Systems and methods for pyrolysis

Abstract

The present invention provides a system and method for pyrolysis, comprising: (i) a gas generator: oxidizing a carbonaceous feedstock in the presence of an oxidizing gas in a gasification zone to form generator gas; discharging the generator gas from the gasification zone through a generator gas outlet, wherein the residual oxygen content of the generator gas is substantially depleted or maintained below a maximum predetermined amount by controlling the ratio of oxygen to carbonaceous feedstock fed to the gasification zone; (ii) a pyrolyzer: feeding the discharged generator gas into a pyrolysis zone; pyrolyzing a pyrolytic organic feedstock in the pyrolysis zone in the presence of the generator gas to produce a carbonaceous pyrolysis product and a gas mixture; discharging the gas mixture from the pyrolysis zone through one or more pyrolyzer gas outlets; and (iii) a first burner: receiving the gas mixture discharged from the pyrolysis zone in a combustion zone; feeding an oxygen-containing gas into the combustion zone; and burning at least a portion of the combustible components present in the gas mixture in the combustion zone to produce a combustion product gas.

Description

[0001] This invention is a divisional application of Chinese patent application No. 202080093571.8, filed on November 27, 2020, entitled "System and Method for Pyrolysis". Technical Field

[0002] This invention relates to pyrolysis systems and methods. The system includes a gas generator, a pyrolyzer, and a burner. The gas generator oxidizes a carbonaceous feedstock, thus forming a generator gas with low oxygen content. The pyrolyzer pyrolyzes the organic feedstock in the presence of the generator gas to produce a carbonaceous pyrolysis product and a gas mixture containing combustible components (including the pyrolysis gas). The burner is used to combust the combustible components present in the gas mixture. The systems and methods of this invention are considered particularly useful for the pyrolysis of biomass and / or the remediation of contaminated biomass (including biosolids) to produce purified biochar products, and various aspects of the invention in relation to these exemplary applications will be conveniently discussed. Background Technology

[0003] Pyrolysis is a high-temperature decomposition process used to convert pyrolytic organic feedstocks (i.e., any feedstock containing at least a portion of organic carbon-based material) under non-oxidizing conditions, particularly when the oxygen content is low enough that endothermic cracking predominates over exothermic oxidation. Typically, this occurs at medium to high temperatures (350-750°C). o C) Operating industrial pyrolysis to produce products for energy, fuel, or chemical applications. Pyrolysis produces three product streams: solid carbonaceous products (char), a condensable pyrolysis oil fraction, and a non-condensable gas fraction.

[0004] Pyrolysis products can be converted into various value-added products or used in their original form for a variety of applications. For example, char can be used for soil improvement, soil remediation, water purification, composite materials, or as fuel. When coke is the primary target product, the oil and / or gas fractions can be burned to provide the energy required to drive the endothermic pyrolysis reaction. Excess energy can be used to generate electricity or utility steam.

[0005] Pyrolysis is considered particularly useful for treating biomass, including biosolids that are byproducts of wastewater treatment plants. The primary target product of such treatments is typically biochar. High-temperature pyrolysis advantageously sterilizes potentially harmful microorganisms in biomass and permanently sequesters a portion of the carbon in the biochar.

[0006] Generally, it is important that facilities for processing biomass are simple to construct and operate, and cost-effective. Furthermore, such facilities are often needed in environments lacking extensive industrial infrastructure. One particular concern is that suitable inert gases, such as piped N2, may not be available for feeding into the pyrolysis reactor.

[0007] One proposed approach to address this concern is to recycle a portion of the flue gas generated from the combustion of the oil and / or gaseous products back to the pyrolysis reactor. However, this requires expensive high-temperature booster fans or intermediate heat recovery steps, where heat exchangers are susceptible to contamination by combustion gases. Furthermore, recovery introduces inherent process complexity, potentially increasing costs and operational challenges.

[0008] A further problem is that, due to the high water content and / or low energy content of biomass feedstocks, the entire pyrolysis process of many biomass sources (including biosolids) requires a significant energy input, even when both the pyrolysis oil and gas fractions are completely combusted. This is undesirable from both an economic and environmental perspective. Furthermore, the energy content and composition of biomass feedstocks are variable, thus flexibly operating the pyrolysis process is desirable to maximize biochar yield while simultaneously maintaining a positive net energy value for different feedstocks.

[0009] Another concern is the potential contamination of biomass feedstocks (including biosolids) with hazardous chemical contaminants such as perfluorinated and polyfluoroalkyl substances (PFAS). PFAS are man-made chemicals, particularly concerning due to their persistence, bioaccumulation, and environmental toxicity. Materials contaminated with PFAS are considered particularly difficult to remediate due to the high thermal stability of these compounds, and therefore may not be adequately cleaned by direct pyrolysis. Furthermore, when using such contaminated feedstocks, post-pyrolysis combustion should be optimized to fully degrade or combust vaporized contaminants (or their partial degradation products) present in the gaseous product stream from pyrolysis. The high temperatures and excess oxygen required to achieve this further complicate efforts to recycle the non-oxidizing combustion product stream back to pyrolysis.

[0010] A further problem in many pyrolysis systems is that heat transfer between combustion and pyrolysis may be unsatisfactory, resulting in poor heat distribution, and consequently, low pyrolysis rates and / or poor or inconsistent char product quality. Furthermore, some feedstocks intended for pyrolysis produce low yields of volatile combustible pyrolysis products (i.e., oil and gas fractions), meaning the pyrolysis product gases are below the flammability window or contain insufficient combustible components to provide heat of pyrolysis during combustion.

[0011] Therefore, there is a continued need for new systems and methods for pyrolysis that at least partially address one or more of the aforementioned drawbacks or provide useful alternatives.

[0012] References to patent documents or other matters given in this document as prior art should not be construed as an admission that the documents or matters are known or that the information contained therein is part of common general knowledge on the priority date of any claim. Summary of the Invention

[0013] The inventors have now discovered that a suitable non-oxidizing feedstock for pyrolysis can be generated in a gas generator located upstream of the pyrolysis unit. In the gas generator, under conditions suitable for producing low-oxygen-content product gases, a carbonaceous feedstock, which may be the same as or different from the pyrolysis feedstock, is oxidized with an oxidizing gas. Advantageously, due to the lack of competing process constraints during the operation of the gas generator, this non-oxidizing gas feedstock is supplied to the pyrolysis unit in a highly controllable manner. Therefore, there is no need to supply a separate inert gas (e.g., pipeline-transmitted nitrogen), and there is no need to recycle the oxygen-deficient gas produced by the combustion / gasification of the pyrolysis gas products. The pyrolysis system of the present invention is simple to construct and inexpensive to operate due to the simplicity of process control and the lack of a recirculation flow. Since post-pyrolysis combustion is not required to produce a suitable pyrolysis feedstock, it can be optimally operated for one or more other purposes.

[0014] Furthermore, the gas generator can be operated under partially oxidizing conditions, resulting in product gases containing combustible components (including carbon monoxide and hydrogen). These components can replenish the pyrolysis gases during combustion of the gas mixture discharged from the pyrolysis unit, thereby increasing the combustibility of the gas mixture delivered to the burner and enhancing the heat of combustion.

[0015] The use of successive gas generators and pyrolyzers can also advantageously facilitate the processing of low-energy-content and / or wet biomass feedstocks, while minimizing or avoiding the need for external energy input. By directing a portion of the feedstock to an exothermic / autothermal gas generator that produces more gas than char, the overall energy balance of the pyrolysis process shifts positively, preferably to at least energy neutrality. Furthermore, there is the opportunity for flexible operation based on feedstock composition. For low-energy-content and / or wet biomass feedstocks, a larger proportion can be directed to the exothermic / autothermal gas generator. For high-energy-content and / or drier biomass feedstocks, the proportion directed to the endothermic pyrolysis process can be increased while maintaining a neutral or positive overall process energy balance, thereby achieving higher biochar yields.

[0016] In some implementations, contaminated solid materials can also be remediated in a gas generator. The contaminants are vaporized and / or partially or completely destroyed in the gas generator via oxidation or thermal degradation mechanisms. The vaporized products are then transported through subsequent pyrolysis and combustion units for further degradation, capture in char products, and / or post-combustion recovery.

[0017] According to a first aspect, the present invention provides a system for pyrolysis, comprising: (i) a gas generator including a vaporization zone and a generator gas outlet, wherein the gas generator is configured to: oxidize at least one carbon-containing feed in the vaporization zone in the presence of an oxidizing gas to form generator gas; and discharge generator gas from the vaporization zone through the generator gas outlet, wherein the residual oxygen content of the generator gas is substantially depleted or maintained below a maximum predetermined amount by controlling the ratio of oxygen to carbon-containing feed to the vaporization zone; and (ii) a pyrolyzer including a pyrolysis zone and one or more pyrolyzer gas outlets, wherein the pyrolyzer is configured to: oxidize at least one carbon-containing feed in the vaporization zone to form generator gas; and discharge generator gas from the vaporization zone through the generator gas outlet. The generator gas discharged from the pyrolysis zone is fed into the pyrolysis zone; in the pyrolysis zone, the pyrolyzable organic feed is pyrolyzed in the presence of the generator gas to produce a carbonaceous pyrolysis product and a gas mixture, the gas mixture containing a combustible component, the combustible component containing pyrolysis gas; and the gas mixture is discharged from the pyrolysis zone through one or more pyrolyzer gas outlets, and (iii) a first burner comprising a combustion zone, wherein the first burner is configured to: receive the gas mixture discharged from the pyrolysis zone in the combustion zone; feed oxygen-containing gas into the combustion zone; and burn at least a portion of the combustible component present in the gas mixture in the combustion zone to produce combustion product gas.

[0018] The carbonaceous feed to the gas generator typically does not contain carbonaceous pyrolysis products from the pyrolyzer. In some embodiments, the pyrolyzer is configured to discharge at least a portion of the carbonaceous pyrolysis products as unoxidized products from the system.

[0019] In some embodiments, the maximum predetermined amount does not exceed 4% by weight, or 2% by weight, such as 1% by weight. In some embodiments, the residual oxygen content of the generator gas is substantially depleted, for example, substantially zero.

[0020] In some embodiments, the oxidizing gas is an oxygen-containing gas, such as air. In some embodiments, the gas generator is configured to partially oxidize at least one carbon-containing feed, such that the generator gas contains carbon monoxide and / or hydrogen.

[0021] In some embodiments, the gas generator is configured to feed a first contaminated solid material into a vaporization zone to vaporize and / or destroy one or more contaminants therein. The gas generator may include a solid material inlet and a solid material outlet, the solid material inlet for feeding the first contaminated solid material into the vaporization zone, and the solid material outlet for discharging purified solid material from the vaporization zone.

[0022] In some embodiments, the system is configured to: separate the feedstock into first and second portions; direct the first portion to a gas generator to form at least a portion of at least one carbon-containing feed; and direct the second portion to a pyrolyzer to form at least a portion of a pyrolyzable organic feed. The system can be configured to adjust the ratio of the first portion to the second portion to change the net energy output of the system.

[0023] In some embodiments, the pyrolysis zone and the combustion zone are separated by a heat transfer baffle configured to transfer heat from the combustion zone to the pyrolysis zone, thereby providing at least a portion of the heat of pyrolysis. One or more pyrolyzer gas outlets may include multiple holes in the heat transfer baffle. The gas mixture can thus be discharged from the pyrolysis zone to the combustion zone through these holes.

[0024] In some embodiments, the pyrolyzer is configured to fluidize the pyrolytic organic feed and carbonaceous pyrolysis products in a generator gas stream within the pyrolysis zone. The system may include one or more heat exchange conduits configured to transport combustion product gases through the pyrolysis zone, thereby heating the fluidized pyrolytic organic feed during use.

[0025] In some embodiments, the system further includes a second burner configured to receive combustion product gases discharged from the first burner and further combust any remaining combustible components therein in the presence of excess oxygen.

[0026] In some implementations, the system further includes an energy generation unit for generating electrical energy and / or steam from the heat released by the combustion of combustible components.

[0027] In some embodiments, the system further includes a drying unit to dry at least one carbon-containing feed and / or a pyrolytic organic feed. The energy for the drying unit can be provided by the heat released from the combustion of the combustible components.

[0028] According to a second aspect of the invention, a pyrolysis method is provided, the method comprising: feeding at least one carbon-containing feedstock and an oxidizing gas into a gasification zone, and oxidizing the carbon-containing feedstock therein to form a generator gas; wherein, by controlling the ratio of oxygen to carbon-containing feedstock fed into the gasification zone, the residual oxygen content in the generator gas is substantially depleted or maintained below a maximum predetermined amount; feeding the generator gas from the gasification zone into a pyrolysis zone; pyrolyzing a pyrolytic organic feedstock in the pyrolysis zone in the presence of the generator gas to produce a carbonaceous pyrolysis product and a gas mixture, the gas mixture comprising a combustible component, the combustible component comprising pyrolysis gas; discharging the gas mixture from the pyrolysis zone into a combustion zone; feeding an oxygen-containing gas into the combustion zone; and burning at least a portion of the combustible component present in the gas mixture in the combustion zone to form a combustion product gas.

[0029] The carbonaceous feed to the gas generator typically does not contain carbonaceous pyrolysis products from the pyrolyzer. In some embodiments, the method further includes discharging at least a portion of the carbonaceous pyrolysis products from the pyrolyzer as unoxidized products.

[0030] In some embodiments, the maximum predetermined amount does not exceed 4% by weight, or 2% by weight, such as 1% by weight. In some embodiments, the residual oxygen content of the generator gas is substantially depleted, for example, substantially zero.

[0031] In some embodiments, the oxidizing gas is an oxygen-containing gas, such as air. In some embodiments, at least one carbon-containing feedstock is partially oxidized, such that the generator gas contains carbon monoxide and / or hydrogen.

[0032] In some embodiments, the method includes feeding a first contaminated solid material into a vaporization zone, wherein one or more contaminants in the first contaminated solid material are vaporized and / or destroyed in the vaporization zone. The contaminants may include one or more fluorinated or brominated compounds, such as one or more perfluorinated and polyfluoroalkyl substances (PFAS). The first contaminated solid material may contain biological solids, such as finely granulated portions of biological solids.

[0033] In an embodiment where the first contaminated material is fed into the gasification zone, the generator gas fed into the pyrolysis zone may contain one or more vaporization products of the contaminant vaporization and / or destruction. At least a portion of the vaporization products may i) be captured in the carbonaceous pyrolysis products and / or ii) be catalytically degraded by the carbonaceous pyrolysis products. Additives (e.g., a calcium source) may be added to the pyrolysis zone to react with the vaporization products, thereby capturing at least a portion of the vaporization products in the carbonaceous pyrolysis products.

[0034] In an embodiment where the first contaminated material is fed into the gasification zone, one or more vaporization products of the contaminant can be combusted or thermally degraded and / or destroyed in an excess oxygen-containing burner in the combustion zone or a further burner downstream of the combustion zone.

[0035] In an embodiment where the first contaminated material is fed into the gasification zone, the method may further include discharging purified solid material from the gasification zone.

[0036] In some implementations, a second contaminated solid material is fed into a pyrolysis zone. This pyrolysis zone then vaporizes and / or destroys one or more contaminants in the second contaminated solid material.

[0037] In some embodiments, the method further includes: separating a feedstock (e.g., biomass or waste feedstock, such as biosolid feedstock) into first and second portions; guiding the first portion to a gasification zone to form at least one portion of at least one carbon-containing feedstock; and guiding the second portion to a pyrolysis zone to form at least one portion of a pyrolytic organic feedstock. The method may further include: adjusting the ratio of the first portion to the second portion to change the net energy output of the system.

[0038] In some implementations, the pyrolysis zone and the combustion zone are separated by a heat transfer baffle. Therefore, at least a portion of the heat of pyrolysis can be provided through heat transfer from the combustion zone to the pyrolysis zone via the baffle. The heat transfer baffle may include multiple holes through which the gas mixture flows from the pyrolysis zone to the combustion zone.

[0039] In some embodiments, the pyrolytic organic feed and carbonaceous pyrolysis products are fluidized in a generator gas stream within the pyrolysis zone. In some such embodiments, the fluidized pyrolytic organic feed is heated by one or more heat exchange conduits that transport combustion product gases through the pyrolysis zone.

[0040] In some implementations, oxygen-containing gas is fed into the combustion zone in an amount sufficient to provide excess oxygen (e.g., at least 5% by weight) in the combustion product gases.

[0041] In some implementations, the residual combustible components in the combustion product gases are further combusted with excess oxygen downstream of the combustion zone.

[0042] In some embodiments, the method further includes generating electrical energy and / or steam from the heat present in the combustion product gases or the heat released from further combustion of the combustion product gases. In some embodiments, the method further includes drying at least one carbon-containing feed and / or pyrolytic organic feed using the heat present in the combustion product gases or the heat released from further combustion of the combustion product gases.

[0043] In some embodiments, the pyrolytic organic feed comprises at least one selected from biomass and waste. In some embodiments, the pyrolytic organic feed comprises biosolids. For example, the biosolids may be the coarse-grained portion of biosolids.

[0044] When the terms “comprising,” “including,” or “contains” are used in the specification (including the claims), they shall be interpreted as specifying the said feature, integer, step, or component, but do not exclude the presence of one or more other features, integers, steps, or components, or groups thereof.

[0045] As used herein, the terms “first,” “second,” “third,” etc., relating to various features of the disclosed apparatus are arbitrarily designated and are intended only to distinguish two or more features that may be incorporated into various embodiments of the apparatus. These terms themselves do not indicate any particular direction or order. Furthermore, it should be understood that the presence of a “first” feature does not imply the presence of a “second” feature, and vice versa, and so on.

[0046] Further aspects of the invention are described in the following specific embodiments. Attached Figure Description

[0047] Embodiments of the present invention will be described herein by way of example, referring only to the accompanying drawings, wherein: Figure 1 A system for pyrolysis according to an embodiment of the invention is schematically depicted.

[0048] Figure 2 Another system for pyrolysis according to an embodiment of the invention is schematically depicted, wherein the contaminated solid material is purified in a gas generator.

[0049] Figure 3 and Figure 3A A side view and a plan view of an integrated pyrolyzer and burner in a pyrolysis system according to another embodiment of the invention are schematically depicted.

[0050] Figure 4 and Figure 4A Side and plan views of an integrated pyrolyzer and burner in a pyrolysis system according to an embodiment of the invention are schematically depicted.

[0051] Figure 5 A system for remediating and pyrolyzing PFAS-contaminated biosolids according to an embodiment of the invention is schematically depicted.

[0052] Figure 6 A system for remediating PFAS-contaminated biosolids and pyrolyzing another organic feedstock, according to an embodiment of the invention, is schematically depicted.

[0053] Figure 7 and Figure 7A A side view and a plan view of an integrated pyrolyzer and burner in a pyrolysis system according to another embodiment of the invention are schematically depicted.

[0054] Figure 8 The three-stage fixed-bed laboratory reactor used in Example 1 is schematically depicted.

[0055] Figure 9A schematic flowchart of the semi-pilot-scale pyrolysis apparatus used in Example 2 is depicted.

[0056] Figure 10 This is shown in Example 2 at 600 o The graph shows the key process temperatures and O2 concentrations in the pyrolyzer during a five-hour pyrolysis test.

[0057] Figure 11 A flowchart of ASPEN Plus used in Example 3 is shown to model the system and method according to an embodiment of the invention.

[0058] Figure 12 Is it displayed as follows Figure 5 The graph depicts the total energy balance of the process, which is a function of the solid content and energy content of the biosolid feedstock, with a gas generator:pyrolyzer feed ratio of 0.2, as modeled in Example 4.

[0059] Figure 13 Is it displayed as follows Figure 5 The graph depicts the total energy balance of the process, which is a function of the solid content and energy content of the biosolid feedstock, with a gas generator:pyrolyzer feed ratio of 0.5, as modeled in Example 4.

[0060] Figure 14 Is it displayed as follows Figure 5 The graph depicts the total energy balance of the process, which is a function of the solid content and energy content of the biosolid feedstock, with a gas generator:pyrolyzer feed ratio of 0.8, as modeled in Example 4. Detailed Implementation

[0061] The present invention relates to a system for pyrolysis. The system includes at least (i) a gas generator, (ii) a pyrolyzer, and (iii) a burner.

[0062] The gas generator includes a vaporization zone and a generator gas outlet, and is configured to oxidize at least one carbon-containing feedstock in the vaporization zone in the presence of an oxidizing gas to form generator gas, and to discharge the generator gas from the vaporization zone through the generator gas outlet. By controlling the ratio of oxygen to carbon-containing feedstock fed into the vaporization zone, the residual oxygen content of the generator gas is substantially depleted or maintained below a maximum predetermined amount.

[0063] The pyrolyzer includes a pyrolysis zone and one or more pyrolyzer gas outlets, and is configured to feed generator gas discharged from a gasification zone into the pyrolysis zone, where, in the presence of the generator gas, the pyrolyzable organic feed is pyrolyzed to produce a carbonaceous pyrolysis product and a gas mixture containing a combustible component, which includes pyrolysis gas, and the gas mixture is discharged from the pyrolysis zone through one or more pyrolyzer gas outlets.

[0064] The burner includes a combustion zone and is configured to receive a gas mixture discharged from a pyrolysis zone in the combustion zone, feed oxygen-containing gas into the combustion zone, and burn at least a portion of the combustible components present in the gas mixture in the combustion zone to produce combustion product gases.

[0065] The present invention also relates to a pyrolysis method that can be performed in the system disclosed herein. The method comprises at least the following process steps: (1) feeding at least one carbon-containing feedstock and an oxidizing gas into a gasification zone, and oxidizing the carbon-containing feedstock therein to form a generator gas, wherein the residual oxygen content of the generator gas is substantially depleted or maintained below a maximum predetermined amount by controlling the ratio of oxygen to carbon-containing feedstock fed into the gasification zone; (2) feeding the generator gas from the gasification zone into a pyrolysis zone; (3) pyrolyzing a pyrolytic organic feedstock in the pyrolysis zone in the presence of the generator gas to produce a carbonaceous pyrolysis product and a gas mixture, the gas mixture comprising a combustible component, the combustible component comprising the pyrolysis gas; (4) discharging the gas mixture from the pyrolysis zone into a combustion zone; (5) feeding an oxygen-containing gas into the combustion zone; and (6) burning at least a portion of the combustible component present in the gas mixture in the combustion zone to form a combustion product gas.

[0066] The following disclosure generally relates to the systems and methods of the present invention.

[0067] Figure 1 The image depicts a pyrolysis system 100 according to an embodiment of the present invention. System 100 includes a gas generator 120, a pyrolyzer 140, and a burner 160. The gas generator 120 includes a reaction vessel having a vaporization zone 122, a feed inlet 124, an air inlet 126, and a generator gas outlet 134. In use, a carbon-containing feed 128 (which may be gas, liquid, or solid) and air 130 are fed into the vaporization zone 122 through inlets 124 and 126, respectively, at a conventional vaporization temperature (e.g., 600 °C). o C to 900 o C) Partial oxidation (i.e., gasification) of the oxidizable components in the feed to form generator gas 132. The hot generator gas 132 is then discharged from the gasification zone 122 through the generator gas outlet 134, the generator gas 132 comprising nitrogen, partially oxidized products (such as carbon dioxide, carbon monoxide, hydrogen, methane, and water), and any residual oxygen.

[0068] The flow rate of air 130 relative to the carbon-containing feed 128 can be controlled to deplete oxygen or maintain the residual oxygen content in the generator gas 132 below a predetermined maximum threshold. Specifically, the oxygen content is controlled to a level suitable for providing effective pyrolysis conditions in the pyrolyzer 140. For example, the oxygen content can be controlled to below 1% by weight, or it can be consumed to essentially zero. Under partially oxidizing conditions where the generator gas contains combustible components such as carbon monoxide and hydrogen, the oxygen content in the generator gas is depleted, i.e., reduced to essentially zero.

[0069] The pyrolyzer 140 includes a reaction vessel having a pyrolysis zone 142, a pyrolyzer gas inlet 144, a solid feed inlet 146, at least one pyrolyzer gas outlet 148, and a solid outlet 150. In operation, generator gas 132 from gas generator 120 is typically fed continuously into the pyrolysis zone 142 through inlet 144. At least during continuous operation (i.e., after startup), gas 132 can be the sole source of the non-oxidizing gas feed for pyrolysis. Solid pyrolyzable organic feed 152 is then pyrolyzed in the pyrolysis zone 142 in the presence of generator gas 132, and can be initially, periodically, or continuously introduced into the pyrolysis zone 142 through inlet 146. At conventional pyrolysis temperatures (e.g., between 250°C...), o C and 750 o The process involves pyrolysis (between C and the feed) to produce carbonaceous pyrolysis products 154 (i.e., char) and pyrolysis gases. Contrary to an undesirable oxidation reaction, the low oxygen content in the generator gas 132 advantageously promotes selectivity for the desired pyrolysis cracking reaction. Furthermore, the hot generator gas 132 provides a portion of the heat required to drive the endothermic pyrolysis reaction. The pyrolysis gases are combined with the generator gas 132 to form a gas mixture 156, which is discharged from the pyrolysis zone 142 through the pyrolysis gas outlet 148. High-quality carbonaceous pyrolysis products 154 are continuously, periodically, or ultimately discharged through the solids outlet 150.

[0070] The burner 160 includes a reaction vessel having a combustion zone 162, at least one gas mixture inlet 164, an air inlet 166, and a burner gas outlet 174. In use, a gas mixture 156 and air 170 are fed into the combustion zone 162 through inlets 164 and 166, respectively, where combustible components in the gas mixture (including pyrolysis gases and partial oxidation products transported from the gas generator 120) are combusted to form combustion product gas 172. Combustion product gas 172 is discharged from the combustion zone 162 through the burner gas outlet 174.

[0071] As will be described in more detail below, the burner 160 and the pyrolyzer 140 may optionally be integrated such that the heat of combustion generated in the combustion zone 162 provides the remaining heat required to drive the endothermic pyrolysis reaction in the pyrolysis zone 142.

[0072] In some embodiments, burner 160 is controlled to provide substantially complete combustion of all combustible products in combustion zone 162. Therefore, excess air 170 is added so that the combustion product gas 172 contains a significant amount of residual oxygen, particularly a higher amount than acceptable in the gaseous products 132 fed into pyrolysis. The excess heat of combustion generated in combustion zone 162 can optionally be used to generate electricity or steam by conventional means.

[0073] In other embodiments, the addition of air 170 to burner 160 is limited, such that a significant amount of residual unburned (or partially burned) combustible components remain in the combustion product gas 172. For example, in embodiments that integrate burner 170 and pyrolysis unit 140 to provide heat of pyrolysis for the combustion reaction, the addition of air 170 and thus the degree of oxidation in combustion zone 162 can be controllable variables for maintaining the temperature in pyrolysis zone 142 within a desired range. In this case, the partially burned product gas 172 can be fed to another burner (not shown), where the remaining combustible products are burned to extinction in the presence of excess oxygen, optionally using the heat to generate electricity or steam.

[0074] Advantageously, due to the lack of competing process constraints, the gas generator 120 supplies a non-oxidizing gas feed to the pyrolysis unit 140 in a highly controllable manner. This eliminates the need to supply a separate inert gas (e.g., piped nitrogen), which may not be a resource available on-site, and eliminates the need to recycle a suitable non-oxidizing gas generated from the controlled combustion / gasification of the pyrolysis gas products. In the single-pass system 100, the burner 160 can therefore be operated efficiently to achieve its primary objectives, namely one or more of the following: i) combustion until all combustible products are extinguished, ii) generation of electricity or steam, and iii) provision of the heat required to drive the endothermic pyrolysis reaction. The pyrolysis system 100 is simple and inexpensive to construct and operate due to the simplicity of process control and the lack of a recirculation flow.

[0075] Furthermore, by conducting the exothermic / autothermal partial oxidation reaction in the gas generator 130, the overall energy balance of the process operating in system 100 is advantageous, even when the energy content of the solid pyrolytic organic feed 152 is low, allowing for the avoidance or reduction of external energy inputs (such as electricity or natural gas). In some embodiments, the process is substantially positive energy, so excess energy can be used to generate electricity or steam. In embodiments where the pyrolytic organic feed 152 produces a low yield of pyrolysis gas, the presence of partial oxidation products from the gas generator ensures that the gas mixture 156 is combustible and that system 100 is positive energy.

[0076] Furthermore, the large amount of carbon present in pyrolytic organic feedstocks can be permanently encapsulated in carbonaceous solid materials (i.e., char), thus avoiding carbon emissions. Due to the non-oxidizing nature of the generator gases, the char products are of high quality and can be applied to soil improvement, environmental remediation, and advanced materials (e.g., for battery storage and catalysts).

[0077] In some embodiments, system 100 is used to process biosolids, for example, in a wastewater treatment facility. The biosolids are thus fed as at least a portion of a pyrolytic organic feed 152 to a pyrolyzer 140, where they are pyrolyzed to form sterile biochar. The biochar then exits the process as all or part of a carbonaceous pyrolysis product 154. Wastewater treatment facilities typically have a methane-rich biogas supply suitable for use as a carbonaceous feed 128. Alternatively, as further described below, another portion of the biosolids can be used as carbonaceous feed 128.

[0078] The pyrolysis system of the present invention can also be used to purify contaminated solid materials, such as contaminated biological solids. Figure 2 The image depicts a pyrolysis system 200 according to this embodiment. Similar numbered objects to system 200 are shown herein. Figure 1 The system 100 described in the figure.

[0079] In system 200, gas generator 220 includes a solid material inlet 282 and a solid material outlet 284. In use, contaminated solid material 286 is fed into gasification zone 222 through inlet 282. Solid material 286 can be fed continuously, periodically, or only initially in a given reaction. Optionally, carbon-containing feed 128 (e.g., fuel, such as biogas) is also fed into gasification zone. However, if the carbon content of material 286 is sufficient to react with air 130 and thus produce the non-oxidizing generator gas 232 as described above, a separate source of carbon-containing feed 128 may not be necessary.

[0080] In vaporization zone 222, contaminants in the contaminated solid material 286 are vaporized and / or partially or completely destroyed by oxidation or thermal degradation mechanisms. After sufficient residence time in the vaporization zone to allow for purification in this manner, the purified solid material 288 can be discharged through outlet 284. The vaporized contaminants or their degradation products are carried away from the vaporization zone 222 by generator gas 232. In some embodiments, these components are then captured in carbonaceous pyrolysis products 254 discharged from pyrolyzer 240 (after pyrolysis of the pyrolytic organic feed 152), further degraded in the pyrolysis zone (including catalytic degradation on the surface of the carbonaceous products), further burned or thermally degraded in burner 260 (or further downstream burners as described herein), and / or recovered from combustion product gases 272 in post-combustion caustic scrubber system 290.

[0081] In some embodiments, the contaminated solid material 286 is contaminated with one or more fluorinated or brominated compounds. For example, the contaminated solid material 286 may be a biosolid portion containing elevated levels of perfluorinated and polyfluoroalkyl substances (PFAS).

[0082] In addition to the advantages already described herein with respect to system 100, the inclusion of gas generator 220 in system 200 provides numerous further advantages. Purifying solid material 286 under oxidizing conditions prior to pyrolyzer 240 allows for the capture of contaminants or their oxidative degradation products in the solid carbonaceous pyrolysis products, or for the catalytic degradation of these products on the solid carbonaceous pyrolysis products. Furthermore, without the constraint that non-oxidizing combustion product gases must be recycled for pyrolyzer 254, burner 260 (and / or further downstream burners) can be operated under conditions specifically tailored to provide maximum combustion of contaminants, such as high-temperature combustion in the presence of a large excess of oxygen. For the specific example of fluorinated compounds (such as PFAS), these conditions are considered necessary for activating the highly stable CF bonds present in the molecule.

[0083] Reference Figure 2 In variations of the described implementation, solid material 286 and pyrolytic organic feed 252 are two portions of the same feedstock (e.g., biomass or biosolid feedstock). Optionally, but not necessarily, this feedstock may be contaminated, for example, by PFAS as described above. The process can be configured to adjust the ratio of the two feedstock portions such that a larger or smaller proportion is fed to the gas generator 220 relative to the pyrolyzer 240. This allows for optimization of the overall energy balance of the system, for example, allowing for maximum production of carbonaceous pyrolysis products 254, while still maintaining a net positive overall energy balance for the system 200, which includes net contributions from any additional processing units, such as feedstock drying units and additional combustion units. This can be particularly advantageous for feedstocks where moisture or energy content can vary.

[0084] Further details of each processing unit in the system of the present invention and the steps of the method of the present invention will now be described.

[0085] Gas generator and partial oxidation The system of the present invention includes a gas generator, the primary function of which is to generate a suitable non-oxidizing gas for feeding into a subsequent pyrolysis unit. In embodiments of the system of the present invention for the remediation of contaminated solid materials, a further key role of the gas generator is as a processing unit for at least partial purification.

[0086] A gas generator typically includes at least one reaction vessel configured to oxidize a carbonaceous feedstock in a gasification zone therein. The feedstock can be gaseous (e.g., natural gas or biogas), liquid (e.g., hydrocarbon fuels), or solid (e.g., biomass, such as biosolids), and the gas generator is configured accordingly. In embodiments where the solid feedstock is oxidized and / or purified in the gasification zone, the reaction vessel can be a fluidized bed or a packed bed reactor. If the carbonaceous feedstock is solid, it can be the same as or different from a pyrolytic organic feedstock that is subsequently pyrolyzed in a pyrolyzer.

[0087] An oxidizing gas is fed into the reaction vessel to oxidize the carbonaceous feed in the vaporization zone. Typically, the oxidizing gas is an oxygen-containing gas (i.e., containing O2), although it will be understood that steam is also suitable for oxidizing carbonaceous feed to produce synthesis gas. Air is the most convenient oxidizing gas, but the use of other oxygen sources is not excluded. In the case of a fluidized bed reactor, the solid feed to the reactor can be fluidized in an oxidizing gas, which advantageously improves mixing and heat transfer in the gas generator.

[0088] The gasification zone of the gas generator operates at the temperature at which the carbon-containing feed undergoes oxidation (and in some embodiments, partial oxidation) reactions. The operating temperature can therefore be between 500°C and... o C and 1100 o Between C, such as between 700 o C and 1000 o Between C, for example, approximately 900 o C. During continuous operation, such a temperature can be maintained by the exothermic oxidation reaction that occurs in the gasification zone, and, as discussed further below, such a temperature can be limited by controlling the feed flow rate.

[0089] Since the generator gas is fed to the subsequent pyrolysis reactor, it must be a suitable non-oxidizing gas. Specifically, the residual oxygen (O2) content should be low, such as less than 4% by weight, or less than 2% by weight, or less than 1% by weight. Therefore, it will be understood that the oxygen added to the gasification zone should be controlled relative to the oxidizable components in the carbonaceous feed, for example, in response to the oxygen content measured in the generator gas or by substoichiometric amounts of oxygen in the feed, to ensure partial oxidation conditions. The addition of oxygen can be controlled by adjusting the mass flow rate of the oxidizing feed gas (e.g., air), although the oxygen content in the oxidizing feed gas can be manipulated alternatively. Alternatively, the addition of the carbonaceous feed to the reactor can be controlled (by adjusting the continuous flow rate or by periodic addition) to maintain the oxygen content in the generator gas below a predetermined maximum concentration.

[0090] In some implementations, the gas generator operates under partial oxidation reaction conditions. Partial oxidation is a form of gasification reaction in which carbonaceous materials are oxidized in substoichiometric amounts of oxygen to form a series of gaseous products, including carbon monoxide, carbon dioxide, hydrogen, methane, and water. The product gases of partial oxidation (also known as syngas) are typically oxygen-deficient, such as having an oxygen content of less than 1% by weight, less than 0.5% by weight, or essentially zero. Due to the presence of carbon monoxide and hydrogen, the mixture of product gases from partial oxidation is typically a reducing gas and contains combustible components (e.g., carbon monoxide and / or hydrogen).

[0091] Purification in gas generator In some embodiments, the gas generator is configured to receive contaminated solid material to destroy or repair it within the gas generator. The contaminated solid material may comprise organic or carbonaceous materials that are inherently susceptible to (partial) oxidation. In such embodiments, the contaminated material may form all or part of the carbonaceous feed to the gas generator. In other embodiments, the contaminated material does not contain sufficient or any oxidizable carbon, and a separate carbonaceous material (such as biogas or natural gas) must be added to form a non-oxidizing generator gas within the gas generator.

[0092] In some embodiments, the contaminated solid material is contaminated with one or more fluorinated or brominated compounds, such as perfluorinated and polyfluoroalkyl substances (PFAS). In some embodiments, the contaminated material treated in the gas generator is a biosolid containing elevated levels of PFAS, such as biosolids generated in wastewater treatment plants.

[0093] In the hot vaporization zone of the gas generator, the PFAS components in the contaminated material are vaporized and partially thermally degraded. Therefore, the generator gas contains vaporized PFAS and various gaseous fluorinated degradation products such as short-chain PFAS, other small fluorinated organic compounds, HF, and alkali metal fluorides. These materials can then be mineralized in the pyrolysis biochar products, further degraded in a pyrolyzer or burner, or recovered and further processed in a downstream scrubber system, as described below.

[0094] In other embodiments, the contaminated solid material is contaminated with hydrocarbons. For example, the contaminated solid material could be soil contaminated with heavy crude oil. The hydrocarbons are vaporized and / or (partially) oxidized in the vaporization zone of a gas generator. The resulting vaporized hydrocarbons or oxidation products are then transported together with the generator gas into a pyrolysis reactor, where they are carbonized to form a portion of solid pyrolysis products, or further transported into a burner for combustion.

[0095] After a suitable residence time, the residual solid material in the gasification zone, having essentially depleted the initial contaminants, is discharged from the gas generator. The inventors have discovered that PFAS-contaminated biosolids can be remediated within the gas generator, rendering PFAS virtually undetectable in the residual solids.

[0096] pyrolysis unit The system according to the invention includes a pyrolyzer for pyrolyzing solid organic feedstocks. The pyrolyzer typically includes at least one reaction vessel configured for pyrolyzing the solid feedstock in a pyrolysis zone therein. In use, the solid feedstock is introduced into the pyrolysis zone, where it is heated in the presence of a non-oxidizing generator gas fed from a gas generator, providing a suitable environment for the pyrolytic cracking reaction to occur. Due to the low oxygen content (and reducing properties in partially oxidizing embodiments) of the generator gas fed from the gas generator, high-quality solid carbonaceous material (char) is produced in the pyrolyzer. Furthermore, the heated generator gas can provide at least a portion of the heat of pyrolysis.

[0097] In some embodiments, the pyrolyzer is configured to fluidize the pyrolyzable organic feed and the resulting carbonaceous pyrolysis products in the generator gas stream; that is, the pyrolyzer is a fluidized bed reactor. This arrangement advantageously improves heat transfer from the hot generator gas to the pyrolysis feedstock and the mixing of the feed and products in the pyrolysis zone. The fluidized bed configuration thus promotes endothermic pyrolysis reactions and ensures the formation of high-quality char products. The generator gas stream from the gas generator to the pyrolysis zone may also contribute to a positive pressure differential between the pyrolysis zone and the downstream combustion zone. This can advantageously facilitate the forward flow of the pyrolysis gas mixture into the burner while preventing or substantially limiting undesirable reverse flow of oxidizing gases from the burner to the pyrolyzer.

[0098] This invention applies to a wide range of solid pyrolytic organic feedstocks, including: 1) waste such as plastics, tires, or any other solid hydrocarbon-containing waste or blends thereof; 2) biomass such as wood, straw, rice husks, coffee husks, and any other type of biomass material; 3) contaminated soil; 4) dried algae; 5) biological solids or sewage sludge; 6) food waste; 7) any type of solid organic or inorganic waste from humans; 8) biomass waste such as green waste or agricultural residues, gastric waste, or blends thereof; and 9) mixed inorganic and organic waste, such as municipal solid waste. For the avoidance of doubt, as used herein, the term "pyrolytic organic feedstock" means any feedstock containing at least a portion of organic carbonaceous material from any source (including synthetic, mineral, and bio-based sources) that can be pyrolyzed to produce pyrolysis products.

[0099] In some embodiments, the pyrolytic organic feedstock is selected from biomass (including biosolids) and waste. This process may be particularly relevant with such feedstocks because it facilitates the sequestration of some carbon content in stable solid products and offsets processing costs by generating value-added char products. Furthermore, by combining an exothermic / autothermal gas generator with an endothermic pyrolyzer, the process can be adapted to a range of biomass feedstocks with low energy content and high moisture content. In some embodiments, the pyrolytic organic feedstock contains water, for example, at least 30% by weight, or at least 50% by weight.

[0100] Typically between 350-750 o The industrial pyrolysis reaction C depends on the feed and target product, and the pyrolysis zone of the pyrolyzer can be suitably configured to operate within this temperature range. Pyrolysis reactions typically produce a mixture of products that, upon cooling, comprises solid carbonaceous products (char), an oil (condensable) fraction, and a gaseous (non-condensable) fraction. The gaseous, oily, and char fractions produced as primary products during pyrolysis vary with the heating rate, temperature, and feedstock, and the pyrolysis process can be correspondingly classified into three process types: slow pyrolysis, fast pyrolysis, and flash pyrolysis. Slow pyrolysis typically produces more char, fast pyrolysis produces more oil, and flash pyrolysis produces more gaseous fraction. It will be understood that when the high reaction temperatures occur in the pyrolysis zone, the oily product fraction of the pyrolysis reaction is essentially in vapor form. Therefore, wherever references in this disclosure refer to the production of "pyrolysis gas" or its further reaction via combustion, the "pyrolysis gas" will be understood to comprise a non-condensable gaseous fraction and a vaporized (but condensable) oil fraction.

[0101] The reaction temperature selected in the pyrolysis zone can depend on the properties of the pyrolytic organic feedstock. For example, in the case of waste plastics, a relatively low temperature such as 250°C is suitable. o C to 400 oC can be suitable. When the feed is biomass (e.g., biosolids from wastewater), a relatively high reaction temperature, such as 400°C, is acceptable. o C to 750 o C can be the preferred option.

[0102] The pyrolytic organic feedstock can be added continuously, periodically, or initially to the pyrolysis chamber. For commercial-scale processes, the pyrolytic organic feedstock is typically added continuously or periodically to obtain a relatively constant pyrolysis gas yield. Suitable residence time for solids in the pyrolysis chamber can be from 10 minutes to one hour, for example, 25 to 30 minutes. Suitable pressure in the pyrolysis chamber can be between 1 and 10 bar, for example, between 1 and 3 bar.

[0103] Pyrolysis is an endothermic reaction, therefore requiring an input energy source, namely the heat of pyrolysis (or enthalpy). A portion of this energy can be obtained from generator gases, which carry the heat generated by the exothermic oxidation reaction occurring in the gas generator. In some embodiments, a portion of the required energy input is provided by the combustion of combustible components (including pyrolysis gas products) in the gas mixture supplied from the pyrolyzer to the burner. Thus, the pyrolyzer and burner can be thermally integrated, as will be described in more detail below.

[0104] The pyrolysis gas generated in the pyrolysis zone combines with the generator gas introduced into the pyrolysis zone to form a gas mixture. This gas mixture contains inert components (such as N2) and combustible components (including pyrolysis gas products and any combustible partially oxidized components formed in the gas generator). As will be described below, the gas mixture is discharged from the pyrolysis zone and sent to the burner.

[0105] The pyrolysis process produces carbonaceous pyrolysis products, also known as char (or biochar in the case of biomass feedstock), which are typically the final product of the process. Char is a particularly desirable product for many biomass and waste pyrolysis applications, both because of its value in applications such as soil amendment, soil remediation, and water purification, and because the carbon in the process feedstock is thus sequestered in a stable solid form rather than emitted as carbon dioxide. Therefore, carbonaceous pyrolysis products are generally not oxidized in burners or gas generators. The properties of pyrolytic char will depend on the properties of the feedstock and the pyrolysis conditions, but typical carbonaceous pyrolysis products are porous solids with a high surface area, for example, greater than 20 m². 2 / g of BET surface area, or in the range of 30 to 100 m² 2 / g.

[0106] Treating contaminants in a pyrolysis unit In some embodiments of the invention, as already described, contaminated solid materials are treated in a gas generator to vaporize the contaminants or their degradation products and transport them in generator gas to a pyrolyzer. These vaporized materials can simply pass through the pyrolysis zone and thus into the burner for further degradation under the high-temperature / strong oxidizing conditions of the combustion zone. However, in some embodiments, the vaporized materials undergo at least partial further degradation or reaction in the pyrolysis zone. For example, it is believed that further degradation reactions of PFAS compounds can be catalyzed on the surface of carbonaceous pyrolysis products in the pyrolysis zone. In some embodiments, contaminants or their degradation products can be captured in the carbonaceous products of pyrolysis, preferably in a harmless form. For example, when the vaporized contaminants include degradation products of fluorinated contaminants (such as PFAS), a calcium source can be added to the pyrolysis zone (e.g., along with a pyrolytic organic feed) to mineralize a portion of the fluorine to CaF2.

[0107] In some implementations, the solid organic feedstock undergoing pyrolysis may itself be contaminated, for example, by PFAS. The solid feedstock entering the gas generator and undergoing pyrolysis may be two parts of the same raw material. For example, a highly contaminated biosolid fraction (e.g., a fine-particle fraction) may be fed to the gas generator, while the less contaminated fraction is the primary source of the pyrolyzable feedstock during pyrolysis. Contaminants in the solid pyrolyzer feedstock may be vaporized and / or thermally degraded in the high-temperature pyrolysis zone, captured in the carbonaceous combustion products, or transported out of the pyrolysis zone in the gas mixture for further degradation in a downstream burner.

[0108] burner The system of the present invention includes at least one burner, which typically includes at least one reaction vessel configured for at least partial combustion of a combustible feed gas in a combustion zone therein. A gas mixture discharged from a pyrolysis zone is fed to the combustion zone to at least partially combust the combustible components therein, and then the combustion product gases are discharged from the burner.

[0109] At least during continuous operation (i.e., after startup), the gas mixture from pyrolysis can be the sole source of combustible products introduced into the burner. Ideally, the overall process can be configured and operated to ensure that no external energy input is required during continuous operation. However, optionally, the burner can be configured to feed and burn another fuel source (e.g., natural gas or biogas). This can be particularly useful during startup to reach the appropriate temperature in the burner or pyrolyzer.

[0110] Oxygen-containing gas is fed into the combustion zone to burn at least a portion of its combustible components. Air is the most convenient oxygen-containing gas, but other oxygen sources are not excluded. For thermal efficiency, the oxygen-containing gas can be preheated, for example, through indirect contact with hot flue gas.

[0111] The burner's combustion zone operates at the temperature at which the combustible components in the gas mixture undergo a combustion reaction. Therefore, the operating temperature can be between 700°C. o C and 1300 o Between C, or between 700 o C and 1100 o Between C, such as between 800 o C and 1000 o Between C, for example, approximately 900 o C. During continuous operation, this temperature can be maintained by the exothermic oxidation reaction that occurs in the combustion zone.

[0112] In some implementations, the burner is operated to provide substantially complete combustion of all combustible products in the combustion zone. Therefore, an excess of oxygen is added, which can favor high combustion temperatures. Sufficient oxygen can be added so that the combustion product gases contain at least 5% by weight, or at least 10% by weight, of oxygen. Such conditions favor high conversion rates of combustible products and, more advantageously, further degradation of contaminants introduced from the gas generator and pyrolysis unit. The excess heat of combustion generated in the combustion zone can be used to generate electricity or steam. This can be accomplished using a heat exchanger located inside or thermally coupled to the combustion zone, or by utilizing the heat carried in the exhaust combustion gases downstream of the burner.

[0113] In other embodiments, the burner is operated to provide only partial combustion of the combustible components fed into the combustion zone. The oxygen supply can be restricted, resulting in a significant amount of residual unburned (or partially oxidized) components remaining in the combustion product gases. This arrangement may be preferred when the burner and pyrolyzer are thermally integrated. Thus, the degree of combustion is controlled by adjusting the oxygen feed, thereby maintaining the temperature in the pyrolysis reactor within a target range. As will be described below, residual combustible products in the combustion product gases can be burned downstream of the burner.

[0114] Integrated pyrolyzer and burner In some implementations, the pyrolyzer and burner are thermally integrated, such that the heat of combustion provides a portion of the heat of pyrolysis. Therefore, the pyrolysis zone and the combustion zone can be separated by a heat transfer baffle that allows heat to flow from the combustion zone, which operates at a higher temperature, to the pyrolysis zone, which operates at a lower temperature. As will be described below, the baffle may be impermeable or include multiple pores.

[0115] Figure 3 and Figure 3AThe image depicts an integrated pyrolyzer-burner according to an embodiment of the invention. The pyrolyzer includes a pyrolysis zone 342 configured to receive a pyrolyzable organic feed 352 and generator gas 332 from a gas generator as described herein. The burner includes a combustion zone 362 adjacent to the pyrolysis zone 342, and an impermeable metal partition 301 defines the boundary between the pyrolysis zone and the combustion zone. Figure 3 Side view and Figure 3A The plan view schematically depicts the pyrolysis zone as cylindrical and the combustion zone as an annular space between the outer wall 302 and the cylindrical partition 301.

[0116] In operation, organic feed 352 and generator gas 332 are fed into pyrolysis zone 342. Optionally, the solid feed is fluidized in the generator gas. At a temperature between 350°C... o C and 750 o The organic feedstock is pyrolyzed at a temperature between C and C to produce pyrolysis gases and solid carbonaceous pyrolysis products, and the carbonaceous products 354 are discharged from the pyrolysis zone 342 after a suitable residence time. The pyrolysis gases combine with the generator gases to form a gas mixture 356, which is discharged from the pyrolysis zone and conveyed to the combustion zone 362 via an external conduit 303. There, the combustible components in the gas mixture are combusted at least partially with the oxygen introduced in the air feed 370. As described herein, the combustion product gases 372 are discharged from the combustion zone and may be sent to a further burner, energy recovery, or post-combustion treatment. A portion of the heat of combustion is transferred from the combustion zone 342 through a metal partition 301, thereby driving the endothermic pyrolysis reaction in the pyrolysis zone 342.

[0117] Figure 4 and Figure 4A The image depicts an integrated pyrolyzer-burner according to another embodiment of the invention. The pyrolyzer includes a pyrolysis zone 442 configured to receive a pyrolyzable organic feed 452 and generator gas 432 from a gas generator as described herein. The burner includes a combustion zone 462 adjacent to the pyrolysis zone 442, and a heat transfer metal partition 401 defines the boundary between the pyrolysis zone and the combustion zone. Figure 4 Side view and Figure 4A As schematically depicted in the plan view, the pyrolysis zone is cylindrical, and the combustion zone is the annular space between the outer wall 402 and the cylindrical baffle 401. The baffle 401 is preferably made of a thermally conductive material (typically metal) and includes a plurality of holes 405 that provide fluid communication between the pyrolysis zone and the combustion zone.

[0118] In operation, organic feed 452 and generator gas 432 are fed into the pyrolysis zone 442. Optionally, the solid feed is fluidized in the generator gas. At a temperature between 350°C... o C and 750 oThe organic feedstock is pyrolyzed at a temperature between 442 and 454 to produce pyrolysis gases and solid carbonaceous pyrolysis products. After a suitable residence time, the carbonaceous products 454 are discharged from the pyrolysis zone 442. The pyrolysis gases are combined with generator gases to form a gas mixture 456, which flows through orifice 405 into combustion zone 462 and exits from the pyrolysis zone. There, the combustible components in the gas mixture are combusted at least partially with oxygen introduced in the air feed 470. As described herein, the combustion product gas 472 is discharged from the combustion zone and can be sent to further burners, energy recovery, or post-combustion treatment.

[0119] The distribution and size of the orifices 405 in the baffle 401 are configured to maintain a pressure difference between the pyrolysis zone 442 and the combustion zone 462. The flow rate of the resulting gas mixture through the orifices is sufficient to prevent or appropriately limit oxygen from entering the pyrolysis zone from the combustion zone. The orifices 405 are also typically small enough, or arranged above the solid bed in the pyrolyzer, to prevent solid particles from being transported from the pyrolysis zone 442 to the combustion zone 462.

[0120] Because the combustion zone maintains a higher temperature, heat is transferred from the combustion zone 462 to the pyrolysis zone 442 through the baffle 401. Heat transfer occurs through conduction by the thermally conductive baffle material and convection through the holes 405, thus providing a portion of the heat required to drive the endothermic pyrolysis reaction in the pyrolysis zone. The degree of combustion in the combustion zone 462 can be controlled to regulate the temperature in the pyrolysis zone. For example, the temperature can be controlled in response to measurements in the endothermic pyrolysis zone to maintain a constant or range-limited reaction temperature. In practice, the temperature in the combustion zone may be approximately 50 to 300 degrees Celsius higher than the temperature in the pyrolysis reaction zone. o C, or 100 to 200 o C.

[0121] Due to the combined convective and conductive heat transfer modes, heat transfer through baffle 401 is highly efficient. Furthermore, the heat of combustion transferred from the combustion zone to the pyrolysis zone is typically sufficient to provide the heat of pyrolysis, thus eliminating the need for external energy input into the process. Other benefits are also envisioned, such as weight and cost reduction, for example, through the use of simple mesh baffles. The complexity and / or operability of the pyrolysis system can also be improved, as it eliminates the need to pipe hot, unstable pyrolysis gases from outside the pyrolysis zone to the combustion zone.

[0122] The integrated pyrolyzer-burner reaction system is described in more detail in the applicant’s co-pending PCT application PCT / AU2019 / 050548, which is incorporated herein by reference. The pyrolyzer and burner of the present invention can be configured and operated according to any of the embodiments disclosed therein.

[0123] When the pyrolyzer is a fluidized bed, the combustion zone can be extended via heat transfer ducts or other conduits that guide hot flue gas through the fluidized bed in the pyrolysis zone. This arrangement provides a larger heat transfer surface area (through the ducts) between the pyrolysis and combustion zones, thereby improving the overall thermal integration between the pyrolysis and combustion reactions. In this case, the heat transfer mode can be dominated by an additional particle convection term (in addition to gas convection, radiation, and conduction) at moderate temperatures. The higher heat transfer from the particle convection term is primarily attributed to the increased particle motion through the heat transfer walls (i.e., the ducts).

[0124] Figure 7 and Figure 7A The image depicts an integrated pyrolyzer-burner according to this embodiment of the invention. The pyrolyzer includes a pyrolysis zone 942 configured to receive a pyrolyzable organic feed 952 via a feed line 903, and to fluidize the feed and the resulting char product in generator gas 932 from a gas generator as described herein. The generator gas 932 is distributed via a distribution plate 904, causing the solids to fluidize in a bed 906. After a suitable residence time, the char product 954 is discharged via a discharge line 907.

[0125] The burner includes a combustion zone 962 adjacent to the pyrolysis zone 942, and a heat transfer metal partition 901 defines the boundary between the pyrolysis zone and the combustion zone. Figure 7 Side view and Figure 7A As schematically depicted in the plan view, the pyrolysis zone is cylindrical, and the combustion zone is the annular space between the outer wall 902 and the cylindrical baffle 901. The baffle 901 is preferably made of a thermally conductive material (typically metal) and includes multiple holes 905 at its top, providing fluid communication between the pyrolysis and combustion zones. Air 970 is fed into the burner through air inlet 910. Figure 7A As seen, inlet 910 is configured to tangentially feed air jet 970 into annular combustion zone 962. Therefore, in operation, a cyclone or vortex-like flow is generated near outer wall 902, as depicted by arrow 909. The combustion reaction in combustion zone 962 can therefore occur primarily near outer wall 902, and thus away from baffle 901. The integrated reaction system includes multiple heat transfer conduits 912 that guide the hot combustion flue gas from combustion zone 962 through fluidized bed 906 in pyrolysis zone 942, and ultimately exit the reactor system as combustion product gas 972 through outlet 916. Figure 7A The configuration with the two pipes spaced apart depicts three such pipes, but it will be understood that one, two, or more than three pipes may be used.

[0126] In operation, organic feed 952 and generator gas 932 are fed into the pyrolysis zone 942, and the solid feed is fluidized in the fluidized bed 906 by the generator gas. At a temperature between 350°C... oC and 750 o The organic feedstock is pyrolyzed at a temperature between C and C to produce pyrolysis gases and solid carbonaceous pyrolysis products, and after a suitable residence time, the carbonaceous products 954 are discharged from the pyrolysis zone 942 through the discharge line 907. The pyrolysis gases combine with the generator gases to form a gas mixture 956, which enters the combustion zone 962 through the flow through the orifice 905 and exits from the pyrolysis zone. There, the combustible components in the gas mixture are combusted at least partially with the oxygen introduced in the air feed 970. The hot combustion gases flow downward in the combustion zone (in the form of a vortex) and then upward through the heat transfer pipe 912 and exit through the outlet 916 (see [link to product description]). Figure 7 (The dashed arrow in the text). As described herein, combustion product gas 972 can be sent to further burners, energy recovery, or post-combustion treatment.

[0127] The heat from the combustion reaction is thus transferred to the pyrolysis zone through the partition 901 and the wall of the transfer pipe 912. As described herein, heat transfer occurs through conduction by the thermally conductive partition and pipe materials, convection through the orifice 405, and through additional particle convection terms. Therefore, a portion of the heat required to drive the endothermic pyrolysis reaction is provided in the pyrolysis zone (supplementing the heat already present in the generator gas 932), resulting in excellent heat transfer efficiency.

[0128] In a further variant of the integrated pyrolyzer-burner, pyrolysis takes place in multiple spaced-apart, vertically arranged heat exchange pipes that pass through a combustion zone. The pyrolyzable organic feed is fluidized in the heat exchange pipes by an upward flow of generator gas. The heat exchange pipes include pipe walls with multiple perforations (forming heat transfer baffles), preferably above the horizontal plane of the fluidized bed, through which a mixture of pyrolysis gas and generator gas flows into the combustion zone for the combustion of a portion of the pyrolysis gas. This shell-and-tube arrangement of the burner and pyrolysis zone provides excellent thermal integration between the combustion and pyrolysis reactions.

[0129] Downstream processing Combustion product gases from the burner can be processed in one or more downstream processing units. As will be understood, the downstream processing design can be configured differently depending on the composition of the combustion product gases.

[0130] In some implementations, as disclosed herein, only the product gases from the main burner may be partially combusted, leaving them containing residual combustible components. In this case, the combustion product gases can be fed to a further burner, which can be operated at high temperatures with excess oxygen. This ensures complete combustion of combustible components and optimal degradation of any residual contaminants and their partial degradation products (present in the combustion product gases from the main burner). Complete combustion in this manner also prevents the emission of unburned compounds and provides the opportunity to recover the maximum energy content from the process.

[0131] Combustion product gases, either directly from the main burner or from further downstream burners, can be fed into a conventionally designed energy generation unit. The energy can be used to generate electricity and / or utility steam. In other embodiments, the combustion product gases are used to preheat the feed to the pyrolyzer and / or gas generator, for example, to dry the feed (remove water). For biomass feedstocks (such as biosolids), water removal is a significant energy borrowing from the overall process energy and is therefore likely an important design consideration to ensure that the combustion product gases (following the successive exothermic gas generator, endothermic pyrolysis, and exothermic combustion units) contain sufficient heat to dry the biomass feedstock.

[0132] Combustion byproduct gases can be sent to a post-combustion capture system. For example, flue gas can be treated in an alkaline scrubber where contaminants and degradation products, including residual PFAS, can be recovered.

[0133] Remediation of PFAS-contaminated biosolids The system and method of the present invention are considered particularly suitable for the treatment and remediation of biological solids, for example in wastewater treatment plants.

[0134] Now refer to Figure 5 Describe an embodiment of the present invention. Figure 5 A system 500 for treating PFAS-contaminated biosolids is described. Initially, the PFAS-contaminated biosolids 501 are passed through a dryer 502, where they are indirectly heated using hot combustion product gases 572 to achieve drying. The biosolids 501 may have a water content of up to about 75% or even higher before drying. The dried biosolids 503 are then pulverized into granular form in a pin mill 504. The pulverized biosolids 505 are then sorted into a fine-particle fraction 586 and a coarse-particle fraction 552 in a shaking sieve 506. The fine-particle fraction of the biosolids contains a higher proportion of clay than the coarse fraction, which is more silica-rich. Clay has high adsorption properties for hydrocarbons and cationic properties. Therefore, anionic PFAS contaminants (along with other anionic salt contaminants and hydrocarbon contaminants) disproportionately aggregate in the fine-particle fraction of the biosolids. Therefore, the contaminated fine particulate portion 586 is directed to the gas generator 520, while the less contaminated large particulate portion 552 is fed to the pyrolyzer 540 as a source of pyrolyzable organic feed. In some embodiments, the ratio of portion 586 to portion 552 can be adjusted to change the net energy output of the system 500.

[0135] In gas generator 520, carbonaceous organic material present in the fine particles of biosolids is partially oxidized in vaporization zone 522 by air feed 530 provided by blower 512. The organic matter content of the dried biosolids is generally sufficient to allow for a reasonably high steady-state temperature (e.g., about 900°C). o C) During continuous operation, the oxygen (O2) in the air 530 is essentially depleted. However, fuel 528 (e.g., natural gas or methane-rich biogas) can be used as an additional carbon-containing feed source for oxidation in the burner 509 of the gas generator 520, either at process start-up or during continuous operation. The relative flow rates of the air 530 and the carbon source (fine particulate portion 586 and fuel 528) are adjusted to provide the desired flow rate of the oxidizing generator gas 532 and a suitable low oxygen content therein, typically less than 1% by weight or essentially zero.

[0136] The high reaction temperature in vaporization zone 522 vaporizes and / or degrades PFAS contaminants in the fine particulate portion 586 of the biosolids, thus transporting the contaminants out of the gas generator 520 in generator gas 532. Experiments have shown that C6 and C8 PFAS in the contaminated biosolids can be substantially depleted in this manner. After sufficient residence time in vaporization zone 522 to allow for the vaporization of organic components and PFAS contaminants, the purified solid residue 588 is discharged from the gas generator.

[0137] The generator gas 532, containing vaporized PFAS and PFAS degradation products, is then fed into the pyrolysis zone 542 of the pyrolyzer 540, where the generator gas 532 provides a suitable non-oxidizing atmosphere conducive to the pyrolysis reaction. A steady-state temperature (e.g., approximately 700°C) is maintained in the pyrolysis zone 542. o C) Pyrolysis of the biosolid portion 552 to form solid biochar and pyrolysis gases (including condensable and non-condensable components). The increased temperature in the pyrolysis zone can also vaporize and / or thermally destroy some of the contaminants present in the biosolid portion 552. Optionally, a calcium source (such as lime) is added to the pyrolyzer, for example, mixed with the biosolid feed 552. It is believed that some of the fluorine in the PFAS can be mineralized to CaF2 and thus captured in the biochar. After a suitable residence time, the biochar 554 is discharged from the pyrolyzer.

[0138] The gas mixture 556, comprising pyrolysis gas products and non-oxidizing generator gas 532, is then fed into the combustion zone 562 of the burner 560. At a high steady-state temperature (e.g., approximately 900°C) oC) In the presence of excess oxygen (in preheated air feed 570), pyrolysis gases and partial oxidation products from the gas generator are combusted. The air feed 570 is preheated in heat exchanger 513 through indirect contact with the hot combustion product gases 572. The high reaction temperature and excess oxygen in combustion zone 562 promote the near-complete combustion of organic components and further oxidative destruction of PFAS contaminants present in gas mixture 556.

[0139] As already described herein, the burner 560 and pyrolyzer 540 are integrated such that the heat of combustion generated in the combustion zone 562 effectively drives the endothermic pyrolysis reaction in the pyrolysis zone 542. Therefore, during continuous system operation, a gas mixture 556 flows through multiple holes in a heat transfer baffle 507 that separates the pyrolysis zone 542 from the combustion zone 562. During startup (or if energy demands need to be balanced during continuous operation), the burner 508 combusts fuel 529 (e.g., natural gas or methane-rich biogas) in the presence of an air feed 510, thereby providing the necessary operating temperatures in the pyrolyzer and burner.

[0140] The hot burner flue gas 572 is then fed to dryer 502, which contains a relatively high residual oxygen content (e.g., about 12% by weight), PFAS decomposition products, and remaining vaporized PFAS. In dryer 502, this provides the heat required to dry the biosolid feed 501. The gas is then fed to energy generation unit 511, where any residual heat is used to generate electricity and / or utility steam in a conventional manner. The flue gas is then passed through heat exchanger 513 and fed to Venturi caustic alkali scrubber 514, where PFAS decomposition products (and any remaining PFAS) are recovered in a circulating alkaline solution 515. Caustic alkali 516 is added to the scrubber circuit as needed to maintain alkalinity. The scrubbed flue gas is then guided by fan 517 through activated carbon bed 518 and then discharged.

[0141] System 500 can be operated to minimize or avoid the need for external energy input via fuels 528 and 529, especially during continuous (after startup) operation. One method for this purpose is to change the mass ratio of the biosolids portion 586 fed to the gas generator 620 to the biosolids portion 532 fed to the pyrolyzer 640. For example, if the biosolid feedstock 501 has a high water content, the overall energy balance of process 500 is negatively affected by the energy consumption required to vaporize the water content. To address this, a larger proportion of the feedstock can be directed to the exothermic gas generator 620 to ensure that the overall process is at least thermally self-sustaining. Conversely, if the biosolid feedstock 501 has a low water content, a larger proportion of the feedstock can be directed to the endothermic pyrolyzer 620 and thus converted into biochar 554.

[0142] A related embodiment of the present invention is shown in Figure 6 Objects with similar numbering in System 600, as described in this article... Figure 5 The system 500 described in the figure is different. However, in system 600, PFAS-contaminated biosolids 601 are dried and then fed to a gas generator 620 without grinding or sorting. Different biomass sources (preferably uncontaminated) are fed to a pyrolyzer 640 as pyrolyzable organic feed 652, where the pyrolyzable organic feed 652 is converted into biochar 654. Simulations show that when 4 tons of contaminated biosolids are used as feed 686 and 6 tons of uncontaminated biomass (such as rice husks) as feed 652 per day, the overall energy balance allows for energy generation.

[0143] Example The present invention is described with reference to the following embodiments. It will be understood that these embodiments are for illustration and not for limiting the invention described herein.

[0144] Example 1 like Figure 8 The remediation of PFAS-contaminated organic soil was schematically depicted in a three-stage fixed-bed reactor. The reactor was constructed from a quartz tube (702) with an inner diameter of 80 mm and a length of 1000 mm, fully equipped with instruments for monitoring and controlling gas flow and temperature. An electric heater (704) with three temperature zones provided heat and temperature to the reactors in three independently controlled reaction zones (706, 708, and 710), with temperature measurement and control provided by individual thermocouples (712, 714, and 716). Controlled airflows (718 and 720) were introduced into the first and third reaction zones (706 and 710), respectively, and the resulting gas outlet stream (722) from the reactor was conveyed through a condenser, followed by a caustic alkali scrubber to condense any non-flammable gases and remove particulate matter, NOx, and SO2. X The gas is then passed through a silica dryer to remove moisture, and then measured in an online micro GC analyzer.

[0145] In each experiment, the contaminated organic solid sample (2g; contaminated with PFAS) was placed in a ceramic boat (724) in the center of the first reaction zone. The uncontaminated pyrolytic organic material sample (2g; rice husk biomass) was placed in a ceramic boat (726) in the center of the second reaction zone. The airflow rates into the first reaction zone (706) and the third reaction zone were then set to 100 ml / min and 350 ml / min, respectively. The set temperatures for the first, second, and third reaction zones were set to 900 °C. o C, 700 o C and 900 oC. Use 35-45 o A ramp rate of C / min heats each zone to its target temperature and holds the target temperature for 1 hour before cooling.

[0146] The contaminated organic material is partially oxidized in the airflow (718) in the first reaction zone (706) at a high target temperature, ultimately leaving residual solid material. Based on the preliminary approximate analysis and final analysis of the complete gasification of the contaminated soil, the airflow velocity (100 ml / min) entering the first reaction zone is selected such that oxygen consumption will result in the O2 content of the airflow entering the combustion zone being less than 1% by weight.

[0147] Therefore, in the second reaction zone (708) under a non-oxidizing gas atmosphere, the uncontaminated pyrolytic organic material is heated to the target temperature (700). o C). Therefore, pyrolysis is expected to dominate in this material, resulting in the production of pyrolysis gases (including condensable and non-condensable organic products) and residual carbonaceous material (biochar).

[0148] The pyrolysis gas, along with oxygen-deficient gas, is transported into the third combustion zone, where it is heated to the target temperature (900°C). o C) Combustion of the pyrolysis gas in the presence of excess airflow 720. Based on a preliminary analysis of the initial and final composition of the uncontaminated pyrolytic organic material during complete pyrolysis, the airflow rate entering the reaction zone is selected to achieve substantially complete combustion, and the flue gas leaving the reactor as flow 722 has an O2 content of at least 12% by weight.

[0149] The experimental results are shown in Table 1 below. Three PFAS components—perfluorohexanesulfonic acid (PFHX), perfluorooctanesulfonic acid (PFOS), and perfluorooctanoic acid (PFOA)—were analyzed to determine their amounts in the initially contaminated soil material, in the residual soil material after combustion, and recovered by the scrubber water. The amount / percentage of destroyed PFAS was calculated as the total amount present in neither the residual soil nor the scrubber water. In all three experiments, the soil material was essentially purified, removing all PFAS components. The C8 PFAS components (PFOS and PFOA) were primarily destroyed during the process, while most of the C6 material (PFOS) was vaporized and recovered in the scrubber. This difference is believed to be due to the lower boiling point of the C6 material allowing vaporization before oxidative destruction in the first reaction zone. Various shorter-chain PFAS components were also detected in the scrubber water, consistent with the partial oxidative destruction of some PFAS.

[0150] Table 1. Example 2 The biosolids were sourced from the Mount Martha Water Recycling Plant of South East Water Corporation in Victoria, Australia. This plant primarily receives domestic and commercial wastewater and treats the wastewater sludge through an activated sludge process followed by anaerobic digestion. After digestion, the solids are processed by dewatering equipment (i.e., centrifuges) and a solar drying facility before being sent for storage. Biosolid samples were initially ground using a pin mill (Chenwei Machinery CW-20B) and then separated using a vibrating screen (Sanfeng Machinery, SF-600). The resulting biosolids, used for pyrolysis, had a particle size of 0.5–2 mm, and their composition is shown in Table 2.

[0151] Table 2. The pyrolysis of biosolids was studied using a semi-pilot-scale pyrolysis apparatus. The process flow diagram of the pyrolysis apparatus is shown in [the diagram]. Figure 9 In the pilot-scale test, each pyrolysis experiment was conducted semi-continuously for 5 hours, with biosolids 852 continuously fed throughout the experiment, and char 854 collected only at the end of each experiment after 5 hours. During startup, the pilot-scale unit was heated by a liquefied petroleum gas (LPG) burner 804. Hot flue gas exiting the LPG burner was used to preheat air 806 and an N2 / CO2 mixture 808 through a heat exchanger 813. The preheated air 870 and N2 / CO2 mixture 832 were then circulated in the reactor system 810 to heat the reactor to the desired temperature. The reactor system 810 was made of 253MA stainless steel and insulated with ceramic fiber insulation to minimize heat loss, and had a concentric geometry with an inner tube serving as a cylindrical pyrolyzer 842. The lower half of the inner tube heat transfer baffle 807 was made of impermeable cylindrical tubes, while the upper half of the baffle consisted of a cylindrical wedge-shaped wire screen 816.

[0152] At the start of each test, biosolids are fed into hopper 812, and N2 is introduced through the N2 purge line. Once the desired reactor temperature is reached, biosolids 852 are continuously fed from the hopper into pyrolyzer 842 at a rate of 0.25 kg / h through a pre-calibrated screw feeder with constant N2 purging. Biosolids 852 are pyrolyzed under bubbling fluidization conditions using a preheated N2 / CO2 mixture 832 containing 85% N2 and 15% CO2 v / v, and fed into the pyrolyzer through distribution plate 814.

[0153] Gases and oil vapors generated in pyrolyzer 842 are continuously transferred to burner 862, i.e., the annular space surrounding pyrolyzer 842, through holes in wedge wire screen 816. The temperature in burner 862 is controlled by adjusting the air inlet rate. In this study, the temperature in the burner was intentionally kept below the pyrolysis temperature to better understand the impact of the pyrolysis process itself on contaminants in the feedstock. Preheated hot air 870 is tangentially fed into the annular burner via nozzle 818 at a velocity >10 m / s, partially burning the pyrolysis gases and vapors, and minimizing air intake into pyrolyzer 842. Residual pyrolysis gases and vapors are sent to water scrubber 822 in burner outlet stream 820, where they are immediately cooled. The condensable pyrolysis oil 824 is condensed in the scrubber water, while the non-condensable pyrolysis gas 826 is sent to the combustion chamber 828 of the LPG burner 804. LPG 830 is fed into the combustion chamber 828 to ensure complete combustion of the non-condensable pyrolysis gas 826 with air 834. Before the flue gas 840 is released to the atmosphere, the hot flue gas is used to preheat the hot air 870 and the N2 / CO2 gas mixture 832 in the heat exchanger 813.

[0154] The O2 concentration within pyrolyzer 842 was continuously monitored using an online gas monitor (Syngas Analyser, Madur Aqua GA40T Plus). The reactor system was equipped with four thermocouples for the following temperature measurements: 1) the internal temperature of pyrolyzer 842 (pyrolysis temperature), 2) the internal temperature of the annular burner 862, 3) the inlet temperature of the N2 / CO2 gas mixture 832 fed into pyrolyzer 842, and 4) the inlet temperature of the air 870 fed into burner 862. At the end of each test, water scrubber samples were collected for oil and PFAS analysis. Biochar 854 was kept in an inert environment while cooling and then collected for analysis.

[0155] Pyrolysis experiments were conducted at three different pyrolysis temperatures: 500, 550, and 600. o C, assuming the average temperature at the thermocouple in the pyrolyzer is the pyrolysis temperature, achieved excellent process stability and pyrolyzer inertness. Figure 10 It was displayed in 600 o The temperatures and pyrolyzer O2 concentrations obtained in experiment C are shown in Table 3. The yields, composition, and average BET surface area (Micromeritics 2000 / 2400) of the biochar products are presented. Scanning electron microscopy (SEM) imaging revealed a highly porous structure with porosity increasing with temperature.

[0156] Table 3. PFAS compounds in biosolid feedstock, biochar products and scrubber water were analyzed, and the results (applicable to all experiments) are shown in Table 4.

[0157] Table 4. A variety of different PFAS compounds are present in bio-solid feedstocks in quantifiable amounts. However, all of these substances are below the detection limit in both biochar and scrubber water. PFAS compounds are vaporized and / or destroyed during the pyrolysis reaction, so the final biochar product is essentially free of PFAS.

[0158] Example 3 The integrated process of soil remediation, pyrolysis, combustion, and energy generation was modeled using ASPEN Plus. Figure 11 The ASPEN Plus flowchart is depicted, and Table 5 below briefly describes the flowchart shown. Figure 11 The ASPEN process model comprises five main process steps: feedstock pretreatment, gasification of contaminated organic solids, pyrolysis of organic waste, combustion of pyrolysis gases, and energy generation from hot flue gas. Key model assumptions include: steady-state conditions, a zero-dimensional model, isothermal reaction (uniform bed temperature), a 30% residual solids yield in the gasification stage, and a 35% biochar yield in the pyrolysis stage.

[0159] Table 5. Pretreatment of the solid feed stream. Hot exhaust gas (FLUEGAS) from a pyrolysis gas burner (COMBUSTR) is used in indirect contact dryers (SOIL-DTY and RH-DRY, respectively) to dry contaminated organic soil and biomass (i.e., rice husk organic waste). Figure 11 The moisture content in the SOIL and RICEHUSK is respectively determined by the amount of water present in the soil and biomass. The air feed to the burner is controlled by design specifications to maintain a sufficiently high exhaust gas flow rate to dry the contaminated organic soil and biomass to the desired moisture content, and the air feed (AIR-HEX) is preheated to 350°C before being fed to the pyrolysis gas burner (COMBUSTR). Figure 11 The SOIL and RICEHUSK flows were specified as unconventional flows, and approximate and final analyses were manually entered based on laboratory experimental data. Flow thermodynamic conditions and mass flow rates were also entered.

[0160] Gasification Reactor. Contaminated soil (SOI-GASI) enters the gasification yield reactor (Y-GASI), where unconventional components are converted via a calculator module to provide a mass flow of conventional components in the module outlet stream (ELE-GASI). Residual ash (ASH) is modeled as an unconventional component with an actual carbon and ash content of 5% by weight. The ash component is then separated in a cyclone separator module (SEP-ASH), sending the remaining soil feed component (GASI-IN) to the gasification reactor module (GASIFIER). The air mass flow (AIR-GASI) entering the gasifier reactor is set based on the specific gasifier product gas (SYNGAS) composition to be achieved, particularly the essentially zero O2 content. At 900... o C reacts the soil and air streams (GASI-IN and "AIR-GASI") via a combustion / gasification reaction in the gasifier reaction module (GASIFIER). The exhaust product stream (SYNGAS) is then sent to the pyrolysis module. The composition of the product stream is shown in Table 7 below.

[0161] Pyrolysis Reactor. Dry rice husk biomass (RH-PYRO) enters the pyrolysis yield reactor (Y-PYRO), where unconventional components are converted via a calculator module to provide a mass stream of conventional components in the module outlet stream (ELE-PYRO). Residual biochar (BIOCHAR) is modeled as an unconventional component with actual C, O, H, N, S, and ash contents. The biochar component is then separated in a cyclone separator module (SEP-CHAR), and the remaining biomass feed (PYRO-IN) is sent to the pyrolysis reactor module (PYRO-YIE). Predictive calculations derived from experimental laboratory results determine the reactor's optimal operating temperature at 700°C. o The gaseous and oil pyrolysis products generated during operation C contain over 100 different compounds as products, with product composition depending on the feedstock composition and laboratory-scale reactor conditions. The pyrolysis product stream (PY-GAS-Y) and the gasifier product stream (SYNGAS) then enter the gas mixing module (PYROLYSE), where they are mixed at 700... o C undergoes further reaction. The resulting gas mixture (PYRO-OUT) is discharged and sent to the burner module.

[0162] Burner. The gas mixture (PYRO-OUT) contains pyrolysis gases produced in the pyrolysis module, and this gas mixture enters the combustion reactor (COMBUSTR), where it is introduced at 350°C. o In the presence of preheated airflow (AIR-COMB) of C, at 900 o C undergoes combustion. Then, hot exhaust gases (FLUEGAS) dry the solid feedstock and preheat the air. Finally, at 500... oIn a boiler operating at C, heat is used to generate energy, and the cooled exhaust gas is passed through a scrubber, an activated carbon bed, and a bag filter before being discharged.

[0163] The main inputs and results of the simulation are shown in Tables 6 through 9 below. Table 6 shows the feed rates and composition of the two solid feeds. Table 7 shows the composition of the product gas (SYNGAS) formed by the partial oxidation of contaminated soil in the gasification reactor. Table 8 shows the results at 700... o C (as described here) and a series of other simulated pyrolysis temperatures and pyrolysis product yields. The biochar product contains approximately 68-70% by weight of fixed carbon. Overall, approximately 30-40% of the carbon fed into the process is sequestered in the biochar.

[0164] Table 9 shows the energy consumption / output for each processing unit. The burner generates sufficient energy to provide the heat of pyrolysis in the pyrolysis unit, even taking energy losses into account. The overall process produces a net thermal energy of 120 kW. Furthermore, the contaminated soil stream is purified, producing biochar as a useful byproduct of the process, thereby capturing most of the carbon in a stable form and thus preventing greenhouse gas emissions.

[0165] Table 6. Table 7. Table 8. Table 9. Example 4. As referenced in this article Figure 5The ASPEN Plus model was used to model an integrated process of gasification, pyrolysis, combustion, and energy generation using a single contaminated biosolid feedstock, employing a modeling method similar to that described in Example 3. The ASPEN process model comprises five main process steps: (1) pretreatment (drying) of wet biosolid feedstock 501 in dryer 502 using hot flue gas 572; (2) gasification of the dried biosolid portion 586 in gas generator 520; (3) pyrolysis of the dried biosolid portion 552 in pyrolyzer 540 in the presence of generator gas 532; (4) combustion of the resulting pyrolysis gas in burner 560; and (5) energy generation from the residual heat in the hot flue gas in energy generation unit 511. Key model assumptions were: steady-state conditions, zero-dimensional model, isothermal reaction (uniform bed temperature), 30% residual solids yield in the gasification stage, and 35% char yield in the pyrolysis stage. The modeled feed rate of bio-solid feedstock 501 to the process is 0.48 tons / day (based on dry weight). Bio-solid feedstock 501 has a water content of 50% by weight and is dried to 15% by weight in dryer 502. The gas generator temperature, pyrolysis temperature, and combustion temperature are modeled as 900°C. o C, 700 o C and 900 o C. The boiler in energy generation unit 511 is at 500 o During operation at C, the air feed 570 is preheated to 350°C in heat exchanger 513. o C.

[0166] The key variables in the study are: (1) the calorific value (total dry calorific value) of the biosolid feedstock 501 - in the range of 11 to 20 MJ / kg; (2) the solid content of the biosolid feedstock 501 - in the range of 20 to 80% by weight; and (3) the feed ratio of the gas generator to the pyrolyzer, i.e. the ratio of the dry biosolid portion 586 fed to the gas generator 520 to the dry biosolid portion 552 fed to the pyrolyzer 540 - in the range of 0.2:0.8 to 0.8:0.2.

[0167] One model output of interest is the overall energy balance of the process, as it is expected that the overall process will generate net heat energy rather than energy input demand, even when the biosolids feed is wet (low solids content) or has a low energy value. Typical biosolids feedstocks have a solids content ranging from 30-50% by weight. The selected total energy generation (or demand) results are shown in... Figure 12 , Figure 13 and Figure 14 In this study, the gas generator:pyrolyzer feed ratios were 0.2:0.8, 0.5:0.5, and 0.8:0.2, respectively. It is evident that when only a small portion of the total biosolids is fed to the gas generator (see...), the feed ratios are significantly lower. Figure 12The gas generator:pyrolyzer feed ratio is 0.2:0.8, making the process nearly energy-neutral, and even requiring energy input in practical scenarios, especially when the solid content of raw material 501 is less than 40%. In contrast, when most of the biosolids are fed to the gas generator (see...), the process is much more efficient. Figure 14 The gas generator and pyrolyzer feed ratio is 0.8:0.2, and the process generates net heat energy in all simulation scenarios.

[0168] For a gas generator:pyrolyzer feed ratio of 0.2:0.8, the biochar yield from pyrolysis will be approximately 0.135 tons / day, with an estimated carbon sequestration percentage of 23%.

[0169] The results show that the process can be flexibly operated according to the feedstock composition. For low-energy-content and / or wet biomass feedstocks, a larger proportion of the feedstock can be directed to the exothermic gas generator to maintain overall positive energy output. For high-energy-content and / or drier biomass feedstocks, there is an opportunity to increase the proportion of biomass feedstock directed to the endothermic pyrolysis process while still maintaining positive energy. The advantage of doing so is that it will achieve higher biochar 654 yield and lower carbon emissions. In all cases, the gas generator advantageously provides a suitable gaseous medium in which pyrolysis can take place without the need to feed inert gas into the process.

[0170] Furthermore, as shown in Examples 1 and 2, contaminated biological solid feedstock 501 (including feedstock contaminated with PFAS) can be repaired during the process because the treatment in the gas generator 620 and pyrolyzer 640 results in the volatilization and / or destruction of contaminants.

[0171] Those skilled in the art will understand that the invention described herein is readily adaptable to variations and modifications beyond those specifically described. It should be understood that the invention includes all such variations and modifications falling within its spirit and scope.

Claims

1. A system for pyrolysis, comprising: (i) A gas generator, comprising a vaporization zone and a generator gas outlet, wherein the gas generator is configured to: In the gasification zone, in the presence of an oxidizing gas, at least one carbon-containing feedstock is oxidized to form generator gas; and Generator gas is discharged from the vaporization zone through the generator gas outlet. By controlling the ratio of oxygen to carbon-containing feed into the gasification zone, the residual oxygen content of the generator gas is essentially depleted or maintained below the maximum predetermined level. (ii) A pyrolyzer comprising a pyrolysis zone and one or more pyrolyzer gas outlets, wherein the pyrolyzer is configured to: The generator gas discharged from the gasification zone is fed into the pyrolysis zone; In the pyrolysis zone, a pyrolytic organic feedstock is pyrolyzed in the presence of generator gas to produce a carbonaceous pyrolysis product and a gas mixture, the gas mixture containing a combustible component, the combustible component containing pyrolysis gas; and The gas mixture is discharged from the pyrolysis zone through one or more pyrolysis gas outlets, and (iii) A first burner including a combustion zone, wherein the first burner is configured to: The combustion zone receives the gas mixture discharged from the pyrolysis zone; Oxygen-containing gas is fed into the combustion zone; and Combustion is performed in the combustion zone to burn at least a portion of the combustible components present in the gas mixture to produce combustion product gases.

2. The system for pyrolysis according to claim 1, wherein the pyrolyzer is configured to discharge at least a portion of the carbonaceous pyrolysis products as unoxidized products from the system.

3. The system for pyrolysis according to claim 1 or 2, wherein the maximum predetermined amount is not greater than 1 wt%.

4. The system for pyrolysis according to any one of claims 1 to 3, wherein the gas generator is configured to partially oxidize at least one carbon-containing feed, such that the generator gas contains carbon monoxide and / or hydrogen.

5. The system for pyrolysis according to any one of claims 1 to 4, wherein the gas generator is configured to feed a first contaminated solid material into a vaporization zone to vaporize and / or destroy one or more contaminants therein.

6. The system for pyrolysis according to claim 5, wherein the gas generator includes a solid material inlet and a solid material outlet, the solid material inlet being used to feed a first contaminated solid material into the gasification zone, and the solid material outlet being used to discharge purified solid material from the gasification zone.

7. The system for pyrolysis according to any one of claims 1 to 6, configured to: separate a raw material into a first portion and a second portion; guide the first portion to a gas generator to form at least a portion of at least one carbon-containing feed; and guide the second portion to a pyrolyzer to form at least a portion of a pyrolyzable organic feed.

8. The system for pyrolysis according to claim 7, configured to adjust the ratio of the first portion to the second portion to change the net energy output of the system.

9. The system for pyrolysis according to any one of claims 1 to 8, wherein the pyrolysis zone and the combustion zone are separated by a heat transfer baffle configured to transfer heat from the combustion zone to the pyrolysis zone, thereby providing at least a portion of the heat of pyrolysis.

10. The system for pyrolysis according to claim 9, wherein one or more pyrolyzer gas outlets include a plurality of holes in a heat transfer baffle.

11. The system for pyrolysis according to any one of claims 1 to 10, wherein the pyrolyzer is configured to fluidize the pyrolyzable organic feed and carbonaceous pyrolysis products in a generator gas stream in the pyrolysis zone.

12. The system for pyrolysis according to claim 11, comprising one or more heat exchange conduits configured to transport combustion product gases through a pyrolysis zone to a pyrolytic organic feed that is heated and fluidized in use.

13. The system for pyrolysis according to any one of claims 1 to 12, further comprising a second burner configured to receive combustion product gases discharged from a first burner and to further combust any residual combustible components therein in the presence of excess oxygen.

14. The system for pyrolysis according to any one of claims 1 to 13, further comprising an energy generation unit that generates electrical energy and / or steam from the heat released by the combustion of combustible components.

15. The system for pyrolysis according to any one of claims 1 to 14, further comprising a drying unit for drying at least one carbon-containing feed and / or a pyrolytic organic feed.

16. A pyrolysis method, the method comprising: At least one carbon-containing feed and an oxidizing gas are fed into a gasification zone, and the carbon-containing feed is oxidized in the gasification zone to form generator gas; wherein the residual oxygen content of the generator gas is substantially depleted or maintained below a maximum predetermined amount by controlling the ratio of oxygen to carbon-containing feed fed into the gasification zone. The generator gas from the gasification zone is fed into the pyrolysis zone; In the pyrolysis zone, a pyrolytic organic feedstock is pyrolyzed in the presence of generator gas to produce a carbonaceous pyrolysis product and a gas mixture, the gas mixture containing a combustible component, the combustible component containing pyrolysis gas; The gas mixture is discharged from the pyrolysis zone to the combustion zone; Oxygen-containing gas is fed into the combustion zone; and Combustion occurs in the combustion zone, where at least a portion of the combustible components present in the gas mixture are burned to form combustion product gases.

17. The pyrolysis method according to claim 16, further comprising discharging at least a portion of the carbonaceous pyrolysis products from the pyrolyzer as unoxidized products.

18. The pyrolysis method according to claim 16 or 17, wherein the maximum predetermined amount is not greater than 1 wt%.

19. The pyrolysis method according to any one of claims 16 to 18, wherein at least one carbon-containing feed is partially oxidized such that the generator gas contains carbon monoxide and / or hydrogen.

20. The pyrolysis method according to any one of claims 16 to 19, comprising feeding a first contaminated solid material into a gasification zone, wherein one or more contaminants in the first contaminated solid material are vaporized and / or destroyed in the gasification zone.

21. The pyrolysis method according to claim 20, wherein the contaminant comprises one or more perfluorinated and polyfluoroalkyl substances (PFAS).

22. The pyrolysis method according to claim 20 or 21, wherein the generator gas fed into the pyrolysis zone contains one or more vaporization products of contaminant vaporization and / or destruction, and wherein at least a portion of the vaporization products i) are captured in carbonaceous pyrolysis products and / or ii) are catalytically degraded by carbonaceous pyrolysis products.

23. The pyrolysis method according to claim 22, further comprising adding an additive to the pyrolysis zone to react with the vaporization products, thereby capturing at least a portion of the vaporization products in the carbonaceous pyrolysis products.

24. The pyrolysis method according to any one of claims 20 to 23, wherein one or more vaporization products of contaminant vaporization and / or destruction are combusted or thermally degraded in the presence of excess oxygen in a combustion zone or a burner further downstream of the combustion zone.

25. The pyrolysis method according to any one of claims 20 to 24, further comprising discharging purified solid material from the gasification zone.

26. The pyrolysis method according to any one of claims 20 to 25, wherein the first contaminated solid material comprises a biological solid.

27. The pyrolysis method according to any one of claims 16 to 26, comprising feeding a second contaminated solid material into a pyrolysis zone, wherein one or more contaminants in the second contaminated solid material are vaporized and / or destroyed in the pyrolysis zone.

28. The pyrolysis method according to any one of claims 16 to 27, further comprising: The raw materials are separated into a first part and a second part; The first portion is guided to the gasification zone to form at least a portion of at least one carbon-containing feedstock; The second part is then directed to the pyrolysis zone to form at least a portion of the pyrolytic organic feed.

29. The pyrolysis method according to claim 28, further comprising: Adjust the ratio of the first part to the second part to change the net energy output of the system.

30. The pyrolysis method according to any one of claims 16 to 29, wherein the pyrolysis zone and the combustion zone are separated by a heat transfer partition, wherein at least a portion of the heat of pyrolysis is provided by transferring heat from the combustion zone to the pyrolysis zone through the partition.

31. The pyrolysis method according to claim 30, wherein the heat transfer baffle includes a plurality of holes through which the gas mixture flows from the pyrolysis zone to the combustion zone.

32. The pyrolysis method according to any one of claims 16 to 31, wherein the pyrolytic organic feed and carbonaceous pyrolysis products are fluidized in a generator gas stream in the pyrolysis zone.

33. The pyrolysis method according to any one of claims 16 to 32, wherein an oxygen-containing gas is fed into the combustion zone in an amount sufficient to provide excess oxygen in the combustion product gases.

34. The pyrolysis method according to any one of claims 16 to 32, wherein the residual combustible components in the combustion product gases are further combusted with excess oxygen downstream of the combustion zone.

35. The pyrolysis method according to any one of claims 16 to 34, further comprising generating electrical energy and / or steam from the heat present in the combustion product gases or the heat released by further combustion of the combustion product gases.

36. The pyrolysis method according to any one of claims 16 to 35, further comprising drying at least one carbon-containing feed and / or pyrolytic organic feed with heat present in the combustion product gas or heat released by further combustion of the combustion product gas.

37. The pyrolysis method according to any one of claims 16 to 36, wherein the pyrolytic organic feed comprises biosolids.

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