal scavenger can be added at multiple of these locations 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 a liquid phase at conditions necessary to accomplish metal reduction and phospholipid hydrolysis based on the feed contaminants. The renewable feedstock can be miscible with water at temperatures as low as 300°C and pressures as low as 1,250 psig. It should be understood that the mixing device 150 can combine the two streams via a Tee connection or can include one or more conventional static mixers, mixing valves, or pumps. The type of mixing device and the degree of mixing depend on the feedstock, its flowability, and its miscibility with water. As shown in FIG. 1, reactant and / or metal scavenger salts 114 can also be added to stream 152. The high-pressure mixed stream 152 is heated in a feed-to-effluent heat exchanger 154 to form a heated stream 156. It should be understood that feed-effluent heat exchanger 154 can be any combination of heat exchangers configured throughout the process to maximize overall thermal efficiency. Stream 156 is fed to heater 158, which can be any type of heater or heat exchanger, which heats the oil-water mixture in stream 160 to a target processing temperature, such as in the range of 150° C. to 350° C., before entering hydrothermal purification reactor 162.

[0028] The hydrothermal purification reactor 162 operates at a high Reynolds number (at least 2,000 or higher), creating turbulent flow dynamics and achieving 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 lipolysis via the Corrugate-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 for the hydrothermal purification reactor 162 may be selected based on the contaminants in the feedstock and the purification requirements. The water-to-oil weight ratio in the hydrothermal purification reactor 162 may be 1:100 to 3:1, such as 1:10 to 1:1. The hydrothermal purification reactor 162 is operated at a pressure sufficient to maintain a liquid phase, such as within the range of 250 to 3,000 psig or 500 to 1,500 psig. The hydrothermal purification reactor 162 is configured to achieve and operate under turbulent flow conditions to optimize mixing and maximize mass and heat transfer. At the operating temperature and pressure, the space time ranges from up to 15 minutes or less than 10 seconds, depending on the specific feedstock and pollutant reduction requirements. As used herein, space time is calculated at standard conditions (20°C temperature and 1 atmosphere pressure) based on the reactor volume and feedstock volume. The actual hydraulic residence time may be calculated based on the operating conditions (temperature and pressure) and the water-to-oil weight ratio. The hydrothermal purification reactor 162 can be a tubular plug flow reactor (PFR). It should be understood that the hydrothermal purification reactor can be operated as an adiabatic reactor or an isothermal reactor due to the very short space time. Different reactor conditions provide a range of mixing, heat transfer, space-time, and product quality scenarios suitable for feedstock types and pollutant reduction requirements. Generally, PFR systems will exhibit Reynolds numbers (Re) of at least 2,000, in the range of 2,000-4,000, or even above 4,000, and will exhibit turbulent flow, intimate mixing, and high heat and mass transfer rates.According to one embodiment, the present invention can employ a combination of space times of up to 15 minutes or less throughout the hydrothermal reaction zone and Reynolds numbers (Re) greater than 4,000. One example of a hydrothermal purification reactor 162 that can be used is the high-rate reactor disclosed in U.S. Pat. No. 10,071,322, the disclosure of which is incorporated herein in its entirety.

[0029] Therefore, the hydrothermal refining reactor is operated under conditions where conversion reactions do not occur and coke is not formed, which would affect performance. Instead, inorganic contaminants are liberated at hydrothermal operating conditions and removed by the integrated hydrothermal refining reactor and oil-water separation system.

[0030] The effluent 164 from the hydrothermal refining reactor 162 is cooled in a feed-to-effluent heat exchanger 154, resulting in a partially cooled product 166, which then passes through a pressure control valve 168, which maintains the system pressure. Reactant and / or metal scavenger salt 114 can also be added to stream 164 after exiting the hydrothermal refining reactor 162. The depressurized product stream 170 is further cooled, if necessary, by a cooling heat exchanger 172. The cooled product stream 170 is then fed to an oil-water separator 176. Separation of the oil phase from the water phase can be performed using at least one of a gravity separator, a hydrocyclone, a centrifuge, and / or any combination thereof, including a gravity separator, electrostatic or coalescer element, and can be accelerated by the use of a demulsifier to reduce the water content of the product. It should be understood that separation can be performed before or after pressure reduction, depending on subsequent processing of the clean product oil. After partial cooling, a high-pressure separator can be employed to produce pressurized clean product oil for subsequent processing to eliminate the need for additional pumping. Clean product oil 178 and process water stream 180 are removed from separator 176. Operated as described above, hydrothermal system 110 rapidly dissociates inorganic contaminants (e.g., salts, minerals, and / or metals), which are separated into process water stream 180, and greater than 95% (e.g., greater than 99%) of the contaminants are removed from contaminated feedstock 132.

[0031] The clean oil 178 may be further processed into chemicals or fuels (not shown), depending on the type of feedstock being processed and the product objectives. The renewable feedstock may be hydrothermally cracked (as described above) into synthetic crude oil via a high-ratio hydrothermal reactor system and then hydroprocessed into transportation fuels or chemicals. Alternatively, the clean renewable oil product 178 may be converted into biodiesel via esterification, or converted into renewable fuels and chemicals via hydrotreating, 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, 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 feedstock and the purpose of the water recovery and reuse. For example, when the hydrothermal system 110 is used to desalinate a feedstock, 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 rapid hydrolysis of triglyceride oil, the clean oil 178 consists primarily of FFAs, and the process water stream 180 contains water and glycerin. Pure glycerin can be recovered from the process water stream 180 by conventional distillation processes.

[0034] Alternatively, the system 110 may be used for degumming or phosphorus removal. Rapid phosphorus removal is most effectively accomplished in the liquid phase, where temperature and pressure are controlled to maintain the water in a saturated phase. Rapid hydrolysis of phospholipids in the hydrothermal purification reactor 162 is achieved by cleaving the phosphate group from the glycerol backbone of the phospholipid, as well as cleaving groups from the phospholipid, such as choline, ethanolamine, serine, or inositol components of the phospholipid, which may include fatty acids and other organic moieties. Phosphoric acid is removed in the aqueous phase of the reaction mixture, while fatty acids, which typically represent greater than 70% by weight of the phospholipids, are retained for subsequent processing into chemicals or fuels. The phosphorus content of clean oil 178 from a high-phospholipid feedstock can be reduced from greater than 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 greatly increased compared to conventional degumming processes. For example, for algal oil containing 6,000 ppm phosphorus, the process of the present invention can increase the yield of low phosphorus oil by more than 10%, such that the clean oil 178 contains clean FFAs with low phosphorus content. The process water stream 180 is a mixture of water and phosphate ions (PO 3- ), which can be recovered and reused as a source of nutrients for growing crops or algae.

[0035] An advantage of the hydrothermal purification process and system of the present invention is that the system's small physical footprint requires low capital and operating costs. The hydrothermal process can operate in a very short space time, such as less than two minutes, resulting in relatively small equipment and low capital costs. When used for degumming, the operating costs for HTP are lower than conventional chemical degumming because no degumming acid is required, the 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 achieves rapid acidification without the need for strong mineral acids to obtain a clean lipid product without the formation of residual waste streams caused by the presence of phospholipids, because phospholipids are hydrolyzed during hydrothermal purification. Not only can the diglyceride residue produced by the hydrolysis of phospholipids be recovered to improve yield, but the oil and aqueous phases can then be easily separated without rag layer formation or residual waste generation. When used for rapid acidification, such as for soap stock 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 a clean lipid product without rag layer formation. The use of weaker acids allows for the use of lower cost construction materials, which reduces capital costs.

[0036] It should be understood that optimal operating conditions depend on the feedstock quality, and that operating conditions can be varied to achieve the desired product quality. Operating conditions can be varied to maximize demineralization (e.g., waste vegetable oil), maximize acidification, maximize phospholipid hydrolysis, or maximize glyceride hydrolysis and glycerin recovery. It should also be understood that the hydrothermal process can be operated in a manner to reduce metals in highly contaminated feedstocks, such as brown grease, and produce a clean lipid product and wastewater containing inorganic contaminants.

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

[0038] (Example) Example 1: Distilled Corn Oil and Used Cooking Oil A 50:50 blend of distilled corn oil (DCO) and used cooking oil (UCO) was fed to 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 combined volumetric flow rates of water and oil. The operating conditions are shown in Figure 1. The pressure was controlled at 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 dosage rate equivalent to 2.6 mmol of phosphoric acid per liter of feed oil. The oil and water were gravity separated in a product separator at 80°C. [Table 1]

[0039] Table 2 compares 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 had occurred. [Table 2]

[0040] Example 2: Brown Grease Brown grease was fed to 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 combined volumetric flow rates of water and oil. Operating conditions are shown in Table 3. Pressure was controlled at 1,000 psig, which ensured that liquid-phase hydrothermal conditions were maintained. Citric acid was added to the feedwater to achieve an acid dosage rate equivalent to 30 mmol citric acid per liter of feed oil. Oil and water were gravity separated in a product separator at 80°C. [Table 3]

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

[0042] Example 3: Crude soybean oil Crude soybean oil is typically refined, bleached, and deodorized to achieve a low-phosphorus and metals product through a multi-stage process. The crude soybean oil used in this example was unrefined and contained more than 500 ppm phosphorus and more than 260 ppm other metals. The crude soybean oil was fed to 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 combined volumetric flow rates of water and oil. The operating conditions are shown in Table 5. The pressure was controlled at 1,000 psig, which ensured that liquid-phase hydrothermal conditions were maintained. Citric acid was added to the feedwater to achieve an acid dosage rate equivalent to 11.4 mmol of citric acid per liter of feed oil. The oil and water were gravity separated in a product separator at 80°C. [Table 5]

[0043] Table 6 compares 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 near 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, yellow-black, odorous liquid obtained as a by-product of the Kraft process for wood pulp production, primarily during the pulping of softwoods. It consists of a mixture of rosin acids, fatty acids, alcohols, sterols, and other alkyl hydrocarbon derivatives. Crude tall oil was fed to 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 combined volumetric flow rates of water and oil. The operating conditions are shown in Table 7. The pressure was controlled at 2,000 psig, which ensured that liquid-phase hydrothermal conditions were maintained. In this example, phosphoric acid was added to the water feed stream. Oil and water were gravity separated in a product separator at 80°C. [Table 7]

[0045] Table 8 compares the feed and product properties. Phosphorus was reduced from 13.4 to less than 1 ppm. Total metals were reduced by 98% 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 for purposes of illustration, based on what are presently considered to be the most practical and preferred embodiments, it should be understood that such detail is for that purpose only, and the present invention is not limited to the disclosed embodiments, but on the contrary, is intended to cover modifications and equivalent arrangements within the spirit and scope of the present description. For example, it should be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment may be combined with one or more features of any other embodiment.

Claims

1. A hydrothermal purification system for reducing contaminants contained in contaminated renewable feedstocks, the hydrothermal purification system comprising: a mixing point where the contaminated renewable feedstock is mixed with at least one of a water feed and a metal scavenger or reactant, the metal scavenger or reactant comprising an acid or salt solution, or a combination of an acid and a salt solution, to form a feedstock-water-reactant mixture; at least one pump located upstream of the mixing point to pressurize the contaminated renewable feedstock and the water feed; at least one heating device for heating the contaminated renewable feedstock and the water feed; a hydrothermal purification reactor system disposed downstream of the mixing point, the hydrothermal purification reactor system is operated under temperature, pressure, and turbulent flow conditions at a Reynolds number of at least 2,000 to maintain a liquid hydrothermal phase that results in rapid reaction of inorganic contaminants with the acid and salt scavengers in the feedstock-water-reactant mixture without causing lipid carbon-carbon bond cracking or isomerization of the feedstock; the hydrothermal purification reactor system has an operating pressure in the range of 250 psig to 3,000 psig and an operating temperature in the range of 225°C to 350°C; a hydrothermal purification reactor system; a separation system for removing a clean oil product stream and a water stream containing said inorganic contaminants from the effluent of said hydrothermal refining reactor system; A hydrothermal purification system.

2. A hydrothermal purification system as described in claim 1, wherein the at least one heating device utilizes heat from the waste liquid of the hydrothermal purification reactor system.

3. A hydrothermal purification system as described in claim 1, wherein the separation system comprises a gravity separator.

4. A hydrothermal purification system as described in claim 3, wherein one or more demulsifiers are added to the separation system.

5. A hydrothermal purification system as described in claim 1, wherein the operating temperature is within the range of 300°C to 350°C.

6. The hydrothermal purification system comprises: a first equalization vessel for the contaminated feedstock, the first equalization vessel enabling equalization of the flow of the contaminated feedstock; a second equalization tank for the water carrier, the second equalization tank enabling equalization of the flow of the water carrier; The hydrothermal purification system of claim 1 further comprising:

7. A hydrothermal purification system as described in claim 6, wherein the first equalization tank controls the feedstock temperature of the contaminated renewable feedstock, and the second equalization tank controls the water temperature of the water supply agent.

8. A hydrothermal purification system as described in claim 1, wherein the weight ratio of water to oil in the hydrothermal purification reactor system is 1:100 to 3:

1.

9. A process for reducing contaminants contained in contaminated renewable feedstocks, the process comprising: using a first equalization tank to equalize the flow of the contaminated renewable feedstock and a second equalization tank to equalize the flow of the water carrier; pressurizing the contaminated renewable feedstock and the water feed; heating the contaminated renewable feedstock and the water carrier; mixing the contaminated renewable feedstock with the water carrier; mixing the water carrier with one or more reactants to form a feedstock-water-reactant mixture prior to mixing the contaminated renewable feedstock with the water carrier; heating the feedstock-water-reactant mixture; feeding the feedstock-water-reactant mixture into a hydrothermal purification reactor; the feed-water-reactant mixture is maintained in a liquid hydrothermal phase and is subjected to temperature, pressure and turbulent flow conditions at a Reynolds number of at least 2,000; the hydrothermal purification reactor has an operating pressure in the range of 225 psig to 3,000 psig and an operating temperature in the range of 225°C to 350°C; And, depressurizing the hydrothermal reactor effluent; cooling the hydrothermal reactor effluent; separating said hydrothermal reactor effluent into an aqueous phase containing inorganic contaminants and an organic phase containing said inorganic contaminants at a lower concentration than said contaminated feedstock; The process includes:

10. The process of claim 9, wherein the hydrothermal purification reactor comprises a tubular plug flow reactor (PFR).

11. The process of claim 9, wherein the hydrothermal purification reactor is configured to operate as one of an isothermal reactor or an adiabatic reactor.

12. The process of claim 9, wherein the one or more reactants comprise an acid or salt solution, or a combination of an acid and a salt solution.

13. The process of claim 9, wherein the operating temperature is in the range of 300°C to 350°C.

14. The process of claim 9, wherein the space time of the feed-water-reactant mixture in the hydrothermal purification reactor is in the range of 10 seconds to 15 minutes.

15. A system for reducing contaminants contained in contaminated renewable feedstocks, the system comprising: a first equalization tank for equalizing the flow rate of the contaminated feedstock; a second equalization tank for equalizing the flow rate of the water feed; at least one feed pump for pressurizing the contaminated feed; at least one water pump for pressurizing the water supply; a first heating device for heating the contaminated material; a second heating device for heating the water carrier; a mixing point where the contaminated renewable feedstock is mixed with at least one of the water feedstock and a metal scavenger or reactant, the metal scavenger or reactant comprising an acid or salt solution, or a combination of an acid and a salt solution, to form a feedstock-water-reactant mixture; at least one mixture heat exchanger for heating the feed-water-reactant mixture; 1. A hydrothermal purification reactor system comprising: the hydrothermal purification reactor system is operated under temperature, pressure, and turbulent flow conditions at a Reynolds number of at least 2,000 to maintain a liquid hydrothermal phase that results in rapid reaction of inorganic contaminants with the feedstock-water-reagent mixture without causing lipid carbon-carbon bond cracking or isomerization of the feedstock; the hydrothermal purification reactor system has an operating pressure in the range of 250 psig to 3,000 psig and an operating temperature in the range of 225°C to 350°C; a hydrothermal purification reactor system; a separation system for removing from the hydrothermal purification reactor system effluent an organic phase containing the inorganic contaminants at a lower concentration than the contaminated renewable feedstock and an aqueous phase containing the inorganic contaminants; A system comprising:

16. The system further comprising a treatment system for the aqueous phase containing the inorganic contaminants; 16. The system of claim 15, wherein the treatment system includes at least one of further processing to recover by-products, applying to land, dewatering and using as an animal feed supplement, or treating in a conventional wastewater treatment process.

17. The system described in claim 15, wherein more than 95% of the inorganic contaminants are removed from the contaminated raw material.

18. The system described in claim 15, wherein the at least one mixture heat exchanger utilizes heat from the effluent of the hydrothermal purification reactor system to heat the feedstock-water-reactant mixture before it enters the hydrothermal purification reactor system.

19. The system described in claim 15, wherein the operating temperature is in the range of 300°C to 350°C.

20. The system of claim 15, wherein the space time of the feedstock-water-reactant mixture in the hydrothermal purification reactor system is in the range of 10 seconds to 15 minutes.

Images