Systems and methods for converting biomass to hydrochar using hydrothermal carbonization

Abstract

Systems and methods of producing hydrochar include a well having a depth, a top positioned at surface, a bottom portion positioned at a subterranean location, the well comprising casing and tubing positioned therein, forming an annulus. The casing and tubing define a hydrothermal carbonization (HTC) reaction zone in a bottom portion of the well and a heat transfer and separation zone above the HTC reaction zone. The well may be heated using high pressure steam and / or a cable having an electric heating element positioned in the tubing in the HTC reaction zone configured to transfer energy to biomass slurry flowing through the tubing, converting some of the biomass slurry into hydrochar by HTC. The well depth and heating are design to produce temperature and pressure in the HTC reaction zone sufficient to form sub-critical water and produce a product fluid comprising the hydrochar.

Description

252-P004WO  SYSTEMS AND METHODS FOR CONVERTING BIOMASS TO HYDROCHAR USING HYDROTHERMAL CARBONIZATION   Cross-reference to related applications

[0001] This application claims domestic priority benefit under 35 U.S.C. § 119(e) from Applicant’s provisional patent application number 63581486, filed September 8, 2023. This application may also be related to Applicant’s co-pending United States provisional patent application numbers 63379127, 63379129, and 63379130 all filed October 11, 2022. All of these patent applications are hereby explicitly incorporated herein by reference.

[0002] BACKGROUND INFORMATION

[0003] Technical Field

[0004] The present disclosure relates in general to systems and methods useful in the production of hydrochar from biomass, where hydrochar is a paste or powder that can be used as a soil amendment simultaneously sequestering carbon, as a carbon neutral fuel similar to lignite, in concrete to add strength and sequester carbon, as a coke alternative, and in other end uses. In particular, the present disclosure relates to systems and methods for production of hydrochar using hydrothermal carbonization (HTC).

[0005] Background Art

[0006] Historically, treating biomass to achieve one or more usable end products and sequester carbon has focused on several “dry” processes, that is, processes requiring dry biomass feedstock, such as pyrolysis, gasification, and incineration. All of these require drying the biomass feedstock, requiring energy input to drive off most of the moisture.        252-P004WO

[0007] At this time, globally, there are no commercial scale hydrothermal carbonization (HTC) operations for converting biomass to hydrochar, largely due to these and other higher temperature and pressure equipment challenges. While use of HTC systems and methods to produce hydrochar have increased, there remains a need for improved HTC systems and methods for production of hydrochar from biomass.

[0008] SUMMARY

[0009] In accordance with the present disclosure, systems, and methods of using same are described which reduce or overcome many of the faults of previously known HTC systems and methods. Systems and methods of the present disclosure comprise converting biomass at high volumetric flow rates into hydrochar using HTC while minimizing hydrothermal liquefaction. The biomass is prepared to generate a biomass slurry for HTC processing.

[0010] A first aspect of the disclosure is a system comprising (or consisting essentially of, or consisting of):  a well having a well depth, a top positioned at a surface location, and a bottom portion positioned at a subterranean location, the well comprising a casing and one or more tubing (in certain embodiments, coiled tubing) positioned therein, forming an annulus there between, the casing and the one or more tubing defining a hydrothermal carbonization (HTC) reaction zone in the bottom portion of the well and a heat transfer and separation zone above the HTC reaction zone;   the well further comprising a cable comprising an electric heating element (and / or a high pressure steam supply conduit providing heat) positioned in one or more of the one or more tubing in the HTC reaction zone and configured to transfer energy endothermically to a biomass slurry flowing downward through at least one of the one or more tubing, and convert at least a portion of the biomass slurry into a composition comprising water and hydrochar by HTC, the biomass slurry entering into the tubing at      252-P004WO  the top of the well at a first temperature and a first pressure, the well depth and the heating sufficient to produce a second temperature and a second pressure in the reaction zone sufficient to maintain water in the composition as liquid.

[0011] A second aspect of the disclosure is a system comprising (or consisting essentially of, or consisting of):  a well having a well depth, a top positioned at a surface location, and a bottom portion positioned at a subterranean location, the well comprising a casing and a single tubing positioned therein, forming an annulus there between, the casing and the tubing defining a hydrothermal carbonization (HTC) reaction zone in a first section of the bottom portion, a return fluid plenum in a second section of the bottom portion, the second section located below the first portion, and a heat transfer and separation zone above the HTC reaction zone;   the well further comprising a cable comprising an electric heating element (and / or a high pressure steam supply conduit providing heat) positioned in the tubing in the HTC reaction zone and configured to transfer energy endothermically to a biomass slurry flowing downward through the single tubing, and convert at least a portion of the biomass slurry into a composition comprising water and hydrochar by HTC, the biomass slurry entering into the single tubing at the top of the well at a first temperature and a first pressure, the well depth and the heating sufficient to produce a second temperature and a second pressure in the reaction zone sufficient to produce a second temperature and a second pressure in the reaction zone sufficient to maintain water in the composition as liquid.

[0012] A third aspect of this disclosure is a method comprising (or consisting essentially of, or consisting of):  flowing a biomass slurry into a top of one or more tubing positioned inside a casing of a well forming an annulus there between, the well having a well depth, a top positioned at a surface location, and a bottom portion positioned at a subterranean      252-P004WO  location, the casing and the one or more tubing defining a hydrothermal carbonization (HTC) reaction zone in the bottom portion of the well and a heat transfer and separation zone above the HTC reaction zone;   heating the biomass slurry flowing downward through the HTC reaction zone employing a cable comprising an electric heating element and / or a high pressure stream supply conduit positioned in one or more of the one or more tubing in the HTC reaction zone;   converting at least a portion of the biomass slurry into a composition comprising water and hydrochar by HTC in the HTC reaction zone, the biomass slurry entering into the one or more tubing at the top of the well at a first temperature and a first pressure, the well depth and the heating sufficient to produce a second temperature and a second pressure in the HTC reaction zone sufficient to maintain the water in the biomass slurry and in the composition as liquid;  flowing the composition comprising the hydrochar upward through the annulus between the casing and the one or more tubing; and  transferring heat between the composition and the biomass slurry in the heat transfer and separation zone.

[0013] A fourth aspect of this disclosure is a method comprising (or consisting essentially of, or consisting of):  flowing a biomass slurry into a top of a single tubing positioned inside a casing of a well forming an annulus there between, the well having a well depth, a top positioned at a surface location, and a bottom portion positioned at a subterranean location, the casing and the single tubing defining a hydrothermal carbonization (HTC) reaction zone in a first section of the bottom portion, a return fluid plenum in a second section of the bottom portion, the second section located below the first portion, and a heat transfer and separation zone above the HTC reaction zone;        252-P004WO  heating the biomass slurry flowing downward through the HTC reaction zone employing a cable comprising an electric heating element and / or a high pressure stream supply conduit positioned in the single tubing in the HTC reaction zone;   converting at least a portion of the biomass slurry into a composition comprising water and hydrochar by HTC in the HTC reaction zone, the biomass slurry entering into the single tubing at the top of the well at a first temperature and a first pressure, the well depth and the heating sufficient to produce a second temperature and a second pressure in the reaction zone sufficient to maintain water in the biomass slurry and in the composition as liquid;  flowing the composition comprising the water and the hydrochar upward through the annulus between the casing and the single tubing; and  transferring heat between the composition and the biomass slurry in the heat transfer and separation zone.

[0014] In accordance with the present disclosure, systems and methods with a single well reactor having a single inner tubing and surface separation facility could process from about 40,000 to about 60,000 tons of wet biomass annually while generating, in one scenario, about 16,000 tons per year of soil or industrial additive, or in another scenario, about 11,000 tons per year of carbon neutral fuel. Industrial additives include application for cement additive and replacement for extracted based coke in metallurgical smelting. In addition, sequestering about 20,000 tons / yr. of CO2 which is the equivalent of the emissions from about 4,300 automobiles using internal combustion engines. Certain systems and methods of the present disclosure generate greater than 6X more energy than they consume, and in certain embodiments greater than 20X more energy than they consume. Certain systems and methods of the present disclosure can use renewable sources of power to operate the process.

[0015] The systems and methods of the present disclosure utilize hydrothermal carbonization for the conversion of biomass to hydrochar. In certain embodiments the      252-P004WO  biomass may, depending upon feed source, be made into a slurry of about 15 to about 25 percent biomass, about 60 to about 90 percent water, and about 1 to about 7 percent inert solids (weight basis); and pumped into a well with an inner and outer tube which could be a non-producing oil and gas well with a typical production casing (outer tube) and production tubing (inner tube). Certain embodiments may comprise pumping the biomass slurry at a flow rate of about 175 to about 225 tons per day into the inner tube at pressure ranging from about 75 to about 125 psi to a depth of about 650 to about 750 m (length of the inner tube) and product fluid returned to the surface in the annulus. An electrically heated cable is located at the bottom of the inner tube and operated to preheat the incoming fluid, in certain embodiments up to about 250 ºC. Preheating comes from the countercurrent flow of hot product fluid in the annulus, the inner and outer tubes essentially forming a tube in tube heat exchanger. The product fluid comprising hydrochar then moves up the annulus along with water and some gases, at less than 5% of biomass (CO2 mostly with some CH4). Technical and safety challenges associated with high pressure slurry pumping, high pressure and high temperature heat exchanger and depressurizing in a continuous process are alleviated. In certain embodiments, heat losses to the environment may be minimized through the selection and placement of thermally resistant and high insulating drilling fluids and / or insulating gel fluids and / or cement during well construction. High solids in the feed material are prone to settling and plugging the wellbore when circulation is temporarily stopped. To avoid this risk, in certain embodiments a non-thermally sensitive inorganic additive may be used to create a shear thinning feed biomass slurry. In certain embodiments, heat transfer and reaction kinetics may be enhanced through the selection of static mixers, pipe geometry and flow regimes in the inner and outer tube. As the biomass is heated to about 250 ºC, hydrothermal carbonization of biomass occurs between temperatures ranging from about 180 to about 250 ºC which increases the hydrochar yield. In certain embodiments of the present disclosure, carbonization is reduced at higher pressures and temperatures, but surprisingly the Higher Heating Value (HHV) of the hydrochar increases.         252-P004WO

[0016] These and other features of the systems and methods of the disclosure will become more apparent upon review of the brief description of the drawings, the detailed description, and the claims that follow. Wherever the term “comprising” is used herein, other embodiments where the term “comprising” is substituted with “consisting essentially of” are explicitly disclosed herein. Wherever the term “comprising” is used herein, other embodiments where the term “comprising” is substituted with “consisting of” are explicitly disclosed herein. Moreover, the use of negative limitations is specifically contemplated; for example, certain systems and methods may comprise several physical components and features but may be devoid of certain optional hardware and / or other features. For example, certain systems may be devoid of auxiliary tanks, pumps, and other equipment. As another example, systems of this disclosure may be devoid of heat exchangers employing inert metals, or other expensive equipment. In yet another example, systems of the present disclosure may be devoid of any unit or component that would introduce an oxidizing chemical into the biomass slurry.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The manner in which the objectives of this disclosure and other desirable characteristics can be obtained is explained in the following description and attached drawings in which:

[0019] FIG.1 schematically illustrates generic HTC systems and methods for producing hydrochar;

[0020] FIG. 2A is a graph illustrating the effect of temperature on hydrochar yield for three different feedstocks, and FIG. 2B is a Van Krevelen diagram plotting H / C ratios against O / C ratios for various feedstocks and hydrochars;         252-P004WO

[0021] FIGS.3A, 3B, 4A, 4B, 6, 8, 8A, 9, 9A, 11, 11A, 16A, 16B, and 17 schematically illustrate various system and method embodiments in accordance with the present disclosure;

[0022] FIG.4A is a schematic representation of a material balance for one system with one feed tube and method embodiment of the present disclosure, illustrating that one embodiment in accordance with the present disclosure can process 160 t / day of wet sludge, generating 45 t / day of hydrochar suitable for soil amendment;

[0023] FIG. 4B is a schematic representation of an energy balance for one system with one feed tube and method embodiment of the present disclosure, illustrating that one embodiment in accordance with the present disclosure generates 4.3 times more energy than consumed if the hydrochar is used as fuel.

[0024] FIG. 5 is a graphical representation of concentration of certain fluorinated chemicals in sewage sludge before hydrothermal carbonization, and concentration in hydrochar after hydrothermal carbonization;

[0025] FIG.7 is a graphical representation of pressure vs. temperature in HTC systems and methods in accordance with the present disclosure;

[0026] FIG.10 is a schematic illustration of an electrical heating element useful in certain embodiments of the present disclosure;

[0027] FIG.12 illustrates schematically days to reach steady state temperature at certain distances from the wellbore wall in certain embodiments of the present disclosure;        252-P004WO

[0028] FIG.13 illustrates graphically heat loss to formation from start up to day 10, up to day 20, and up to day 30 respectively, at a distance 0.37 meter from the wellbore center in certain embodiments of the present disclosure; and

[0029] FIGS.14 and 15 illustrate a carbon dioxide balance in certain embodiments of the present disclosure.

[0030] It is to be noted, however, that the appended drawings are not to scale and illustrate only typical embodiments of this disclosure, and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. Identical reference numerals are used throughout the several views for like or similar elements.

[0031] DETAILED DESCRIPTION

[0032] In the following description, numerous details are set forth to provide an understanding of the disclosed methods, systems, and apparatus. However, it will be understood by those skilled in the art that the methods, systems, and apparatus may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. All U.S. published patent applications, U.S. Patents, and non-patent literature referenced herein are hereby explicitly incorporated herein by reference. In the event definitions of terms in the referenced patents and applications conflict with how those terms are defined in the present application, the definitions for those terms that are provided in the present application shall be deemed controlling. Where a range of values describes a parameter, all sub-ranges, point values and endpoints within that range are explicitly disclosed herein. This document follows the well-established principle that the words “a” and “an” mean “one or more” unless we evince a clear intent to limit “a” or “an” to “one.” For example, when we state “flowing a biomass slurry into a top of a tubing positioned inside a casing of a well”, we mean that      252-P004WO  the specification supports a legal construction of “a tubing” that encompasses structure distributed among multiple physical structures, and a legal construction of “a well” that encompasses structure distributed among multiple physical structures.

[0033] Certain common terms are defined as follows:

[0034] “PFA” means polyfluorinated aliphatic and is sometimes used as a shorthand for so-called “forever” chemicals, chemicals that resist destruction by natural methods.

[0035] “PFAS” means polyfluoroalkyl substances.

[0036] “WWTP” mean wastewater treatment plant.

[0037] “PFBA” means perfluorobutanoic acid and its salts.

[0038] “PFPA” means perfluoro phosphonates and their salts.

[0039] “PFHxA” means perfluorohexanoic acid and its salts.

[0040] “PFHxPA” means perfluorohexyl phosphonate and its salts and derivatives.

[0041] “PFOA” means perfluorooctanoic acid and its salts.

[0042] “PFNA” means perfluorononanoic acid and its salts.

[0043] “PFDA” means perfluorodecanoic acid and its salts.

[0044] “PFBS” means perfluorobutane sulfonate.      252-P004WO

[0045] “PFHxS” means perfluorohexane sulfonate.

[0046] “PFOS” means perfluorooctane sulfonic acid, and salts thereof, and N-substituted sulfonamides such as N-methyl perfluorooctane sulfonamidoethanol, MeFOSE.

[0047] The challenge to decrease the world’s reliance on fossil fuels requires the implementation of cost-effective, large-scale, renewable energy-based transport fuel projects. Ong et al., “A Kraft Mill-Integrated Hydrothermal Liquefaction Process for Liquid Fuel Co-Production”, pp. 1-23, Processes 2020, 8, 1216 (2020), MDPI, Basel, Switzerland (hereafter Ong et al.).

[0048] Bioenergy is a renewable energy that uses biomass to produce energy. Biomass can be sewage sludge, manure, municipal solid waste, agriculture, forest residues, energy crops and others. The major concerns of bioenergy are biomass availability, sustainability issues and competition between the alternative uses of biomass (for instance, competition for feed and food). Hence, the use of waste streams may contribute to an improvement of bioenergy production. Moreover, the use of waste for production of energy contributes to a circular economy that, in turn, is a global plan for reduction of waste generation and reduction of the use of resources. Moura, T. C. P., “Modelling of Wet Air Oxidation in a Deep Well Reactor for Biomass Treatment”, Master dissertation (October 2021), available from À Faculdade De Engenharia Da Universidade Do Porto Em Chemical Engineering (hereafter “Moura”).

[0049] The estimated annual global volume of biomass (as of 2020) is as presented in Table 1:      252-P004WO  Table 1. Estimated Annual Global Volume of Biomass (as of 2020) Global Summary Biomass (Annual)

[0050] Hydrothermala o a o ec o ogy

[0051] Hydrothermal carbonization (HTC) is a thermochemical conversion process that uses heat to convert wet biomass feedstocks to hydrochar. HTC is performed at about 180 to about 250°C, under autogenous (automatically generated) pressure, with residence time ranging from about 0.5 to about 8 hours. The major advantage of HTC over other high temperature thermochemical conversion techniques such as pyrolysis, is the HTC process treats wet waste, which allows feedstocks to be converted without pre-drying. Certain system and method embodiments described herein in accordance with the present disclosure are explicitly recited as without any biomass drying unit operations, and without any biomass drying process steps, meaning that there is no added energy to the system for drying the wet biomass. Other embodiments may be recited as “without substantial biomass drying”, meaning that an initially wet biomass may be dried a de minimis amount prior to entering the system merely by the action of the sun on a hot day, or in other relatively hot atmospheric conditions.

[0052] A wide variety of feedstocks, including aquatic biomass, agricultural residues, and industrial and animal wastes, are suitable. Water acts as a good medium for heat transfer in HTC, but if variability in the feedstock particle size is too large and reaction time is      252-P004WO  too short, there might be some mass transfer limitations. Hence, the particle size should be homogeneous or nearly so to promote uniform heat and mass transfer.

[0053] A relatively small amount of gases (primarily CO2) and an aqueous slurry are produced. The aqueous slurry is centrifuged or filtered to separate the process water and solids (wet cake) to produce a carbon-rich hydrochar. The wet cake can be further dried and pelletized depending upon final use.

[0054] Multiple reactions occur during the HTC process, namely hydrolysis (reaction with water), dehydration (removal of water), decarboxylation (removal of carboxyl groups which results in the liberation of CO2), and aromatization (formation of aromatic compounds). These reactions occur under high temperature and pressure and play a vital role in lowering the hydrogen to carbon (H / C) and oxygen to carbon (O / C) ratios to produce the carbon-rich hydrochar.

[0055] Hydrochar yield depends upon the type of feedstock, the solids loading (ratio of feedstock to water), and the process temperature and residence time (Table 2, from Hydrothermal Carbonization: Upgrading Waste Biomass to Char, originally posted Jan 11, 2021, Shyam Sivaprasad, Graduate Research Associate, Dr. Ashish Manandhar, Postdoctoral Researcher, Dr. Ajay Shah, Associate Professor, Department of Food, Agricultural and Biological Engineering, The Ohio State University.

[0056] Hydrochar yield decreases with increased severity of process conditions, in other words, higher temperature and longer residence time, which decomposes more of the cellulosic and hemicellulosic fractions in the feedstock. (FIG. 2A, from Gallant, R.; Farooque, A.A.; He, S.; Kang, K.; Hu, Y., A Mini-Review: Biowaste-Derived Fuel Pellet by Hydrothermal Carbonization Followed by Pelletizing, Sustainability, 2022.      252-P004WO

[0057] Despite lower yield, at higher temperatures and longer residence times, the hydrochar has a higher carbon content with a higher heating value (HHV). J González- Arias, M E Sánchez, E J Martínez, C Covalski, A Alonso-Simón, R González, J Cara- Jiménez, Hydrothermal Carbonization of Olive Tree Pruning as a Sustainable Way for Improving Biomass Energy Potential: Effect of Reaction Parameter on Fuel Properties (2020) (FIG. 2B - operating temp & residence time tests). At 220 C, hydrochar yields were the highest but longer residence times were required to reduce O / C ratio and increase heating value. At 280 ºC, hydrochar yields were the lowest but had highest heating value although the improvements were minimal over 250 ºC. For the purposes of scaling and operational efficiency, the optimum temperature and residence time occurs at 250 ºC at 3 hours where the hydrochar has an O / C of <0.3 and HHV of 27.9 MJ / kg. Thermal degradation of cellulose and hemicellulose could lead to the formation of water-soluble organic acids such as levulinic acid, formic acid, lactic acid and acetic acid; and thus, would lower the yield of hydrochar but increase the yield of the aqueous phase. These organic acids can then be further separated or extracted or distilled for creating additional valuable byproducts from the HTC process. Table 2. Hydrochar yields for various feedstocks under different HTC conditions Feedstock Feedstock Temp., (ºC) Residence Hydrochar r t tim (min) i ld (%)      252-P004WO

[0058] Comparison of Hydrochar and Biochar

[0059] Wet feed pyrolysis requires very high energy costs to pre-dry the wet biomass feedstock and is uneconomical with wet slurry biowastes. Table 3 provides a comparison of hydrochar produced by HTC and biochar produced by pyrolysis. Table 4 provides a list of potential advantages of HTC over pyrolysis. Table 3. Comparison of Hydrochar and Biochar Characteristic Hydrochar Biochar (hydrothermal (pyrolysis) e      252-P004WO  Table 4. Advantages of HTC over Pyrolysis Advantages Hydrothermal Pyrolysis carbonization e

[0060] Benefits of HTC and Hydrochar ●

[0061] Avoids feedstock pre-drying: HTC does not require pre-drying of biomass and can utilize feedstocks of varying moisture contents, which saves energy and costs for drying before processing. This is one of the major benefits of HTC compared to other thermochemical processing methods that require dry feedstocks to produce char. ●

[0062] Enhanced hydrophobicity: The hydrochar has less moisture and is more hydrophobic than raw feedstock. These attributes separate more water through 252-P004WOmechanical separation equipment, decrease transportation costs and improve shelf life by impeding wettability and rot during storage. ●

[0063] High nutrient recovery: HTC promotes enhanced nutrient recovery as both solid (hydrochar) and process water possess essential nutrients, including phosphorus, potassium and nitrogen, which are vital for plant growth. ●

[0064] Improved dewatering efficiency: HTC enhances the dewatering efficiency of raw feedstocks as it helps release the bound water and thus is highly beneficial for biosolids management. If dewatered or dried hydrochar must be disposed, the cost of transport and disposal is significantly reduced. ●

[0065] Lower environmental impact: HTC has the potential to minimize environmental impacts of waste biomass as it recovers more energy, and emits much less pollutants and odor, than incineration, landfilling, and composting

[0019] . Generates 6.2 x more energy than it consumes. Generates minimal gases compared to other thermochemical conversion technologies. ●

[0066] Reduces pharmaceuticals & PFAS chemicals: WWTP sludge contains contaminants such as pathogens, pharmaceuticals and highly stable carcinogen compounds. These contaminants can be significantly reduced or eliminated through HTC. Table 5 lists some pharmaceuticals and their destruction by HTC. ●

[0067] Operates on electrical power: HTC conversion process can be operated on electrical power which can be easily sourced from low carbon and renewable energy. ●

[0068] High char conversion: HTC generates minimal gases and highest yields compared to other thermochemical conversion processes. ●

[0069] Onsite Operations: HTC systems can be economical for small biowaste generators such as a WWTP site for a population of 200,000 - 400,000.      252-P004WO  Table 5. Destruction of Pharmaceuticals by HTC MeasuredConcentration after Removal during concentration in HTC HTC

[0070] Environmental Contaminant Reduction

[0071] As illustrated in Table 6, there is no significant concentration of PFAs in biochar produced from sewage sludge.      252-P004WO  Table 6. PFAs in hydrochar Unit Concentration inConcentration Threshold sewage sludge in biochar limit values

[0072] As illustrated in FIG. 5, HTC offers great reduction in PFAs. Pre-investigations of micropollutant load in sewage sludge and hydrochar from hydrothermal carbonization (HTC) of sewage sludge. HTC was carried out for four hours at 210 °C and 15 bar with sewage sludge from the wastewater treatment plant Hollenstedt, Germany (Eyser, C.V. (2016). Behavior of micropollutants during hydrothermal carbonization of sewage sludge.)

[0073] Drawbacks of HTC and Hydrochar

[0074] Drying of hydrochar: After mechanical separation and dewatering of hydrochar, some applications require drying and pelletization. The drying step is energy intensive consuming more than the HTC process itself.

[0075] Contaminants: Depending upon the feedstock used, the products may also contain undesirable metals, such as Ni, Pb, Cd, Cr, which are distributed among solid and liquid fractions post HTC.      252-P004WO

[0076] Dissolved organics in water phase: The formation of acidic compounds such as acetic, levulinic, formic, and lactic acids may result in pH as low as      3.6. While this makes it easier to hydrolyze biomass, the excess water must be treated requiring aerobic or anaerobic digestion and neutralization, or return to WWTP. Neutralized treated water is beneficial as a fertilizer.

[0077] Typical heavy metal concentrations in WWTP sludge are illustrated in Table 7. Table 7. Typical heavy metal concentrations in WWTP sludge Concentration Criteria * they and application

[0078] Referring now to the figures, FIG. 1 a schematic generic flow diagram of hydrothermal carbonization is presented. Hydrothermal carbonization (HTC) is a thermochemical process that depolymerizes biomass present in a pretreated wet biomass slurry 5 into hydrochar slurry 7 in a HTC reactor 6 operating at moderately high temperature and pressure and sufficient time to decompose the solid natural polymeric structure to mostly solid compounds. It is a flexible conversion process due to the variability of bio-based or waste feedstock 2 that have been successfully tested. Biomass wet waste 2 does not require drying but may optionally be pretreated to remove      252-P004WO  undesirably small and large particle size materials in a pretreater 4. An HTC product slurry 7 is routed to a phase separator and drying unit 8 where the product slurry 7 is separated into a water stream 9 that is separated and recycled to pretreater 4, and a stream 13 comprising primarily hydrochar. Hydrochar stream 13 may be used as a carbon neutral fuel 10, as a soil nutrient 11, and / or as a mechanical strength additive, for example in cement and / or replacement for metallurgical coke. In the latter three products, carbon sequestration is an additional key feature. The key advantage of why the HTC process is successful is because the feedstock 2 of the HTC process does not have to undergo a separate drying process but undergoes pretreatment 4 to provide the pretreated biomass slurry 5. Water 9 in the HTC process serves as a reactant and catalyst in the subcritical region as the properties of the water change in the extreme. (Water has a critical point of 374 ºC and 221 bar (22.1 MPa).) In the subcritical region, the dielectric constant of water decreases significantly, as compared to ambient water. For example, the dielectric constant of water changes from about 80 at 20 ºC and decreases below 20 at 300 ºC.

[0079] To my knowledge, no one has used hydrochar as an additive in cement, or even conducted research on the topic. The properties of hydrochar and biochar are not so close (see Table 3, in particular the structural, pH, and porosity differences) as to be able to predict that the addition of hydrochar to cement will be beneficial to the properties of the cement. There has been some published research on adding biochar to cement. Gupta, et al., Utilization of biochar from unwashed peanut shell in cementitious building materials – Effect on early age properties and environmental benefits, Fuel Processing Technology, 218 (2021) 106841 reported:  ●

[0080] Cementitious mixtures with 3 wt% peanut shell biochar experience a faster rate of setting and shorter final setting time by up to 1–1.50 h; ●

[0081] Degree of hydration at 3-day and 7-day age of cement paste and cement- fly ash paste can be enhanced by 15–23% due to the addition of 3 wt% of biochar; ●

[0082] Addition of 1 wt% and 3 wt% biochar enhance compressive strength at 1- day, 3-day and 7-day age by 18–20%; and      252-P004WO  ●

[0083] Addition of 1 wt% biochar, and combination of biochar and fly ash can reduce shrinkage under sealed conditions.

[0084] The water in the hydrothermal carbonization process acts as a solvent and a reactant. When water is heated close to its critical temperature in a pressurized system, it begins to behave as a non-polar liquid and dissociates much easier. The non-polar behavior of the liquid helps to solvate the organics in the biomass, and the H3O+ and OH- ions aid in the conversion of biomass molecules into more desirable compounds.

[0085] Some feedstock is converted into solid elemental carbon char from hydrothermal carbonization (HTC) which is a thermochemical conversion process that uses heat to convert wet biomass feedstocks to hydrochar. HTC occurs at temperatures ranging from about 180 ºC to about 250 °C, under autogenous (automatically generated) pressure, with feedstock residence time ranging from about 0.5 to 8 hours in previously known reactors. Ahmad, F., et al., “Hydrothermal processing of biomass for anaerobic digestion – A review”, Renewable and Sustainable Energy Reviews, 98, 108-124 (2018).; Khan, T. A., et al., “Hydrothermal carbonization of lignocellulosic biomass for carbon rich material preparation: A review, Biomass and Bioenergy, 130, 105384 (2019). This solid carbon cannot revert to carbon dioxide or methane and subsequently be released to the atmosphere. When used as a soil amendment or industrial additive, the carbon is removed from the atmosphere with minimal degradation over decades period of time. The use of hydrochar can improve soil quality by enhancing its water and nutrient retention properties. Zhang, Z., et al., “Insights into biochar and hydrochar production and applications: a review”, Energy, 171, 581-598 (2019). However, the char may contain toxic compounds in low concentration which could limit its use as soil amendment without exceeding regulatory limitations as illustrated in Table 6. Sivaprasad, S. et al., “Hydrothermal Carbonization: Upgrading Waste Biomass to Char”, Department of Food, Agricultural and Biological Engineering, The Ohio State University, January 11, 2021. Hence the converted biomass into liquid and solid products is carbon negative or      252-P004WO  in other words, carbon is removed from the atmosphere. While there are benefits of Hydrothermal Liquefaction (HTL), it reduces HTC hydrochar yields. If the objective is to maximize hydrochar yields as is the case for the systems and methods of the present disclosure, then the feed slurry should remain in the temperature range of about 180 ºC to about 250 °C environment, and for residence time as long as sufficient to produce the hydrochar yield desired (from about 0.5 hour to about 4 hours, or from about 0.5 hour to about 3 hours, or from about 0.5 hour to about 2 hours, or from about 0.5 hour to about 1 hour). Residence times over about 4 hours is impractical as it would require very large wellbore and / or very low flow rates.

[0086] Wet biomass feedstocks—properties and preparation for processing (Elliott et al., Hydrothermal liquefaction of biomass: Developments from batch to continuous process, Bioresource Technology 178 (2015) 147–156 )

[0087] Most biomass can be processed in HTC systems and methods of the present disclosure because of the hydrophilic nature of biomass and the reasonable ease in forming water slurries of biomass particles at pumpable concentrations, typically from about 5 to about 35 percent dry solids. In embodiments using lignocellulosic biomass, which is lower in moisture content, recovery and reuse of the water for slurry preparation is a key feature. For high-moisture biomass, like algae, some dewatering is desired prior to processing in order to lessen the processing costs of excessive water. Table 8 presents some common feedstock utilized in HTC systems and methods of the present disclosure. Wet feedstocks are particularly suited for the HTC systems and methods of the present disclosure and especially algae biomass. This means additional energy spent to achieve a dry feedstock required for most thermochemical biofuel pathways is not required and nor is additional water added as required for a dry biomass feedstock for HTC systems and methods of the present disclosure. Their pumpability has been demonstrated on a large scale. The particle size is in direct correlation to pumpability and pressure control in continuous reactors. In certain embodiments using woody biomass, grinding prior to      252-P004WO  processing as is discussed herein is employed. Microalgae, some strains of macroalgae and certain manures and sludges are of suitable small size for direct processing. A further advantage of using hydrothermal processing for sludges and manures is the effect of sterilizing bioactive contaminants and reduction of residual pharmaceuticals. Table 8. Summary of HTC feedstock (Elliott et al.) Feedstock Lignocellulosics Macroalgae Microalgae Manures Sewer Sludge (dry basis) n

[0088] Systems and Methods of the Present Disclosure

[0089] The systems and methods of the present disclosure continuously convert biomass at high volumetric flow rates into hydrochar using hydrothermal carbonization. Biomass is prepared to generate a biomass slurry for HTC processing. As discussed herein, HTC occurs at moderate pressures and temperatures, for example from about 35 bar (508 psi) to about 60 bar (870 psi), and from about 180 ºC to about 250 ºC, or from about 40 bar (580 psi) to about 47 bar (682 psi) and from about 200 ºC to about 225 ºC, or about 40 bar (580 psi) and about 200 ºC. These temperatures and pressures are very challenging operating conditions particularly under continuous processing conditions. In previously known systems and processes, specialized pumps, depressurizing valves and pressure      252-P004WO  recovery, heat exchangers not commercially available, exotic metallurgy and atypical wall thicknesses were required. In addition, there are numerous issues related to excessive wear and tear, safety, redundancy requirements and very high costs. In particular, at least some of the high thermal energy required to heat the feed biomass slurry to the desired HTC temperatures should be recovered for economic viability. Ordinarily this would require heat exchangers capable of operating at the target HTC temperatures and pressures which are not commercially available for the relatively high processing rates.

[0090] At this time, globally, there are no commercial scale operations, largely due to these challenges. To overcome many of these challenges, systems and methods of the present disclosure utilize a moderately deep well, in certain embodiments wells commonly drilled and constructed for oil and gas production. These wells can safely and inexpensively generate the pressures required via hydrostatic pressure by using commonly available metallurgy, dimensions and geometry. The depth of the well determines the pressure. In certain embodiments, as in embodiment 100 illustrated schematically in FIGS. 3A and 3B, the well includes an inner tubing 32 and an outer tubing (casing) 30 where the feed slurry enters inner tubing 32 at the top 44 of the well at the surface 46 and flows to the bottom portion 42 of the well, and product fluid 7 returns to the surface in an annulus 38 formed between inner tubing 32 and casing 30. No high- pressure pumping is required as the systems and methods take advantage of the hydraulic U tube effect and hydrostatic pressure simultaneously. Biomass slurry 5 is heated at the bottom of the well to the target temperature by a heating element 36 of an electric cable 34 but prior to reaching bottom portion 42 of the well, while product fluid 7 returning in annulus 38 preheats the incoming biomass slurry 5. The majority of the heat in product fluid 7 is recovered via the transfer of thermal energy from the hot product fluid 7 flowing upward in annulus 38 to the incoming cold feed biomass slurry 5 in a heat transfer and separation zone 40. In systems and methods of the present disclosure, the temperature of the preheated feed slurry in inner tubing 32 is boosted at bottom portion 42 (HTC reaction zone) of the well under pressure to ensure the biomass slurry fluid remains as a liquid for      252-P004WO  the hydrothermal carbonization reactions to occur. The well will essentially be our reactor. The heat source comes from the submersed electrical resistance heater cable (34, 36 powered by a power source 48, which may employ grid power or other power) which is commonly used in oil and gas production to reduce viscosity of heavy oils and waxes, flow assurance and to increase production or other methods of heating inner tubing 32. Also illustrated in FIG. 3B are pressure chart 52, depth chart 54, and a schematic scale model of the well reactor at 1: 3,720 scale ratio (FIG.3A).

[0091] To perform the efficient operation of an HTC plant in terms of total operating costs and optimal physio-chemical performance, certain systems and methods of the present disclosure may employ: (a) energy recovery; (b) feed slurry preheating; c) boost heating to reach HTC temperature; and d) drilling fluid and / or insulating gels and / or cements having insulating properties to minimize heat losses. Some or all of these may be satisfied by the design of specific thermal components, as well as configuration design of the processing systems. In certain embodiments, thermal management in systems and embodiments of the present disclosure may include one or more of the following components: (1) a heat exchanger which is designed to ensure the thermal energy recovery with primary functions of feed biomass slurry preheating and product fluid cooling; (2) the electrical heater, which serves to boost the temperature after pre-heating; and (3) the well reactor where the majority of chemical HTC reactions occur.

[0092] In certain embodiments, the well can be a non-producing oil and gas well which is an operational liability to the owner of the well requiring an expensive plug and abandonment procedure. In addition, a non-producing well can be an environmental liability that can leak fluids and methane into the environment. Methane is more than 25 times as potent as carbon dioxide at trapping heat in the atmosphere. The systems and methods of the present disclosure turn these liabilities into valuable assets. The technology reverses these negative environmental impacts while simultaneously      252-P004WO  generating a hydrochar vs. extraction of crude oil thereby significantly reducing greenhouse gas (GHG) emissions.

[0093] FIG.4A illustrates a high-level process flow diagram and material balance of one system and method embodiment of the present disclosure which will be described in more detail herein in various embodiments. All streams are expressed in metric tons / day. Feed biomass slurry stream 5 includes 210 metric tons / day biomass slurry, which includes 32 dry ash free metric tons / day biomass, 169.9 metric tons / day water, and 8.1 metric dry tons / day solids, as depicted in chart 60. A recovered gas stream 15 includes 1.2 metric tons CO2and 0.1 metric tons / day CH4, as depicted in chart 62. An HTC product slurry stream 7 includes 19.1 dry ash free metric tons / day hydrochar, 176.3 metric tons / day water, and 8.1 dry metric tons / day solids, as depicted in chart 64. The hydrochar slurry stream 7 may be routed to a dewatering process (centrifuge or belt press or other unit) to produce cake 13. Of the 176.3 metric tons / day water, wet hydrochar stream 13 comprises 18.2 metric tons / day water, of which about 15.2 tons / day may be recovered as a condensed water stream 21 and combined with recovered water stream 9, about 50.2 tons / day of which is recycled to the feed slurry mixer, while about 123.3 tons / day water in stream 23 may be treated or returned to a WWTP. Hydrochar cake stream 13 includes 45.5 wet tons / day wet hydrochar, of which 19.2 tons / day is hydrochar, 18.1 tons / days is water, and 8.1 dry tons / day is ash solids as depicted in chart 66. The hydrochar cake 19 may be routed to a drying process (thermal dryer) to produce 19.2 dry ash free tons / day of dry hydrochar, as illustrated in chart 68.

[0094] An energy balance for the high-level process flow diagram illustrated in FIG.4A is presented in FIG. 4B. Feed preparation (if required) may use about 0.72 MWh / day, while the electrical heating cable in well reactor 6 may use about 7.2 MWh / day. Separation equipment 8 may use about 1.7 MWh / day, while the largest energy input would be for the production of dry hydrochar from hydrochar cake generated from separation equipment, using about 15.2 MWh / day. However, the recovered hydrochar      252-P004WO  will provide about 106 MWh / day, and the use of feed / product heat exchanger(s) 14 would further increase energy efficiency. (“MWh / day” means megawatt hours per day.)

[0095] Generating Hydrothermal Reactions in Systems and Methods of the Present Disclosure

[0096] Feed Biomass Slurry Characteristics and Processing Rates

[0097] In certain systems and methods of the present disclosure the biomass is prepared to achieve consistent physical and chemical properties such that it can be easily pumped using simple centrifugal pumps at low pressures. One example of typical properties includes those shown in Table 9:    Table 9. Typical Biomass Properties Biomass as Received 160 t / day Recycle Water Biomass Slurry as Prepared Add d t HTC y y y yThe prepared biomass slurry is pumped at low pressures (for example, less than 100 psi, or less than 75 psi, or less than 50 psi) into a well to generate hydrostatic pressure to depths of about 700 m (2,300 ft). At these depths, the hydrostatic pressure of the slurry reaches about 898 psi (61 bar) which is the target pressure for HTC. In practice, the depths could range from about 500 m (1,650 ft) to about 700 m (2,300 ft) which would generate      252-P004WO  a hydrostatic pressure of ranging from about 43 bar (642 psi) to about 61 bar (898 psi) depending upon the density of the slurry, as shown in Table 10:   Table 10. Typical Flow Rate and Density of Feed Biomass Slurries Mass Flow Rate 8,750 kg / hr. Densit 111 k / L  Referring again to embodiment 100 as illustrated in FIGS.3A and 3B, biomass slurry 5 enters inner tubing 32 at the top of the well 44 at the surface 46 and flows to the bottom 42 of inner tubing 32 and product fluid 7 returns to the surface 46 in annulus 38. Inner tubing 32 contains an electric resistance heating cable (34, 36) to raise feed biomass slurry 5 temperature to the target HTC temperature.

[0098] Slurry Preparation

[0099] Biomass has a wide range of liquid and solid material types, content and particle size. In certain embodiments, before the biomass can be processed, in certain embodiments it may be mechanically and chemically prepared to make a homogenous slurry suitable for pumping into a wellbore.

[0100] Mechanical Preparation of Feed Slurry

[0101] In certain systems and methods of the present disclosure, biomass having a wide particle size distribution is processed to increase surface area to promote HTC chemical      252-P004WO  reactions, allow it to pass through narrow piping and pump’s rotor / stator housing, and reduce settling in the biomass slurry. In certain systems and methods of the present disclosure, this may be accomplished using a series of equipment for reducing biomass particle size as described in our co-pending United States provisional patent application number 63379127, previously incorporated herein by reference, including, for example, but not limited to chippers, shredders, re-shredders, grinding pumps, and hammermills (also known as pulverizers).

[0102] Chemical Preparation Feed Slurry

[0103] In certain embodiments, various chemicals may be used to assist with the process such as corrosion inhibitors, cleaning chemicals such as surfactants, pH adjustment chemicals, heterogeneous and non-heterogeneous catalysts, and temperature resistant rheological additives such as bentonite.

[0104] The relatively high solids content in the feed slurry material are prone to settling and high risk of plugging the wellbore with solids when circulation is temporarily stopped. To avoid this risk, from about 0.1 to about 5 wt. percent (based on weight of feed biomass slurry) of a thermally resistant viscosifier capable of operating at 250 ºC may be used to reduce the settling rate of solids. In certain embodiments, the viscosifier generates a non-Newtonian slurry that is thixotropic, exhibiting a stable form at rest but becoming fluid when agitated to reduce solids settling rate; this is called “shear thinning.” This fluid flow behavior also reduces high friction losses when flowing thus resulting in lower pump pressures and low Reynolds numbers which negatively impact heat transfer coefficients. High heat transfer coefficients are important to reduce the requirement for high tube surface area for heat exchange between the inner tubing 32 and product fluid flowing in annulus 38. One such viscosifier is bentonite which after hydration, the bentonite particles expand 10 – 20 times their original volume. Bentonite is a mixture of      252-P004WO  various clay minerals that consists of from about 60 to about 80 percent montmorillonite. Further accompanying minerals can include quartz, mica, feldspar, pyrite or also calcite.

[0105] Fluids containing clays such as bentonite exhibit a pronounced thixotropic behavior. Thixotropic materials are fluids containing some form of structure as a result of formation of flocs or aggregates between suspended particles or moieties. In clay suspensions the formation of structure is promoted by increased encounter between suspended particles, which can result from Brownian motion of the particles or from the velocity gradient when the bulk of the material is sheared. Tehrani, A., “Thixotropy in Water-Based Drilling Fluids”, M-I SWACO Research and Technology Centre, Aberdeen, United Kingdom. Annual Transactions of the Nordic Rheology Society, Vol. 16, 2008. Fluids may be characterized as non-Newtonian plastic; Bingham plastic; non- Newtonian pseudoplastic (shear-thinning, n < 1); Newtonian material, n = 1; and non- Newtonian, dilatant (shear-thickening, n > 1), where “n” is a parameter known as the “flow index” in the three-parameter rheological model for fluids known as Herschel- Bulkley fluids.

[0106] In certain embodiments, bentonite can be prehydrated with fresh water into a fluid and mixed with the feed biomass slurry. Alternatively, bentonite can be added directly to the feed biomass slurry while ensuring that the water phase in the feed biomass slurry is within pH and hardness range to fully hydrate. In addition to modifying the rheological properties, bentonite has distinctive features such as a versatile metal free catalyst that can be used to promote various chemical reactions. Bentonite clays have a variable net negative charge, which is balanced by Na, Ca, Mg and, or H adsorbed externally on the interlamellar surfaces. The structure, chemical composition, exchangeable ion type and small crystal size of the clay are responsible for several unique properties, including a large chemically active surface area, a high cation exchange capacity and interlamellar surfaces having unusual hydration characteristics as previously mentioned. Odom, I. E., “Smectite clay minerals: properties and uses”, American Colloid Company, Phil Trans.      252-P004WO  R. Soc. Land. A311, 391- 409 (1984). Catalysts can potentially reduce reaction temperatures and increase biocrude yields.

[0107] Water and Sludge Recycling

[0108] HTC product slurry exiting the annulus of the wellbore of the reactor contains gas and liquid phases. Gases are separated from the liquids in a gas / liquid separator, while a hydrochar lamella separator separates the mostly liquid phase comprising water, hydrochar into two primary streams: a wet hydrochar stream and water, each containing varying degrees of the other stream. The wet hydrochar stream may be routed to a solids liquid separator, such as a vibrating screen followed by one or more centrifuges or belt press to generate relatively water free hydrochar, and then to a hydrochar thermal dryer.

[0109] The aqueous phase separated from the process can be recycled and mixed directly with the feed material as part of the feed biomass slurry preparation. The separated hydrochar solids contain unreacted biomass solids, carbonized biomass and other inert feed solids residuals. The hydrochar solids separated from the process can be used for soil amendment or as an inert carbon rich product for fuel, and / or used as a mechanical strength additive to concrete or metallurgical coke replacement or other materials.

[0110] Well Reactor Construction Examples

[0111] FIG. 6 schematically illustrates another system and method embodiment 200 in accordance with the present disclosure. In embodiment 200, the well is constructed using an existing oil and gas production well, so that terminology is used. The well includes of production tubing 104 serving as the inner tubing, and a production casing 102 serving as an outer tubing that is bonded to the subsurface formation using cement 90, forming a well annulus 106. Multiple inner tubes could be used but for simplicity, only one is described in this embodiment. “Casing” in this embodiment includes a conductor casing      252-P004WO  92, surface casing 94, intermediate casing 96, and production casing 102. Drilling mud (also referred to herein as drilling fluid) or insulating gel fluid such as POLAR-VIS viscosifier used in combination with Isotherm NT, an oil based insulating packer fluid both available from SLB, Houston, Texas, USA can be used between the upper portions of production casing 102 and the formation 28, and between casings 94, 96, and 102, as illustrated in FIG.6. The inner tubing length is selectively sized (or modified as described in other embodiments to achieve the selected length) to achieve the desired hydrostatic pressure. In embodiment 200 the inner tubing 104 length is typically about 700 m. This type of well construction is commonly used in the production of oil and gas.

[0112] The graph of FIG.7 illustrates schematically the temperature and pressure of the feed biomass slurry (upper dotted line) of embodiment 200 as it travels down the inner pipe of the wellbore while increasing temperature and depth / pressure. The return HTC product fluid (lower dotted line) exits the inner tube and travels to the surface as it decreases in temperature and pressure. Depth and pressure are directly correlated with hydrostatic pressure. The graph also shows the general pressure and temperature environments where HTC physical chemical reactions occur. As previously indicated, the time spent in the HTC favorable environments should be maximized as further explained herein.

[0113] Referring to FIGS.8 and 8A, another well HTC reactor embodiment 300 of the present disclosure is presented, comprising two primary zones and a third zone:  ●

[0114] Heat Transfer & Sub-surface Separation Zone (110);  ●

[0115] HTC Reaction Zone (112); and  ●

[0116] Return (product) fluid plenum (114).

[0117] In the Heat Transfer & Sub-surface Separation Zone 110, hot reacted HTC fluid that is heated at the bottom of the well travels to the surface in annulus 38. The HTC fluid in zone 110 preheats incoming feed slurry stream 5 in inner tubing 32 from ambient to      252-P004WO  approximately 200 ºC. Most of the heat is recovered via the transfer of thermal energy from the hot fluid in annulus 38 to incoming cold feed slurry 5 in inner tubing 32 while the remaining heat is lost to formation 28. In addition, the hydrochar generated from the HTC reactions coalesce and separate from water in annulus 38 in zone 110. There is sufficient hydrostatic pressure to ensure that the water does not boil to steam.

[0118] In HTC Reaction Zone 112, the temperature of preheated feed slurry 5 flowing downward in inner tubing 32 is boosted from about 200 ºC to about 250 ºC at the bottom portion of the well, 112. At this depth and in zones 112, 114, the feed biomass slurry is under sufficient pressure to ensure the fluid remains as a liquid and not turn to steam which is critical for HTC reactions to occur. The heat source comes from a submersed electrical resistance heater cable 36 inside inner tubing 32. A cement plug 116 is used to create the plenum zone 114. FIG.8A illustrates schematically the cross section 8A-8A, illustrating schematically with arrows the heat loss to formation (118), heat transfer from hot HTC product fluid 7 to cold feed biomass slurry 5 (120), and heat transferred to feed biomass slurry 5 from electrical resistance heating cable 36 (122). The arrows show the direction of the heat transfer. Cable 36 heats the fluid in inner tubing 32 which then transfers the heat to the fluid in the annulus which then transfers some heat to the formation which is lost. This cross-section illustration in FIG.8A changes with depth. It will essentially be the same if the cross-section is taken higher up the reactor but with no heating cable (only the power cable) and the heat source arrows will be in the opposite direction as identified in FIG.8A.

[0119] As the temperature of the feed biomass slurry 5 increases, sufficient pressure must be applied to ensure that feed biomass slurry 5 remains substantially (at least 95 percent, or at least 99 percent) in the liquid phase and above the liquid-gas saturation curve (FIG. 7) as the feed slurry is heated and cooled in the deep well reactor system for two reasons: ●

[0120] To ensure that steam is not generated that can impact fluid flow and heat transfer coefficient; and       252-P004WO  ●

[0121] To ensure energy is not wasted for the energy intensive step of water vaporization. The pressure in the system is generated by the hydrostatic pressure, as illustrated in the graph in FIG.7 which illustrates the feed biomass slurry (upper straight dotted line) and return HTC fluid (lower straight dotted line) are not in proximity to the saturation line (curved dotted line) thereby eliminating the risk of steam generation.

[0122] Alternative Heating Method – High pressure steam

[0123] FIG.17 presents a embodiment 700 in accordance with the present disclosure. In embodiment 700, high pressure steam 55 at a temperature of about 250 ºC is transferred to the bottom of the wellbore to the same depth as the electric cable heater via a tube 31 inside the inner tubing 32 (essentially replacing the cable). The pressure of the steam is higher than the hydrostatic pressure of the surrounding slurry. Once pass through high pressure steam generators are common place and used throughout heavy oil and SAGD operations for extracting bitumen. The high-pressure (about 62 bar, or 900 psi) steam is allowed to mix with the slurry near the bottom of the wellbore (at 56, as indicated by the arrows) and condense at 57, thereby transferring all of the thermal energy in the steam. High quality steam is not necessary as all of the steam will be condensed. This is an efficient way of generating low cost thermal energy at the surface and transferring to the wellbore. The condensed water is relatively small and is separated and treated with the aqueous phase as previously described. To meet water specifications for steam boilers, subsequent typical treatment is required.

[0124] Well HTC Reactor Design With Sensor Cable

[0125] While there is no standard well design given the numerous possible combinations of tubing lengths, tubing diameters, metallurgy, thickness, connectors, and the like, the following example provides insight into the process equipment and methods, operating      252-P004WO  parameters, features and limitations that determine deep well HTC reactor design. (Refer to Table 11.) Table 11. Well Construction Mechanics Inner Tube (Production 500 - 700 m Tubin ) Len th

[0126] Since there is no advantage in higher pressures to promote HTC reactions, the length of inner tubing 32 should be kept to the minimum length to minimize heat losses to the environment, cost of power and heater cable (34, 36), reduce repairs / maintenance and well intervention costs. If greater residence time is required, the length of inner tubing 32 could be increased and / or increase the diameter of outer tubing (casing) 30. As illustrated schematically in FIGS.11 and 12 of my co-pending United States provisional      252-P004WO  patent application number 63379127, a sensor cable may be provided, having connections to one or more temperature sensors (for example, a 260 ºC sensor and a 300 ºC sensor), and secured to collars using coupling cable clamps / protectors.

[0127] Most existing oil and gas production wells exceed the typical depth required for HTC reactions. Therefore, in certain embodiments using such wells, the well may be sealed from the unused bottom portion of the well. There are three primary methods of sealing a well at the bottom of the outer tubing that are commonly used in oil and gas well construction: cement plug, cast iron bridge plug and packer. A plug of cement or cast iron or similar material placed as a slurry in a specific location within the wellbore and which has been set to provide a means of pressure and flow isolation. An inner cement or cast iron plug (such as 116 from FIG. 8) and an outer cement or cast iron plug positioned between outer tubing 30 and formation 28 may be employed. Cement or cast iron plugs are preferred due to simplicity and ability to withstand high temperatures. A packer can be run into a wellbore with a smaller initial outside diameter that then expands externally to seal the wellbore. An inflatable packer employs flexible, elastomeric elements that expand. The well can be sealed at depths ranging from about 5 to about 10 m below a bottom or distal end of the inner tubing to create an upper plenum above the inner cement plug 116 and a lower plenum below the inner cement plug 116 to ensure:

[0128] sufficient space in the upper plenum for the fluid 5 to reverse flow towards the surface,

[0129] allow for the thermal expansion of inner tubing 32 (calculations indicate that the inner tube 32 will expand and grow in length approximately 0.9 – 1.3 m depending upon steel type)

[0130] provide separation that cools the wellbore fluid 5 between inner tubing 32 bottom and the seal if a non-cement / iron plug or seal 116 is used, and

[0131] prevent the flow of fluids or gasses via lower plenum from the original oil and gas bearing formation.       252-P004WO

[0132] Inner and Outer Tubes Design Examples

[0133] Tubing suitable for use as inner tubing 32 useful in the systems and methods of the present disclosure are made of corrosion resistant material, high thermal conductivity and low wall thickness. The wall thickness is determined primarily by structural requirements due to weight of pipe and joint connections and primarily for pressure differential across the pipe wall as the pressure is essentially the same. Inner tubing 32 is affixed to the wellhead at the surface which forces the thermal expansion of inner tubing 32 axially in the downward direction where a sufficient gap exists in the upper plenum between the bottom of inner tubing and plug 116.

[0134] Inner tubing 32 diameter is designed to provide relatively high velocity and turbulent flow regime to: ●

[0135] Increase heat transfer coefficient for the heat transfer from the hot product fluid 7 traveling up to the surface in annulus 38 to the cold biomass slurry 5 traveling to the bottom of inner tubing 32;  ●

[0136] Minimize deposition and fouling of the inside wall of inner tubing 32;  ●

[0137] Increase rate of hydrolysis and dehydration of the wet slurry biomass.

[0138] In contrast to my co-pending United States provisional patent application number 63379127, where the goal is to minimize residence time of the feed biomass slurry 5 in inner tubing 32 until the (deeper) HTL reaction zone is reached to less than about 45 minutes to minimize the time the feed slurry spends in the carbonization environment (temperatures ranging from about 180 to about 250 ºC) which the feed biomass slurry must pass through to reach HTL temperature and pressure environments lower in the well reactor, the primary goal in the systems and methods of the present disclosure is to increase residence time of the feed biomass slurry 5 in inner tubing 32 in the HTC zone (FIG.7).        252-P004WO

[0139] Conversely, in annulus 38, outer tube 30 (casing) diameter is designed to provide low velocity and laminar flow regime to: ●

[0140] Increase residence time for HTC reactions to occur in HTC reaction zone 112;  ●

[0141] Promote decarboxylation for the removal of carboxyl groups which results in the liberation of CO2 and aromatization. These reactions lower the hydrogen to carbon (H / C) and oxygen to carbon (O / C) ratios to produce the carbon-rich hydrochar in inner tubing 32;

[0142] Embodiments Using Coiled Tubing as Inner Tubing

[0143] In certain embodiments, such as embodiment 700 illustrated schematically in FIG. 17 of my co-pending United States provisional patent application number 63379127, inner tubing 32 can be a coiled tubing string supplied by Halliburton, Schlumberger, Weatherford, and the like, typically on a truck. Coiled tubing (CT) is a long, continuous thin walled length of pipe wound on a reel or spool. The pipe is straightened prior to pushing into a wellbore and rewound to coil the pipe back onto the transport and storage spool. Depending on the pipe diameter (3 / 4 in. to 4-1 / 2 in.) and the spool size, coiled tubing can range from 2,000 ft to 15,000 ft (610 to 4,570 m) or greater length. To deploy CT downhole, the CT operator spools CT off the reel, usually assisted by a crane, and leads it through a gooseneck, which directs the CT downward to an injector head, where the CT is straightened just before it enters the borehole at wellhead. The portability of a coiled tubing unit allows the removal of the tubing from the well for inspection and maintenance, clean any deposition on the tubing wall and repairs and maintenance that can be spooled back onto the reel. A CT unit could be installed permanently and fully integrated with the wellhead. In certain embodiments, a lower pressure-rated wellhead could be employed.         252-P004WO

[0144] Material build up on the exterior wall of inner tubing 32 is expected. Less material is expected on the interior wall of the inner tubing 32 due to high velocity and low residence time. My co-pending United States provisional patent application number 63379127 describes a cleaning system enclosed in a box with high pressure water sprayer nozzles around inner tubing 32 with fluid collection, separation and return to high pressure pump loop can be utilized. Surfactants, acids and caustic chemicals may also aid in the removal of any deposition. The tube continuously moves through cleaning system in these embodiments. The nozzle design, number of nozzles, nozzle flow rates, nozzle exit pressure, and nozzle positioning will vary from system to system, but certain embodiments may feature two sets of four flat fan nozzles with fan angle ranging from about 25 to about 36 degrees spray positioned in a spiral staircase manner essentially covering the pipe twice (available from Lechler or the like), flow rates ranging from about 20 to about 40 L / min (about 5 to about 10 gpm) per nozzle, at nozzle exit pressures ranging from about 10 to about 20 bar (from about 145 to about 290 psi), the nozzles set back about 1 to about 1.5 times the pipe diameter, and positioned in a spiral around the pipe offset 90 degrees from each other and the same in the axial direction. Flow rates, exit pressures, and angle of attack from nozzle to nozzle may be the same or different.

[0145] In certain embodiments, the heater cable, sensor cable and sensors can be integrated into the coiled tubing where the coiled tubing is preassembled with the heater cable placed inside the coiled tubing prior to mobilizing on location. These embodiments would provide for greater assurance of proper heater cable placement and reduces risk of potential blockages in the inner tubing when on location.

[0146] Multiple Feed Biomass Slurry Tubes

[0147] For maximum capital, footprint, startup and heat loss efficiency, in certain embodiments, such as embodiment 400 illustrated schematically in FIGS. 9 and 9A, multiple feed biomass slurry inner tubings 32 may be utilized within a single wellbore,      252-P004WO  each having its own heater cable 36. The wellbore geometry should be such that the fluid velocities, residence times and flow regimes remain in the same range as outlined herein. Generally, this would involve a larger diameter outer tubing 30 to accommodate a larger flow through annulus 38. In these embodiments the flow to each inner tubing 32 would be controlled to be independent and monitored so as not to have reverse flow. It will be understood that other embodiments are possible than those illustrated in FIGS.9 and 9A. For example, the number of inner tubing 32 and heater cables 34, 36, may be lower or higher than illustrated. FIG.9A illustrates a cross section of a wellbore with seven inner tubing 32 and seven heater cables 36 within an outer casing 30.

[0148] Heat Source Method

[0149] The downhole power and heating cable 34 consists of two sections: power transmission and heating. FIG. 10 illustrates schematically a portion of the power transmission cable, with some parts cut away, including the heating element 34, magnesium oxide insulation 190, and a stainless steel sheath 192. In certain embodiments, the power transmission and heating sections are bonded together in series and wound on a single spool at the surface. As explained in my co-pending United States provisional patent application number 63379127, a coiled power cable provides the required voltage from a power control cabinet to the coiled heating cable. The downhole heating cable provides the heating density required for maintaining wellbore temperature. This designed cable will produce heat via resistance and the skin effect principle for safe and effective heating downhole of the feed biomass slurry.

[0150] Heating Cable Specifications (Expected)

[0151] Power Cables:

[0152] Cable Size: OD Ø30mm (Ø1.181in), Three phase.

[0153] Core Conductor

[0154] Rated Voltage: 1,500 V       252-P004WO

[0155] Working Temperature Range: 250°C @ about 500 m

[0156] Working Temperature Range: 600°C @ 160 m

[0157] Tensile Strength: 630MPa (91.4ksi)

[0158] Cable Weight: 3.0kg / m (2.02lbs / ft)

[0159] Heater Cable:

[0160] Rated Power: 300kW

[0161] Insulation Resistance: about 300MΩ ^km or greater (Temperature at 20°C, Humidity 80%)

[0162] Sheath Outer Tubular Material: 316L Stainless Steel (eq. to US ASTM Gr.240)

[0163] Heater Cable Length: about 160m at 600°C (1,112°F).

[0164] The length of the heater cable is determined by the watt density of the heater cable, typically ranging from about 0.8 to about 2.0 W / m, and the heating requirement. Higher heating power watt density is desirable as it will reduce the time to heat the formation resulting in a faster startup of feed biomass slurry.

[0165] Power Distribution Design for Heater Cable

[0166] In certain embodiments, the control cabinet power may be 400 kilowatts with a three phase AC input voltage of 480V or 600V, depending on main grid voltage. The medium voltage fuse cabinet (203) may be rated 1,600V at 135A from the transformer to protect the heater cable.

[0167] Heater cable and Wellhead Adapter

[0168] The wellbore containing the inner and outer tubes along with the plug seal completely isolates the formation therefore influx of fluids into the wellbore is not possible which eliminates any unwanted high-pressure event. Since the wellbore is never      252-P004WO  in communication with the producing formation when the cable is in the well, a lower specification well head adapter design can be adopted compared to a traditional well head requiring high pressure specifications. The pressure at the well head adapter is expected to be less than 100 psi to accommodate pressure line losses in the inner / outer tubes and any back pressure required for the surface downstream separation equipment. The heating cable is run on the inner diameter of the tubing and therefore the cable weight will be hung off at the wellhead.

[0169] Heat Transfer

[0170] One of the biggest advantages of systems and methods of the present disclosure is the ability to transfer heat without the addition of a high-pressure heat exchanger to the overall process, high pressure safety systems and instrumentation. The heat from the HTC product fluid moving to the surface in the annulus is efficiently and safely transferred to the cold feed biomass slurry moving through the inner tube via the inner tube wall. Efficient heat transfer between the inner and outer tubes is critical to minimize energy consumption and controlling high returning product fluid 7 temperatures.

[0171] As illustrated in FIGS.11 and 11A, embodiment 500, feed biomass slurry enters the well in most embodiments at ambient temperature and low pressure, about 50 psi for example. The feed biomass slurry rapidly increases in temperature in inner tubing 32 at 18.1 and 18.7 ºC / min in heat transfer and sub-surface separation zone 110 and HTC reaction zone 112, respectively. This high rate of heat transfer is due to the high velocity in inner tubing 32. The temperature gradient in inner tubing is positive 0.08 ºC / m (as illustrated at 242) vs. negative gradient of 0.12 ºC / m in the annulus (as illustrated at 240) as heat is transferred to the feed biomass slurry in inner tubing 32. The difference in inner tubing and annulus is due to the temperature differential which is required for the heat transfer. The thermal energy from the exiting fluid can be further recovered by preheating the feed biomass slurry with commonly available high surface area plate frame heat      252-P004WO  exchangers or heat exchanger designs that can operate in the relatively low temperature and pressure environments at the surface. Alternatively, the separated water in the HTC product fluid 7 can be mixed directly with the feed biomass slurry as part of the makeup water to harness all the energy in the HTC product fluid 7. Separation equipment at surface will need to withstand the operating temperature of the outbound HTC product fluid 7. As illustrated schematically in FIG. 11A, arrows 246 illustrate heat loss to formation 28, and arrows 244 illustrate temperature increase in the HTC reaction zone. And arrows 242 illustrate the heat transfer to the HTC project fluid 7 resulting in temperature increase.

[0172] Modeling transient heat loss to the formation is a geomechanical, thermal and fluid flow problem which can be conducted with finite and discrete elemental methods as typically used for modeling heat and steam transfer to the heavy oil or bitumen formation such as steam assisted gravity drainage production. Heat transfer and thermodynamic equations can be used to calculate the heat losses over time. Fundamentally, the thermal energy is transferred to the formation via the outer tube wall and cement bond interface between the outer tube and formation from the heated fluid with the heater cable as the source.

[0173] Heat Loss to Formation

[0174] In order to model heat loss to the formation, several characteristics and parameter assumptions must be made including geological properties, wellbore construction, thickness and length of wellbore materials, thermal conductivity and specific heat of steel, concrete, drilling fluids and formation, surface areas and impacted formation volume, operating and formation temperature. Calculated results based on the assumptions described herein are illustrated schematically in FIG.12. Calculations were conducted in equally spaced segments in the vertical direction. In systems and methods of the present disclosure the temperature inside the wellbore is assumed to be equal to the temperature      252-P004WO  of the outer tubing. This generates a temperature gradient with the reservoir temperature at a particular distance from the interface. It is generally understood that formation temperatures increase with depth at approximately 0.025 ºC / m but is location specific and dependent upon many geological factors and can be as high as 0.04 ºC / m. (SINTEF. “Drilling the world's hottest geothermal well”, ScienceDaily, 23 October 2015).

[0175] Overtime, as illustrated in FIG. 12, as heat is lost radially to the formation, the formation temperature will rise and exceed the natural formation temperature eventually reaching a steady state temperature at a particular distance. The time taken to reach the outer edge temperature at a particular distance was modeled and the results depicted in FIG.27 of my co-pending United States provisional patent application number 63379127. This can be generally referred to as “soak time”.

[0176] Heat loss to the formation is greatest at the cold start of the process where the temperature gradient between the fluid 7 in the annulus and the formation 28 is the greatest. The heat loss to the formation reduces over time as the formation around the wellbore increases in temperature, specifically the delta T associated at that depth which is variable with depth, i.e. heat loss is greater at the bottom of the wellbore vs surface. Initially, the majority of the heat is transferred to the formation as the starting fluid 5 (feed biomass slurry or a simple water starting fluid) is circulated through the wellbore. The starting fluid is circulated in and out of the wellbore until the formation reaches target temperature after which the feed biomass slurry can be fed into the deep well reactor. As depicted in FIG. 13, When the heat loss to the formation equals the heat output of the heaters (300 kW), then the net heat to the feed biomass slurry is initiated. As time passes, an increasing amount of heat is transferred to the feed biomass slurry while heat loss to the formation is decreasing. Practically, this means the feed biomass slurry processing rate increases and cost of energy decreases over time.          252-P004WO

[0177] Heat loss to the formation is the greatest source of energy requirement for the systems and methods of the present disclosure. The graph in FIG. 13 shows the accumulated thermal energy and the distribution to the fluid 5 and formation. Once the formation is heated sufficiently, i.e. at about Day 4 or 5, a greater portion of the heat added to the system is distributed to the fluid. For example, at Day 2 only 33 percent of the energy is transferred to the fluid versus 64 percent at Day 10. This trend continues slowly but indefinitely, i.e.91 percent after four years.

[0178] Wellbore Heat Loss Reduction Methods

[0179] In certain embodiments, steps can be taken to minimize wellbore heat losses through wellbore design but cannot be eliminated. The following list summarizes methods to minimize losses:

[0180] insulating cement,

[0181] drilling fluid selection, and

[0182] placement of cement.

[0183] Insulating Cement

[0184] This technique is illustrated in FIGS. 31, 31A, 31B, and 31C of my co-pending United States provisional patent application number 63379127. Those figures illustrate schematically use of thermal resistant insulating cement at the time of well construction to reduce heat losses. In a typical wellbore with a drilling rig, a cement float collar and cement guide shoe may be used with a cementing head and cementing manifold to inject insulating cement (for example comprising perlite). In these embodiments, the casing is bonded to the formation using insulating cement. Drilling fluid is allowed to permeate and flow between the formation and the insulting cement at certain locations.         252-P004WO

[0185] Cement has a wide range of thermal conductivity 0.62 - 3.3 W / mK depending upon temperature, moisture condition and types of coarse aggregate. For the purposes of modeling, 1.7 W / mK was used. Significant improvements in insulating properties can be made with the addition of fly ash (Shahedan, et al., “Thermal Insulation Properties of Insulated Concrete”, Revista de Chimie. 70. 10.37358 / RC.19.8.7480 (2019)); use of foamed thermal resistant cement; or the addition of perlite to the cement. Perlite is an amorphous volcanic glass and thermal conductivity as low as 0.15 W / mK is possible. In particular, foamed thermal resistant cement may withstand stresses and loads that occur in well construction during the curing, pressure test, completion, production, and injection phases of its life and provide zonal isolation during the life of the well. Petty et al., “Life Cycle Modeling of Wellbore Cement Systems Used for Enhanced Geothermal System Development”, Proceedings 28th Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, January 27-29, 2003. The density of cement is 1.96 kg / L and was reduced to 1.08 kg / L with 20% foam cement, a 45 percent reduction. In addition, the thermal conductivity of the 20 percent foam cement was reduced by 65 percent. Maddi, “Smart Foam Cement Characterization for Real Time Monitoring of Ultra-Deepwater Oil Well Cementing Applications” (2016). The overall impact of a 65 percent reduction in thermal conductivity of cement on the entire wellbore results in an initial reduction of 4 percent in heat loss based on the example wellbore.

[0186] Drilling Fluid Selection

[0187] During drilling and well construction, some drilling fluid permeates into the formation between the cement and the formation, and some drilling fluid remains behind the most outer casing and the formation by design, typically between 1 mm - 50 mm respectively. Intuitively using a lower thermal conductivity drilling fluid when drilling makes good sense because the thermal conductivity of generic water-based fluid is around 0.575 ^^ ^^. ^^ (Hong et al., “Influence of MoS2Nanosheet Size on Performance of Drilling Mud”) and that of generic oil-based fluid is around 0.275 ^^ ^^. ^^ (Fazelabdolabadi et al.,      252-P004WO  “Thermal and rheological properties improvement of drilling fluids using functionalized carbon nanotubes”). Alternatively, a well can be drilled using air drilling methods in formations where there is no influx of water or hydrocarbon liquids. Compressed air at high flow rates and moderate pressures are used to circulate through the well bore. Air drilling eliminates the use of liquids entirely thereby inherently generating a porous and insulating layer between the outer casing and the formation and the cement and the formation. Mist and foam drilling can also provide similar benefits as they use limited amounts of water.

[0188] Placement of Cement

[0189] The placement of cement between the casing and borehole is to ensure wellbore security, support casing, corrosion protection, isolating formation fluids and pressure containment. At intermediate depths, typical placement of cement is not taken to the surface. Where possible, the depth of cement should be kept to a minimum due to the thermal conductivity of cement at 1.7 W / mK vs drilling fluid at 0.572 W / mK. Drilling fluid provides better insulating properties than cement. In alternative embodiments, drilling fluid behind the casing can be displaced entirely with insulating cement along with non-insulating cement used for securing the casing This provides the benefit of structural integrity of cement and improved reduction in heat losses to the formation based on 0.572 W / mK for drilling fluid vs 0.15 W / mK for insulating cement as previously described.

[0190] Geothermal

[0191] One might believe that geothermal energy could be applied as a CO2-free and natural source of heat, however there is a practical limitation to the access to geothermal energy. The temperatures at which the HTC well reactors operate in accordance with the present disclosure are above any current geothermal wells which are typically less than      252-P004WO  150 ºC. At deeper levels, drilling operations and materials integrity are faced with major challenges. Steel becomes brittle, and materials such as plastics and electronics either fail or start to melt. Normally, wellbore tool electronics only function for a short time at temperatures greater than 200 ºC. These problems must be resolved if the extraction of high-temperature geothermal heat is to become a going concern. However, geothermal energy can still play an important role in certain embodiments in minimize energy requirements by reducing heat loss to the formation by reducing the delta T between the fluid in the annulus and the formation. Smaller the delta T, lower the heat loss as previously discussed.

[0192] CO2Balance

[0193] FIGS.14 and 15 illustrate a carbon dioxide balance in certain embodiments of the present disclosure treating waste water, 502, in a WWTP, 504. The WWTP 504 produces a biomass 506 which is fed to an HTC system 508 as explained herein, producing hydrochar 510, thus averting landfill or land application (box 508) of biomass 506. Hydrochar may be dried and transported to an end use location (box 512), and may be used as carbon neutral fuel 514 in a hydrochar combustion system (520), and / or used as a soil amendment (box 516), whereby the hydrochar permanently sequesters majority of the carbon (box 522), averting further landfill or land application (box 518). As an example, FIG.15 illustrates graphically that a gross amount of 27,486 tons / year CO2may be averted, with some CO2being generated in the HTC process (about 2367 tons / year), some CO2 being generated by hydrochar drying (about 1066 tons / year), some CO2 generated in transporting hydrochar (about 11 tons / year), some CO2 generated during the slow hydrochar decomposition (about 3990 tons / year), and some CO2generated by transporting solids to landfills, leaving a net amount of CO2 averted to be about 19,980 tons / year.          252-P004WO

[0194] Process Flow Diagram & Operations

[0195] Process Flow Diagram

[0196] FIGS.16A and 16B combined represents a schematic process flow diagram of one embodiment 600 of an overall system and method of the present disclosure for processing biomass from a WWTP into hydrochar.

[0197] While not required in all embodiments, embodiment 600 includes equipment at both surface and subsurface that are fully integrated. The process takes in biomass materials and outputs five primary products: 1. wet bulk hydrochar for sale as a soil amendment, 2. dry hydrochar for sale as a soil amendment, 3. dry hydrochar for sale as a fuel, and / or cement additives and / or metallurgical coke; 4. methane for energy recovery; and 5. Liquid fertilizer. A small amount of carbon dioxide produced is either vented, or may be useful for dry ice production, steel mill slag blanketing operations, carbonic acid production, and the like, if the volume of carbon dioxide is enough to make this commercially attractive.

[0198] Waste water 602 is collected and routed to a WWTP 604, where a slurry (sludge) is formed. The sludge is partially dewatered in a dewatering unit 605, for example a belt press, a plate and frame press filter, hydrocyclone, centrifuge, and the like. Some water is then recycled (607) while a wet biomass stream 606 is formed. This part of the WWTP is typical and existing. Wet biomass 606 which is typically transported offsite for disposal by the WWTP is then combined with HTC water 628 in a process unit 608 to form the feed biomass slurry 5, where HTC water is water removed from hydrochar formed during the HTC process. Process unit 608 may include mixing facilities and may include combining one or more additives with the biomass and HTC water, as needed or desired. Feed biomass slurry 5 is then routed through one or more heat exchangers 610 where heat is transferred from a degasified product slurry 638 to feed biomass slurry 5.      252-P004WO  Feed biomass slurry 5 then is routed to a well reactor 634, as described herein, producing a reactor product stream 7 that includes hydrochar. A gas / liquid separator 639 separates reactor product stream 7 into degassed hydrochar stream 638 and gas stream 640, the latter of which is further separated in a gas treatment facility 642 (which may include a knock-out drum, a chiller, and a methane / carbon dioxide separator, such as an adsorption unit) into CO2 vent gas, 644, and methane for combustion heat or power, 646. Electricity (636) is supplied to the heater cable of well reactor 634.

[0199] A hydrochar lamella separator 612 receives cooled, degasified hydrochar stream 638 from heat exchanger 610, producing HTC water 628 and a partially dewatered hydrochar stream that is routed to a solids wash column 614, where Total Organic Carbon (TOC) is reduced in the partially dewatered hydrochar by washing with treated water, 630. Solids wash column 614 produces a partially dewatered, TOC reduced hydrochar stream that is routed to a hydrochar centrifuge 616, producing a second partially dewatered, TOC-reduced hydrochar stream that is fed for further drying to a hydrochar thermal dryer, 618, which uses a fuel 620 and in turn produces dried hydrochar for packaging, 622, and for later use either as dry hydrochar for sale as a soil amendment, 624, or dry hydrochar for sale as a fuel, 626. Alternatively, or in addition thereto, hydrochar centrifuge 616 may produce a wet bulk hydrochar stream for sale as a soil amendment, 632.

[0200] All of process units 614, 616, and 618, and in some cases the hydrochar lamella separator 612, produce water streams 650, 662, 664, and 648, all of which are routed to an HTC process water tank 652. In the case of water stream 664, which will be a wet steam, a condenser is provided, 666. HTC process water may be treated to remove dissolved organics, and receive pH treatment, in a unit 654, while some (or all) of the HTC process water may be used a liquid fertilizer, 660. HTC process water that has had dissolved organics removed and adjusted for pH may then be routed to treated water tank      252-P004WO  630, and a portion used in solids wash column 614, with the remainder routed back to the WWTP 604.

[0201] In embodiment 600, one or more additives may be mixed into the biomass slurry in tank 608, such as catalysts, pH adjustment chemicals such as sodium hydroxide or sulfuric acid, chlorine, and the like. The feed biomass slurry 5 is prepared to meet flow and viscosity characteristics suitable for pumping as described herein. Feed tanks may be equipped with agitators which could include circulating pumps with jets or standard shaft / impeller agitators to ensure solids remain suspended in the slurry. Feed tanks can also receive various chemicals to assist with the process such as corrosion inhibitors, cleaning chemicals such as surfactants, pH adjustment chemicals such as sodium hydroxide, sulfuric acid, chlorine, and the like, heterogeneous and non-heterogeneous catalysts, and thermal resistant rheological additives such as bentonite.

[0202] The biomass slurry may be pumped by a vertical multistage centrifugal slurry pump capable of pumping up to 10,000 L / hr., 100 cP, 1.5 SG and 7 bar such as a Gol Pump model SBI 10 - 16. Biomass slurry 5 from feed tanks is pumped at <100 psi pressure and ambient temperature into the feed preheater heat exchanger 610, which may be a plate frame heat exchanger or other design, where feed biomass slurry 5 is heated with return degassed HTC product fluid 638 (from which light ends have been removed in two-phase separator 639). HTC product fluid 7 comprises products from the hydrothermal carbonization reactions of the biomass, including hydrochar, water, gasses, and inert materials at temperature less than about 70 ºC and less than about 100 psi. The feed biomass slurry 5 is heated from ambient to about 20 ºC less than the HTC product fluid temperature or approximately 50 ºC in feed preheater heat exchanger 610. Optionally, in certain embodiments, a coiled tubing unit and high-pressure cleanout unit may be employed, as discussed previously herein.        252-P004WO

[0203] The purpose of the well reactor 634 is to take the feed biomass slurry 5 and apply sufficient pressure, temperature and residence time for HTC reactions to occur. After the conversion of the biomass slurry, the HTC product fluid and gas byproducts are returned to the surface for separation and recovery. The preheated feed biomass slurry 5 enters the well biomass conversion reactor 634 through the inner tubing 32 of the reactor (about 500 m to about 700 m (about 1500 to about 2100 ft.) in length that comprises two zones. As the feed biomass slurry 5 travels to the bottom of inner tubing 32, it gathers heat from HTC product fluid 7 in annulus 38 to about 180 ºC to 350 m, referred to herein as Zone 1, Heat Transfer & Sub-surface Separation (110). HTC product fluid 7 travels to the surface counter-currently to feed biomass slurry 5. Feed biomass slurry 5 is further subjected to heat from the heater cable 36, raising the temperature from about 180 ºC to the target of 250 ºC, referred to as Zone 2 HTC Reaction (112). In this example, the residence time of feed biomass slurry 5 in inner tubing 32 in Zone 1 and 2 are about 11 minutes and about 3 minutes, respectively, which times may vary depending on the feed biomass slurry characteristics, well reactor structure, and efficiency of the heater cable. The residence times in the annulus 38 between inner and outer tubing in Zones 1 and 2 are about 73 minutes and about 26 minutes respectively. The velocity of feed biomass slurry 5 in inner tubing 32 may range from about 0.6 to about 1.5 m / s, and velocity of HTC product fluid 7 in annulus 38 may range from about 0.05 to about 0.3 m / s. Feed biomass slurry 5 exits inner tubing 32 at about 700 m and enters return plenum 114 where the flow is thereafter channeled to annulus 38 where HTC product fluid 7 travels to the surface. HTC reactions occur in Zone 2 (112), both in inner tubing 32 and in annulus 38 at temperatures ranging from about 200 ºC to about 250 ºC and pressures ranging from about 40 to about 65 bar. In this example, the residence time of HTC product fluid 7 in annulus 38 in Zone 1 (110) and Zone 2 (112) are about 83 minutes and about 29 minutes, respectively, in embodiment 600.

[0204] In most embodiments, while not absolutely necessary, before the feed slurry flow to the well reactor can be initiated the wellbore is heated to ensure that feed biomass      252-P004WO  slurry 5 will reach the target temperature. In these embodiments, initially, the temperature of the steel tubing / casing, concrete and adjacent drilling fluid is heated followed by the formation to a certain distance as described previously herein. This is generally referred to as the soak period which has been calculated to be approximately 15 days based on assumptions of well construction and formation characteristics used in the modeling. The heat is provided by circulating a heat soak fluid, for example, but not limited to inorganic fluids such as water, steam, nitrogen, air, synthetic air, and organic fluids, such as natural gas, light hydrocarbons, glycol solutions, and the like through inner tubing 32 and heated with the 300 kW heater cable 36. The heat soak fluid, if not already at temperature (such as when steam is used), is heated to about the same temperature as the feed biomass slurry. The heat soak fluid in annulus 38 heats outer steel tubing / casing, cement and / or drilling fluid, and the formation. In the case of water used as the heat soak fluid, the same water is returned to inner tubing inlet and recirculated. After about 4 days of recirculating and heating, the feed biomass slurry can be initiated at a rate that matches the heat energy available which equals the heat generation from the heater cable less the heat loss to the formation as previously discussed. Heat loss to the formation is continuously decreasing over time and therefore the feed biomass slurry feed rate can be increased accordingly.

[0205] The heat soak period can be accelerated by adding heat at the surface to the water or other heat soak fluid exiting annulus before returning to the inner tubing. The heating at the surface can be performed by a traditional water heater, raising the temperature to below boiling point of approximately 90 ºC while ensuring that the annulus water temperature does not exceed boiling temperature. This accelerated heat soak configuration is not illustrated in FIGS.16A and 16B.

[0206] Process Control Methods

[0207] To ensure efficient and safe transfer and separation of fluids, systems and methods of the present disclosure are controlled by one or more programmable logic controllers.        252-P004WO

[0208] Subsurface

[0209] Two methods are described to control the heater cable which in turn provides the desired set temperature and subsequently the heat transfer required for the HTC reactions. A first method is to use a thermocouple (TC) with a cable to measure the temperature of the inner tubing wall. The temperature delta between target and measured will trigger the power controls to turn on / off the power to the heater cable to maintain temperature. In certain embodiments, three TCs may be used: TC1, a primary TC to control the heater cable, may be placed at the bottom of the inner tubing which will be used to ensure that the temperature of the feed biomass slurry has reached a set point of about 250 ºC. A second thermocouple, TC2 may be used to confirm the expected target temperature of 180 ºC at the start of the heater section. Both TC1 and TC2 can be used jointly in certain embodiments to minimize response time and troubleshooting. A third thermocouple, TC3, may be placed midway of the high temperature-rated power supply cable (lower portion, at greater depth) and is used to protect the lower temperature-rated power supply cable (upper portion, extending from the high temperature-rated power supply cable to surface). If the TC3 temperature exceeds 250 ºC, essentially a High High trigger, then power to the heater cable can be stopped until high temperature subsides.

[0210] Hydrochar Properties (Zhang et al, “Hydrothermal Carbonization for Hydrochar Production and Its Application”)

[0211] Heating Value

[0212] HTC reactions including dehydration and decarboxylation convert lignocellulosic biomass into a high value solid fuel with High Heating Value (HHV) of 24 - 30 MJ / kg similar to that of lignite and subbituminous coal. These deoxygenation and dehydration reactions cause hydrochar to have high hydrophobicity and increased carbon content compared to the raw feedstocks due to the decrease in the number of low energy H-C and      252-P004WO  O-C bonds and increase of high energy C-C bond, thereby increasing the energy density of biomass feedstock.

[0213] Soil Amendment

[0214] Hydrochar is increasingly used as a soil amendment in degraded and contaminated soils. Numerous studies show that hydrochar applied to the soil can effectively increase the porosity of the soil and the content of soil organic matter (SOM), and provide a good environment for soil microbial growth and reproduction, thus improving soil quality and increasing crop yield.

[0215] Hydrochar has an important impact on soil porosity. For example, 2% (w / w) hydrochars addition to soil decreased the bulk density of the soil by 0.1 g / cm3, and increased the porosity by 3.4%. The degree of the increase of the porosity depends on process conditions and particle size.

[0216] Soil moisture is one of the most important material components in agro- ecosystems, which is vital to plants and animals, usually expressed by the available water capacity (AWC). The addition of hydrochar can increase soil water content by enhancing soil porosity and aggregate formation and by changing soil tortuosity; large particles of char can block pores. Moreover, hydrochar particles are known for having more porosity to retain water due to their spherical shape and deformability.

[0217] Soil cation exchange capacity (CEC), as an important indicator of soil fertility and buffering capacity, reflects the ability of the soil to absorb and supply exchangeable nutrients. Additionally, the 13C NMR spectra and the SEM-EDS analyses showed that hydrochars are rich in oxygen containing functional groups, such as hydroxyl, ester, aldehyde, nitro, ketone, phenolic, and carboxyl groups. Presence of these functional groups on the surface of hydrochar can significantly enhance the CEC      252-P004WO

[0218] From the foregoing detailed description of specific embodiments, it should be apparent that patentable systems and methods have been described. Although specific embodiments of the disclosure have been described herein in some detail, this has been done solely for the purposes of describing various features and aspects of the systems and methods, and is not intended to be limiting with respect to the scope of the systems and methods. It is contemplated that various substitutions, alterations, and / or modifications, including but not limited to those implementation variations which may have been suggested herein, may be made to the described embodiments without departing from the scope of the appended claims.

Claims

252-P004WO  What is claimed is:

1. A system comprising:  a well having a well depth, a top positioned at a surface location, and a bottom portion positioned at a subterranean location, the well comprising a casing and one or more tubing (in certain embodiments, coiled tubing) positioned therein, forming an annulus there between, the casing and the one or more tubing defining a hydrothermal carbonization (HTC) reaction zone in the bottom portion of the well and a heat transfer and separation zone above the HTC reaction zone;   the well further comprising a cable comprising an electric heating element positioned in one or more of the one or more tubing in the HTC reaction zone and configured to transfer energy endothermically to a biomass slurry flowing downward through at least one of the one or more tubing, and convert at least a portion of the biomass slurry into a composition comprising water and hydrochar by HTC, the biomass slurry entering into the tubing at the top of the well at a first temperature and a first pressure, the well depth and the electrical heating element sufficient to produce a second temperature and a second pressure in the reaction zone sufficient to maintain water in the composition as liquid.

2. The system of claim 1 wherein the heat transfer and separation zone is positioned and has a length sufficient to allow heat transfer between the biomass slurry flowing turbulently through the one or more tubing and the product fluid traversing through the annulus, and simultaneously allow the reacted product fluid to transition from a substantially biomass slurry to a substantially hydrochar slurry product fluid flows out of the well.

3. The system of claim 1 wherein the casing and the one or more tubing are configured into a substantially parallel counterflow heat exchanger.         252-P004WO  4. The system of claim 1 devoid of any structure or equipment to introduce an oxidizer chemical into the biomass slurry.

5. The system of claim 1 wherein the well is cemented with insulating cement.

6. The system of claim 1 wherein the well depth ranges from about 500 m to about 700 m (from about 1,500 feet to about 2,300 feet).

7. The system of claim 1 wherein the well depth is at least 500 meters (at least 1,500 feet), and the heat transfer and separation zone is positioned at and configured so that it has a length ranging from about 400 meters to just under 500 meters.

8. The system of claim 1 wherein the well is an abandoned and / or non-producing hydrocarbon production well.

9. The system of claim 1 wherein the well is a new construction well.

10. The system of claim 1 wherein the well is devoid of submersible pumps, and the well is constructed to allow continuous circulating turbulent flow of the biomass slurry into the well and laminar product fluid flow out of the well.

11. The system of claim 1 wherein the one or more tubing is configured to produce turbulent biomass slurry flow through the one or more tubing.

12. The system of claim 1 wherein the electric heating element has a power rating ranging from about 0.8 to about 2.0 W / m of heating element length.        252-P004WO  13. The system of claim 1 wherein the well depth, tubing inner diameter, and electrical heating element are sized sufficiently to control temperature of the biomass slurry to a temperature ranging from about 180 ºC to about 250 ºC to promote HTC.

14. The system of claim 1 comprising a facility to form the biomass slurry, the facility comprising tankage and a mixer to mix a biomass slurry precursor composition with one or more non-thermally sensitive inorganic additives to form the biomass slurry, wherein the biomass slurry has shear thinning rheological properties.

15. A system comprising:   a well having a well depth, a top positioned at a surface location, and a bottom portion positioned at a subterranean location, the well comprising a casing and a single tubing positioned therein, forming an annulus there between, the casing and the tubing defining a hydrothermal carbonization (HTC) reaction zone in a first section of the bottom portion, a return fluid plenum in a second section of the bottom portion, the second section located below the first portion, and a heat transfer and separation zone above the HTC reaction zone;   the well further comprising a cable comprising an electric heating element positioned in the tubing in the HTC reaction zone and configured to transfer energy endothermically to a biomass slurry flowing downward through the single tubing, and convert at least a portion of the biomass slurry into a composition comprising water and hydrochar by HTC, the biomass slurry entering into the single tubing at the top of the well at a first temperature and a first pressure, the well depth and the electrical heating element sufficient to produce a second temperature and a second pressure in the reaction zone sufficient to produce a second temperature and a second pressure in the reaction zone sufficient to maintain water in the composition as liquid.

16. The system of claim 15 wherein the heat transfer and separation zone is positioned and has a length sufficient to allow heat transfer between the biomass slurry flowing      252-P004WO  turbulently through the tubing and the product fluid traversing through the annulus, and simultaneously allow the reacted product fluid to transition from a substantially biomass slurry to a substantially hydrochar slurry product fluid flows out of the well.

17. The system of claim 15 wherein the casing and the tubing are configured into a substantially parallel counterflow heat exchanger.

18. The system of claim 15 devoid of any structure or equipment to introduce an oxidizer chemical into the biomass.

19. The system of claim 15 wherein the well depth is at least 500 meters (at least 1,500 feet), and the heat transfer and separation zone is positioned at and configured so that it has a length ranging from about 400 meters to just under 500 meters.

20. The system of claim 15 wherein the well is devoid of submersible pumps, and the well is constructed to allow continuous circulating turbulent flow of biomass into the well and laminar product fluid flow out of the well using only hydrostatic head.

21. The system of claim 15 wherein the tubing is configured to produce turbulent biomass slurry flow through the tubing.

22. The system of claim 15 wherein the well depth, tubing inner diameter, and electrical heating element are sized sufficiently to control temperature of the biomass slurry to a temperature ranging from about 180 ºC to about 250 ºC to promote HTC.

23. The system of claim 17 wherein the tubing is coiled tubing.      252-P004WO  24. A system comprising:  a well having a well depth, a top positioned at a surface location, and a bottom portion positioned at a subterranean location, the well comprising a casing and one or more tubing (in certain embodiments, coiled tubing) positioned therein, forming an annulus there between, the casing and the one or more tubing defining a hydrothermal carbonization (HTC) reaction zone in the bottom portion of the well and a heat transfer and separation zone above the HTC reaction zone;   the well further comprising a third conduit positioned in one or more of the one or more tubing in the HTC reaction zone and configured to convey high pressure steam to a steam and slurry mixing region near a bottom of the well and to transfer energy endothermically to a biomass slurry flowing downward through at least one of the one or more tubing, and convert at least a portion of the biomass slurry into a composition comprising water and hydrochar by HTC, the biomass slurry entering into the tubing at the top of the well at a first temperature and a first pressure, the well depth and the high pressure steam having a flow rate and temperature sufficient to produce a second temperature and a second pressure in the reaction zone sufficient to maintain water in the composition as liquid.

25. A method comprising:  flowing a biomass slurry into a top of one or more tubing positioned inside a casing of a well forming an annulus there between, the well having a well depth, a top positioned at a surface location, and a bottom portion positioned at a subterranean location, the casing and the one or more tubing defining a hydrothermal carbonization (HTC) reaction zone in the bottom portion of the well and a heat transfer and separation zone above the HTC reaction zone;   heating the biomass slurry flowing downward through the HTC reaction zone employing a cable comprising an electric heating element positioned in one or more of the one or more tubing in the HTC reaction zone;        252-P004WO  converting at least a portion of the biomass slurry into a composition comprising water and hydrochar by HTC in the HTC reaction zone, the biomass slurry entering into the one or more tubing at the top of the well at a first temperature and a first pressure, the well depth and the electrical heating element sufficient to produce a second temperature and a second pressure in the HTL reaction zone sufficient to maintain the water in the biomass slurry and in the composition as liquid;  flowing the composition comprising the hydrochar upward through the annulus between the casing and the one or more tubing; and  transferring heat between the composition and the biomass slurry in the heat transfer and separation zone.

26. The method of claim 25 comprising flowing the biomass slurry and the product fluid in a substantially parallel counterflow arrangement.

27. The method of claim 25 comprising flowing the product fluid out of the well and to a facility for separating the product fluid into a liquid stream comprising water, raw hydrochar, and gaseous products, further separating the liquid stream into the water, the raw hydrochar, and the gaseous products, and treating the raw hydrochar to produce a wet hydrochar or a dry hydrochar suitable for sale.

28. The method of claim 27 wherein the gaseous products are treated to produce a natural gas stream, and the natural gas stream is routed to a power generator.

29. The method of claim 27 wherein the biomass slurry is preheated prior to entering the well by receiving heat from the liquid stream in a preheat heat exchanger.

30. The method of claim 27 comprising delivering the biomass slurry into the one or more tubing at the top of the well to generate enough hydraulic energy to force the product fluid to exit the annulus to be routed to the facility for separating the product fluid into      252-P004WO  the liquid stream comprising water, raw hydrochar, and gaseous products without pumping, allowing continuous circulating flow of the biomass slurry into the well and product fluid out of the well using only hydrostatic head.

31. The method of claim 25 wherein the heat transfer and separation zone is positioned and has a length sufficient to allow heat transfer between the biomass slurry flowing downward through the one or more tubing and the product fluid traversing upward through the annulus.

32. The method of claim 25 performed without introducing an oxidizer chemical into the biomass slurry.

33. The method of claim 25 wherein the electric heating element has a power rating ranging from about 0.8 to about 2.0 W / m of heating element length.

34. The method of claim 25 comprising constructing the well depth, tubing inner diameter, and electrical heating element sufficiently to control temperature of the biomass slurry to a temperature ranging from about 180 ºC to about 250 ºC to favor HTC of the biomass slurry.

35. The method of claim 25 comprising shear-thinning a biomass slurry precursor composition with one or more non-thermally sensitive inorganic additives to form the biomass slurry.

36. The method of claim 25 wherein the biomass slurry comprises one or more PFAS compounds, and the method comprises decomposing substantially all of the PFAS compounds.      252-P004WO  37. The method of claim 36 wherein the PFAS are selected from the group consisting of: perfluorobutanoic acid and its salts; perfluoro phosphonates and their salts and derivatives; perfluorohexanoic acid and its salts; perfluorooctanoic acid and its salts; perfluorononanoic acid and its salts; perfluorodecanoic acid and its salts; perfluorobutane sulfonate; perfluorohexane sulfonate; and perfluorooctane sulfonic acid, and salts thereof, and N-substituted sulfonamides thereof; and combinations and mixtures or one or more of thereof.

38. The method of claim 25 wherein the biomass slurry comprises one or more pharmaceuticals, and the method comprises decomposing substantially all of the pharmaceuticals.

39. The method of claim 38 wherein the pharmaceuticals are selected from the group consisting of ibuprofen, carbamazepine, bezafibrate, fenofibric acid, metoprolol, propranolol, clarithromycin, roxithromycin, erythromycin, and combinations and mixtures thereof.

40. A method comprising:  flowing a biomass slurry into a top of a single tubing positioned inside a casing of a well forming an annulus there between, the well having a well depth, a top positioned at a surface location, and a bottom portion positioned at a subterranean location, the casing and the single tubing defining a hydrothermal carbonization (HTC) reaction zone in a first section of the bottom portion, a return fluid plenum in a second section of the      252-P004WO  bottom portion, the second section located below the first portion, and a heat transfer and separation zone above the HTC reaction zone;   heating the biomass slurry flowing downward through the HTC reaction zone employing a cable comprising an electric heating element positioned in the single tubing in the HTC reaction zone;   converting at least a portion of the biomass slurry into a composition comprising water and hydrochar by HTC in the HTC reaction zone, the biomass slurry entering into the single tubing at the top of the well at a first temperature and a first pressure, the well depth and the electrical heating element sufficient to produce a second temperature and a second pressure in the reaction zone sufficient to maintain water in the biomass slurry and in the composition as liquid;  flowing the composition comprising the water and the hydrochar upward through the annulus between the casing and the single tubing; and  transferring heat between the composition and the biomass slurry in the heat transfer and separation zone.

41. The method of claim 40 comprising positioning the heat transfer and separation zone at a length sufficient to allow heat transfer between the biomass slurry flowing through the tubing and the product fluid traversing through the annulus.

42. The method of claim 40 comprising performing the HTC reaction without introducing any oxidizer chemical into the biomass slurry.

43. The method of claim 40 comprising providing the well with a well depth of at least 500 meters (at least 1,640 feet) and positioning the heat transfer and separation zone at a length ranging from about 200 meters to just under 400 meters (660 feet to just under 1,320 feet).      252-P004WO  44. The method of claim 40 performed without submersible pumping, allowing continuous circulating flow of biomass into the well and product fluid out of the well using only hydrostatic head.

45. The method of claim 40 comprising providing the well depth, tubing inner diameter, and electrical heating element sufficiently to control temperature of the biomass slurry to a temperature ranging from about 180 ºC to about 250 ºC to favor HTC of the biomass slurry.

46. The method of claim 40 performed using coiled tubing as the single tubing.

47. The method of claim 46 comprising cleaning of the coiled tubing as it is pulled out of the well.

48. The method of claim 40 comprising sensing temperature of the biomass slurry as it passes through the HTC reaction zone.

49. The method of claim 40 wherein the biomass slurry comprises one or more PFAS compounds, and the method comprises decomposing substantially all of the PFAS compounds.

50. The method of claim 49 wherein the PFAS are selected from the group consisting of: perfluorobutanoic acid and its salts; perfluoro phosphonates and their salts and derivatives; perfluorohexanoic acid and its salts; perfluorooctanoic acid and its salts; perfluorononanoic acid and its salts; perfluorodecanoic acid and its salts; perfluorobutane sulfonate;      252-P004WO  perfluorohexane sulfonate; and perfluorooctane sulfonic acid, and salts thereof, and N-substituted sulfonamides thereof; and combinations and mixtures or one or more of thereof.

51. The method of claim 40 wherein the biomass slurry comprises one or more pharmaceuticals, and the method comprises decomposing substantially all of the pharmaceuticals.

52. The method of claim 41 wherein the pharmaceuticals are selected from the group consisting of ibuprofen, carbamazepine, bezafibrate, fenofibric acid, metoprolol, propranolol, clarithromycin, roxithromycin, erythromycin, and combinations and mixtures thereof.

53. A method comprising:  flowing a biomass slurry into a top of one or more tubing positioned inside a casing of a well forming an annulus there between, the well having a well depth, a top positioned at a surface location, and a bottom portion positioned at a subterranean location, the casing and the one or more tubing defining a hydrothermal carbonization (HTC) reaction zone in the bottom portion of the well and a heat transfer and separation zone above the HTC reaction zone;   heating the biomass slurry flowing downward through the HTC reaction zone employing high pressure steam flowing downward in one or more steam conduits positioned in one or more of the one or more tubing in the HTC reaction zone;   converting at least a portion of the biomass slurry into a composition comprising water and hydrochar by HTC in the HTC reaction zone, the biomass slurry entering into the one or more tubing at the top of the well at a first temperature and a first pressure, the well depth and the high pressure steam sufficient to produce a second temperature and a      252-P004WO  second pressure in the HTC reaction zone sufficient to maintain the water in the biomass slurry and in the composition as liquid;  flowing the composition comprising the hydrochar upward through the annulus between the casing and the one or more tubing; and  transferring heat between the composition and the biomass slurry in the heat transfer and separation zone.

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