CORROSION IN A REACTOR SYSTEM

BACKGROUND

[0001] Supercritical water gasification is an emerging technology with great potential to generate clean energy from sources that are typically considered waste, such as biowaste, or unclean fuel sources, including coal and other fossil fuels. During the supercritical water gasification process, water is heated to very high temperatures (for example, above about 647 Kelvin) under high pressure (for example, about 22 megapascals) that prevents the water from turning into steam. The high temperatures and high pressures during the supercritical water gasification generate a highly corrosive environment due to the presence of corrosive ions under the temperature and pressure conditions.

[0002] Conventional techniques to manage corrosion caused by supercritical water involve the constant replacement of corroded parts or constructing system components from corrosive resistant materials that can be expensive and largely ineffective. Such techniques may be too time consuming and cost-prohibitive because the corrosive ions can still contact the surfaces of system components, which can lead to surface breakdown. As such, there is not a method to reduce corrosion that operates by preventing the actual formation of the corrosive ions within system components during the supercritical water gasification process.

SUMMARY

[0003] This disclosure is not limited to the particular systems, devices and methods described, as these may vary. The terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope. [0004] As used in this document, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. Nothing in this disclosure is to be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by virtue of prior invention. As used in this document, the term "comprising" means "including, but not limited to."

[0005] In an embodiment, a supercritical water gasification process may comprise providing a slurry having water to at least one of a plurality of system components. During the process, a temperature in at least one of the plurality of system components may be increased to a first temperature while a pressure in at least one of the plurality of system components is maintained at, or less than, a first pressure. The process may further comprise increasing the pressure in at least one of the plurality of system components to a second pressure at the first temperature, maintaining the first temperature and the second pressure for a first time period, increasing the temperature and pressure in at least one of the plurality of system components to a second temperature and a third pressure, respectively, and maintaining the second temperature and third pressure for a second time period.

[0006] In an embodiment, a reactor for supercritical water gasification may comprise a chamber configured to allow an increase in temperature while maintaining a pressure, and a salt collection chamber configured to collect salt precipitated during a process performed in the chamber.

[0007] In an embodiment, a supercritical water gasification process may comprise moving a slurry having corrosive ions disposed therein through a supercritical water gasification system to generate a fuel product. A temperature and a pressure of the slurry may be maintained such that the ionic product of water in the slurry does not increase above a corrosive ionic product value, thereby reducing corrosion of at least a portion of the supercritical water gasification system due to the corrosive ions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 depicts an illustrative supercritical water system according to some embodiments.

[0009] FIG. 2A depicts a temperature and pressure path for a fluid during a supercritical water gasification process.

[0010] FIG. 2B depicts a temperature and pressure path for a supercritical water gasification process according to some embodiments.

[0011] FIG. 3 depicts a supercritical water gasification operation cycle according to some embodiments.

[0012] FIG. 4 depicts a flow diagram for an illustrative method of reducing corrosion in a supercritical water gasification system.

DETAILED DESCRIPTION

[0013] The terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope.

[0014] The present disclosure relates generally to a system and methods for reducing corrosion in supercritical water gasification systems (or supercritical water reactor systems) by decreasing the amount of corrosive ions formed during the supercritical water reaction process. In particular, some embodiments provide for controlling the conditions within supercritical water gasification systems components ("system components") to prohibit corrosive ion formation within fluid flowing through the supercritical water gasification systems. Illustrative system components include, without limitation, heaters, pre- heaters, pumps, reactor vessels ("reactors"), heat exchangers, and gas/liquid separators. In an embodiment, the temperature and/or pressure of the fluid, such as a slurry feedstock, may be controlled such that the ionic product of the fluid is maintained below a certain value and/or within a certain range. For example, one embodiment provides that the ionic product of the

-22 2 2

fluid is maintained below about 10 ^" mol /l . In this manner, the concentration of corrosive ions in the fluid may be diminished or even eliminated, reducing corrosion of the inner surfaces of system components, thereby increasing the lifespan of system components and the overall efficiency of the system.

[0015] FIG. 1 depicts an illustrative supercritical water gasification system according to some embodiments. As shown in FIG. 1, a supercritical water gasification system 100 may include a feedstock inlet 130 for introducing a slurry 155 into the system. The slurry 155 may comprise a high pressure slurry feed. The feedstock may include any type of matter capable of undergoing supercritical water gasification, including, without limitation, biomass fluids (for example, micro algae fluids, bioresidues, biowastes, or the like), slurries of coal and other fossil fuels, and oxidizable wastes. Accordingly, the supercritical water gasification system 100 may be configured to operate as various gasification systems, including, without limitation, a coal gasification system, a biomass gasification system, a waste oxidation system, a hydroprocessing reactor system, and a pressurized water reactor system. The slurry 155, along with air 150 and fluid 135, may be fed into a heater 105, such as a gas-fired heater, with the flow controlled at least partially by a pressure pump 185. In an embodiment, the fluid 135 may include water. The combination of the slurry 155 and the fluid 135 may be heated in the heater 105. According to some embodiments, the heater 105 may be used to heat the slurry 155 prior to the slurry entering the reactor vessel 110. The fluid 135 (for example, water) may be used to generate steam 140, for instance, in order to recover heat in certain flue gasses 145. In an embodiment, the steam 140 may be used outside of the gasification process (for example, as a heat source). Certain gases, such as steam 140 and flue gas 145, may be exhausted from the heater. The heated slurry 155 may be fed into a reactor vessel 110. In an embodiment the slurry 155 may be heated by combining it with superheated steam or supercritical water before it is fed into a reactor vessel 110.

[0016] Prior to entering or within the reactor vessel 110, the slurryl55 may be heated under pressure to become a supercritical fluid. In an embodiment, the pressurization of the slurry 155 may be delayed such that the slurry will be supercritical after it leaves the pressure pump 185. The temperatures and pressures for generating a supercritical fluid may depend on the type of fluid and the composition thereof (for example, the type and concentration of ions at different temperatures and pressures). In an embodiment in which the fluid 155 includes water, the fluid may be heated to at least about 647 Kelvin at a pressure of at least about 22 megapascals to become a supercritical fluid. During the supercritical water gasification process, the slurry 155 may be heated to various other temperatures, including about 650 Kelvin, about 700 Kelvin, about 800 Kelvin, about 900 Kelvin, about 950 Kelvin, about 1200 Kelvin, about 1500 Kelvin, or ranges between any two of these values (including endpoints). The slurry 155 at supercritical temperatures may be at various pressures during the supercritical water gasification process, such as about 22 megapascals, about 23 megapascals, about 24 megapascals, about 25 megapascals, about 30 megapascals, about 35 megapascals, about 40 megapascals, or values between any two of these values (including endpoints).

[0017] The slurry 155 may include corrosive ions such as the ions of various inorganic salts. The corrosive ions may be highly corrosive to the components of the supercritical water gasification system 100, such as the inside surface of system components, including the heater 105, the reactor vessel 110, and/or any pipes connecting the components together. In an embodiment, the corrosive ions may include anions and/or cations. Non- limiting examples of anions include chloride ions, fluoride ions, sulfide ions, sulfate ions, sulfite ions, phosphate ions, nitrate ions, carbonate ions, bicarbonate ions, hydroxide ions, oxide ions, and cyanide ions. Non-limiting examples of cations include, without limitation, potassium cations, calcium cations, ammonium cations, magnesium cations, and sodium cations.

[0018] The supercritical fluid in the slurry may react with the slurry 155 within the reactor vessel 110 to generate a reactor product 160. In an embodiment, the fluid 155 may include one or more catalysts configured to facilitate the gasification reactions. The reactor product 160 may move through one or more heat exchangers, such as a heat recovery heat exchanger 115 and a cool-down heat exchanger 125. A gas/fluid separator 120 may be provided to separate the reactor product 160 into the desired fuel gas product 165 and waste products 170, such as fluid effluent, ash and char. The fuel gas product 165 may include any fuel capable of being generated from the feedstock slurry 155 responsive to reacting with the fluid 135 under supercritical conditions. Illustrative fuel gas products 165 include, but are not limited to, hydrogen-rich fuels, such as ¾ and/or CH ₄ .

[0019] During the supercritical water gasification process, the fluid 135 may be heated to various temperatures under different pressures within the supercritical water gasification system 100 . In addition to supercritical conditions, the slurry 155 may be in a subcritical condition, wherein the slurry 155 is at a high temperature that is below the supercritical temperature or at a high pressure that is below the supercritical pressure. In an embodiment wherein the slurry 155 includes water, subcritical water may have a temperature of about 570 Kelvin, about 600 Kelvin, about 610 Kelvin, about 620 Kelvin, about 630 Kelvin, about 647 Kelvin, or in a range between any of these values (including endpoints). In an embodiment wherein the slurry 155 includes water, the pressure of the fluid at the subcritical temperature may be about 8 megapascals, about 12 megapascals, about 16 megapascals, about 20 megapascals, about 22 megapascals, about 25 megapascals, or in a range between any of these values (including endpoints).

[0020] The slurry 155 may also include corrosive ions that are highly corrosive to the system components of the supercritical water gasification system 100, for example, in subcritical conditions. The presence of corrosive ions in the slurry 155 may depend on various factors, such as the pressure and/or temperature of the subcritical slurry. For instance, in a supercritical water gasification process in which the pressure of the slurry 155 is above the supercritical pressure while the temperature of the slurry is below the supercritical temperature, the slurry may be highly corrosive. According to some embodiments, the slurry 155 may be heated to supercritical temperatures while the pressure remains below supercritical pressure. For these embodiments, the slurry 155 may be much less corrosive to system components.

[0021] The supercritical water reactor system 100 depicted in FIG. 1 is provided for illustrative purposes only and may include more or fewer components as required, such as one or more valves, pre-heaters, reactor vessels, pumps for pumping the fluid 135 through the system and other components known to those having ordinary skill in the art. In addition, the flow of the slurry 155 through the supercritical water reactor system 100 is not limited to the particular path depicted in FIG. 1, as this is provided for illustrative purposes only. The components of the supercritical water gasification system 100, such as the reactor vessel 110, heater 105, and the like, may be fabricated from various materials, such as common corrosion resistant metals including, without limitation, nickel alloy, chrome-molybdenum alloy, nonmagnetic iron-based alloy, and/or certain ceramic materials.

[0022] As depicted in FIG. 1, a sensor 175 may be configured to receive information associated with components of the supercritical water gasification system 100, such as the reactor vessel 110. The sensor 175 may be configured to measure various properties, including, without limitation, temperature, pressure and flow rate within a system component. A controller 180 may be in communication with the sensor 175. The controller 180 may generally include a processor, a non-transitory memory or other storage device for housing programming instructions, data or information regarding one or more applications, and other hardware, including, for example, a central processing unit (CPU), read only memory (ROM), random access memory, communication ports, controllers, and/or memory devices, non-transitory computer-readable media, and other components known to those having ordinary skill in the art. The controller 180 may be configured to receive information from the sensor 175. Certain operational aspects of the supercritical water gasification system 100 may be directed by the controller 180, such as heating elements, pumps, valves (for example, valves configured to vent pressure), or the like. In an embodiment, the controller 180 my execute control software configured to control operation of one or more components of the supercritical water gasification system 100 to carry out aspects of embodiments disclosed herein. The sensor 175 and the controller 180 depicted in FIG. 1 are non-limiting as they are provided for illustrative purposes only. Embodiments provide for various other configurations, including, without limitation, one or more sensors associated with a one or more system components, one or more controllers associated with one or more sensors and/or system components, or combinations thereof.

[0023] Although a supercritical water gasification system is used as an illustrative example herein, embodiments are not so limited. For example, embodiments may include any other type of supercritical water reaction system capable of operating according to some embodiments described herein, including supercritical water oxidation systems.

[0024] FIG. 2A depicts a temperature and pressure path for a fluid during a supercritical water gasification process. As shown in FIG. 2A, a fluid undergoing a supercritical water gasification process may be controlled to various temperatures 210 and pressures 205 during the process. The fluid may include any fluid capable of generating a product fuel through the supercritical water gasification process, such as a coal slurry. For each temperature and pressure, the fluid and/or water in the fluid may have an ionic product 215 value or range of ionic product values, such as those depicted in FIG. 2A. The units depicted for the ionic product 215 represent the exponent "e" in the following form: 1 x 10 ^e . As known to those having ordinary skill in the art, the ionic product 215, K, is generally a measure of the tendency of an amphiprotic solvent, XH, to take up or to lose a hydron in the following reaction: XH + XH = X¾ ⁺ + X ^~ . In such a reaction, K _\ = axm ⁺ x αχ ^~ , where a m and ax ^" are the activities of X¾ ⁺ and X ^~ , respectively. The ionic product 215 of water, K^, is given by the following: K-w = «H3o ⁺ X «OH ^~ ; ~ 10 ^"14 mol ² dm ^"6 at 299 Kelvin. As indicated by FIG. 2A, the ionic product 215 of a fluid changes based on the temperature and/or pressure of the fluid. As used herein, the ionic product 215 is not limited to the ionic product of pure water, as it may refer to one or more other fluids (e.g., feedstock slurries) and/or water contained therein.

[0025] During the supercritical water gasification process the fluid follows a temperature and pressure path 220 as it proceeds through the various stages of the process. For example, the fluid may be at a temperature of less than about 500 Kelvin and a pressure of about 1 megapascal when entering the supercritical water gasification system. The fluid may then be heated in a heater to about 570 Kelvin at a pressure of about 23 megapascals before being fed into a reactor vessel where it may be heated to above 850 Kelvin at a pressure of about 35 megapascals.

[0026] The path 220 depicted in FIG. 2A illustrates a temperature and pressure progression for fluid in a typical supercritical water gasification process. Above the critical point of water (about 647 Kelvin and about 22 megapascals), the solubility of inorganic salts decreases rapidly, causing the inorganic salts to precipitate and attach to the inner surfaces of system components, which may cause corrosion and/or clog piping connecting system components. At pressures 205 above about 8 megapascals and temperatures 210 above about 574 Kelvin, the ionic product 215 of water increases rapidly from about 10 ^~45 mol ² /l ² to about 10 ^~12 mol ² /l ² , causing disassociation of ions, for example, of inorganic compounds. It is the relatively high ionic product 215 of fluid during certain phases of the supercritical water gasification process and the availability of hetero ions that generates a corrosive environment that leads to the breakdown of system components. For example, a coal slurry may contain a mix of hetero atoms including, chlorine, sulfur, potassium, and/or nitrogen which may become free ions during the supercritical water gasification process.

[0027] At low pressures 205, for temperatures above about 570K 210, the ionic

-40 2 2

product of water remains very low, for example, about 10 ^" mol /l or below. Conventional supercritical water gasification operating cycles increase pressure 205 before and during the increase in temperature 210. As such, in the subcritical zone, the ionic product 215 is very high, for example, 10 ^"12 mol ² /l ² or above. As the temperature 210 increases above the critical point of water, the ionic product 215 falls such that at about 775 Kelvin and about 23 megapascals, the ionic product is about 10 ^"25 mol ² /l ² , more than 10 orders of magnitude lower than in the subcritical zone.

[0028] FIG. 2B depicts a temperature and pressure path for a supercritical water gasification process according to some embodiments. As shown in FIG. 2B, embodiments modify the pressure 205 at different temperatures 210 during the supercritical water gasification process to generate a temperature and pressure path 225 such that the fluid does not have an ionic product 215 greater than about 10 ^"20 mol ² /l ² . As described in more detail in reference to FIG. 3, embodiments provide for maintaining the pressure 205 below about 8 megapascals while raising the temperature 210 during the supercritical water gasification process. Accordingly, the fluid avoids high ionic product zones 230, 235 where the fluid is the most corrosive.

[0029] FIG. 3 depicts a supercritical water gasification operation cycle according to some embodiments. As shown in FIG. 3, a supercritical water gasification operation cycle may include multiple phases 380, 382, 384, 386, 388, 390 for processing a fluid 300 to generate a fuel product 375. As shown in FIG. 3, a supercritical water gasification operation cycle may start with a fluid 300 at ambient temperature (for example, less than about 400 Kelvin) and at a pressure less than about 8.6 megapascals (for example, about 8 megapascals) being fed through a slurry inlet 305 to a heat exchanger 310 (for example, a heat recovery heat exchanger). The fluid 300 enters a heating phase 380 in the heat exchanger 310 in which the pressure of the fluid 300 is maintained at less than about 8.6 megapascals, while the temperature of the slurry is raised to a temperature of about 674 Kelvin to about 775 Kelvin. According to some embodiments, the pressure of the fluid 300 during the heating phase 380 must be monitored and controlled because the increasing temperature of the fluid will operate to increase the pressure of the fluid. As such, pressure may have to be vented or otherwise released in order to prevent the pressure of the fluid 300 from rising above 8 megapascals. In an embodiment, the excess pressure may be captured for use when pressurization is required within the operation cycle, such as in the pressurization phase 382. During the heating phase

-45 2 2 -28 2 2

380, the ionic product of the fluid 300 may be from about 10 ^" mol /l to about 10 ^" mol /l .

[0030] Once the fluid 300 reaches the temperature of the heating phase, under a pressure of less than about 8 megapascals, the fluid will enter a pressurization phase 382. In the pressurization phase 382, the pressure of the fluid 300 will be raised to about 23 megapascals to about 28 megapascals, which is above the pressure of 23 megapascals at the critical point of fluid 300 (using water as an example). In an embodiment, a pressure pump 315 may be used to pressurize the fluid 300. During the pressurizing phase 382, the ionic product of the fluid 300 may be from about 10 ^"28 mol ² /! ² to about 10 ^"23 mol ² /l ² . At this temperature, salts, such as inorganic salts, will precipitate out of the fluid 300 under a suitable applied pressure during a salt precipitation phase as will be described below.

[0031] As the fluid 300 passes the critical point of water in the pressurizing phase 382, a salt precipitation phase 384 may occur within a salt precipitator reactor 320. The inorganic salts in the fluid have a low solubility at about 775 Kelvin and at about 23 megapascals and will precipitate out of the fluid 300. Non-limiting examples of inorganic salts include sodium chloride, ammonium sulfate, ammonium phosphate, ammonium chloride, ammonium carbonate, and ammonium sulfite, potassium chloride, potassium sulphate, potassium phosphate, potassium nitrate, calcium chloride, calcium sulfate, and calcium nitrate. The inorganic salts may include corrosive ions such as chloride ions, fluoride ions, sulfide ions, sulfate ions, sulfite ions, phosphate ions, nitrate ions, carbonate ions, bicarbonate ions, hydroxide ions, and cyanide ions. During the salt precipitation phase, at least a portion of the corrosive ions may precipitate out of the fluid 300. In some embodiments, precipitation may occur rapidly and may be collected and removed from the salt precipitator reactor 320. In one embodiment, a gravity feed collection element may be positioned at the bottom of the salt precipitator reactor 320 to collect the precipitated salt. The throughput of the fluid 300 through the salt precipitator reactor 320 in the salt precipitation phase 384 may be managed to ensure that the fluid is in this phase for a sufficient amount of time, such that all or substantially all of the inorganic salts precipitate out of the fluid. For instance, the flow of fluid 300 may be controlled so that the fluid is in the salt precipitator reactor 320 for a minimum residence time. In an embodiment, the residence time may be about 30 seconds, about 1 minute, about 2 minutes, about 5 minutes, or ranges between any two of these values (including endpoints). [0032] The fluid 300 may flow from the salt precipitation reactor 320 to a heater 350. The heater 350, in addition to receiving and heating the fluid 300, may be configured to receive water 335 and air 330 and to vent out steam 340 and flue gas 345. In the heater 350, the fluid 300 may enter a conversion phase 386 in which the temperature of the fluid may be increased to about 925 Kelvin to about 975 Kelvin, and the pressure of the fluid may be increased to about 25 megapascals to about 35 megapascals. During the supercritical phase, the temperature of the fluid 300 will be at or above the critical temperature and critical pressure. The critical temperature of water is about 647 Kelvin and the critical pressure of water is about 22 megapascals. In an embodiment, the temperature and pressure of the fluid 300 before entering the supercritical state may be maintained such that the water in the fluid is in a vapor state. According to embodiments, the pressure of the fluid 300 may be raised, at least in part, by increasing the temperature of the fluid within the confined space of the heater and/or reactor. For instance, if the temperature of the fluid 300 is increased from about 700 Kelvin to about 925 Kelvin in a confined space (for example, a space that does not or substantially does not release pressure), the pressure of the fluid may increase from about 25 megapascals to about 33 megapascals. As such, very little, if any, additional pressurization may be required to obtain the desired pressure during the conversion phase 386. The ionic

-22 2 2

product of the fluid during the conversion phase may be about 10 ^" mol /l .

[0033] According to some embodiments, conversion may occur rapidly within a reactor vessel 325, for instance, in less than 1 minute. As such, embodiments provide for management of the throughput of the fluid 300 to ensure a fluid residence time at the conversion phase 386 temperature and pressure conditions sufficient for full conversion. During the conversion phase 386, the slurry portion of the fluid 300 will react with the supercritical water portion of the fluid within the reactor vessel 325 to generate one or more reactor products, such as hydrogen, carbon dioxide, methane and carbon monoxide and other lightweight hydrocarbons in small quantities. In an embodiment, heat may be recovered during the conversion phase 386 for use during one or more other phases within the operation cycle.

[0034] The ionic product in the reactor vessel 325 may be about 10 ^~22 mol ² /l ² . This ionic product level is about 10 orders of magnitude lower than the ionic product reached during conventional supercritical water gasification process cycles. In addition, when the fluid 300 has reached the conversion phase 386, most of the inorganic salts have been removed from the fluid, further diminishing a source of system component corrosion.

[0035] During a pressure letdown phase 388, the pressure of the fluid decreases as it flows out of the reactor vessel 325 and toward a second heat exchanger 360 (for example, a cooling heat exchanger). According to some embodiments, given the effective removal of hetero ions when the fluid 300 reaches the pressure letdown phase 388, the fluid is far less corrosive. As such, there may be more flexibility in the pressure letdown phase 388 parameters which may be configured to satisfy other constraints. For example, the fluid may be maintained at a higher pressure during the pressure letdown phase as a higher fluid density is more conducive to efficient heat recovery and CO ₂ recovery and sequestration may occur using more compact storage of product gases. In an embodiment, the pressure during the pressure letdown phase 388 may be reduced to less than about 8 megapascals. Embodiments provide that the pressure may be recovered for other phases of the supercritical water gasification process, such as the pressurization phase. For example, steam which has been separated from inorganic salts, product gases and char waste may be recycled for other process phases. In an embodiment, a pressure reservoir may be configured to recover and store released pressure. As the pressure returns to less than about 8 megapascals, the ionic product of the fluid 300 reduces to less than about 10 ^~40 mol ² /l ² . [0036] During the cooldown phase 390, the fluid 300 may be cooled using a heat exchanger 355. A gas/liquid separator 360 may be used to collect product gases 375 from solution and to release certain waste products 370, such as ash and char effluent. Illustrative product gases include hydrogen (¾), methane (CH ₄ ), carbon monoxide (CO), and carbon dioxide (CO ₂ ). In an embodiment, heat may be recovered during the cooldown phase 390 for use during one or more other phases of the supercritical water gasification operation cycle, such as the heating phase 380.

[0037] In the supercritical water gasification process depicted in FIG. 3, the ionic product of the fluid 300 does not go above 10 ^~22 mol ² /l ² . Accordingly, the corrosiveness of the fluid 300 during the supercritical water gasification process may be diminished independent of other factors, such as system component design, system component materials, slurry concentration, or the like, that would otherwise have an influence on the corrosion rate.

[0038] The supercritical water gasification process depicted in FIG. 3 is for illustrative purposes only and may include more or fewer phases 380, 382, 384, 386, 388, 390 in one or more different sequences. In addition, the temperatures and pressures described in relation to the phases 380, 382, 384, 386, 388, 390 are non-limiting, as any temperature, pressure and/or temperature-pressure combination may be used during any phase that is capable of operating according to the teachings herein.

[0039] Although embodiments, such as the process depicted in FIG. 3, are described as occurring within multiple system components (for example, salt precipitation reactor 320, a heater 350, and the like), embodiments are not so limited. More or less components, including more or less than depicted in FIG. 3, may be used according to embodiments.

[0040] FIG. 4 depicts a flow diagram for an illustrative method of reducing corrosion in a supercritical water gasification system. As shown in FIG. 4, a supercritical water gasification system may receive 405 a slurry including corrosive ions. The components of the supercritical water gasification system may be configured 410 to control the temperature and the pressure of the slurry as the slurry flows through the supercritical water gasification system. The components of the supercritical water gasification system may maintain 415 the temperature and the pressure of the slurry such that the ionic product of water in the slurry does not increase above a corrosive ionic product value. For example, one embodiment provides that the ionic product of the fluid is maintained below about 10 ^~22 mol ² /l ² . The supercritical water gasification system may operate to generate 420 synthesis gas from the slurry through a supercritical water gasification process.

EXAMPLES

Example 1: Biomass Supercritical Water Gasification System

[0041] A supercritical water gasification system ("system") will be configured to generate an ¾ synthesis gas from an aqueous biomass slurry formed from organic plant waste. The system will include a heat recovery heat exchanger, a salt precipitation vessel, a reactor vessel, a heater, and a cooldown heat exchanger connected in fluid communication in series. The system components will be formed from a nickel alloy material.

[0042] A series of pumps will be used to force the biomass slurry through the system, which will enter at a temperature of about 350 Kelvin and a pressure of about 0.5 megapascals. The biomass slurry will enter a heating phase within the heat recovery heat exchanger. In the heating phase, the biomass slurry will be heated to a temperature of about 720 Kelvin and the pressure will be capped at about 8 megapascals. A portion of the heat used for the heating phase will be from heat energy captured during a subsequent cool down phase. The pressure will be maintained at about 8 megapascals by venting pressure from the heat recovery heat exchanger that builds up during heating of the coal slurry. [0043] During a pressurization phase, the biomass slurry will flow toward a pressure pump configured to pressurize the biomass slurry to a pressure of about 24 megapascals as the biomass slurry flows toward the salt precipitation vessel. Within the salt precipitation vessel, the biomass slurry will reach a temperature of about 720 Kelvin at a pressure of about 24 megapascals. Inorganic salts such as sodium chloride, ammonium sulfate, ammonium phosphate, ammonium chloride, ammonium carbonate, and ammonium sulfite will precipitate out of the biomass slurry within the salt precipitation vessel. The flow of the biomass slurry through the salt precipitation vessel will be controlled such that the biomass slurry is resident in the salt precipitation vessel for sufficient time to remove precipitated salts from the slurry, about 2 minutes.

[0044] During a conversion phase, the biomass slurry will flow through the heater and into the reactor vessel. The biomass slurry will be heated using indirect heating to a temperature of about 925 Kelvin. As a result of heating the biomass slurry within a confined space, the pressure of the biomass slurry will increase to about 31 megapascals. The ionic product of the biomass slurry will be about 10 - ^" 22 mol 2 2

fl during the conversion phase. During the conversion phase, the biomass slurry will react with the supercritical water to produce a reactor product and waste products, such as liquid effluent, ash and char.

[0045] The reactor product and waste products will flow out of the reactor vessel during a pressure letdown phase in which the pressure of the fluid including the reactor product and waste products will be about 5 megapascals. Pressure released during the pressure letdown phase will be captured and used to pressurize the biomass slurry during the pressurization phase. The reactor product and waste products will enter a cooldown heat exchanger during a cooldown phase in which the fluid containing the reactor product and waste products will decrease to about 450 Kelvin. A gas/liquid separator will be used to separate the ¾ fuel gas product and the liquid effluent, ash and char waste products. [0046] Removing inorganic salts from the biomass slurry and maintaining the

-22 2 2

ionic product of the biomass slurry below 10 ^" mol fl operates to diminish the number of corrosive ions in the fluid moving through the system. In this manner, the nickel alloy material used to form the system components will corrode at a low rate compared to conventional systems, prolonging the lifespan of the system components and the efficiency of the supercritical water gasification process. Additionally, the system will have longer service intervals and require less cleaning and maintenance as compared to a conventional system.

Example 2: Sensor System for Supercritical Water Coal Gasification System

[0047] A supercritical water gasification system ("system") will be configured to generate a synthesis gas including ¾, CO2, CH ₄ , and CO from an aqueous liquid coal slurry. The system will include the following system components: a heat recovery heat exchanger, a heater and a cooldown heat exchanger formed from a nickel alloy material, a salt precipitation vessel and a reactor vessel formed from a nickel alloy material, a pressurization pump, and a depressurization component. The system components will be in fluid communication, connected in series with the coal slurry flowing through the system components in the following order: heat recovery heat exchanger, pressurization pump, salt precipitation vessel, heater, reactor vessel, depressurization component, and cooldown heat exchanger.

[0048] Each of the system components, except for the pressurization pump and the depressurization component, will include a temperature sensor configured to measure the temperature of fluid flowing through the system component. Each temperature sensor will be configured to measure temperature in the range of about 600 Kelvin to about 1400 Kelvin. In addition, each system component will include a pressure sensor configured to measure the pressure within the system component. Each pressure sensor will be configured to measure pressure in the range of about 0.1 megapascals to about 45 megapascals. Each system component will also include a flow sensor configured to indicate whether a fluid is flowing through the system component.

[0049] A central control device will be in communication with each of the temperature, pressure and flow sensors. The central control device will include a processor configured to execute control software adapted to receive information from each of the sensors. The control software will determine where the coal slurry is flowing within the system using the flow sensors and will determine the temperature and pressure of the coal slurry using the temperature and pressure sensors of the system component experiencing coal slurry flow. The control software will be configured to obtain the operational temperature and pressure for each system component during the phases of the supercritical water gasification process. Operational aspects of the system components will be controlled by the control software to maintain the operational temperature and pressure if they are not within a threshold variance from limits.

[0050] The control software will control the heating and pressure elements of the heat recovery heat exchanger during a heating phase to ensure that the fluid is heated to about 720 Kelvin at a pressure below 8 megapascals. As the fluid flows into the pressure pump during the pressurization phase, the control software will monitor the pressure of the fluid to ensure that the pressure of the fluid increases to about 25 megapascals. The control software will receive information from the flow sensor that the fluid is flowing through the salt precipitation vessel and that a salt precipitation phase has commenced. The control software will control the temperature and pressure elements of the salt precipitation vessel to ensure that the temperature of the fluid is about 720 Kelvin and that the pressure is about 25 megapascals. The flow of the fluid through the salt precipitation vessel will be controlled by the control software such that the residence time of the fluid within the salt precipitation vessel is sufficient to ensure all precipitated salts are removed from the fluid, about 1 minute. [0051] The control software will detect that the fluid is flowing through the heater and into the reactor vessel and that a conversion phase has commenced. The control software will control the heating and pressure elements of the heater and the reactor vessel such that the temperature of the fluid will reach about 920 Kelvin at a pressure of about 32 megapascals within the reactor vessel in order to generate the reactor product. The control software will detect that the fluid is flowing into a depressurization component and will monitor the pressure using the pressure sensor to ensure that the pressure of the fluid decreases to less than about 8 megapascals. As the fluid flows into the cooldown heat exchanger, the control software will monitor the temperature of the fluid to ensure that it is cooling down to a temperature below 570 Kelvin before entering a gas/liquid separator where the fuel gas product is separated from the fluid.

[0052] The monitoring and control of the temperature, pressure and/or flow of the fluid during the phases of the supercritical water gasification process will ensure that the concentration of corrosive ions will be sufficiently diminished during the conversion phase. The diminished concentration of corrosive ions will reduce the corrosive effects during the reaction of the supercritical water with the coal slurry within the reactor vessel, thereby prolonging the lifespan of system components and the overall efficiency of operating the system. Additionally, the system will have longer service intervals and require less cleaning and maintenance as compared to a conventional system.

[0053] In the above detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

[0054] The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds, compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0055] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

[0056] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (for example, bodies of the appended claims) are generally intended as "open" terms (for example, the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to"). While various compositions, methods, and devices are described in terms of "comprising" various components or steps (interpreted as meaning "including, but not limited to"), the compositions, methods, and devices can also "consist essentially of or "consist of the various components and steps, and such terminology should be interpreted as defining essentially closed-member groups. It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (for example, "a" and/or "an" should be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (for example), the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, or the like" is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (for example, " a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, or the like). In those instances where a convention analogous to "at least one of A, B, or C, or the like" is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (for example, " a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, or the like). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

[0057] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0058] As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, and so on. As a non- limiting example, each range discussed herein can be readily broken down into a lower third, middle third and an upper third. As will also be understood by one skilled in the art all language such as "up to," "at least," and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth. [0059] Various of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art, each of which is also intended to be encompassed by the disclosed embodiments.