Method and system for processing waste

Abstract

A method of processing waste is provided, wherein the waste includes human and / or animal digestion waste and / or waste of plant origin. The method comprises the following steps: receiving waste input into a reactor pressure vessel; heating and pressurizing the reactor pressure vessel to perform a hydrothermal carbonization process on the waste material; separating a portion of the liquid from the solids of the product produced by the hydrothermal carbonization process; the solid component is subjected to a gasification and / or pyrolysis process to produce syngas and / or pyrolysis gas. A system for performing the method is also provided.

Description

Technical Field

[0001] The present disclosure relates to a method and system for processing waste materials. Background Art

[0002] The unintentional release of untreated sewage into lakes, rivers and seas via combined stormwater overflows (CSOs) is a serious problem in the UK, causing pollution that is of great harm to the environment and the public. Population growth and rapid urbanisation will increase the amount of sewage sludge generated, which will exacerbate this problem. The sustainable and efficient disposal of sewage sludge is an absolute necessity for a resilient, strong and sustainable society, especially those pursuing a circular economy.

[0003] In industrialized societies, sewage waste is processed in sewage treatment plants. Some of the solid portion of the waste is collected when it arrives at the treatment plant, which is called primary sludge. The remainder, which makes up the bulk of the sludge, is "essentially" feed for bacteria. The bacteria consume the waste so efficiently that up to 80% of the waste is converted into biomass (secondary sludge), which must also be disposed of. Overall, the disposal of primary and secondary sludge can account for 60% of the operating costs of a sewage treatment plant.

[0004] Sewage waste is also a major problem in remote areas without modern sewage treatment infrastructure. In rural areas of industrialized countries or urban areas of low- and middle-income countries (LMICs), on-site sanitation systems (OSS) are prioritized. In OSS, fecal sludges are stored locally and must be collected and disposed of, which is very cumbersome and expensive. The disposal of such sludges is complicated because, on the one hand, they are a resource rich in energy, nitrogen and phosphorus. On the other hand, they are also pollutants, containing potent oxygen-depleting carbon sources, greenhouse gases (nitrous oxide and methane), eutrophication-inducing nutrients (nitrogen and phosphorus) and pathogens as well as various micropollutants, including plastics, endocrine-disrupting compounds, antimicrobial resistance genes and heavy metals. However, water is the most troublesome component. Raw sludges have 97% to 99% water, although they can be thickened to 90% to 95% water or actively dewatered to 15% to 40% solids.

[0005] The water industry has developed successful and complex strategies for disposing of biosolids, which refers to primary and secondary sludge in UK industry terminology. They are usually treated in anaerobic digesters (AD) to recover energy and reduce the biomass volume. The sludge produced is usually disposed of and the liquid must be treated. Currently, the UK produces around 8,500 tonnes of sludge per day, 87% of which goes to land, which is not a resilient and sustainable solution.

[0006] While the energy generated by AD makes a welcome contribution to our net zero goals and some phosphorus can be captured by chemical precipitation, the availability of land for sludge disposal (land banking) is an ongoing concern for the industry. Concerns about emerging contaminants and Environmental Protection Agency regulations to control river pollution may limit land disposal. Therefore, there is an urgent need to develop innovative technical solutions. The success of these solutions will have a significant impact on public health and the environment. Summary of the invention

[0007] According to one aspect of the present disclosure, a method for processing waste is provided, wherein the waste includes human and / or animal digestion waste and / or waste of plant origin, for example, the waste may or may not have undergone a process of biological pretreatment such as anaerobic and / or aerobic digestion and / or a process of pretreatment with anaerobic and / or aerobic and / or anoxic bacteria. The method includes: receiving the waste input into a reactor pressure vessel; heating and pressurizing the reactor pressure vessel to perform a hydrothermal carbonization process on the waste; separating at least a portion of the liquid from the solid component (wet hydrochar) of the product produced by the hydrothermal carbonization process; performing a pyrolysis and / or gasification process (e.g., a thermal gasification process) on the solid component (e.g., the remaining solid component) to, for example, produce synthesis gas and optional pyrolysis gas, such as volatile hydrocarbons and / or organic compounds, respectively.

[0008] When processing biosolids, biomass and organic materials, it is beneficial to position hydrothermal carbonization upstream of thermal gasification because hydrothermal carbonization removes nitrogen compounds and increases the C / O and C / H ratios of the hydrochar for subsequent gasification and production of low-NOx, high-heat-value syngas.

[0009] Positioning the hydrothermal carbonization and thermal gasification technologies in this way also eliminates microplastics, PFASs, and antibiotics, as any unhydrolyzed chemicals remain in the solid hydrothermal char fraction, which is then gasified and converted to a usable syngas and high-ash carbon residue. Additionally, the heat and electricity generated and captured from the combustion of the high heating value syngas can be used to provide the heat and electricity needs of both technologies.

[0010] By combining these two technologies, integrating the generated thermal and electrical energy as well as waste heat, and incorporating process intensification principles in the design of the hydrothermal carbonization reactor and expansion vessel, an innovative technical solution was developed to address and treat the problem of contaminated sludge disposal in land reserves.

[0011] The method may include drying the separated solid component (wet hydrochar) to a target moisture content. The wet hydrochar may be dried using a direct rotary dryer. The wet hydrochar may be dried using waste heat (e.g., waste heat recovered from the hydrothermal carbonization step). Waste heat in the form of hot combustion gases may be transferred to convectively dry the wet hydrochar from a starting solids content of 40% to 70% to a final solids content of at least 90% by mass. Waste heat may be fed to the direct rotary dryer co-currently or counter-currently.

[0012] Waste material may include digestate sludge, for example resulting from anaerobic and / or aerobic digestion of human and / or animal digestive waste and / or waste of plant origin. The digestate sludge may be treated with a flocculant or coagulant.

[0013] The reactor pressure vessel can be heated to a reaction temperature greater than 160 degrees Celsius, such as between 160 degrees Celsius and 260 degrees Celsius, or greater than 180 degrees Celsius, such as 200 degrees Celsius, to carry out a hydrothermal carbonization process. The reactor pressure vessel can be heated at a rate between 2 degrees Celsius and 5 degrees Celsius per minute for 60 minutes to 90 minutes to reach the reaction temperature. The reactor pressure vessel can be kept at a reaction temperature of 30 minutes to 240 minutes, or 30 minutes to 60 minutes. In one example, the reactor pressure vessel can be kept at a reaction temperature of about 4 hours. The reaction temperature and pressure of the reactants in the reactor pressure vessel can be maintained to realize the subcritical conditions of the water in the reactor pressure vessel, such as making water behave as a subcritical fluid. The reaction temperature and pressure of the reactants in the reactor pressure vessel can be configured to reduce the dielectric constant of the water in the reactor pressure vessel, so that the dielectric constant is similar to the dielectric constant of nitrogen-containing and phosphorus-containing compounds. For example, the reaction temperature and pressure of the reactants within the reactor pressure vessel can be configured to reduce the dielectric constant of water within the reactor pressure vessel to less than 40, such as between 20 and 30, such as between 20 and 25.

[0014] The operating temperature of the high pressure reaction vessel can be selected based on the desired outcome of the process. The outcome may be one or more of: (i.) higher hydrochar yield, (ii.) higher nutrient recovery, (iii.) specific partitioning of heavy metals between the solid phase and the aqueous phase, or any other desired outcome.

[0015] The hydrothermal carbonization process may be conducted as a continuous series of batch operations using a plurality of reactor pressure vessels configured to sequentially receive the waste material and conduct the hydrothermal carbonization process at staggered time periods that are less than the total duration of the hydrothermal carbonization process.

[0016] The method may further include discharging the product of the hydrothermal carbonization process into an expansion vessel at a pressure lower than the pressure of the reactor pressure vessel. For example, before the step of separating the liquid from the solid components and / or before the step of drying the wet hydrothermal char. In some arrangements, the method may include discharging the product of the hydrothermal carbonization process into two or more expansion vessels in parallel, the two or more expansion vessels being at a pressure lower than the pressure of the reactor pressure vessel.

[0017] The method may include circulating gas from the expansion vessel through a gas heat exchanger configured to transfer heat from the expansion vessel gas to the input waste material, such as before the waste material is received in the reactor pressure vessel. Additionally or alternatively, the method may include circulating the separated liquid through a liquid heat exchanger configured to transfer heat from the separated liquid to the input waste material, such as before the waste material is received in the reactor pressure vessel. The gas heat exchanger may be arranged downstream of the liquid heat exchanger relative to a passage through which the waste material is input to the reactor pressure vessel.

[0018] Can be separated by physical separation process with liquid and solid component.For example, can use filter press or solid / liquid centrifuge that liquid and solid component are separated.Separated liquid can be used as fertilizer (for example liquid fertilizer of quick release nutrient) output, and / or can be supplied to anaerobic fermenter to produce biogas and / or reduce the carbonaceous oxygen demand of process water before being discharged into for example environment.Separated liquid can also further process and / or mix with carbon residue (for example, the high ash carbon residue produced by the method, for example depends on the composition of the carbon residue produced).

[0019] The method may also include burning the synthesis gas and optional pyrolysis gas such as volatile hydrocarbons and organic compounds produced by the gasification process in a gasifier to generate electricity. For example, during steady-state operation of the method, the electricity generated by the gasifier can be used to power a heater for the reactor pressure vessel. The method may include providing electricity from a source separate from the gasifier to heat the reactor pressure vessel during a startup procedure. Alternatively, the electricity generated by the gasifier can be used to power other electrical equipment at a plant where the method is performed.

[0020] The method may also include delivering a portion of the generated synthesis gas as an input to the gasification process. A portion of the generated synthesis gas can be burned to heat the reactants of the gasification process. The method may also include providing a combustible gas, such as natural gas and / or propane and / or liquefied petroleum gas (LPN) and / or liquefied natural gas (LNG), as an input to the gasification process from a source separated from the gasification reactor, such as during the startup procedure of the method for processing waste. During the startup procedure of the method for processing waste, the combustible gas can be burned to heat the reactants of the gasification process. Once the synthesis gas is available for combustion to heat the reactants, the combustible gas can no longer be provided as an input to the gasification process.

[0021] The method may include circulating combustion gas (e.g. from a gasifier, gasifier, ground flare or burner) around the reactor pressure vessel to heat the reactor pressure vessel and perform the hydrothermal carbonization process. The combustion gas supplied to the top of the separated solids may be combustion gas that has been circulated around the reactor pressure vessel.

[0022] The method may also include circulating combustion gases produced by combustion for heating gasification process reactants to heat input waste upstream and / or inside the reactor pressure vessel. During steady-state operation, the hydrothermal carbonization high-pressure reactor can be heated using (e.g., only using) waste heat (combustion gases) from the gasification step. The reactor pressure vessel or each reactor pressure vessel may include a heating jacket, and the combustion gases may be transferred from a hot gasifier (e.g., from a hot gasifier hood exhaust device) to pass through the heating jacket. Thermal energy is transferred from the hot combustion gases to the reactor pressure vessel to heat the contents of the reactor pressure vessel to the desired operating temperature. During startup, a natural gas / propane burner may be used to heat the reactor pressure vessel with hot combustion gases through the heating jacket to heat the contents of the reactor pressure vessel to the desired operating temperature. The method may also include cleaning the syngas produced by the gasification process to remove pollutants in the syngas before the syngas is used for other purposes as part of the waste processing method.

[0023] The method may further comprise providing an input of further comminuted optional non-biodegradable waste to the gasification process.

[0024] The method may further include recycling at least a portion of the contaminants (eg, tars and / or oils) removed from the syngas as an input to the gasification process.

[0025] According to another aspect of the present disclosure, a system for processing waste, wherein the waste includes human and / or animal digestion waste and / or plant-derived waste, for example, the waste may or may not have undergone a process such as pretreatment with a biological process (e.g., anaerobic and / or aerobic digestion) and / or a process of pretreatment with anaerobic and / or aerobic and / or anoxic bacteria. The system includes: a reactor pressure vessel assembly, which includes one or more reactor pressure vessels, which are used to receive an input of waste and heat and pressurize the waste in the vessel to perform a hydrothermal carbonization process of the waste; a separation unit, which is used to separate liquid from solid components produced by the hydrothermal carbonization process; a gasification reactor vessel, which is used to receive solid components and perform a gasification and / or pyrolysis process on the separated solids in the gasification reactor vessel to, for example, produce synthesis gas and / or pyrolysis gas, respectively.

[0026] The reactor pressure vessel assembly may also include one or more expansion vessels for receiving the hydrothermal carbonization process product (referred to as hydrothermal carbon slurry) from the one or more reactor pressure vessels at a lower pressure than the reactor pressure vessel.

[0027] The system may also include a gas heat exchanger configured to receive gas from one or more expansion vessels and transfer heat from the gas to the input waste. The gas received from the one or more expansion vessels may include, for example, mainly steam. The system may also include a liquid heat exchanger configured to receive the liquid separated by the separation unit (which may be referred to as nutrient-rich process water) and transfer heat from the liquid to the input waste. The gas heat exchanger may be arranged downstream of the liquid heat exchanger relative to the passage of the waste input to the reactor pressure vessel assembly (e.g., through the heat exchanger).

[0028] The system may also include a direct rotary dryer for removing moisture from the wet hydrothermal carbon (separated solid components). The direct rotary dryer may be used to remove moisture via convection drying using waste heat from the hydrothermal carbonization process.

[0029] The system may also include a gas generator for generating electricity using the synthesis gas produced by the gasification reactor. The reactor pressure vessel assembly may include one or more electric heaters for heating the reactants in the reactor pressure vessel. The electric heater may be electrically connected to the gas generator. Additionally or alternatively, the reactor pressure vessel assembly may include one or more jackets for example arranged around the reactor pressure vessel respectively. The jacket may be configured to receive the gas (e.g., combustion gas from a natural gas / propane burner and / or a gasification reactor vessel) heated and the reactants in the heating reactor pressure vessel.

[0030] The system may also include a syngas cleaning unit for removing pollutants such as acid gases, tars and / or oils and / or entrained solids in the syngas produced by the gasification reactor vessel. The syngas cleaning unit may be arranged between the gasification reactor vessel and the gas generator (and / or (if provided) ground flare) relative to the flow of the syngas. The syngas cleaning unit may include a wet wall scrubber. The wet wall scrubber may include a plurality of nozzles for spraying water to increase the contact surface area between the syngas and the water. The syngas cleaning unit may also include one or more baffles configured to promote turbulence of the gas passing through the cleaning unit. In some arrangements, the syngas cleaning unit may include a cyclone separator and / or a dry scrubber system and / or a water scrubber system for removing entrained solids, such as a venturi quencher, a cyclone scrubber and / or a packed bed scrubber, for removing aerosol tar and / or oil and acid gases present in the syngas. The syngas purification unit may also include a condenser configured to remove water in the saturated syngas before combustion in the gas generator. The system may also include a pollutant recycle conduit for recycling at least a portion of the pollutants (eg, tar) removed from the syngas to the gasification reactor.

[0031] The gasification reactor may include one or more burners for burning gas to heat the reactants in the gasification process. The system may include a syngas supply pipeline for supplying syngas output by the gasification reactor (e.g., from downstream of the syngas cleaning unit) to the one or more burners. The burners may be further configured to burn natural gas / propane / LPG / LNG to heat the reactants in the gasification reactor, for example, when the syngas is insufficient to heat the gasification reactor, such as during system startup.

[0032] The reactor pressure vessel assembly may include a plurality of reactor pressure vessels and one or more expansion vessels. The reactor pressure vessel may be configured to store reactants and products at a higher pressure than the expansion vessel. The expansion vessel may be configured to receive the reaction product within the corresponding reactor pressure vessel.

[0033] The reactor pressure vessel assembly can be configured to operate in a continuous series of batch procedures, wherein reactants are sequentially input to a plurality of reactor pressure vessels. The reaction products within the reactor pressure vessels can be sequentially output to an expansion vessel. The hydrothermal carbonization process can be performed in staggered time periods within sequential reactor pressure vessels.

[0034] The reactor pressure vessel assembly may further include one or more conduits for directing the gas from the expansion vessel to one or more heat exchangers for heating the reactants input to the respective reactor pressure vessels. The conduits may be arranged so that the gas from the expansion vessel is directed to a heat exchanger configured to heat the reactants in the next reactor pressure vessel receiving the reactants in the continuous series of batch procedures.

[0035] The system may include a combustion gas conduit for directing the combustion gas from the gasification reactor to the reactor pressure vessel assembly. The system may also include one or more combustion gas heat exchangers, such as a combustion gas heating jacket, for transferring heat from the combustion gas to the waste material input to the reactor pressure vessel assembly.

[0036] According to another aspect of the present disclosure, a reactor pressure vessel assembly is provided, comprising a plurality of reactor pressure vessels and one or more (e.g., a single or a corresponding number of) expansion vessels, wherein the reactor pressure vessels are configured to store reactants and products at a pressure higher than the expansion vessel pressure, optionally wherein each expansion vessel is associated with a different reactor pressure vessel, wherein the expansion vessel is configured to receive reaction products within the reactor pressure vessel (e.g., the corresponding reactor pressure vessel).

[0037] The reactor pressure vessel assembly may further include one or more conduits for conveying gas from the expansion vessel to one or more heat exchangers for heating the reactants input to the corresponding reactor pressure vessel or into the corresponding reactor pressure vessel.

[0038] The reactor pressure vessel assembly can be configured to operate in a continuous series of batch procedures, wherein reactants are sequentially input into a plurality of reactor pressure vessels, reaction products within the reactor pressure vessels are sequentially output to an expansion vessel, and a hydrothermal carbonization procedure is performed within sequential reactor pressure vessels in staggered time periods.

[0039] The piping may be arranged so that gas from the expansion vessel is delivered to a heat exchanger configured to heat reactants within the next reactor pressure vessel to receive reactants in a continuous series of batch procedures.

[0040] Each reactor pressure vessel may be associated with a heater (e.g., an electric heater) for heating the reactants within the reactor pressure vessel. Each reactor pressure vessel may be associated with a heat exchanger (e.g., a heating jacket) for receiving combustion gases and transferring heat from the combustion gases to the reactants within the corresponding reactor pressure vessel.

[0041] The system may also include a dryer, such as a direct rotary kiln, for drying the separated solid components to a target moisture content, such as using a convection drying process.

[0042] The system may include a surface flare unit configured to receive syngas, for example from a syngas cleaning unit, and combust the syngas to produce combustion gas for heating the reactor pressure vessel and / or supplying to a dryer for drying separated solid components, for example during a startup procedure of the system.

[0043] The system may include an electrical generator combustion gas conduit configured to direct combustion gas from the gas generator to the reactor pressure vessel assembly for heating the reactor pressure vessel assembly, such as during steady-state operation of the system.

[0044] The system may include one or more burners for supplying hot combustion gases to heat the reactor pressure vessel components, such as during a startup procedure of the system.

[0045] In order to avoid unnecessary duplication of effort and repeated text in the specification, certain features are described only with respect to one or several aspects or embodiments of the present invention. However, it should be understood that, where technically possible, features described with respect to any aspect or embodiment of the present invention may also be used with any other aspect or embodiment of the present invention. For example, features described with respect to the first aspect mentioned may be combined with features of the second aspect mentioned. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] For a better understanding of the invention, and in order to more clearly show how the invention may be implemented, reference will now be made, by way of example, to the accompanying drawings, in which:

[0047] Figure 1 is a schematic diagram of a system arranged in accordance with the present invention for processing waste material comprising biosolids, such as human and / or animal digestive waste and / or waste of plant origin, which may or may not have been subjected to anaerobic and / or aerobic digestion;

[0048] Figure 2 is a flow chart depicting a method arranged in accordance with the present invention for processing waste material comprising biosolids, such as human and / or animal digestive waste and / or waste of plant origin, which may or may not have been subjected to anaerobic and / or aerobic digestion;

[0049] Figure 3 is a schematic diagram of another system arranged in accordance with the present invention for processing waste material comprising biosolids, such as human and / or animal digestive waste and / or waste of plant origin, which may or may not have been subjected to anaerobic and / or aerobic digestion; and

[0050] Figure 4 is a flow chart depicting another method arranged in accordance with the present invention for processing waste material comprising biosolids, such as human and / or animal digestive waste and / or waste of plant origin, which may or may not have been subjected to anaerobic and / or aerobic digestion. DETAILED DESCRIPTION

[0051] refer to Figure 1 , a system 2 for processing waste will now be described. The system can be used to process waste containing biomass and / or biosolids. For example, human and / or animal digestion waste and / or waste of plant origin, which may or may not have undergone anaerobic and / or aerobic digestion. As described above, biosolids can refer to primary sludge, and / or secondary sludge, and / or mixed sludge, and / or digested sludge, and / or activated sludge that have been thickened and / or dehydrated to a solid concentration of 5% to 40%. The system includes a reactor pressure vessel assembly 10, which includes one or more reactor pressure vessels 12, which may also be referred to as high-pressure reaction vessels in this specification. System 2 also includes a separation unit 20 and a gasification reactor assembly 30.

[0052] Reactor pressure vessel assembly 10 includes an input for receiving waste materials (e.g., biosolids and / or biomass). For example, primary sludge, and / or secondary sludge, and / or mixed sludge, and / or digested sludge, and / or activated sludge that has been thickened and / or dehydrated to a solid concentration of 5% to 40%, and metabolites of aerobic or anaerobic digestion of human, animal and / or plant waste. These sludges may also contain dead and live bacteria. The sludge provided at the input may be produced by a sludge thickening process, wherein the water concentration of the sludge has reached, for example, a solid reduced to about 5% to 40%. Therefore, the sludge input to reactor pressure vessel assembly 10 may contain about 10% to 20% solids (e.g., solids containing biomass) and about 80% to 90% liquid (e.g., water). In some arrangements, biosolids may contain flocculants or coagulants. The digested sludge input to reactor pressure vessel assembly 10 may be received in one or more of one or more reactor pressure vessels 12.

[0053] The reactor pressure vessel assembly 10 may be configured to heat and pressurize the sludge within the reactor pressure vessel 12 to perform a hydrothermal carbonization process.

[0054] When organic materials such as biosolids and biomass are exposed to the subcritical conditions of hydrothermal carbonization, they begin to hydrolyze, removing (cracking) oxygen-containing compounds, nitrogen-containing compounds, and phosphorus-containing compounds from the solid material. In addition, nitrogen-containing compounds are converted to ammonium and phosphorus-containing compounds are converted to phosphate ions under neutral and slightly alkaline pH conditions.

[0055] The purpose of the hydrothermal carbonization process can be one or more of the following: (i.) chemically dehydrating the organic solids in the feedstock to increase the carbon to oxygen and / or carbon to hydrogen ratio of the solid component of the sludge (hydrochar), (ii.) recovering nitrogen- and phosphorus-containing compounds by "cracking" them from the organic solids in the feedstock and dissolving them in the aqueous phase of the hydrochar slurry, (iii.) hydrolyzing microplastics, perfluoroalkyl substances and antibiotics into their respective harmless, soluble by-products, (iv.) killing bacteria / microorganisms present in the feedstock by exposure to high temperature and pressure, (v.) rupturing / cracking animal and plant cells present in the feedstock to allow the intracellular fluid to overflow into the hydrochar slurry, and / or (vi.) separating a portion of the water present in the hydrochar slurry by producing steam through pressure throttling.

[0056] In the hydrothermal carbonization process, the solids in the sludge (e.g., components containing biosolids and / or biomass) can be converted into carbon-containing molecules that are more suitable for use as reactants, such as suitable for pyrolysis and / or gasification in the process of pyrolysis and / or gasification, such as described below. More specifically, in order to carry out the hydrothermal carbonization process, the sludge can be heated to a reaction temperature greater than 160 degrees Celsius, greater than 170 degrees Celsius, or greater than 180 degrees Celsius, such as between 160 degrees Celsius and 260 degrees Celsius. For example, the sludge can be heated to about 200 degrees Celsius, and a reaction pressure greater than 0.6MPa, greater than 1.5MPa, or greater than or equal to 2MPa, such as between 0.6MPa and 4.7MPa or between 2MPa and 2.5MPa can be reached. The reactor pressure vessel can be heated at a rate of 2 degrees Celsius to 5 degrees Celsius per minute for 60 minutes to 90 minutes to reach the reaction temperature. The sludge can be kept at the reaction temperature and pressure for 30 minutes to 240 minutes, or 30 minutes to 60 minutes. In one example, the reactor pressure vessel can be kept at the reaction temperature for more than 3 hours, such as about 4 hours, or more than 4 hours.

[0057] The operating temperature of the high pressure reaction vessel can be selected based on the desired results. The results may be one or more of: (i.) higher hydrochar yield, (ii.) higher nutrient recovery, (iii.) specific partitioning of heavy metals between the solid phase and the aqueous phase, or any other desired results.

[0058] The reactor pressure vessel assembly 10 may include a plurality of reactor pressure vessels 12. Figure 1In the illustrated arrangement, the reactor pressure vessel assembly 10 includes four reactor pressure vessels 12. However, in other arrangements, the reactor pressure vessel assembly 10 may include any other number of reactor pressure vessels, such as between two and four pressure vessels. The reactor pressure vessel assembly 10 may be configured to carry out the hydrothermal carbonization process of the sludge in a series of batch operation modes similar to a continuous process. For example, the processing (e.g., heating and pressurization) of the sludge in each reactor pressure vessel may be staggered in a time period that is less than the total duration of the sludge being processed in the reactor pressure vessel. For example, the heating of the sludge in each pressure vessel may begin approximately 1 to 2 hours after the heating of the sludge in another pressure vessel begins.

[0059] During the system's startup procedure, each reactor pressure vessel 12 can be filled with input biosolids and / or biomass. However, it should be understood that due to the staggered startup of the processes in each reactor pressure vessel, the completion time of the processes in each reactor pressure vessel 12 will be staggered, and the filling of the reactor pressure vessels for future batches, for example, during steady-state operation of the system, can also be staggered, such as so that the reactor pressure vessels are filled sequentially.

[0060] The reactor pressure vessel assembly 10 may include one or more heaters 11 for heating the waste in the reactor pressure vessel, such as reactants of a hydrothermal carbonization process. For example, the reactor pressure vessel assembly 10 may include a heater 11 associated with each corresponding reactor pressure vessel 12. The heater may be an electric heater. During the startup procedure of the system 2, power may be supplied to the one or more heaters from a power source (e.g., a power grid) external to the system to heat the reactor pressure vessel 12 to the reaction temperature. However, as described below, during steady-state operation of the system 2, power may be generated within the system 2 to power one or more heaters 11.

[0061] At the reaction temperature and pressure, the dielectric constant of the water in the sludge can be reduced so that it is similar to the dielectric constant of nitrogen- and phosphorus-containing compounds that may be present in the input raw materials or hydrothermal carbon slurry, for example. For example, the reaction temperature and pressure of the reactants in the reactor pressure vessel can be configured to reduce the dielectric constant of the water in the reactor pressure vessel to less than 40 or less than 30, for example between 20 and 30 or between 20 and 25. This allows these ionic components to dissolve from the hydrothermal carbon solids and enter the aqueous phase. In addition, microplastics, perfluoro and polyfluoroalkyl substances, and antimicrobial resistance genes are hydrolyzed into their own harmless soluble components under the subcritical conditions of hydrothermal carbonization. Therefore, the solubility / miscibility of macronutrient substances (such as nitrogen and / or nitrogen-containing compounds) in water can be increased compared to atmospheric temperature and pressure. In addition, the hydrothermal carbonization process can cause nitrogen and / or nitrogen-containing components to be released from the solid components of the sludge. Thus, the conditions of the hydrothermal carbonization process can result in the dissolution of nitrogen and nitrogen-containing compounds (e.g. ammonium ions) in the sludge into the water, optionally after having been released from the solids. In addition, the removal of oxygen-containing compounds increases the C / O ratio (carbon: oxygen) and C / H ratio (carbon: hydrogen) of the hydrothermal carbon solids, significantly increasing the calorific value of the pyrolysis gas or synthesis gas, respectively, during pyrolysis or thermal gasification.

[0062] In some arrangements, during the hydrothermal carbonization process, reactive (e.g., nucleophilic) substances (e.g., organic acids and / or calcium oxide) may be added to the reactor pressure vessel to promote hydrolysis reactions, such as the release of ammonium ions. The released ammonium ions may then be dissolved in water.

[0063] In addition to promoting the dissolution of nitrogen and nitrogen-containing compounds in the water and optionally their release from the solids of the sludge, the carbonization reaction conditions can similarly cause other organic and / or inorganic substances (e.g., macronutrients, such as phosphorus, and phosphorus- and potassium-containing compounds) to be released from the solids and / or such substances to be dissolved in the water.

[0064] The reactor pressure vessel assembly 10 may include one or more expander vessels 14. The product from the hydrothermal carbonization process, such as a hydrothermal carbon slurry, may be output from the reactor pressure vessel 12 to one or more expander vessels 14 at a lower pressure than the reactor pressure vessel. The product of the hydrothermal carbonization process may contain between 10% and 20% solids. The hydrothermal carbon slurry may be discharged from the reactor pressure vessel into the expander vessel under gravity. For example, the pressure within the expander vessel may be approximately atmospheric pressure. The pressure reduction (e.g., a rapid reduction in pressure) of the hydrothermal carbonization product within one or more expander vessels may result in structural rupture of the solid component of the product, which in turn may release further amounts of nitrogen, phosphorus, potassium (and compounds containing nitrogen, phosphorus and potassium) and organic matter from the solid, such as into the liquid of the product. In addition, discharging the product of the hydrothermal carbonization process into the expansion vessel 14 may result in the rupture of any bacteria (e.g., pathogens and / or microorganisms) present in the product. Therefore, the product of the hydrothermal carbonization process within the expansion vessel may be sterile. Furthermore, discharging the product into the expansion vessel 14 may result in up to 20% of the water (by mass) in the hydrothermal carbon slurry being converted to steam, for example, essentially instantaneously.

[0065] exist Figure 1 In the illustrated arrangement, the reactor pressure vessel assembly 10 includes a single expansion vessel 14 that is configured to receive the hydrothermal carbonization product from each reactor pressure vessel 12. However, in other arrangements, any other number of expansion vessels 14 may be provided. For example, a plurality of expansion vessels 14 corresponding to the number of reactor pressure vessels 12 may be provided. In such an arrangement, the expansion vessel may be associated with one or more of the reactor pressure vessels 12 (e.g., the corresponding reactor pressure vessels), for example, and configured to receive the product from one or more of the reactor pressure vessels 12 (e.g., the corresponding reactor pressure vessels). In one or more arrangements, two expansion vessels 14 may be provided, for example, in total or for each reactor pressure vessel 12.

[0066] The system 2 may also include a gas heat exchanger / steam condenser 4. The gas heat exchanger / steam condenser 4 may be configured to receive a gas, such as steam, from the expansion vessel 14 and transfer heat from the gas to the waste material to be input to the reactor pressure vessel assembly 10. The system 2 may include one or more conduits 16 for conveying a gas, such as water vapor, from the expansion vessel 14 to the gas heat exchanger 4.

[0067] The separation unit 20 may be disposed downstream of the reactor pressure vessel assembly 10. The separation unit 20 may be arranged to receive the product of the hydrothermal carbonization process. For example, the separation unit 20 may be arranged to receive the product of the hydrothermal carbonization process from the reactor pressure vessel 12 or the expansion vessel 14 (if present). In some arrangements, the system 2 may include a slurry pump configured to transfer the hydrothermal carbon slurry from the expansion vessel 14 to a buffer / holding container (not shown) located upstream of the separation unit 20, from which the slurry may be fed to the separation unit. The buffer / holding container may be thermally insulated. The hydrothermal carbon slurry may then be fed from the buffer / holding container to the separation unit at a temperature of 20°C to 80°C.

[0068] After the products of the hydrothermal carbonization reaction have been output from the reactor pressure vessel 12 and / or expansion vessel 14, a brief sparge of high pressure municipal tap water may be provided into the vessels to wash away any remaining hydrothermal carbon solids and help minimize fouling of these vessels.

[0069] The separation unit 20 can be configured to separate at least a portion of the liquid present in the product of the hydrothermal carbonization process from the solid components. For example, the separation unit 20 can be configured to separate at least a portion of the water present in the product and any substances dissolved in the water. The separated solid components can be referred to as wet hydrothermal carbonization.

[0070] The separation unit 20 can be configured to separate the liquid from the solid component by a physical separation process (e.g., a physical dehydration process). For example, the separation unit 20 can include a filter press. Alternatively, the separation unit 20 can include any other device suitable for separating at least a portion of the liquid (e.g., water) present in the hydrothermal carbonization product from the solid component, such as a solid / liquid centrifuge. When the separation unit includes a filter press, the hydrothermal carbon slurry can be pumped to an absolute pressure of 4 to 17 bars. The filter press can be operated in batch feed or continuous mode. The output from the separation unit can contain 40% to 70% solids.

[0071] The system 2 may include a liquid heat exchanger 6. The liquid heat exchanger 6 may be configured to receive liquid separated by the separation unit and transfer heat from the liquid to waste to be input to the reactor pressure vessel assembly 10. The liquid heat exchanger 6 may be arranged upstream of the heat exchanger 4 relative to the flow of aqueous material through the heat exchanger 4 and the liquid heat exchanger 6. In some arrangements, the system 2 may include a buffer tank 7, which may be insulated. The buffer tank 7 may be configured to store the liquid separated by the separation unit 20 until it is needed to heat the waste input to the reactor pressure vessel, such as when the next batch of sludge is input to one or more reactor pressure vessels 12. The system 2 may also include a pump 8 for pumping liquid from the separator unit 20 and / or the buffer tank 7 to the liquid heat exchanger 6.

[0072] The system 2 may further include one or more liquid conduits 18 for conveying the liquid separated by the separation unit 20 to a liquid heat exchanger, for example, via a buffer tank 7 and / or a pump 8 .

[0073] As described above, one or more substances, such as macronutrient substances, such as nitrogen, potassium, phosphorus, nitrogen-containing compounds, potassium-containing compounds, phosphorus-containing compounds, and organic compounds (e.g., soluble organic compounds) may be dissolved or mixed with the liquid products of the hydrothermal carbonization process. As described below, such substances may not be desirable to include as reactants in the gasification process for producing synthesis gas. Therefore, by separating at least a portion of the liquid from the solid components of the hydrothermal carbonization product, the concentration of these substances in the solid phase product can be reduced.

[0074] The liquid separated from the product of the hydrothermal carbonization process can be stored for use by another method. For example, the stored liquid can be used in the process of producing fertilizer (for example, liquid fertilizer of rapid release nutrients), and / or can be fed to an anaerobic fermenter to produce biogas and / or reduce the carbon-containing oxygen demand of process water before being discharged to, for example, the environment. The separated liquid can also be further processed and / or mixed with the carbon residue (for example, high ash carbon residue) produced by the gasification reactor, for example, depending on the composition of the carbon residue produced. The liquid separated from the product of the hydrothermal carbonization process can be referred to as the process water rich in nutrients.

[0075] The gasification reactor assembly 30 includes a gasification reactor vessel 32, which is arranged to receive solid components separated from the products of the hydrothermal carbonization process and unseparated residual liquid. The gasification reactor assembly 30 is configured to perform a pyrolysis and / or gasification process (e.g., a thermal gasification process) on the solid components in the gasification reactor to, for example, produce synthesis gas and / or pyrolysis gas, respectively. In other words, the gasification and / or pyrolysis process can produce a mixture of synthesis gas and hydrocarbons (e.g., volatile hydrocarbons). The features described herein with reference to gasification may also be applicable to pyrolysis, and vice versa. Similarly, the features described herein with reference to synthesis gas may also be applicable to pyrolysis gas, and vice versa. The solid components separated from the products of the carbonization process and the remaining water can form reactants for the gasification process in the gasification reactor.

[0076] Hydrothermal char, preferably containing at least 90% solids (by mass), may be buffered and / or metered and / or continuously fed to the gasification reactor. During the gasification process, water present in the reactants may be superheated into steam and may react with carbonaceous matter within the solid components. More specifically, water may react with solid carbon to produce hydrogen and carbon monoxide in a water gas reaction, water may react with carbon monoxide to form hydrogen and carbon dioxide in a water gas shift reaction, and water may react with hydrocarbons to produce carbon monoxide and hydrogen in a steam reforming reaction. Other side reactions may also occur within the gasification reactor.

[0077] The gasification reactor assembly 30 may include an indirectly heated rotary kiln. Alternatively, the gasification reactor assembly may include a fixed bed gasifier. Still alternatively, the gasification reactor assembly may include any other suitable gasifier.

[0078] The gasification reactor assembly 30 may include one or more burners 34 configured to heat reactants, such as to produce superheated steam. The burner may be a dual / multiple fuel burner configured to operate using natural gas (e.g., methane and / or propane and / or liquefied petroleum gas (LPN) and / or liquefied natural gas (LNG)) and / or syngas (or a mixture of syngas and hydrocarbons, such as volatile hydrocarbons). The burners may be positioned equidistantly along the heated length of the reactor shell to provide the thermal energy required for the gasification reaction. Each burner may be independently controlled based on the temperature measured by one or more temperature sensors, such as corresponding temperature sensors, positioned in the gasification reactor assembly, such as a shield. The burner may be configured to maintain an independent temperature set point up to and including 1000°C. This may allow the heated length of the rotating reactor shell to have a desired temperature or a desired temperature distribution to obtain additional operational flexibility.

[0079] During the startup procedure of the system 2, natural gas and / or propane and / or LPN and / or LNG may be supplied from a source external to the system 2 (e.g., from a pipeline network) to be combusted by the burner of the gasification reactor assembly to heat the reactants. The natural gas may be supplied via the natural gas inlet 38. However, during steady-state operation of the system 2, the syngas produced by the gasification process may be supplied to the burner, as described below, and may be used to heat the reactants within the gasification reactor vessel.

[0080] The gasification reactor assembly 30 may include a combustion air inlet 36 for supplying oxygen or air (e.g., atmospheric pressure air) to one or more burners 34. A fan, such as a fixed speed fan, may be configured to provide the combustion air required for gasification reactor operation during startup and / or steady state. Nitrogen may be supplied by a nitrogen inlet 39 to selectively purge and seal at the feed and discharge ends of the reactor and auxiliary equipment. Nitrogen may be supplied to the system to reduce the risk of syngas being discharged to the environment and air entering the gasification system.

[0081] In addition to syngas, the product of the gasification process can be a high-ash carbon residue and / or biochar, which can be removed from the system 2 via the biochar outlet 33. Due to the nature of the gasification process, the biochar can be free of microplastics and / or per / polyfluoroalkyl substances and / or antibiotics. The carbon residue can contain metals, such as soft metals and heavy metals contained in the original feedstock. In some arrangements, the carbon residue can contain most of the metals present in the original feedstock. In some arrangements, the biochar can be mixed with a liquid separated from the product of the hydrothermal carbonization process.

[0082] The syngas output from the gasification reactor may contain acidic gases and / or entrained solids and / or tars and / or oils and / or oil aerosols. The system 2 may further include a syngas cleaning unit 40. The syngas cleaning unit 40 may be arranged downstream of the gasification reactor assembly 30, such as immediately downstream, relative to the flow of the syngas from the gasification reactor assembly to receive the syngas produced by the gasification reaction.

[0083] The syngas cleaning unit 40 can be configured to remove pollutants in the syngas produced by the gasification reactor assembly 30. In particular, the syngas cleaning unit can be configured to remove entrained solids (e.g., carbon solids), acid gases (e.g., hydrogen chloride, hydrogen sulfide), oils, and tars. The syngas cleaning unit 40 can include a cyclone separator, which is configured to recycle solids / fine particles entrained in the dirty syngas. The syngas cleaning unit 40 can additionally or alternatively include a dry scrubber and / or a water scrubber, such as a venturi quencher, a cyclone scrubber, a packed bed scrubber, and / or a wet wall scrubber, and the water scrubber can be configured to remove tar and / or oil, and neutralize the acid gases present in the dirty syngas. The cyclone separator and the water scrubber can be arranged in series. For example, a dry and / or water scrubber can be arranged downstream of the cyclone separator. The syngas cleaning unit can include a plurality of nozzles to increase the contact surface area between the syngas and the circulating water to improve the pollutant removal rate. Additionally or alternatively, the syngas cleaning unit may include any other device suitable for removing one or more pollutants in the syngas, such as baffles for promoting turbulent gas flow.

[0084] The synthesis gas leaving the water scrubber system can be saturated with water. The system can also include a condenser 46 for condensing water vapor in the synthesis gas produced by the gasification reactor assembly. As shown, the condenser 46 can be arranged downstream of the synthesis gas cleaning unit 40 relative to the flow of the synthesis gas. The water condensed from the synthesis gas by the condenser 46 can be combined with the pollutants removed from the synthesis gas by the synthesis gas cleaning unit 40. In some arrangements, the condenser can be provided as a part of the synthesis gas cleaning unit 40. For example, the condenser can be arranged in series with the water scrubber downstream of the water scrubber.

[0085] The water from the water scrubber system may contain unreacted corrosive solution and reactive salts from the neutralized acid gases. The water stream may be stored and treated before being discharged, for example, to a municipal sewage network via a wastewater outlet 35. Depending on the composition of the material, e.g., the average composition, the recovered solids / fines from the cyclone separator may be added to the high ash carbon residue from the gasification reactor and / or to the dry hydro-hot char input to the gasification reactor.

[0086] The system 2 may include a gas supply conduit 42 for supplying syngas and / or pyrolysis gas to the burner of the gasification reactor assembly. The gas supply conduit 42 may extend from a location downstream of the syngas cleaning unit 40 and optionally downstream of the condenser 46 relative to the flow of the syngas / pyrolysis gas to the burner 34. As described above, during steady-state operation of the system 2, the cleaned syngas and / or pyrolysis gas may be combusted by the burner 34 in the gasification reactor assembly 30 to heat the reactants for the gasification process. In this way, when the system 2 is operating in a steady state, the fuel for the burner may not need to be obtained from a source external to the system.

[0087] The system 2 may include a combustion gas recirculation conduit 38 configured to recirculate the combustion products of natural gas and / or syngas and / or pyrolysis gas at the combustor 34 to a combustion gas heat exchanger 19 disposed in the reactor pressure vessel assembly. The combustion gas heat exchanger 19 may be configured to transfer heat from the combustion gas to the reactor pressure vessel 12. After passing through the combustion gas heat exchanger, the combustion gas may be exhausted from the system.

[0088] The system 2 may also include a pollutant recirculation conduit 338 (at Figure 3 ), which is used to recycle at least a portion of the contaminants (e.g., tars and / or oils, such as organic or synthetically derived hydrocarbons optionally containing chains of 5 or more carbon molecules) that have been removed from the syngas in the syngas cleaning unit 40 to the gasification reactor vessel 32 as a reactant for the gasification process. Alternatively, the contaminants can be removed from the system.

[0089] The system 2 may also include an electric generator 50. The electric generator may be configured to receive the syngas generated by the gasification reactor assembly 30, for example after being cleaned by the syngas cleaning unit 40 and optionally after passing through the condenser 46, and combust the syngas to generate electricity. The electric generator may be any suitable generator. For example, the electric generator may include a gas turbine for combusting the syngas to drive the generator.

[0090] In some arrangements, the electric generator 50 can be electrically connected to the reactor pressure vessel assembly 10, for example, to the heater 11 of the reactor pressure vessel assembly 10. During steady-state operation of the system, the electricity from the electric generator 50 can be used to heat the reactants in the reactor pressure vessel 12 to perform the hydrothermal carbonization process of the waste. In some arrangements, the electricity generated by the gas generator can be used to power other electrical equipment in the plant where the system 2 is provided.

[0091] In some arrangements, the electricity generated by the power generator 50 by consuming (e.g., burning) the syngas produced by the gasification reactor assembly can be greater than the electricity required to heat the reactor pressure vessel 12 for the hydrothermal carbonization process of the waste. In such an arrangement, the electricity can be supplied to an electrical system external to the system 2, such as a power grid or an electrical energy storage system, such as a battery system. Therefore, the system 2 can include a power terminal 52 for electrically connecting the power generator 50 to the external power system.

[0092] As described above, during steady-state operation of the system, the energy input requirements of the hydrothermal carbonization process and the gasification process can be met by burning the syngas and / or pyrolysis gas (or a mixture of syngas and hydrocarbons, such as volatile hydrocarbons) produced by the system. Thus, the system 2 may not require energy from an external source to continue operating in the steady phase, and may output energy as excess syngas and / or pyrolysis gas and / or as electricity via terminal 52 during steady-state operation.

[0093] refer to Figure 2 , a method 200 for processing waste material will now be described. The method may be performed using the system 2 described above. One or more steps of the method 200 may be performed sequentially, such as during a startup process of the system 2. Alternatively, during steady-state operation of the method 200, the steps of the method 300 may be performed substantially simultaneously and continuously (e.g., in a continuous series of batches).

[0094] The method includes a first step 202 in which an input of waste material is received into a reactor pressure vessel, such as the reactor pressure vessel assembly 10. The waste material includes biosolids and / or biomass (e.g., compliant and / or non-compliant biosolids) and water. For example, the waste material may include primary sludge, and / or secondary sludge, and / or mixed sludge, and / or digested sludge, and / or activated sludge that has been thickened and / or dewatered to a solids concentration of 5% to 40%. The waste material may contain 10% to 20% solids.

[0095] The method also includes a second step 204, in which a reactor pressure vessel is heated to carry out a hydrothermal carbonization process, such as a hydrothermal carbonization process of biosolids and / or biomass. In particular, the reactor pressure vessel can be heated to a reaction temperature greater than 160 degrees Celsius, such as between 160 degrees Celsius and 260 degrees Celsius, or greater than 170 degrees Celsius or greater than 180 degrees Celsius, such as approximately 200 degrees Celsius, and a reaction pressure greater than 1.5MPa, or greater than or equal to 2MPa, such as between 2MPa and 2.5MPa can be reached. The reactor pressure vessel can be heated at a rate of 2 degrees Celsius to 5 degrees Celsius per minute for 60 minutes to 90 minutes to reach the reaction temperature. Waste material can be kept at reaction temperature and pressure for 30 minutes to 240 minutes, longer than 3 hours, such as about 4 hours, or longer than 4 hours or 30 minutes to 60 minutes.

[0096] The hydrothermal carbonization process may be conducted as a continuous series of batch operations using a plurality of reactor pressure vessels configured to sequentially receive the waste material.

[0097] The hydrothermal carbonization product may contain 10% solids or more, such as 10% to 20% solids. In a first example, the hydrothermal carbonization product exits the reactor pressure vessel assembly at a temperature of about 100 degrees Celsius or more.

[0098] The method 200 may further include, before the step of separating the liquid from the solid components, discharging the product of the hydrothermal carbonization process, for example from the reactor pressure vessel, to one or more expansion vessels, such as the above-mentioned expansion vessel 14. The pressure of the product of the hydrothermal carbonization process in the expansion vessel may be lower than the pressure in the reactor pressure vessel.

[0099] The method also includes a third step 206 in which liquid (eg, water and substances dissolved in the water) is separated from a solid component (hydrochar) produced by the hydrothermal carbonization process.

[0100] The method further comprises a fourth step 208 in which the separated solid components are subjected to a gasification process, such as a thermal gasification process such as pyrolysis, to produce synthesis gas.

[0101] The method 200 may further include circulating gas (e.g., water vapor) in the expansion vessel through a gas heat exchanger (e.g., gas heat exchanger 4) configured to transfer heat from the expansion vessel gas to the input waste material, e.g., before the waste material is received in the reactor pressure vessel.

[0102] The method 200 may further include circulating the separated liquid, e.g., from the third step, through a liquid heat exchanger, e.g., liquid heat exchanger 6, configured to transfer heat from the separated liquid to the input waste, e.g., before the waste is received in the reactor pressure vessel. The gas heat exchanger may be disposed downstream of the liquid heat exchanger relative to the passage of the input waste to the reactor pressure vessel assembly.

[0103] The input waste may be at ambient temperature prior to passing through the gas heat exchanger and the liquid heat exchanger, and may be at a temperature of up to 80 degrees Celsius when entering the high pressure reactor vessel.

[0104] The method 200 may also include burning the syngas produced by the gasification process in a gas-powered electric generator (e.g., electric generator 50) to generate electricity. The electricity generated by the electric generator may be used to power a heater for the reactor pressure vessel, such as during steady-state operation of the method. The method may also include providing electricity from a source separate from the electric generator to heat the reactor pressure vessel during a startup procedure.

[0105] The method may also include providing a combustible gas (e.g., natural gas and / or propane and / or LPN and / or LNG) as an input to the gasification process from a source separate from the gasification reactor during a startup procedure of the method for processing waste. The combustible gas may be combusted, for example, at the burner 54 of the gasification reactor assembly 30 to heat the reactants of the gasification process during a startup procedure of the method for processing waste.

[0106] The method may also include delivering a portion of the generated syngas and / or pyrolysis gas as an input to the gasification process. A portion of the generated syngas may be combusted, for example, by a burner 34 of a gasification reactor assembly to heat the reactants of the gasification process. During steady-state operation of the method, for example, once the syngas is available for combustion to heat the reactants, the combustible gas may no longer be provided as an input to the gasification process.

[0107] The method 200 may further include recirculating combustion gases generated from combusting reactants used to heat the gasification process at the combustor to heat input waste material upstream of and / or within the reactor pressure vessel of the reactor pressure assembly.

[0108] During steady-state operation of the process, the waste within the reactor pressure vessel may be heated using any combination of: a gas heat exchanger / steam condenser, a liquid heat exchanger, recirculated combustion gases from combustion at the burner and / or combustion gases from a gas generator used to heat reactants during gasification (e.g., such as, for example, respectively, circulating through one or more jackets disposed around the reactor pressure vessel), and / or using a heater (e.g., an electric heater 11) disposed in the reactor pressure vessel assembly. As described above, the heater 11 may be powered using electricity generated by the electric generator 50.

[0109] However, during the start-up procedure of the process, heat may be supplied to the reactor pressure vessel using only the heater of the reactor pressure vessel assembly.

[0110] The method may further include cleaning the syngas produced by the gasification process to remove pollutants in the syngas and / or pyrolysis gas. As part of the method for processing waste, the syngas may be cleaned before being used for other purposes. In particular, the syngas may be cleaned before being burned by a gasifier to generate electricity and / or supplied to a burner of a gasification reactor assembly. The syngas may be cleaned using the syngas cleaning unit described above. The method may further include recycling at least a portion of the pollutants removed from the syngas as an input to the gasification process.

[0111] Additionally or alternatively, the method may include passing the syngas and / or pyrolysis gas through a condenser to remove water vapour from the syngas, for example before the syngas is used for other purposes as part of the method.The syngas may be passed through a condenser after removal of contaminants.

[0112] refer to Figure 3 , a system 300 for processing waste materials according to another arrangement of the present disclosure will now be described. The system 300 may be similar to the one described above with reference to Figure 1 The system 2 described above may include system 2. The features described above with respect to system 2 may be equally applicable to system 300, and vice versa. Specifically, the features described below with respect to system 300 may be provided as part of system 2. System 300 may be used to process waste containing biomass and / or biosolids. For example, human and / or animal digestion waste and / or waste of plant origin, which may or may not have undergone anaerobic and / or aerobic digestion. System 300 includes a reactor pressure vessel assembly 10, which includes one or more reactor pressure vessels 12 and one or more expansion vessels. System 300 also includes a separation unit 20 and a gasification reactor assembly 30. In addition, system 300 may also include a syngas cleaning unit 40 and / or an electric generator 50.

[0113] System 300 differs from system 2 in that the reactor pressure vessel assembly includes a jacket 302 disposed around the reactor pressure vessel 12 for circulating combustion gas around the reactor pressure vessel to heat the reactants within the reactor pressure vessel. The system may include one or more first natural gas / propane burners 372 configured to burn natural gas and / or propane and / or LPN and / or LNG and produce hot combustion gas for circulation through the jacket. During startup of system 300, the first natural gas / propane burner 372 may be operated to heat the reactor pressure vessel. In this case, further heaters, such as those described above with reference to Figure 1 An electric heater is described.

[0114] The jacket 302 may be configured to receive combustion gases from the gasification reactor 32 and / or the power generator 50. During steady-state operation of the system 300, the reactor pressure vessel may be heated, for example, solely by the heat of the combustion gases from the gasification reactor and / or the power generator 50. As shown, the system 300 may include a power generator combustion gas conduit 376 for conveying combustion gases from the power generator 50 to the jacket 302. In such an arrangement, the first natural gas / propane burner 372 may not be operated during steady-state operation of the system 300.

[0115] The or each reactor pressure vessel 12 may be rotated, for example about an axis having a vertical component (e.g. a vertical axis), using an electric or hydraulic motor. This may ensure that the hot combustion gases are evenly distributed over the surface area of ​​each vessel. The or each reactor pressure vessel may contain internal baffles to help mix / disturb the feedstock when rotating to promote uniform heat transfer and limit fouling.

[0116] The system 300 also includes a feedstock preparation unit 310. Waste input to the system 300 may be received at the feedstock preparation unit before being fed into the reactor pressure vessel 12. The feedstock preparation unit 310 may include one or more feedstock storage tanks 312. Figure 3 In the arrangement shown, the feedstock preparation unit 310 includes two feedstock holding units.

[0117] The feedstock preparation unit is configured to ensure that the feedstock is fed to the reactor pressure vessel at or within a desired input range of solids concentration and / or temperature.

[0118] Feedstock (including biosolids), such as from a conventional wastewater treatment plant, can be received at the feedstock preparation unit via a first waste input 314. The feedstock can be received in a first feedstock storage tank 312a of the feedstock preparation unit. The feedstock received via the first waste input 314 can have a solids concentration between 5% and 40%. The desired input range of feedstock solids concentration for the reactor pressure vessel can be between 10% and 20%. Diluted wastewater (treated or untreated), such as wastewater from a wastewater treatment plant, can be received at the feedstock preparation unit 310 via a second waste input 316. The feedstock preparation unit can be configured to mix the dilute wastewater received by the second waste input 316 with the feedstock received via the first waste input 314.

[0119] The system 300 may also include an organic waste input 315 for organic waste, such as organic waste including one or more of a high concentration of cellulose, lignocellulose, and / or lignin compounds. For example, the organic waste may include chicken manure, olive pomace, wheat husks, chopped biomass, etc. The co-processed waste biomass may contain a solid concentration of 1% to 100%. The remainder may be primarily water. The organic waste may be provided as an input to a feedstock preparation unit along with waste material and optional dilution wastewater. Thus, the organic waste may be provided as an input to a reactor pressure vessel, for example, along with waste material and wastewater.

[0120] During the hydrothermal carbonization process, the presence of organic waste in the feedstock can improve the fixation of soft and heavy metals present in the biosolids with the solid carbon present in the organic waste. Additionally or alternatively, the heavy metals and solid carbon can be forged together under the high temperature conditions in the gasification reactor to form a non-leachable mineral matrix, i.e., a high ash carbon residue, which can improve the adsorption of compounds in nutrient-rich process waters, as described below.

[0121] The raw material slurry in the first raw material storage tank 312a can be pumped through the liquid heat exchanger 6, for example, to receive heat from the nutrient-rich process water. The heat from the nutrient-rich process water can be received at a temperature of 20°C to 80°C. The raw material slurry in the first raw material storage tank 312a can be pumped to the second raw material storage tank 312b through the liquid heat exchanger. The raw material slurry in the second raw material storage tank can be pumped through the gas heat exchanger 4, for example, to receive the latent heat of the gas (e.g., steam) from the expansion vessel 14. The raw material slurry pumped through the gas heat exchanger can be returned to the second raw material storage tank before being supplied to the reactor pressure vessel. The desired input temperature range of the waste to be fed to the reactor pressure vessel, for example for a hydrothermal carbonization process, can be between 15°C and 100°C.

[0122] In the gas heat exchanger 4, the steam may be condensed into potable water, which may be output from the system via the potable water output 318. The nutrient-rich process water that has passed through the liquid heat exchanger 4 may be transferred to a product mixing / adsorption unit 360 (described in more detail below) and / or output as a nutrient-rich process water output 322. The nutrient-rich process water may be used as a quick-release nutrient liquid fertilizer product, or fed to an anaerobic digester for biogas production and reduction of carbonaceous oxygen demand before discharging the "cleaned" water to the environment.

[0123] The system 300 may further include a dryer unit 330 configured to remove entrained moisture from the wet hydrochar using, for example, a convection drying method to produce dry hydrochar having a predetermined moisture content. The wet hydrochar output from the separation unit 14 may be fed to the dryer unit via a screw conveyor.

[0124] The dryer unit 330 may include a direct rotary dryer. Hot combustion gases from the jacket 302 of the high pressure reactor vessel, for example, which have been circulated through the jacket, may be transferred to the dryer unit 330 via a combustion gas dryer conduit 332. The combustion gases may pass through the dryer unit in a co-current or counter-current direction with the wet hydrochar feed. The dryer unit may include an internal riser configured to lift the hydrochar solids within the dryer to mix the solids with the hot combustion gases. The hydrochar may be dried to a solids concentration of at least 90% solids and output from the dryer unit to a gasifier. The wet combustion gases may leave the dryer unit via a wet combustion gas conduit 334 carrying entrained steam.

[0125] The system 300 may also include a dryer exhaust gas cleaning unit 340. The dryer exhaust gas cleaning unit may receive wet combustion gas from the dryer unit via conduit 334. The wet combustion gas may be received by the dryer exhaust gas cleaning unit at a temperature above its dew point temperature to avoid condensation. The dryer exhaust gas cleaning unit may be configured to remove and recover solid hydrochar entrained in the wet combustion gas that has been used to dry the wet hydrochar. The dryer exhaust gas cleaning unit may include a cyclone separator or a bag filter for removing the solid hydrochar. The wet combustion gas may then be output from the system 300 via a wet combustion gas outlet 342.

[0126] The system 300 may also include a shredded (crushed) non-biodegradable waste input 336. The crushed non-biodegradable waste may also be referred to as "shredded screenings". For example, if available from a wastewater treatment plant, the shredded screenings feedstock may be fed to the gasification reactor 30. The shredded screenings may include any combination of inorganic (non-metallic) waste materials including plastics (PP, HDPE, LDPE, PVC, PS, PET, and other plastics), synthetic rubbers (household cleaning gloves, "medical grade" gloves, other rubbers), and / or various synthetic household waste materials (wet wipes, sanitary materials, cleaning materials, etc.). The shredded screenings may be added to the dry hydrochar and mixed thoroughly to evenly distribute the shredded material in the hydrochar prior to feeding to the gasification reactor.

[0127] Additionally or alternatively, as described above, the tar and / or oil collected by the syngas cleaner 40 can be recycled to the gasification reactor as an optional feedstock and carbon recovery method. For example, in addition to or as an alternative to the shredded screenings, the tar and / or oil can be added to the dry hydrochar and mixed (e.g., thoroughly mixed) to evenly distribute the material in the hydrochar before feeding to the gasification reactor. The tar and / or oil can be fed to the gasification reactor via the contaminant recycle conduit 338.

[0128] The system 300 may further include a gasification feed mixing unit 335 configured to mix (e.g., uniformly mix) the hydrothermal char and / or the tar and / or oil collected from the syngas cleaner and / or the shredded screenings. For example, the gasification feed mixing unit 335 may include a high shear mixing screw located in a mixing tank.

[0129] The system 300 may also include a surface flare unit 350. During startup and shutdown of the system 300, the syngas produced by the gasification process may not meet specifications and be incompatible with operating the power generator 50. In addition, during startup, hot combustion gases may be required for heating the high pressure reactor vessel and for drying the wet hydrochar. The surface flare unit 350 may be configured to receive syngas from the cleaning unit, for example, during startup and / or shutdown of the system, and react the syngas with oxygen to produce hot combustion gases, which may be directed to the high pressure reactor vessel, such as the jacket 302, via a surface flare combustion gas conduit 378.

[0130] During steady-state operation of the system, the syngas (e.g., all of the syngas) from the cleaning unit 40 can be delivered to the power generator 50, and the surface flare unit 350 can be maintained in standby mode with a pilot flame. Waste heat in the form of hot combustion gases from the gasification reactor and the power generator can then be used to operate the hydrothermal carbonization and convection drying steps. However, when, for example, the ambient temperature is very low and heat is lost to the environment from the interconnecting piping system, the hot combustion gases transferred to the hydrothermal carbonization and convection drying steps can be supplemented with hot combustion gases from the surface flare unit 350, if necessary.

[0131] System 300 may further include a hydrogen separation unit 380. The hydrogen separation unit may be configured to receive the clean syngas from the cleaning unit 40 and to separate and concentrate the hydrogen present in the clean syngas. In particular, the hydrogen separation unit may be configured to use pressure swing adsorption and / or membrane technology to separate and concentrate hydrogen. The composition and water content of the dry hydrothermal char feedstock delivered to the gasifier may affect the hydrogen concentration in the syngas. In an arrangement where hydrogen is a desired product from system 300, the hydrogen separation unit may be operated to separate and purify hydrogen from the remaining volatile organic compounds of the clean syngas. The remaining syngas after separation of hydrogen may be rich in carbon monoxide, volatile hydrocarbons and volatile organic compounds, and may have a high calorific value. The remaining syngas may be provided to a ground flare unit 350 and / or an electric generator 50.

[0132] The system 300 may also include a mixing / adsorption tank 360. The mixing / adsorption tank may be configured to receive the nutrient-rich process water that has passed through the liquid heat exchanger 4 and at least a portion of the solid product output from the gasification reactor. Mixing these two streams may produce a slow nutrient release solid fertilizer product for the agricultural market, which is output from the cleaning / mixing tank via a slow nutrient release solid fertilizer outlet 362.

[0133] In addition, the high surface area of ​​the carbon residue can be used to capture and store phosphate ions and ammonium ions contained in the nutrient-rich process water, releasing these nutrients into the soil at a slower rate than liquid fertilizers. As described above, the inclusion of organic / biomass waste in the feedstock of the hydrothermal carbonization process can result in the production of a carbon residue with improved adsorption properties. In particular, the high surface area of ​​the mesopores present in the high-ash carbon residue improves the retention of ammonium ions present in the nutrient-rich carbon residue during the adsorption step. This may limit the loss of these nutrients and potential contamination of shallow groundwater aquifers. Before the "cleaned" water is discharged to the environment, for example, via water outlet 364, the remaining filtered process water can be anaerobically digested for the production of biogas and the reduction of carbonaceous oxygen demand.

[0134] The system 300 may also include a second natural gas / propane burner 374. During the startup procedure of the system 300, the second natural gas / propane burner may be configured to burn natural gas and / or propane and deliver the hot combustion gases to the dryer unit 330 to dry the wet hydrochar in the dryer unit. During steady-state operation and / or when there is sufficient thermal energy in the hot combustion gases output from the jacket 302 surrounding the high-pressure reaction vessel 12 to the dryer unit to dry the hydrochar to a desired solid percentage (e.g., by mass), the second natural gas / propane burner 374 may be shut down to no longer burn natural gas and / or propane.

[0135] refer to Figure 4 , a method 400 for processing waste material will now be described. The method may be performed using the system 300 described above. The method 400 may be similar to the method 200 described above, and may include the method 200. Features described with respect to the method 200 may equally apply to the method 400, and vice versa. One or more steps of the method 400 may be performed sequentially, such as during a startup process of the system 2. Alternatively, during steady-state operation of the method 400, the steps of the method 400 may be performed substantially simultaneously and continuously (e.g., in a continuous series of batches).

[0136] The method includes a first step 402 in which an input of waste material is received into a reactor pressure vessel, such as the reactor pressure vessel assembly 10. The waste material includes biosolids and / or biomass and water. For example, the waste material may include primary sludge, and / or secondary sludge, and / or mixed sludge, and / or digested sludge, and / or activated sludge that has been thickened and / or dewatered to a solids concentration of 5% to 40%.

[0137] The method also includes a second step 404, wherein the reactor pressure vessel is heated to perform a hydrothermal carbonization process, such as a hydrothermal carbonization process of biomass.

[0138] The method 400 may include an expansion step 405, wherein the product of the hydrothermal carbonization process is discharged into an expansion vessel (e.g., expansion vessel 14) at a pressure lower than the pressure within the reactor pressure vessel in which the hydrothermal carbonization process is performed (e.g., at atmospheric pressure). As described above, a pressure reduction, such as a rapid pressure reduction, of the hydrothermal carbonization product within one or more expander vessels may result in a structural rupture of the solid component of the product, which in turn may release further amounts of nitrogen, phosphorus, potassium (and compounds containing nitrogen, phosphorus, and potassium) and organic matter from the solid, such as into a liquid phase and / or a gas phase of the product. In addition, discharging the product of the hydrothermal carbonization process into the expansion vessel 14 may result in the rupture of any bacteria (e.g., pathogens) present in the product. Thus, the product of the hydrothermal carbonization process within the expansion vessel may be sterile. In addition, discharging the product into the expansion vessel 14 may result in up to 20% of the water (by mass) in the hydrothermal carbon slurry being converted to steam, such as substantially instantaneously. The expansion step 405 may include removing steam released from the product.

[0139] The method further comprises a third step 406 in which the liquid (eg, water and substances dissolved in the water) is separated from the solid components (hydrochar) produced by the hydrothermal carbonization process, for example by a separation unit (eg, separation unit 14 described above).

[0140] The method also includes a drying step 408, wherein the separated solids are dried, such as using a drying unit 330, so that the percentage of solids (by mass) is a desired percentage for input to the gasification process. The separated solids can be dried using a convection drying process, such as circulating hot combustion gases through a dryer unit.

[0141] The method further comprises a fourth step 410, wherein the separated solid components are subjected to a gasification process, such as a thermal gasification process such as pyrolysis, to produce syngas.

[0142] The method may also include a fifth step 412, in which the syngas produced by the gasification process is cleaned, for example using a syngas cleaning unit 40, so that the syngas is suitable for use in an electrical generator, such as the electrical generator 50. For example, in the fifth step, the dirty syngas may be passed through a cyclone separator or other device to remove entrained solids from the syngas and / or through a water scrubber or dry scrubber to remove acid gases, oils, and / or tars from the syngas. In the fifth step 412, the syngas (e.g., syngas that has passed through a water scrubber) may be passed through a condenser to remove moisture from the syngas.

[0143] The method 400 may also include a sixth step in which the cleaned syngas is used (eg, combusted) to generate electricity, such as via an electrical generator 50 .

[0144] Those skilled in the art will appreciate that while the invention has been described by way of example with reference to one or more exemplary examples, the invention is not limited to the disclosed examples and that alternative examples may be constructed without departing from the scope of the invention as defined by the appended claims.

Claims

1. A method for processing waste material, wherein the waste material comprises human and / or animal digestive waste and / or waste of plant origin, wherein the method comprises: receiving waste material input into a reactor pressure vessel; heating and pressurizing the reactor pressure vessel to perform a hydrothermal carbonization process on the waste material; separating at least a portion of the liquid from a solid component of a product produced by the hydrothermal carbonization process; The solid components are subjected to a gasification and / or pyrolysis process to generate synthesis gas and / or pyrolysis gas.

2. A method according to claim 1, wherein the waste comprises primary sludge, and / or secondary sludge, and / or mixed sludge, and / or digested sludge, and / or activated sludge which has been thickened and / or dewatered to a solids concentration of 5% to 40%, for example resulting from anaerobic and / or aerobic digestion of human and / or animal digested waste and / or waste of plant origin.

3. The method according to claim 1 or 2, wherein the reactor pressure vessel is heated to a reaction temperature greater than 160 degrees Celsius, such as 200 degrees Celsius, to carry out the hydrothermal carbonization process.

4. The process of claim 3, wherein the reactor vessel is maintained at the reaction temperature for 30 minutes to 240 minutes, such as about 4 hours, or 30 minutes to 60 minutes.

5. The process according to any one of the preceding claims, wherein the reaction temperature and pressure of the reactants within the reactor pressure vessel are maintained to achieve subcritical conditions of the water within the reactor pressure vessel.

6. The method of claim 5, wherein the reaction temperature and pressure of the reactants within the reactor pressure vessel are configured to reduce the dielectric constant of water within the reactor pressure vessel to less than 40, such as between 20 and 30, such as between 20 and 25.

7. The method according to any one of the preceding claims, wherein the hydrothermal carbonization process is carried out as a continuous series of batch operations, using a plurality of the reactor pressure vessels, the plurality of the reactor pressure vessels being configured to sequentially receive the waste material and to carry out the hydrothermal carbonization process in staggered time periods, the staggered time periods being less than the total duration of the hydrothermal carbonization process.

8. The method according to any one of the preceding claims, wherein the method further comprises: Prior to the step of separating the liquid from the solid components, the product of the hydrothermal carbonization process is discharged into an expansion vessel at a pressure lower than that of the reactor pressure vessel.

9. The method according to claim 8, wherein the method comprises: Gas from the expansion vessel is circulated through a gas heat exchanger configured to transfer heat from the gas of the expansion vessel to input waste material before the waste material is received in the reactor pressure vessel.

10. The method according to the preceding claim, wherein the method comprises: The separated liquid is circulated through a liquid heat exchanger configured to transfer heat from the separated liquid to an input waste material before the waste material is received in the reactor pressure vessel.

11. The method according to claims 9 and 10, wherein the gas heat exchanger is arranged downstream of the liquid heat exchanger with respect to the passage of the waste material input to the reactor pressure vessel.

12. A method according to any one of the preceding claims, wherein the liquid is separated from the solid components by a physical separation process.

13. The method according to any one of the preceding claims, wherein the liquid is separated from the solid components using a filter press.

14. The method of claim 12 or 13, wherein the method comprises drying the separated solid components to a target moisture content using a convection drying process.

15. The method according to any one of the preceding claims, wherein the method further comprises combusting the syngas and / or pyrolysis gas produced by the gasification and / or pyrolysis process in a gasifier to generate electricity.

16. The method according to claim 14 or 15, wherein drying the separated solid components comprises feeding combustion gas, for example from the gas generator and / or burner, over the separated solid components, for example in a direct rotary dryer.

17. A method according to claim 15 or 16, wherein the electricity generated by the gas generator is used to power a heater of the reactor pressure vessel, for example during steady state operation of the method.

18. A method according to any one of claims 15 to 17, wherein the method comprises providing electrical power from a source separate from the gas generator to heat the reactor pressure vessel during a start-up procedure.

19. The method according to any one of the preceding claims, wherein the method comprises circulating combustion gases, for example from a gas generator or a burner, around the reactor pressure vessel to heat the reactor pressure vessel and perform the hydrothermal carbonisation process.

20. A method according to claims 19 and 16, wherein the combustion gas supplied over the separated solids is a combustion gas which has been circulated around the reactor pressure vessel.

21. The method according to any one of the preceding claims, wherein the method further comprises: A portion of the generated syngas is delivered as an input to the gasification process, wherein a portion of the generated syngas is combusted to heat reactants of the gasification process.

22. The method according to any one of the preceding claims, wherein the method further comprises: During the startup procedure of the method for processing waste, a combustible gas, such as natural gas, is provided as an input to the gasification process from a source separate from the gasification reactor, wherein during the startup procedure of the method for processing waste, the combustible gas is burned to heat the reactants of the gasification process.

23. A method according to claims 21 and 22, wherein once the syngas is available for combustion to heat the reactants, the combustible gas is no longer provided as an input to the gasification process.

24. The method according to any one of claims 20 to 23, wherein the method further comprises: The combustion gases generated by the combustion of reactants used to heat the gasification process are circulated to heat input waste upstream and / or within the reactor pressure vessel.

25. The method according to any one of the preceding claims, wherein the method further comprises: The syngas produced by the gasification process is cleaned to remove contaminants in the syngas before the syngas is used for other purposes as part of the method of processing waste.

26. The method according to claim 25, wherein the method further comprises: At least a portion of the pollutants removed from the syngas are recycled as input to the gasification process.

27. A method according to any preceding claim, wherein the method further comprises providing an input of further comminuted, optionally non-biodegradable waste to the gasification process.

28. A system for processing waste material, wherein the waste material comprises human and / or animal digestive waste and / or waste of plant origin, wherein the system comprises: a reactor pressure vessel assembly comprising one or more reactor pressure vessels for receiving an input of said waste material and heating and pressurizing said waste material within the vessel to perform a hydrothermal carbonization process on said waste material; a separation unit for separating liquid from solid components produced by the hydrothermal carbonization process; A gasification reactor vessel is used to receive the solid components and perform a gasification and / or pyrolysis process on the separated solids in the gasification reactor vessel to generate synthesis gas and / or pyrolysis gas.

29. The system of claim 28, wherein the reactor pressure vessel assembly further comprises one or more expansion vessels for receiving the hydrothermal carbonization process product from the one or more reactor pressure vessels at a lower pressure than the reactor pressure vessel.

30. The system of claim 29, wherein the system further comprises: A gas heat exchanger / steam condenser is configured to receive gas, such as steam, from the one or more expansion vessels and transfer heat from the gas to the input waste material.

31. The system of any one of claims 28 to 30, wherein the system further comprises: A liquid heat exchanger is configured to receive the liquid separated by the separation unit and transfer heat from the liquid to an input waste material.

32. The system of claims 30 and 31, wherein the gas heat exchanger is disposed downstream of the liquid heat exchanger relative to the passage of the waste material input to the reactor pressure vessel assembly.

33. The system of any one of claims 28 to 32, wherein the system further comprises: A gas generator for generating electricity using the synthesis gas generated by the gasification reactor.

34. The system of claim 33, wherein the reactor pressure vessel assembly comprises one or more electric heaters for heating reactants within the reactor pressure vessel, wherein the electric heaters are electrically connected to the gas generator.

35. The system of any one of claims 28 to 34, wherein the system further comprises a syngas cleaning unit for removing contaminants from the syngas produced in the gasification reactor vessel.

36. The system of claims 34 and 35, wherein the syngas cleaning unit is disposed between the gasification reactor vessel and the gas generator relative to the flow of the syngas.

37. The system of claim 35 or 36, wherein the syngas cleaning unit comprises a wet wall scrubber.

38. The system of any one of claims 35 to 37, wherein the system further comprises a pollutant recycle conduit for recycling pollutants removed from the syngas to the gasification reactor.

39. The system of any one of claims 28 to 38, wherein the gasification reactor comprises one or more burners for burning gas to heat reactants in the gasification process; wherein the system comprises a syngas supply pipeline for supplying syngas output by the gasification reactor to the one or more burners.

40. The system of any one of claims 28 to 39, wherein the reactor pressure vessel assembly comprises a plurality of reactor pressure vessels and one or more expansion vessels, wherein the reactor pressure vessels are configured to store reactants and products at a higher pressure than the expansion vessels, and wherein the expansion vessels are configured to receive reaction products within corresponding ones of the reactor pressure vessels.

41. The system of claim 40, wherein the reactor pressure vessel assembly is configured to operate in a continuous series of batch procedures, wherein reactants are sequentially input into the plurality of reactor pressure vessels, reaction products within the reactor pressure vessels are sequentially output to the expansion vessel, and the hydrothermal carbonization process is performed within sequential reactor pressure vessels in staggered time periods.

42. The system of claim 41, wherein the reactor pressure vessel assembly further comprises one or more conduits for directing gas from the expansion vessel to one or more heat exchangers for heating reactants input to the corresponding reactor pressure vessel.

43. The system of claim 42, wherein the conduit is arranged so that gas from the expansion vessel is directed to the heat exchanger, which is configured to heat reactants within the next reactor pressure vessel to receive reactants in a continuous series of batch procedures.

44. The system of any one of claims 28 to 43, wherein the system comprises a combustion gas conduit for directing the combustion gas from the gasification reactor to the reactor pressure vessel assembly and one or more combustion gas heat exchangers for transferring heat from the combustion gas to the waste material input to the reactor pressure vessel assembly.

45. The system of any one of claims 28 to 44, wherein the system further comprises a dryer, such as a direct rotary kiln, for drying the separated solid components to a target moisture content using a convection drying process.

46. ​​A system according to claim 33 or any one of claims 34 to 45 as dependent upon claim 33, wherein the system includes an electric generator combustion gas conduit configured to direct the combustion gas from the gas generator to the reactor pressure vessel assembly for heating the reactor pressure vessel assembly, such as during steady-state operation of the system.

47. A system according to any one of claims 28 to 46, wherein the system comprises one or more burners for supplying hot combustion gases to heat the reactor pressure vessel assembly, such as during a start-up procedure of the system.

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