Fixed-bed gasifier

Abstract

Provided herein is a gasifier, preferably a fixed-bed, slagging updraft oxygen gasification reactor or gasifier, featuring features that facilitate the gasification of heterogeneous waste streams and produce syngas with minimal levels of condensable tars while simultaneously removing molten slag from the bottom of the bed via a cooled slag collector ("CSC"), syngas and other compositions produced therefrom, and processes including same.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 313,796, filed February 25, 2022, which is incorporated by reference herein in its entirety for all purposes.

[0002] Field The present technology relates to gasification reactors or gasifiers, preferably fixed-bed slagging updraft oxygen gasifiers, compositions produced therefrom, and processes involving same. [Background technology]

[0003] Significant limitations have prevented gasifiers from being employed to gasify heterogeneous wastes, except in combination with coal. Furthermore, while the ash from clean wood gasifiers can be applied to land, this is not the case for heterogeneous wastes or treated waste wood, which are generally classified as hazardous wastes. There remains a great need for gasifiers that can be used with feedstocks other than coal, such as biomass, plastic waste, and other heterogeneous waste streams. Such gasifiers would not have high parasitic electrical loads and would not be overly sensitive to feedstock morphology, especially excessive fineness. Summary of the Invention

[0004] In one aspect, provided herein is a gasifier, preferably for gasifying heterogeneous waste. In one embodiment, the gasifier is a fixed bed gasifier. In another embodiment, the gasifier is an oxygen-blown gasifier. In another embodiment, the gasifier is a slagging gasifier.

[0005] In another aspect, provided herein is a synthesis gas composition, also referred to simply as synthesis gas, and other compositions. In one embodiment, the synthesis gas composition is provided by gasifying heterogeneous waste using a gasifier provided herein.

[0006] In another aspect, a process for gasifying heterogeneous waste is provided herein. In one embodiment, the process includes gasifying the heterogeneous waste in a gasifier provided herein. In one configuration embodiment, the slag produced by gasifying the heterogeneous waste in a gasifier provided herein is non-leachable according to the TCLP test.

[0007] In one embodiment, the gasifier does not include a plasma torch. In another embodiment, the gasifier does not include a bed permeable additive. An illustrative example of a bed permeable additive is 50-100 mm lump coke with a narrow particle size distribution.

[0008] The present invention is directed, in part, to a fixed bed, slagging updraft oxygen gasification reactor having features for facilitating the gasification of a heterogeneous waste stream containing a wide size range and high volatility materials typically associated with waste streams to produce a synthesis gas with minimal levels of condensable tars exiting the gasification reactor, while allowing the slag to be freely discharged from the bed through one or more slag holes to a molten slag reservoir where further conversion of any residual carbon can occur before the slag is tapped and / or quenched using conventional methods.

[0009] In one embodiment, the gasifier is characterized as a vertically oriented vessel with multiple distinct zones to achieve the above objectives. In one embodiment, the feedstock is fed into the gasifier at mid-height with multiple feed ports to achieve uniform distribution. Additional bed permeable materials or slag additives can also be fed by gravity from the top of the vessel if required for optimal operation. The feedstock flows downward through the bed and the gasification reaction is supported by oxygen and steam injected through multiple lances (also known in the industry as tuyere) distributed around the circumference at different heights to control the temperature profile throughout the bed to achieve efficient gasification. Without being bound by theory, it is generally desirable to maintain a relatively slow heating rate up to the final peak temperature of gasification to allow controlled pyrolysis in the upper section, minimize tar production, and maximize the formation of secondary char or carbonaceous solids that provide substrates for the oxygen gasification reaction below. Peak gasification temperatures are achieved in the lower gasifier, and the ratio of oxygen to steam injected through the lances is controlled to achieve an operating temperature of at least about 1250°C, and preferably greater than about 1500°C, to ensure complete conversion of the solid carbonaceous material, as well as effective melting ("slagging") of the mineral and ash content of the feedstock. Lance placement can be varied with respect to perimeter spacing, position relative to bed height, downward angle, and offset angle from normal (i.e., a line perpendicular to the tangent to the wall of the reactor vessel at the location of the lance) to create an optimal temperature profile and ensure consistent movement of the bed across the diameter of the gasifier.

[0010] In one embodiment, the gasifier is further characterized by having an actively cooled bed support structure (referred to as a cooled slag collector or "CSC") located above the molten slag reservoir. The CSC supports the upper bed, collects the molten slag, and directs the slag to one or more slag holes for free drainage by gravity into the slag reservoir. The CSC is actively cooled to ensure the formation of a protective skull according to design principles known to those skilled in the art. See Nelson, LR and Hundermark, RJ (2016) "The tap-hole - key to furnace performance," Journal of the South African Society of Mining and Metallurgy, Vol. 116, pp. 465-490, incorporated herein by reference in its entirety. A CSC with multiple slag holes around the periphery can promote redistribution of solid material flow from the center of the gasifier to the outer diameter and ensure material movement throughout the cross section of the gasifier. This allows for the gasification of more heterogeneous materials without the need for bed permeable additives and high levels of coal or coke co-feed for stable operation.

[0011] In one embodiment, the slag can be discharged under gravity into a slag reservoir with a slag level and a headspace above, rather than being tapped directly from the bottom of the bed. Oxy-fuel burners are provided in the headspace of the slag reservoir in a manner very similar to a glass melting furnace to ensure that the slag remains in the optimum temperature range for tapping, typically between about 1250°C and about 1500°C. Adjusting the burners controls the temperature to maintain an optimum viscosity for tapping and granulation without excessive refractory corrosion or erosion due to excessive slag temperatures. Without wishing to be bound by theory, it is believed that the combustion gases CO from the oxy-fuel burners at temperatures above about 1500°C can be used to produce a high-temperature slag. 2 and H 2 The O maintains the desired slag temperature and also reacts with residual carbon and particles that may fall through the slag holes and may float freely on the slag surface if the molten slag has a high specific gravity. Carbon and CO 2 and H 2These endothermic gasification reactions of O produce additional carbon syngas CO and H 2 This results in a slag with a very high conversion to argon and minimal carbon content, which ensures complete vitrification of the mineral material and desirable properties for downstream market applications such as road base or cement additive. The combustion gases then flow upwards through the slag hole and optional bypass to provide additional auxiliary heat to the lower gasification zone. This allows the gasification of feedstocks with high volatile and ash contents, where otherwise the oxygen reaction would not even generate enough heat to completely melt the ash. In particular, this allows the use of feedstocks with volatile content of 45% or more, thereby reducing or preferably eliminating the need for coal or coke in the feedstock in a particularly cost-effective manner without the high parasitic electrical load resulting from, for example, plasma torches. The oxy-fuel burner allows the gasifier to operate without an exogenous fuel source, using any convenient gaseous or liquid fuel such as natural gas, landfill gas, propane, diesel, etc., most preferably recycled syngas or purge gas from the operation of a downstream syngas purification unit.

[0012] In one embodiment, the gasifier of the present invention is further characterized by having side walls of variable diameter and which may be vertical or conical with angles selected to optimize the flow and residence time of gas and solids in each zone. As used herein in one embodiment, the upper zone above the side feed port where additional oxygen and steam lances and / or burners are positioned to reheat the syngas exiting the top of the bed to temperatures typically below about 500° C. to above about 1000° C., preferably above about 1100° C., with a residence time of at least about 2 seconds and up to about 5 seconds. By controlling the residence time, temperature, and oxygen and steam, it is possible to achieve a temperature range of about 100 to about 200 g tar / Nm 3 The high tar content characteristics of the upflow syngas gasifier, which is in the range of approximately 5 g tar / Nm 3 Less than 2g tar / Nm 3 Less than 1 g tar / Nm 3(Tars are defined as hydrocarbons heavier than C3 compounds.) Prior to exiting the gasifier, the syngas is quenched to an intermediate temperature, typically below about 800°C, to avoid fouling of downstream heat recovery and solids removal operations with sticky ash components.

[0013] In one embodiment, the syngas leaving the gasifier enters the cyclone at about the same temperature as the upper zone, but not less than 900° C., an example of which is Na 2 OK 2 The carbonaceous particles are removed at a temperature sufficient to minimize condensation of alkali salts, including but not limited to O, NaCl, and KCl, which facilitates recovery and recycling of the carbonaceous particles to the gasifier.

[0014] These and other aspects of the invention can be applied to the general purpose of converting multiple different waste streams into a synthesis gas that can be converted into multiple end products using techniques known to those skilled in the art. Without being limited thereto, the aforementioned exemplary products include hydrogen, synthetic natural gas, methanol, ammonia, liquid fuels, and gaseous feedstocks for microbial fermentation to produce feed proteins, biodegradable polymers, or alcohol. In another embodiment, CO2 having a purity of greater than about 95%, preferably greater than about 99.5% is produced. 2 By-products are recovered from the purge gas or tail gas after conversion of syngas to products.

[0015] The following disclosure provides, among other things, these and other aspects of the invention, as well as non-limiting examples of various embodiments of the invention. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional elevation view of an example gasifier according to various embodiments. [Diagram 2] FIG. 13 is a cross-sectional elevation view of a cooled slag collector and lower slag reservoir according to various embodiments. [Diagram 3]FIG. 13 is a cross-sectional elevation view of a lower slag reservoir with slag level control and continuous tapping applicable to various embodiments. [Figure 4] FIG. 13 is a cross-sectional elevation view of a cooled slag collector with a taphole arrangement and a lower quench nozzle for collecting granular slag in a reservoir according to various embodiments. [Diagram 5] FIG. 2 is a schematic diagram showing the placement of gasifier lances along the circumference of the gasifier applicable to various embodiments. [Figure 6] 6 and 7 are partial schematic diagrams of a cooled slag collector ("CSC") having multiple slag holes that can be applied to various embodiments, with cutaway views showing limpet coils for cooling the plate and helical cooling coils for cooling the slag holes. [Figure 7] 6 and 7 are partial schematic diagrams of a cooled slag collector ("CSC") having multiple slag holes that can be applied to various embodiments, with cutaway views showing limpet coils for cooling the plate and spiral cooling coils for cooling the slag holes. [Figure 8] FIG. 8 is a temperature profile of the top surface of the steel plate of the CSC of FIGS. 6 and 7 modeled in Ansys CFD, in accordance with various embodiments. [Figure 9] 1A-1C are cross-sectional plan views of nozzle orientations in a polisher section of a gasifier according to various embodiments. [Figure 10] 1 is a schematic output of gas flow profiles from a CFD (computational fluid dynamics) analysis of a polisher section of a gasifier, according to various embodiments. [Figure 11] 7 is a graph with temperature and film thickness of flowing slag modeled for a single slug hole 10 of the CSC shown in FIG. 6. [Figure 12] 12 and 13 are photographs of a physical example of the cooled slag collector of FIG. 6 before and after operation in an exemplary gasifier, according to various embodiments. [Figure 13]12 and 13 are photographs of a physical example of the cooled slag collector of FIG. 6 before and after operation in an exemplary gasifier, according to various embodiments. [Figure 14] FIG. 1 is a partial schematic diagram of a CSC with a single slug hole 10 designed to build a stable protective layer of cooling slug according to various embodiments. [Figure 15] 15 and 16 are temperature profiles modeled in ANSYS Fluent CFD for the design of FIG. 14 where the thermal properties of the material and cooling geometry do not produce a stable protective layer of cooling slug, in accordance with various embodiments. [Figure 16] 15 and 16 are temperature profiles modeled in ANSYS Fluent CFD for the design of FIG. 14 where the thermal properties of the material and cooling geometry do not produce a stable protective layer of cooling slug, in accordance with various embodiments. [Figure 17] 17 and 18 are temperature profiles modeled in ANSYS Fluent CFD for the design of FIG. 14 with improved material and cooling geometries to support the formation of a stable protective layer of cooling slug, in accordance with various embodiments. [Figure 18] 17 and 18 are temperature profiles modeled in ANSYS Fluent CFD for the design of FIG. 14 with improved material and cooling geometries to support the formation of a stable protective layer of cooling slug, in accordance with various embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Detailed Description definition In this specification and the claims that follow, reference will be made to a number of terms that have the following meanings. It should be noted that the specific embodiments are not intended as exhaustive descriptions or as limitations to the broader aspects discussed herein. An aspect described in conjunction with a specific embodiment is not necessarily limited to that embodiment and can be practiced with any other embodiment(s).

[0018] The terms "approximately," "about," "substantially," and similar terms used in connection with numerical ranges herein will be understood by those of ordinary skill in the art and will vary to some extent depending on the context in which they are used. Where there is a use of a term that is not clear to a person of ordinary skill in the art given the context in which it is used, the term will be plus or minus 10% of the disclosed value. When "approximately," "about," "substantially," and similar terms are applied to structural features (e.g., to describe its shape, size, orientation, direction, etc.), these terms are intended to cover slight variations in the structure that may result, for example, from the manufacturing or assembly process, and are intended to have a broad meaning consistent with common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Thus, these terms should be interpreted as indicating that non-substantial or insignificant modifications or variations of the described and claimed subject matter are considered to be within the scope of the disclosure set forth in the appended claims.

[0019] In this specification and in the claims that follow, reference will be made to a number of terms that have the following meanings: All numerical designations, such as temperature, time, concentrations, and weight, including their respective ranges, are approximations that may be modified (+) or (-), as appropriate, usually by increments of 0.1, 1.0 or 10.0. All numerical designations may be understood as preceded by the term "about."

[0020] The singular forms "a," "an," and "the" include plural references unless the context clearly indicates otherwise. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of individually referring to each individual value within the range, unless otherwise indicated herein, and each individual value is incorporated into the specification as if it were individually set forth herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context. Any examples provided herein, or the use of exemplary language (e.g., "etc.") are merely intended to facilitate a better understanding of the embodiments, and do not limit the scope of the claims unless otherwise stated. No language in the specification should be construed as indicating any non-claimed element as essential.

[0021] Bed material refers to the solid material present in the gasifier above the cooled slag collector and includes fresh feed material at the top, partially devolatilized material in the next lower zone, and solid carbonaceous material that has been substantially devolatilized and contains residual ash in the lowest gasification zone.

[0022] The term "comprising" means that any recited elements are necessarily included, and that other elements may be optionally included. "Consisting essentially of" means that the recited elements are necessarily included, and that elements that materially affect the basic and novel characteristics of the recited elements are excluded, and that other elements may be optionally included. "Consisting of" means that all elements other than the recited elements are excluded. Embodiments defined by each of these terms are within the scope of the present invention.

[0023] Gasification refers to the gasification of coal, liquids, dust, slurries, and includes the gasification of waste materials, such as the gasification of heterogeneous waste materials. Low temperature gasification (usually below about 1000°C) produces dry ash as waste. Higher temperature gasification, such as that performed by slagging gasifiers, operates above the melting point of the ash (usually above about 1400°C) and produces molten slag that is usually rapidly cooled. A gasifier or gasification reactor performs the gasification. Gasifiers include fixed bed, fluidized bed, circulating fluidized bed, and entrained bed gasifiers.

[0024] Heterogeneous waste refers to municipal solid waste ("MSW"), wood, agricultural waste, shredded tires, coal, petroleum coke, or hydrocarbon waste streams having various particle morphologies, such as, but not limited to, in the size range of 6 mm to 100 mm, outside the range that can be processed by existing fluidized bed, entrained stream, or fixed bed gasification processes.

[0025] Synthesis gas ("syngas") is a gas made up of CO, H 2 , CO 2 , H 2 O, C.H. 4 The gaseous product from the gasification of heterogeneous waste is composed of higher hydrocarbons, including C1, C2, and C3 compounds, condensable hydrocarbons (i.e., tar), and solids carried along with the synthesis gas, including carbonaceous soot and mineral ash components.

[0026] Lambda refers to the ratio between the amount of oxygen actually present in the combustion chamber and the amount of oxygen that should be present to obtain "perfect" combustion. Thus, if the mixture contains exactly the amount of oxygen needed to burn the amount of fuel present, the ratio will be 1:1, and lambda will equal 1.00. If the mixture contains more oxygen relative to the amount of fuel (a lean mixture), lambda will be greater than 1.00. If the mixture contains less oxygen relative to the amount of fuel (a rich mixture), lambda will be less than 1.00.

[0027] A lance is a device that is inserted into the gasifier and secured to the vessel via a suitable flange to allow oxygen, steam, auxiliary fuel gas, and CO2 A lance refers to an apparatus having one or more fluid passages, which may be arranged as separate tubes or annular channels, for injecting one or more gasifying agents or feedstocks, including, liquid feedstocks, powdered solid feedstocks, at high velocities in the preferred range of 100-125 m / sec into the bed material to allow for effective penetration and mixing. The fluid passages are contained within an outer shell that is cooled with cooling water or other suitable means to protect the materials of construction from the elevated temperatures within the gasifier. A lance does not require auxiliary power sources for plasma torches, etc. A lance also does not require ignition devices, burner management systems, and fuel / oxidant ratio control (i.e., lambda) as in the case of burners.

[0028] Tar refers to hydrocarbons having more than three carbon atoms (C3), including, for example, but not limited to, oxygenated compounds formed during gasification from the gasification of heterogeneous waste.

[0029] Descriptive embodiments In one aspect, provided herein is a gasifier, preferably for gasifying heterogeneous waste. In one embodiment, the gasifier is a fixed bed gasifier. In another embodiment, the gasifier is an oxygen-blown gasifier. In another embodiment, the gasifier is a slagging gasifier.

[0030] In one embodiment, the gasifier includes one or more locations (e.g., ports) within the vessel. The ports can be configured to feed a heterogeneous waste stream into the vessel. The one or more ports can be disposed above a feed bed of the gasifier. The feed bed, among other purposes, feeds the heterogeneous waste as a stream to the gasifier.

[0031] In another embodiment, the gasifier can include multiple lances positioned around the gasifier vessel. The lances are useful, for example, for introducing oxygen and / or steam gasifier reactants into the vessel. In certain embodiments, the lances are positioned at multiple heights relative to the level of the bed material.

[0032] In another embodiment, the gasifier includes a tar destruction zone located above the bed and within the gasifier vessel. In one embodiment, the tar destruction zone can include multiple burners arranged around the periphery. In one embodiment, the one or more burners are arranged at multiple heights within the tar destruction zone. In certain embodiments, the burners operate at greater than stoichiometric oxygen levels. Stoichiometric oxygen is the ratio of oxygen and CO required to completely combust one mole of fuel. 2 and H 2 As a non-limiting example, 1 mole of C x H y O for burning hydrocarbons 2 The stoichiometric requirement is x + y / 4 moles of O 2 is equal to.

[0033] In another embodiment, the gasifier includes a cooled slag collector. Preferably, the slag collector can be located at the bottom of the bed material. For example, the slag collector can support the bed material. In certain other embodiments, the slag collector comprises at least one slag hole. In certain other embodiments, the slag collector comprises a plurality of slag holes. The slag holes allow, among other things, for the slag to be discharged to a slag reservoir. Preferably, the slag collector is below the slag holes. More preferably, the slag holes allow for an upward backflow of gas.

[0034] In another embodiment, the gasifier comprises a slag reservoir. In one embodiment, the slag reservoir comprises a plurality of burners (e.g., a second plurality of burners) and a headspace. Preferably, the burners are disposed within the headspace. Among other things, the burners maintain the temperature of the slag. In certain embodiments, the CO 2 and H 2 The O-containing burner combustion gases consume or gasify any residual carbon in the slag prior to slag tapping.

[0035] In another embodiment, the lance is offset from the horizontal.In another embodiment, the lance is offset from the normal to the interior refractory surface of the gasifier.

[0036] In another embodiment, the tar destruction zone has a residence time of at least about 2 seconds, and most preferably about 5 seconds, to achieve effective tar destruction. As used herein, effective tar destruction refers to the destruction of all or substantially all of the tar so that the syngas can be further processed in the operation of heat recovery and solids removal units downstream of the gasifier without contamination from residual tar that condenses as the temperature of the syngas is reduced.

[0037] In another embodiment, the temperature of the tar destruction zone is at least about 2000° F. (1093° C.). In another embodiment, the tar destruction zone temperature is greater than about 2200° F. (1204° C.).

[0038] In another embodiment, the burners in the tar destruction zone can be operated at an oxygen molar ratio to stoichiometric requirement or lambda between about 0.5 and about 6.0. As used herein, lambda 1 is defined as the oxygen required for complete stoichiometric combustion of the auxiliary fuel supplied to the burner.

[0039] In another embodiment, additional injectants can be introduced into the tar destruction zone through nozzles that do not meet the definition and function of a burner. Non-limiting examples of injectants include oxygen, steam, recycled syngas, and vaporized hydrocarbon waste.

[0040] In another embodiment, the cooled slag collector is internal to the gasifier vessel. For example, the cooled slag collector can be disposed within a cavity defined by the vessel. The cooled slag collector can include at least one cooling feature. The cooling feature can maintain the steel frame or another type of frame and refractory components within design temperature limits of less than 350° C. for the steel frame and less than 1760° C. for the refractory components. In another embodiment, the cooled slag collector includes one or more limpet coils. In another embodiment, the cooled slag collector includes an internal copper coil within the refractory material for cooling. In one embodiment, the cooling is balanced with heat absorbed from the gasifier. For example, the heat absorbed from the gasifier can form a protective skull layer within the slag collection hearth zone and within the slag hole (e.g., slag flow area). The protective skull layer can minimize erosion and corrosion of the protective refractory and can prevent slag freezing (e.g., preventing the slag flow from freezing, preventing consistent slag collection).

[0041] In another embodiment, the slag reservoir allows the slag to be held for an average residence time of more than one hour to ensure complete conversion of the residual carbon.

[0042] In one embodiment, the gasifier is not equipped with a plasma torch. In another embodiment, the gasifier does not include a bed permeable additive. An illustrative example of a bed permeable additive is lump coke with a narrow particle size distribution.

[0043] In another aspect, provided herein is a synthesis gas composition, also referred to simply as synthesis gas, and other such compositions. In one embodiment, the synthesis gas composition is provided by gasifying heterogeneous waste. In one embodiment, the synthesis gas composition exits the top of the polisher section of the gasifier. In another embodiment, the synthesis gas composition has a flow rate of about 5 g / Nm 3 In another embodiment, the synthesis gas composition preferably has a tar content of less than about 2 g / Nm3 In another embodiment, the synthesis gas composition has a tar content of less than about 10 g / Nm 3 Less than 5 g / Nm 3 It has a carbonaceous soot (including mineral ash) content of less than 100%.

[0044] In another embodiment, the syngas composition is soot-free or substantially soot-free. In another embodiment, a cyclone is used to collect a portion of the soot particles prior to cooling to less than about 950° C. In some embodiments, the soot is removed by a baghouse after cooling the syngas to about 250° C. without cooling below the dew point of the gas. In some embodiments, the soot in the syngas is collected during wet gas scrubbing, optionally dewatered in filters, centrifuges, hydrocyclones, flotation cells, or other suitable devices, and recycled to the solids feeder of the gasifier. In another embodiment, the soot separated during wet gas scrubbing is circulated back to the gasifier as a slurry and injected into the gasifier via one or more lances having injection nozzles.

[0045] In one embodiment, the syngas provided herein is further converted into a gaseous feedstock for microbial fermentation to produce hydrogen, synthetic natural gas, methanol, ammonia, liquid fuels, and feed proteins, biodegradable polymers, or alcohol, including the syngas compositions provided herein or produced from the syngas compositions provided herein.

[0046] In one embodiment, the CO provided herein has a purity of greater than about 95%, preferably greater than about 99.5%. 2 By-products are recovered from the purge gas or tail gas after conversion of syngas to products.

[0047] In one configuration embodiment, the slag produced by gasification of heterogeneous waste in the gasifiers provided herein is non-leachable according to the TCLP test. In another embodiment, provided herein is a road base or cement additive comprising the slag provided herein.

[0048] In another aspect, a process for gasifying heterogeneous waste is provided herein. In one embodiment, the process includes gasifying the heterogeneous waste in a gasifier provided herein. In another embodiment, the heterogeneous waste material requires no or substantially no pre-treatment, limited to removal of hazardous materials such as large items that cannot be shredded, metals, rocks, and explosives. In another embodiment, the heterogeneous waste material requires only basic shredding to a preferred size range of about ¼ inch to about 2 inches (6 mm to 50 mm). In another embodiment, the heterogeneous waste requires drying only if the moisture content is greater than about 20% by weight.

[0049] In another embodiment, the oxygen to steam ratio used by the lance disposed within the material bed is from about 1.5 to about 4.5 kgO 2 / kg steam range.

[0050] Specific non-limiting advantages A-C of the techniques provided herein are described below.

[0051] A. They offer the ability to control the chemical composition of the slag to produce a vitrified, glassy slag material in which impurities are completely immobilized and do not leach. This allows the slag to be beneficially used in commercial applications such as road base. In contrast, the ash produced by low-temperature gasification contains leachable toxic elements and frequently requires disposal in hazardous landfills.

[0052] B. They significantly reduce the high tar content typically present in the syngas from fixed-bed updraft gasifiers without the need for the operation of costly downstream tar separation and recovery units. Heterogeneous waste gasification in updraft gasifiers is accompanied by the production of significant levels of tar in the syngas. In certain heterogeneous waste and biomass gasifiers, excessive tar production is a serious problem causing fouling of process equipment, and despite best efforts to prevent such buildup using sonic horns, scrapers, or high velocity jets, costly shutdowns for periodic cleaning are inevitable.

[0053] C. These allow for the gasification of heterogeneous waste streams with high volatile matter content, a broad particle size distribution from about 6 to about 100 mm (about 1 / 4 inch to about 4 inches), and the ability to handle high fines content (e.g., greater than about 10% material less than about 6 mm) with minimal pretreatment in a fixed-bed oxygen-blown slagging gasifier without the aid of a plasma torch and auxiliary bed permeants such as coke or coal.

[0054] 1 illustrates in elevation and cross-section one embodiment of a gasifier of the present invention. The gasifier converts carbon-containing feedstocks, including but not limited to municipal solid waste ("MSW"), wood, agricultural waste, coal, petroleum coke, or hydrocarbons, into CO, H 2 , CO 2 , H 2 O, C.H. 4 The crude oil is converted into synthesis gas ("syngas"), which is comprised of higher hydrocarbons, including C1, C2, and C3 compounds, heavier condensable hydrocarbons (i.e., tar), and solids carried along with the synthesis gas, including carbonaceous soot and mineral ash components.

[0055] Generally, components such as lances, ports, and burners have multiple units, and references to singular items should be understood to apply to multiple units as well. Any reference to a singular or multiple components is not meant to limit the scope of the description in any way.

[0056] In some embodiments, the gasifier has a shell or walls constructed of refractory-lined steel with external cooling jackets in some sections as necessary to maintain temperatures within the design specifications of the materials of construction. Gasification occurs in several major sections, each performing a different function with the overall goal of converting the feedstock into tar-free synthesis gas and molten slag.

[0057] In some embodiments, the gasifier of the present invention is further characterized by having sidewalls of variable diameter and may be vertical or conical with a slope selected to optimize the flow and residence time of gas and solids in each zone. As highlighted in FIG. 1, the sidewall angle off vertical is generally between about 5° and about 25° and is optimized based on the feed characteristics, the desired residence time of each zone, and the aspect ratio. While the present invention is not limited by any particular set of geometric features, as will be appreciated by those skilled in the art, it is desirable to optimize the residence time, superficial gas velocity, and bed H / D to provide sufficient residence time while maintaining the desired fluid flow regime with fully developed gas flow (i.e., sufficient bed height to ensure complete distribution and reaction of the gas without channeling and premature breakthrough) while remaining below the fluidization velocity and limiting carryover of solids into the syngas.

[0058] In some embodiments, solid feedstock is fed into the gasifier above the material bed in zone 3 through one or more ports 4 using a suitable solids feeder. Any suitable solids feed arrangement can be used, including but not limited to: a) pneumatic, b) a series of lock hoppers and slide valves, c) a rotary feeder also known as a star feeder, or d) a screw feeder. A particularly preferred feeder is a plug screw feeder with a conical screw section to compress the feedstock and form an effective gas barrier between the feed system and the gasifier. The screw feeder has an optional extension to feed the material inside the gasifier towards the center of the material bed to improve dispersion and gasification efficiency. Additional feedstock can be optionally fed from the top of the gasifier through feed port 7 as needed to ensure uniform dispersion across the cross section of the gasifier. Optionally, bed additives or fluxing agents can also be fed through port 7 to adjust bed permeability or slag properties as needed for stable operation.

[0059] In some embodiments, the feedstock fed to zone 3 is heated by the rising hot synthesis gas ("syngas") produced by the gasification reaction in zone 4, resulting in drying, devolatilization, and pyrolysis of the feedstock. Without being bound by theory, pyrolysis occurs in the absence of oxygen and is believed to convert the solid feedstock into a mixture of: a) H2O through evaporation and chemical dehydration of free water; 2 O vapor, b) CO, CO 2 , H 2 and CH4, permanent gases including C2 / C3 hydrocarbons ("HC"); c) gases of the general formula CH x O yand d) a series of chemical reactions that convert the char into tar compounds having a carbon content of about 90% or more than about 95%, but still contain covalently bound oxygen and / or hydrogen. Without being bound by theory, it is generally desirable to maintain a relatively slow heating rate up to the final peak temperature of gasification to allow controlled pyrolysis in the upper section, minimize tar production, and maximize the formation of secondary char or carbonaceous solid carbon that provides a substrate for the oxygen gasification reaction in the lower section. The heating rate is primarily controlled by the bed level or bed volume in zone 3, with higher bed levels resulting in longer residence times and slower heating rates. Preferred heating rates in zone 3 are less than about 10° C. / min, less than about 7.5° C. / min, or less than about 5° C. / min.

[0060] In some embodiments, the devolatileted solid char descends into zone 4 where the gasification reactants oxygen and steam are injected at a controlled ratio via the upper set of lances 3 and the lower set of lances 2. Providing the gasification reactant injection points at different heights improves distribution and ensures steady movement of bed material to maintain uniform gasification and even distribution of the generated syngas across the cross section of the bed, preventing potentially hazardous conditions associated with channeling and oxygen breakthrough. Gasification reactions are well known to those skilled in the art and include, but are not limited to, the following reactions: TIFF2025508265000002.tif54137

[0061] Reactions 1, 4, and 5 are exothermic (i.e., release heat) to raise the gasification temperature and provide heat to support endothermic reactions 2, 3, and 6. The objective of the gasifier of the present invention is to completely convert all minerals and ash to a fully vitrified slag, and also to melt any incidental metals present in the feedstock. In some embodiments, temperatures above about 1500°C, preferably above about 1750°C to about 2000°C, just prior to lances 2 and 3 are required to achieve this important objective. The high temperature zone just prior to lances 2 and 3 in zone 4 is referred to in the art as the tuyere zone or lance raceway zone, and extends from the injection point to the material bed with a raceway length of greater than about 1 foot, greater than about 2 feet, or greater than about 3 feet, depending on the bed permeation characteristics, peak temperature, and injection rate of reactants from the lance. The reactants are injected, for example, at velocities ranging from about 75 to about 150 m / sec, preferably from about 100 to about 125 m / sec, to optimize effective penetration into the bed and limit wear on the refractory wall and lance tip while inducing recirculation to provide effective contact between the gasification reactants and the carbonaceous char. Synthesis gas produced in zone 4 rises through the bed into zone 3 to provide heat for drying, devolatilization, and pyrolysis of the feedstock.

[0062] Another objective of the gasifier of the present invention is to maximize carbon conversion and produce molten slag with a well-controlled glassy (i.e., amorphous) structure and minimal carbon content that can be effectively separated and collected from a bed of heterogeneous feed material without the need for expensive and unsustainable bed permeants such as coal or coke. In some embodiments, this objective is accomplished by having an actively cooled cone-shaped bed support structure (called a cooled slag collector or "CSC") located above the molten slag reservoir zone 6, separating the headspace of the slag reservoir zone 6 from the slag collection hearth zone 5 while maintaining the upward flow of combustion gases from the oxy-fuel burner 1 through the center of the slag hole 10 (FIG. 6) and the gravity annular flow of slag from the collection or hearth zone 5 along the wall of the slag hole 10 and discharging into the slag reservoir zone 6. The CSC has a support steel plate 16 welded to a ring or wafer body mounted between the gasifier body break flanges for ease of removal and maintenance. The CSC has one or more slag holes 10 and is provided with limpet coils welded to the plate and optional spiral cooling coils surrounding the slag holes to provide cooling and maintain the structural metal within its design temperature limits, and to form a protective slag skull on the surface of the refractory to extend the life of the refractory according to design principles known to those skilled in the art. FIG. 8 shows the temperature profile on the top surface of a structural steel plate 16 from a computational fluid dynamics ("CFD") analysis conducted using Ansys Fluent to evaluate the effectiveness of a limpet coil welded directly to the bottom surface. Modeling confirmed the feasibility of maintaining the steel temperature within the design limits of 350°C.

[0063] In one embodiment, the CSC is an internal feature as highlighted in Figure 1 that has the outer wall of the gasifier remaining substantially vertically oriented (i.e., similar to a false bottom. As will be appreciated by those skilled in the art, this is beneficial for pressurized gasifiers where a conical outer wall is undesirable.

[0064] In another embodiment shown in FIG. 2, the CSC 9 is integrated with the outer body of the vessel, and the slag hole 10 is located at the apex of the conical section that discharges the slag into the slag reservoir zone 6. This particular configuration is different from the internal CSC, which is usually not limited in the number of slag holes, and usually features only a single slag hole. In this design, all cooling features except for the central slag hole cooling feature are external to the vessel, resulting in a simpler design with less concern of internal leakage of cooling water into the gasifier. The central slag hole and associated cooling features are combined into a compact assembly designed as a wafer body that is inserted between two body flanges that are much smaller compared to FIG. 1. These advantages must be weighed against the additional complexity in designing the conical outer walls of the lower zone 5 and upper zone 6 with angles g° and h°, respectively, and the complexity associated with the installation of cooling and refractory materials.

[0065] In another embodiment, as shown in FIG. 3, the rate of molten slag discharge through taphole 12 shown in FIG. 1 is controlled to keep the slag level in zone 6 constant. This is accomplished by balancing the pressure drop through 12 with the internal pressure within the gasifier. In some embodiments, the pressure drop is controlled by a mechanical device 20, such as a mechanical valve, to limit the size of the taphole opening. For example, the mechanical valve can limit the size of the taphole based on the pressure differential across the taphole. In some embodiments, another vessel 14 is added, which may be a non-limiting example of a N2000 slag pump, via inlet 21. 2 12 or depressurized via vent 22, the combined action of which controls the pressure drop across 12 to control the slag level in zone 6. For example, additional vessel 14 can seal the slag outlet and contain inert gas to create pressure within additional vessel 14, where the pressure in additional vessel 14 can control or influence the pressure differential across the taphole.

[0066] In another embodiment, a quench chamber is provided below zone 5, as shown in Figure 4. In this case, the slag hole 10 effectively becomes the taphole, and the taphole burner 1 is used to control the slag flow and temperature through the taphole. The slag flowing through the taphole is quenched using recirculating water through spray nozzles 13 to form granular slag, typically less than 6 mm in size, which is collected underwater in the quench chamber 14, from where it is discharged through port 15 by a rotary feeder or similar device.

[0067] In certain embodiments, the CSC comprises a plurality of slag holes. Without being bound by theory, the plurality of slag holes around the periphery of the CSC can disrupt the core flow of solids in the bed and redirect the solids towards the outer diameter and active lance raceway, ensuring material movement throughout the cross section of the gasifier and allowing for gasification of heterogeneous material without the need for expensive and energy intensive feed preparation such as pelletizing or briquetting, or the use of bed permeable additives such as co-feeding coal or coke for stable operation.

[0068] In some embodiments, the oxy-fuel burner 1 is located in the headspace of the slag reservoir zone 6 to ensure that the slag remains in the optimum temperature range for tapping through the slag tap hole 12, typically in the range of about 1250°C to about 1500°C. Adjusting the burner controls the temperature to maintain optimum viscosity for tapping and granulation without excessive slag temperature causing excessive refractory corrosion or erosion. At temperatures above about 1500°C, the oxy-fuel burner combustion gas, CO 2 and H 2 The O maintains the desired slag temperature and also reacts with residual carbon and particles that may have fallen through the slag holes and may float freely on the slag surface if the molten slag has a high specific gravity. Without wishing to be bound by theory, it is believed that the carbon and CO 2 and H 2 These endothermic gasification reactions of O produce additional carbon syngas CO and H 2This results in a slag with minimal carbon content, ensuring full vitrification of the mineral matter within the glassy slag structure that is well suited for downstream market applications such as road base and cement additives.

[0069] In some embodiments, the desired gasification temperature in gasification zone 4 is controlled by the amount and ratio of oxygen and steam reactants injected through lances 2 and 3, as well as the auxiliary heat provided by oxy-fuel burner 1 in the headspace of slag reservoir zone 6. As will be appreciated by those skilled in the art, the ratio of oxygen and steam injected controls the relative contributions of the endothermic and exothermic reactions listed in reactions 1-6 to achieve the desired temperature for effective gasification and slagging. Combustion gases from the headspace of zone 6 are generally controlled within a temperature range of about 1500°C to about 1750°C and flow upwardly to zone 4 through the center of slag hole 10 via bypass line 11, which allows entry into zone 2 for differential pressure control as needed. Temperatures in the lance raceways can exceed 2000°C, but the gas CO present in the combustion gases from burner 1 is not affected. 2 and H 2 Due to the endothermic reaction with O (Rxn. 2 and 3) and the steam injected from lances 2 and 3, the final syngas emerges from zone 4 at a temperature of less than about 1500° C., less than about 1250° C., or less than about 1000° C. This syngas exchanges heat with bed material in zone 3 to support drying, devolatilization and pyrolysis reactions and enters the tar breaking or polisher zone 2, typically at a temperature of less than about 600° C., less than about 500° C., or even less than about 400° C., depending on the moisture and volatile matter content of the feedstock.

[0070] Another object of the present invention is to provide a method for the production of tar at a rate of about 100 to about 200 g tar / Nm3 without using a catalyst or a chemical absorption and recycling process for tar. 3 The high tar content characteristics of the upflow gasifier, which is in the range of approximately 5 g tar / Nm 3 Less than 2g tar / Nm 3 less than 1 g tar / Nm 3The aim is to reduce the total tar content of the synthesis gas to less than about 1000° C. (tars are defined as hydrocarbons heavier than C3 compounds). This objective is achieved by heating the synthesis gas to a temperature of greater than about 1000° C., greater than about 1100° C., and preferably greater than about 1200° C. via reaction with additional oxygen provided by burner 5, designed to operate with a significant excess of stoichiometric oxygen having a lambda of greater than about 1.0, greater than about 1.5, greater than about 2.5, or greater than about 5.0, which is needed to balance the heating provided by the combustion of the auxiliary fuel gas with the partial oxidation of tar species in the synthesis gas. Tar content can vary widely depending on the feed composition, and when the tar content is high, most of the heating required to achieve the target temperature is provided by the tar partial oxidation ("POX") reaction, rather than the combustion of the auxiliary fuel gas. A burner rather than a lance is used to provide the very hot oxygen. Without wishing to be bound by theory, it is believed that contacting very hot oxygen with hydrogen and steam produces hydroxyl and other reactive radicals, producing additional synthesis gas CO and H from the tar without the addition of a catalyst, according to the following general reaction (not balanced): 2 It is believed to facilitate an effective transition to TIFF2025508265000003.tif5150

[0071] The slope y and height of the sidewalls of the tar polisher zone 2 are selected to achieve a residence time at temperature greater than about 2 seconds, greater than about 3 seconds, greater than about 4 seconds, and preferably greater than 5 seconds. Additional syngas is produced by the POX reaction, increasing gas flow. The slope y of the sidewalls is selected to counter this effect by increasing the cross-sectional flow area over the height of the polisher section 2 to maintain superficial velocities within an acceptable range determined in part by the maximum size solid particles carried with the syngas. By careful control of residence time, temperature, and oxygen and steam addition, a flow rate of about 2 g / Nm 3 Less than about 1 g / Nm 3 Tar content of less than about 10 g / Nm 3 Less than 7.5g / Nm 3Less than 5 g / Nm 3 It has been found that minimal levels of soot as a by-product of less than 100% can be consistently achieved. A syngas with low tar content provides significant benefits to the operation of downstream processing units, including solids removal and waste heat recovery, by reducing fouling, improving overall reliability and on-line time, and maintaining peak operating efficiency of these unit operations. The above objectives are achieved by reducing the CO and H already present in the syngas. 2 It was found that this could be achieved by minimizing the combustion losses of the incoming CO and H. After careful experimentation, it was surprisingly found that most of the auxiliary heat was generated by the incoming CO and H. 2 It was found that the reaction originates from a tar reaction rather than a stoichiometric reaction. Without wishing to be bound by theory, it is believed that when good contact is provided, H 2 The energetic free radicals, likely generated from ethanol, are then thought to react with tar species. During these reactions, the tars are converted to synthesis gas and the energy content of the free radicals is trapped in chemical bonds rather than being converted to heat (i.e., combustion).

[0072] The syngas exiting Zone 2 is substantially free of tar and contains low levels of ash components that can form sticky deposits and fouling in downstream heat recovery and solids removal equipment.

[0073] In some embodiments, to prevent fouling from these sticky ash components, the syngas is quenched in zone 1 to an intermediate temperature, typically less than about 800° C., using water injected through spray nozzles 6 before it exits the gasifier via port 8. It is preferable to use demineralized water to avoid fouling and deposits in the spray nozzles.

[0074] In some embodiments, the syngas is not quenched in zone 1, but enters a cyclone upon exiting port 8 to remove and recover carbonaceous particulate matter from the syngas prior to substantial cooling. 2 O, Na 2One will realize that there will be less contamination from condensed alkaline salts such as O, KCl, NaCl, etc. The recovered particulates are suitable for reintroduction into the gasifier.

[0075] In some embodiments, the lances and burners in each zone can be angled both with respect to the horizontal and with respect to the normal (a line perpendicular to the tangent to the inner refractory wall), as shown in Figures 1 and 5. The gasifier of the present invention is not intended to be limited by any particular set of angles, as it can be optimized for each situation by one skilled in the art depending on the feed composition and the desired injection rates and angles in the different zones. Without limiting the above, a typical range for these angles is between about 0° and about 25°.

[0076] In a non-limiting example that serves merely to illustrate the effect of varying the angular orientation of the burner or lance, a separate tar polisher is provided to process the syngas from the gasifier without an integrated tar polisher zone 2. The syngas exiting zone 3 is sent to a separate polisher after exiting the gasifier via port 8. The polisher inlet and burner are shown in schematic plan view in FIG. 9. Burner 5 is offset from both the horizontal and normal at angles l° and k°, respectively. A CFD analysis was performed to create a defined swirl pattern that ensures good mixing and contact of the tar species with the hot reactants generated by burner 5 of excess lambda, as shown in FIG. 10. EXAMPLES

[0077] Example 1: Tar conversion using an alternative polisher with an excess lambda burner Pellets derived from municipal solid waste (MSW) having the composition in Table 1 were fed at a rate of 120 kg / hr to a demonstration scale gasifier with a 40 inch (1.0 meter) inner hearth diameter and a total height of 15 feet (4.6 meters). Oxygen was fed through the lance at a rate of 30 kg / hr, with the lance oxygen to steam ratio set at 2.4 (m / m) or a steam flow rate of 12.5 kg / hr. The 150 g / Nm3 The tar-laden synthesis gas, containing 1000 s of tars (defined as hydrocarbons > C3+ all oxygenated species), was fed directly into a separate tar polisher vessel via two tangentially arranged inlets as shown diagrammatically in Figure 9. The polisher was equipped with four (4) burners 5 as shown in Figure 9. The burners used propane as the supplemental fuel and were used to control the temperature of the polisher at the desired set point of 1093°C (2000°F). 20 kg / hr of excess oxygen (i.e., above the stoichiometric requirement for combusting the supplemental fuel) was fed to the burners.

[0078] Table 1. Composition of MSW pellets fed to the gasifier TIFF2025508265000004.tif210156

[0079] A sample of the syngas exiting the polisher was collected and analyzed using EPA Method TO-14 and analyzed by GC / FID to detect all species heavier than methane. For purposes of reporting tar content, C2 and C3 species (>90% ethane and small amounts of ethylene and propane) were excluded. Tar is generally understood to refer to the condensable components, while the C2 and C3 components mentioned above remain as permanent light gases in the syngas.

[0080] Table 2: Tar Destruction of Polishers Based on EPA TO-14 Tar Analysis TIFF2025508265000005.tif40152

[0081] Filtration test shows soot content is 4-5g / Nm 3The polishing efficiency was estimated to be in the range of 100-150% by weight, confirming that all condensable tar species were effectively destroyed. Any tar not converted to syngas or light alkanes was converted to soot, which was easily separated in the wet gas scrubbing section of the process. Essentially no condensable polycyclic aromatic compounds, hydrocarbons, or any chlorinated hydrocarbons were detected, confirming the effectiveness of the polisher in converting tar species to valuable syngas components without producing harmful by-products. The soot is recovered, dehydrated, and then recycled to the gasifier to avoid producing a waste stream.

[0082] Example 2: Modeling and testing of a CSC slag hole to evaluate slag and refractory temperatures and slag flow The cooled slag collector (CSC) shown in Figures 6 and 7 was modeled to evaluate the temperature profile of the flowing slag and refractory in a single slag hole. The inside diameter of the slag hole 10 was set at 3 inches and the overall length of the slag hole was set at 8 inches. A 3 / 4 inch diameter cooling coil 18 with a single 8 inch diameter loop was placed directly on the steel plate 16 (i.e., 2.5 inches of refractory between the flowing slag and the cooling surface).

[0083] A spreadsheet model was developed that stepwise integrates the heat flow from the top to the bottom of the hole. The main model input parameters are highlighted in Table 3.

[0084] (Table 3) Model parameters and calculation method for CSC slag hole TIFF2025508265000006.tif78164

[0085] The calculation was set up in polar coordinates to account for the change in cross-sectional area of ​​heat flow as a function of radius. A step size of 0.1 to 1 mm was used to integrate over the entire length of the hole. As is typical for counterflow heat transfer calculations (the slag and combustion gas boundary temperature conditions are on opposite sides), iterative calculations are required to solve the problem. This was set up in a spreadsheet using techniques known to those skilled in the art.

[0086] Slag viscosity is very sensitive to temperature and was calculated based on laboratory T250 measurements (at temperature where viscosity = 250 poise) and corrected to other temperatures based on the correlation developed by Mills et al., supra. It should be noted that the T250 of slag at 2012°F is lower than the T250 of MSW ash at 2118°F, as reported by the analytical laboratory and summarized in Table 5. CaCO 3 Adding slag additives changes the optical basicity and SiO 2 The ash content of the MSW pellets was 10.8% (see Table 1), and the additional CaCO 3 The amount of added CaCO was 1.7% (relative to MSW). 3 The slag viscosities resulting from the incorporation of CaCO are summarized in Table 4. 3 The calculated optical basicity including the above was 0.638.

[0087] The film thickness of the flowing slug was calculated using correlations for annular flow in drainage systems with air backflow in high-rise buildings. See Buitenhuis, M. (2017) "What flow rates can go through a drainage system-a theoretical background," pp. 24-28. https: / / high-rise.aliaxis.com / wp-content / uploads / Research-What-flow-rates-can-go-through-a-drainage-system-09-17-132-1.pdf, which is incorporated herein by reference in its entirety.

[0088] (Table 4) 1.7% CaCO 3 Slag viscosity of MSW pellets with added TIFF2025508265000007.tif45128

[0089] It was quickly established that a layer of insulating paper was necessary to prevent excessive cooling and freezing of the slag in the slag hole. The final solution, shown in Figure 10, used 1 / 8 inch insulating paper to ensure that the cooling effect was directed to the structural steel without the slag in the slag hole freezing. As is evident from Figure 10, the refractory hot surface is maintained below 2900°F at the top of the slag hole and above 2200°F at the bottom of the slag hole. This ensures that the refractory is maintained within its design limit of 3200°F, but is always hot enough to ensure that the slag viscosity is below 100 poise (10,000 cP). The insulating paper is also maintained well below its design limit of 2200-2500°F. The temperature values ​​in Celsius (°C) and Fahrenheit (°F) are related by the formula C=5 / 9(F-32).

[0090] As confirmed by modeling, it is feasible to separate and collect slag in a slag reservoir via the CSC of the present invention, while maintaining all materials within their design limits and preventing the slag from freezing.

[0091] A CSC was fabricated and tested in the gasifier of Example 1. Before and after photographs of the CSC, Figures 12 and 13, respectively, are shown from operational testing of the unit. There is no evidence of slag freezing within the slag holes 10 of the unit.

[0092] Example 3: Design and modeling of a scaled-down commercial CSC The Example 2 CSC, containing six 3-inch ID slag holes 10, was successfully designed, built, and tested in a demonstration-scale gasifier. The focus of this first generation CSC was to ensure that the slag viscosity was kept low enough (<100 poise) so that significant "frozen layer" and "skull" would not develop and continue to build up, which could completely block the holes. However, as can be seen in FIG. 13, there is evidence of refractory erosion within the holes. The next generation CSC to be modeled and designed was to incorporate features present in the commercial deployment of this technology, namely: (i) a single slag hole in the center of the gasification vessel, and (ii) the components would need to actively create and maintain a skull layer of slag on the top surface of the CSC and inside the slag hole to better insulate and protect the CSC components / structural materials from erosion and temperature excursions.

[0093] Simulations were created in ANSYS Fluent to analyze and tune the selected materials of construction, location of cooling circuits, dimensions of all components, and operating flow rates under various scenarios / case studies. Figure 14 shows a representative, but non-limiting example of such a design. The top surface of the CSC component has a silicon carbide based ceramic insert 31 that provides high thermal shock resistance and high conductivity to remove sufficient heat from the flowing molten slag and allow sufficient cooling to promote, form, and maintain a slow moving, low temperature, low conductivity protective skull layer. In the center of the conical silicon carbide insert 31 is a 3 inch slag hole 10. Copper tubing provides the cooling circuit 33 to remove approximately 200,000 BTU / hr of heat to allow for the formation of the skull. The coolant velocity (modeled as pure water in these simulations) is maintained in the range of 10-30 ft / sec and a pressure of 50 psig to prevent localized film boiling.

[0094] The shell (and vessel break flange) 36 is protected from the high process temperatures by the selection of refractory and insulating fabric 32, and by the cooling circuit 37 which in this design is located inside the vessel. Future designs where more vertical space is available will allow for the installation of external cooling (limpet coils or dimple jackets) on the outside of the vessel shell 36.

[0095] In FIG. 15, the temperature results for one CSC design are displayed with temperature contours ranging from a minimum of 80° F. (black) to 2700° F. (light gray). The corresponding image, FIG. 16, zooms in on the silicon carbide insert 31 and the flowing slag region 30 and displays temperature contours from 1800° F. (light gray) to 2700° F. (black), with temperatures below 1800° F. displayed in white. 1800° F. / 982° C. is chosen for most flux slag compositions encountered during waste processing, and temperatures below this level result in a significant increase in viscosity, essentially leading to the formation of a “frozen” skull. As can be seen from FIG. 16, in this particular design configuration, the molten slag would essentially remain above this 1800° F. threshold, so no frozen skull would be produced in this case, an unacceptable condition.

[0096] 17 and 18 show that the result of the improved design (incorporating the insulating cloth behind the main cooling circuits 33) is that the heat removal provided by these cooling circuits can be directed towards cooling the silicon carbide inserts 31, and thus the skull layer (white area in FIG. 18 with a temperature below 1800° F.) is now in the molten slag region, as the intent of the present invention is detailed. A further benefit of this design improvement is that the reduced heat removal from the process (as the refractory 32 below / behind the insulating cloth 34 is no longer cooled to a greater extent by the cooling circuits 33) increases the overall efficiency of the gasifier compared to a non-optimized design.

[0097] Example 4: Preparation and testing of slags to confirm vitrification and non-leaching properties The MSW pellets of Example 1, with an ash content of 10.8%, were analyzed to determine the elemental composition of the ash as summarized in Table 5 below. Prior to being fed to the gasifier of Example 1, the MSW pellets were doped with 1.7% additional CaCO (relative to the MSW feed). 3 CaCO was added. 3 The addition level of CaCO was calculated based on Mills et al., supra, to achieve a slag optical basicity of 0.638, which was found to achieve an optimum balance of reducing slag viscosity without being overly corrosive to the gasifier refractory lining, particularly slag reservoir zone 6. 3 The effect of the addition is to lower the T250 of the slag at 2012°F versus 2118°F for the MSW ash, as reported in Table 5. Without wishing to be bound by theory, the addition of CaCO 3 SiO 2 It reduces viscosity by breaking down the network.

[0098] Table 5. Ash analysis of MSW pellets (same MSW pellets as used in Example 1) TIFF2025508265000008.tif208138

[0099] The gasifier was operated as in Example 1, with the slag collected in slag reservoir zone 6 and held at a temperature of 2700°F for 8 hours, at which point the tap hole was opened to allow the slag to flow directly into a water-filled quench chamber. Without wishing to be bound by theory, it is understood that rapid quenching of the slag results in a glassy structure under conditions where the chemistry of the slag is adjusted to ensure that the chemical composition is within the glassy region, as described by Mills et al., supra. Without wishing to be bound by theory, it is believed that the glassy structure promotes effective vitrification of the minerals and minimizes leaching.

[0100] The slags were submitted to leaching tests, including Total Threshold Limit Concentration or TTLC, Soluble Threshold Limit Concentration or STLC (TTLC and STLC are both California requirements), and the U.S. Federal EPA Toxicity Characterization Leaching Procedure or TCLP.

[0101] The results of the tests are summarized in Table 6 and it is clear from the data that the protocol followed was effective in producing a non-leached slag that could be used for commercial applications.

[0102] Table 6: Results of slag leaching tests (TTLC, STLC and TCLP) TIFF2025508265000009.tif108161

[0103] The embodiments illustratively described herein may be suitably implemented in the absence of any element or elements, limitations, or limitations not specifically disclosed herein. Thus, for example, terms such as "comprising," "including," and "containing" are to be understood broadly and without limitation. Furthermore, the terms and expressions used herein are used as terms of description and not of limitation, and the use of such terms and expressions is not intended to exclude any equivalents of the features shown and described or portions thereof, but is recognized to be subject to various modifications within the scope of the claimed technology. In addition, the phrase "consisting essentially of" will be understood to include the elements specifically recited and additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase "consisting of" excludes any elements not specified.

[0104] The present disclosure should not be limited in terms of the specific embodiments described in this application. As will be apparent to those skilled in the art, many modifications and variations can be made without departing from the spirit and scope thereof. In addition to those recited herein, functionally equivalent methods and compositions within the scope of the present disclosure will be apparent to those skilled in the art from the foregoing description. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure should 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 the present disclosure is not limited to specific 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.

[0105] In addition, where features or aspects of the disclosure are described in terms of a Markush group, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual members or subgroups of members of the Markush group.

[0106] As will be understood by those skilled in the art, for any or all purposes, especially in terms of providing a written description, all ranges disclosed herein also include any and all possible subranges and combinations of those subranges. Any recited range can be easily recognized as fully described and allowing for at least one-half, one-third, one-quarter, one-fifth, one-tenth, etc., of the same range to be broken down. As a non-limiting example, each range discussed herein can be easily broken down into a lower third, a middle third, an upper third, etc. As will also be understood by those skilled in the art, all language such as "up to," "at least," "greater than," "less than," etc., refers to a range that includes the recited numbers and can then be broken down into subranges as discussed above. Finally, as will be understood by those skilled in the art, a range includes each individual member.

[0107] All publications, patent applications, issued patents, and other references mentioned herein are herein incorporated by reference as if each individual publication, patent application, issued patent, or other reference was specifically and individually indicated to be incorporated by reference in its entirety. Definitions contained in any text incorporated by reference are excluded to the extent they conflict with definitions in this disclosure.

[0108] Other embodiments are within the scope of the following claims.

Claims

1. 1. A fixed-bed oxygen-blown slagging gasifier for gasifying heterogeneous waste, comprising: one or more ports within said gasifier vessel for feeding said heterogeneous waste stream into said vessel; a plurality of lances disposed about the vessel within a level of bed material for injecting oxygen and steam gasifier reactants into the vessel; a tar destruction zone located above the level of the bed material and within the vessel of the gasifier; a plurality of burners disposed about the periphery of the vessel within the tar destruction zone and configured to operate at above stoichiometric oxygen levels; a cooled slag collector disposed at the bottom of the bed material for supporting the bed material, the cooled slag collector having at least one slag hole for allowing free discharge of slag into a slag reservoir below the cooled slag collector and for allowing upward backflow of gas; Including, The slag reservoir includes a headspace and a second plurality of burners disposed within the headspace, the second plurality of burners configured to maintain a slag temperature of a quantity of slag and to consume or gasify any residual carbon within the quantity of slag prior to a slag tapping operation.

2. 10. The gasifier of claim 1, wherein the plurality of lances are offset from a horizontal plane and from a normal to an interior refractory surface of the gasifier.

3. 10. The gasifier of claim 1, wherein the tar destruction zone has a residence time of at least 2 seconds.

4. 10. The gasifier of claim 1, wherein the temperature in the tar destruction zone is at least 2000°F (1093°C).

5. 10. The gasifier of claim 1, wherein the temperature in the tar destruction zone is greater than 2200°F (1204°C).

6. 10. The gasifier of claim 1, wherein the plurality of burners are configured to operate at an oxygen molar ratio to stoichiometric requirement for complete combustion between 0.5 and 6.

0.

7. 10. The gasifier of claim 1, wherein the plurality of burners are offset from a horizontal plane and from a normal to an interior refractory surface of the gasifier.

8. 10. The gasifier of claim 1, wherein the cooled slag collector is disposed within the vessel and includes at least one cooling feature for maintaining the steel frame and refractory components of the gasifier below their respective design temperature limits of 350°C and 1760°C.

9. 2. The gasifier of claim 1, wherein the cooled slag collector is disposed within the vessel and includes at least one cooling feature for maintaining steel frame and refractory components of the gasifier within their respective design temperature limits, the at least one cooling feature including at least one limpet coil and at least one auxiliary copper coil.

10. 2. The gasifier of claim 1, wherein the cooled slag collector is disposed within the vessel and includes at least one cooling feature for maintaining the steel frame and refractory components of the gasifier within their respective design temperature limits, and wherein heat absorbed from the gasifier forms a protective skull layer in the slag collection hearth zone and inside the slag hole, the protective skull layer minimizing erosion and corrosion of protective refractories and preventing slag freezing.

11. 10. The gasifier of claim 1, wherein the slag reservoir is configured to hold and enable slag for an average residence time of greater than one hour to ensure complete conversion of residual carbon.

12. 10. The gasifier of claim 1, wherein the slag level in the slag reservoir is controlled by a mechanical valve restricting the size of the taphole based on a pressure differential across the taphole.

13. The slag level in the slag reservoir is An additional vessel that seals the slag outlet and is pressurized with inert gas to control the pressure differential across the taphole. The gasifier of claim 1 , wherein the gasifier is controlled by:

14. 2. The gasifier of claim 1, wherein the slag level in the slag reservoir is controlled by a mechanical valve and an additional vessel, the mechanical valve controls the slag level by restricting the taphole based on a pressure differential across the taphole, the additional vessel sealing a slag outlet and containing an inert gas, the inert gas pressurizing the additional vessel to control the pressure differential.

15. The synthesis gas exiting the top of the polisher section of the gasifier had a flow rate of 5 g / Nm ３ 2. The gasifier of claim 1 having a tar content of less than 1000 ppm.

16. 10. The gasifier of claim 1, wherein said amount of slag is non-leachable according to a TCLP test.

17. 10. The gasifier of claim 1, wherein the heterogeneous waste requires pre-processing including only basic shredding into the size range of 1 / 4 inch to 2 inches (6 mm to 50 mm).

18. 10. The gasifier of claim 1, which does not include a plasma torch.

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