Biomass processing plant and methods

Abstract

The present invention provides a processing plant comprising an HTC unit (1) whereby a first gas stream (F) containing CO2 is generated from a high temperature high pressure chamber vessel (1, 104), at least a portion of CO2 from the first gas stream being subsequently passed through a solution containing sodium carbonate to form sodium bicarbonate, whereby at least a part of the portion of the CO2 stream is prevented from being released into the atmosphere, and wherein said formed sodium bicarbonate is precipitated and removed from solution. It further provides a plant comprising a high temperature high pressure chamber vessel (1, 104) and a mixer (9, 106) for mixing additives; as well as an apparatus (1000) for performing HTC wherein a continuous flow of biomass sludge is processed through a sludge pump (102), followed by a steam jacketed screw conveyor (103), followed by a continuous stirred tank reactor vessel CSTR (104), followed by a cooling screw conveyor (105) resulting in an HTC sludge.

Description

[0001] BIOMASS PROCESSING PLANT AND METHODS

[0002] Field of the invention

[0003] The present invention relates to hydrothermal carbonization (HTC) of biomass.

[0004] Introduction

[0005] Large amounts of solid organic waste accumulate and have to be disposed of by food processing plants and sewage treatment plants. Various methods have been deployed to reduce the carbon footprint of the treatment process as well as reduce waste landfill. Most of the current methods do not provide a complete solution because even though they may convert the waste into something useful (for example energy or fertilizer), they are often not a complete solution because they still emit CO2 into the atmosphere.

[0006] Hydrothermal Carbonization (HTC) is a relatively new method of treating solid organic waste. In one method, the HTC converts wet organic solids into chemicals which when dried form a stable dry hydrophobic solid that can be stored and used as either a fuel or as a soil amendment. HTC soil amendments, however, are not optimal due to the low pH caused by organic acids which form in the HTC process. HTC dried solids can be burned by combustion or pyrolysis to recover their energy value.

[0007] HTC has been used as a method to pre-treat wet solid waste prior to anaerobic digestion. In this process, the solids remain mixed with the liquid and are subsequently broken down and converted into biogas by methanogenic bacteria. The biogas is then burned for its energy value. Using this method, however, some solids, such as lignin, are not broken down and remain as a digester sludge that is rich in minerals, but is often discarded as a waste.

[0008] Other methods include simply drying the wet solid organic waste and then burning it or pyrolyzing it to recover its energy content. Solid wastes that are simply dried, however, are generally hydrophilic, and are prone to molding over time, and therefore cannot be stored.

[0009] In any of the methods where solid waste is converted to energy, or where HTC is used to create a stable solid fuel, carbon dioxide is released in the process. In addition to carbon dioxide, other harmful gases, such as sulfur dioxide, cause pollution in the environment and must be removed from the exhaust gas prior to being released into the air. Existing technologies use chemicals such as calcium carbonate, sodium carbonate, or sodium bicarbonate as cleansing agents that remove sulfur dioxide from the gas. These chemicals add to the cost of operating a solid waste processing facility.

[0010] Another method of getting energy value from dry solid waste is pyrolysis. Pyrolysis heats the organic material in the absence of water or oxygen, which causes the material to break down into volatile gases that can be used as fuel. Pyrolysis has the disadvantage that it must be dried before it is pyrolyzed, which requires energy; however, it has the advantage that most of the carbon left behind is black carbon, which can also have value on its own as well as have value as an additive to soil.

[0011] Both HTC and pyrolysis emit CO2, which is a major air contaminant; however, since these methods are not using fossilized solid waste as their fuel source, the release of CO2 after combustion would be considered carbon neutral. If, however, the CO2 emissions can be captured, then the processing plant could be considered carbon negative. In addition, if the solid waste treatment process produces a soil amendment that stays in the ground, then that would also be considered carbon negative.

[0012] During the HTC process, large molecules like cellulose (C8), chitin (C8), and lignin (C18) will break down into smaller molecules like organic acids (C2-C6). The organic acids will have a relatively low pH, mostly ranging from 3.0 - 4.0. These acids, especially in the higher carbon range are not very soluble in water, unlike their inorganic strong acid counterparts. This acidity is likely undesirable for a soil amendment, and it is very difficult to separate these organic acids from the solids after the HTC process is complete. Hence, even though the solid organic nuggets, which are the primary product of the HTC process, may work well as fuel source to provide heat, it may be very difficult to find a large market for an acidic soil amendment. It would be ideal if the solid amendments could be tailored to fit the desired pH at a particular farm or agricultural region.

[0013] Many of the non-volatile minerals found in solid organic waste have taken the form of a chelated mineral, which is a form where the mineral ion is bonded to an organic molecule, like an organic acid. In this specification, chelated mineral preferably means a mineral ion that is bound to an organic molecule, rather than bound to oxygen. Common minerals like Ca, Mg, Mn, Zn, Fe, P, and K, have chelated versions that are common in waste organic matter. This form of mineral is highly desirable for integration into the life cycle of agriculture because generally, it is easier for living cells (in plants or animals) to take up these forms as compared to the completely oxidized minerals for the simple reason that a chelated bond is easier to break as compared to an oxygen bond. This is one of the reasons why HTC is attractive for the development of soil amendments.

[0014] When the HTC solids are separated from the liquid, and dried, they become a stable solid that is loaded with chelated minerals. When these solid products are used as a combustible fuel source, the minerals become completely oxidized as the carbon, oxygen, and hydrogen atoms all become gas emissions of primarily carbon dioxide (CO2) and water (H2O). Most minerals do not form gas and remain behind as fully oxidized minerals which take the form of a non-volatile ash. While the ashes from a biomass fueled boiler, for example, may be loaded with minerals, the minerals are in a form that is not easily taken up by plants. An interesting characteristic of many of the oxidized mineral ions is that they dissolve in water, and when dissolved they form highly basic solutions (high pH). For example, CaO has a pH of 12, compared to its simplest chelated version CaCO3, which has a pH of 9 (three orders of magnitude lower on the pH scale).

[0015] Almost all processes that convert biomass to energy release CO2 into the atmosphere. Here, we will consider three of them. First, the HTC process releases CO2 during the high-heat and high- pressure stage where the carbon molecules are broken, but note that it is not from combustion, but rather from a wet high pressure hydrolysis which has very moderate temperatures (180- 220C). With the HTC process, the carbon from the solid nuggets which are eventually formed after separation and drying isn’t released to the atmosphere unless the formed nuggets are burned for fuel.

[0016] Second, the pyrolysis process releases CO2 when the volatile gases that it releases during heating are burned for their energy. Since the pyrolysis process doesn’t use oxygen, a lot of the carbon is not released into the atmosphere but remains behind as a solid pure carbon (commonly called carbon black or biochar) - which could be burned to ash if desired, but typically is instead recovered to prevent the carbon from going into the atmosphere. Like the ash from normal combustion, the carbon black is rich in non-volatile minerals; however, in the case of pyrolysis, the minerals are chelated to the carbon black rather than being fully oxidized. In addition, the pyrolyzed carbon products have many complex and relatively large carbon structures consisting of thousands and millions of connected carbon atoms. These complex carbon structures are ubiquitous with another term called Biochar. Biochar has been proven to be an extremely valuable soil amendment for two reasons: First, the structures themselves provide ideal “houses” for soil borne bacteria, whose function it is to digest chelated mineral or mineral oxides, and provide the nutrition to the plants through their roots. Second, the biochar itself is not degraded (or “eaten’) by the biology of the soil, and can remain in the soil for centuries. This makes it a very sought after ingredient of organic soil amendments. In the natural environment, biochar is made during forest fires, and is one of the key reasons why nature flourishes after a fire. Biochar also is a key to soil water retention, making the soil so that the plants which grow in it are more tolerant to drought.

[0017] Finally in the biomass to energy sector, anaerobic digestion plays a role where microbes convert nutritious organic molecules, (such as soluble, mineral rich, chelated organic acids), into methane gas (CH4) and CO2. Anaerobic digestion takes place in a liquid sludge, where the solids are predominantly the anaerobic bacteria, but also include aerobic bacteria. Many of the bacteria that are in a digester are good bacteria for soils, which is one of the reasons why the effluent of a biodigester makes an excellent organic fertilizer. The HTC process is sometimes used as a pretreatment for an anaerobic digester, because it breaks down the larger, more complex molecules, into easier to digest molecules for the very sensitive methanogens which convert the carbon molecules into methane (CH4).

[0018] The production of sodium bicarbonate is an excellent method of using CO2 from waste streams. In this process, sodium carbonate is dissolved in a solution, and CO2 is bubbled through the solution to make sodium bicarbonate. The sodium bicarbonate is then crystallized and removed as a white powder that has high value.

[0019] Grain wastes from breweries typically consist of 16-25% cellulose (08) and 11-27% lignin (018), which are large molecules that are difficult for anaerobic digesters to breakdown, which result in large amounts of undigested solid sludge after digestion.

[0020] Most HTC reactors operate in a batch or semi batch mode, rather than a continuous mode. A batch or semi batch apparatus has a fundamental disadvantage in that portions of the apparatus itself must be heated up, pressurized, and cooled down during each batch or semi batch. A continuous mode would be more advantageous for high volume production as it would operate in a steady state and would be much more energy efficient as well as have a higher capital utilization.

[0021] Furthermore, in the case of waste from food processing companies, the conversion of the waste does not reduce their US Environmental Protection Agency Scope-3 emissions - that is, emissions that are the result of activities from assets not owned or controlled by the reporting organization, but that the organization indirectly affects in its value chain. In order for the waste conversion to reduce scope-3 emissions, it would have to reduce the carbon footprint of the supply chain to the food processor, which means reducing the carbon footprint of the grain and other crops on the farms where the food was grown. Hence, if a soil amendment were produced from the organic waste of a food processing facility, and returned to the farm where the raw food was originally grown, and if said soil amendment reduced the carbon footprint of said raw food crops, then it would reduce the Scope-3 emissions of said food processor.

[0022] Summary of the invention

[0023] According to an aspect of the present invention, there is provided an HTC unit whereby a first gas stream containing CO2 is generated from a high temperature high pressure chamber vessel, where at least a portion of CO2 from the first gas stream is subsequently passed through a solution containing sodium carbonate to form sodium bicarbonate, (hence avoiding that portion of the CO2 stream from being released into the atmosphere, wherein said formed sodium bicarbonate is precipitated and removed from solution, thus causing a portion of carbon from the solid waste to be transformed into solid sodium bicarbonate.

[0024] According to another aspect, there is provided a method whereby a first gas stream containing CO2 is generated from a high temperature high pressure chamber vessel, where at least a portion of CO2 from the first gas stream is subsequently passed through a solution containing sodium carbonate to form sodium bicarbonate, (hence avoiding that portion of the CO2 stream from being released into the atmosphere, wherein said formed sodium bicarbonate is precipitated and removed from solution, thus causing a portion of carbon from the solid waste to be transformed into solid sodium bicarbonate.

[0025] In the HTC unit and method, preferably, at least a portion of liquid sludge from the HTC unit is subsequently passed into a anaerobic digester which produces: biogas; a liquid effluent; and a liquid / solid sludge containing live bacteria; whereby said biogas stream is subsequently burned for its energy content producing a second stream containing CO2 and other gases, whereby said second stream containing CO2 is combined with first said stream containing CO2, and subsequently a portion of said combined stream is processed through a solution containing sodium carbonate to form sodium bicarbonate, hence avoiding that portion of the second CO2 stream from being released into the atmosphere, wherein said formed sodium bicarbonate is precipitated and removed from solution, thus causing a portion of carbon from the solid waste to be transformed into solid sodium bicarbonate.

[0026] Preferably, in addition or instead, a portion of the dry BioNuggets produced by the HTC are subsequently pyrolyzed which produces a stream of volatile combustible gases as well as a solid residue that contains >90 wt%% carbon substance called biochar; whereby, said volatile combustible gases are burned for their energy content producing a third stream containing CO2 and other gases, whereby said third stream containing CO2 is combined with said first stream containing CO2, and subsequently a portion of said combined stream is processed through a solution containing sodium carbonate to form sodium bicarbonate, hence avoiding that portion of the CO2 stream from the third stream from being released into the atmosphere, wherein said formed sodium bicarbonate is precipitated and removed from solution, thus causing a portion of carbon from the solid waste to be transformed into solid sodium bicarbonate.

[0027] Preferably, in addition or instead, a portion of the dry BioNuggets produced by the HTC unit are subsequently burned for their energy content, producing a non volatile ash consisting of one or more non volatile oxidized minerals and producing a fourth gas stream containing CO2 and other gases, whereby said fourth stream containing CO2 is combined with said first stream containing CO2, and subsequently a portion of said combined stream is processed through a solution containing sodium carbonate to form sodium bicarbonate, hence avoiding that portion of the CO2 from the fourth stream from being released into the atmosphere, wherein said formed sodium bicarbonate is precipitated and removed from solution, thus causing a portion of carbon from the solid waste to be transformed into solid sodium bicarbonate..

[0028] Preferably, a portion of the ash produced from burning the BioNuggets, is inserted and mixed into the sludge of the HTC unit between the high temperature high pressure vessel and the solid / liquid separation apparatus. Preferably, the amount of ash inserted into said sludge is sufficient to maintain a dry BioNugget soil pH of between 6.0 - 8.0.

[0029] Preferably, in addition or instead, Calcium Carbonate is added to the ash stream which is inserted into the sludge of the HTC unit between the high temperature high pressure vessel and the solid / iquid separation apparatus.

[0030] Preferably, the amount of Calcium Carbonate inserted into said sludge is sufficient to maintain a soil pH of between 6.0 - 8.0.

[0031] Preferably, the source of Calcium Carbonate is derived from sustainable aragonite so as to not substantially increase the carbon footprint of the BioNugget.

[0032] Preferably, a portion of the biochar is inserted and mixed into the sludge of the HTC unit between the high temperature high pressure vessel and the solid / liquid separation apparatus.

[0033] Preferably, the biochar mass content in the dry BioNugget is maintained between 2-20%.

[0034] Preferably, a portion of the solid / liquid sludge stream produced by the biodigester is inserted and mixed into the sludge of the HTC unit between the high temperature high pressure vessel and the solid / liquid separation apparatus.

[0035] Preferably, the exit temperature of the HTC drying apparatus process is kept between 50 - 100C, preferably less than 80C.

[0036] Preferably, said combined streams containing CO2 have a CO2 concentration of 10 wt% or higher.

[0037] Preferably, an additional injection of separately cultivated soil thriving bacteria is injected into the sludge stream prior HTC drying.

[0038] Preferably, the gas stream containing CO2 is cleansed of impurities by injecting a spray containing a portion of the centrate liquid from the SBC solid / liquid separation unit. According to a further aspect of the present invention, there is provided a method of performing HTC wherein a continuous flow of biomass is processed through a sludge pump, followed by a steam jacketed screw conveyor, followed by a continuous stirred tank reactor vessel, followed by a cooling screw conveyor.

[0039] According to a further aspect of the present invention, there is provided an apparatus for performing HTC comprising sludge pump for processing a continuous flow of biomass, a steam jacketed screw conveyor, a continuous stirred tank reactor vessel, and a cooling screw conveyor. These are preferably provided in order, although intermediate parts may also be included.

[0040] In this method and apparatus, preferably, the rotational speed of the steam jacketed screw conveyor is used to control the temperature of sludge entering the CSTR.

[0041] Preferably, the CSTR outlet gas pressure relief setpoint is a function of the reactor temperature.

[0042] Preferably, the outlet of the cooling screw conveyor contains a control valve which is used to maintain the sludge level of the CSTR.

[0043] Preferably, the rotational speed of the cooling screw conveyor is used to control the pressure drop across said cooling screw conveyor.

[0044] Preferably, the pH of the resulting sludge is controlled by mixing combustion ashes into the resulting sludge.

[0045] Preferably, living bacterial biology is added to the resulting sludge.

[0046] Preferably, pyrolytic biochar is added to the resulting sludge.

[0047] According a further aspect of the invention, there is provided A processing plant comprising: an HTC unit whereby a first gas stream containing CO2 is generated from a high temperature high pressure chamber vessel, at least a portion of CO2 from the first gas stream being subsequently passed through a solution containing sodium carbonate to form sodium bicarbonate, whereby at least a part of the portion of the CO2 stream is prevented from being released into the atmosphere, and wherein said formed sodium bicarbonate is precipitated and removed from solution.

[0048] Preferably, liquid from the HTC unit is subsequently passed into an anaerobic digester which produces: biogas, a liquid effluent, and a liquid / solid sludge; said biogas stream is subsequently burned for its energy content producing a second gas stream containing CO2 and other gases, at least a portion of said second stream containing CO2 is combined with first said gas stream containing CO2; and at least a portion of said combined stream is passed through the solution containing sodium carbonate to form sodium bicarbonate.

[0049] Preferably, a dry product produced by the HTC unit is subsequently pyrolyzed to produce volatile combustible gases and a solid residue that contains >90 wt% biochar; whereby, said volatile combustible gases are burned for their energy content producing a third gas stream containing CO2 and other gases, at least a portion of said third stream containing CO2 is combined with said first stream containing CO2; and at least a portion of said combined stream is passed through the solution containing sodium carbonate to form sodium bicarbonate.

[0050] Preferably, a dry product produced by the HTC unit is subsequently burned to produce a nonvolatile ash consisting of one or more non-volatile oxidized minerals and a fourth gas stream containing CO2 and other gases, at least a portion of said fourth stream containing CO2 is combined with said first stream containing CO2; and at least a portion of said combined stream is passed through the solution containing sodium carbonate to form sodium bicarbonate.

[0051] Preferably, a portion of the ash produced from burning the dry product is inserted and mixed into sludge of the HTC unit between the high temperature high pressure vessel and a solid / liquid separation apparatus.

[0052] Preferably, the amount of ash inserted into said sludge is sufficient to maintain a pH of the dry product between 6.0 - 8.0.

[0053] Preferably, a portion of the biochar is inserted and mixed into sludge of the HTC unit between the high temperature high pressure vessel and a solid / liquid separation apparatus.

[0054] Preferably, the biochar mass content in the dry product is maintained between 2-20%. Preferably, a portion of the solid / liquid sludge stream produced by the anaerobic digester is inserted and mixed into sludge of the HTC unit between the high temperature high pressure vessel and a solid / liquid separation apparatus.

[0055] Preferably, the exit temperature of an HTC drying apparatus (3) is kept between 50 - 100C, preferably less than 80C.

[0056] Preferably, an additional injection of separately cultivated soil thriving bacteria is injected into the sludge stream prior HTC drying.

[0057] Preferably, said combined streams containing CO2 have a CO2 concentration of 10 wt% or higher.

[0058] According to a still further aspect of the present invention, there is provided a plant according to the preceding claims, comprising an SBC solid / liquid separation unit for removing said sodium bicarbonate, and a gas cleaner for cleansing the gas stream containing CO2 of impurities by injecting a spray containing a portion of centrate liquid from the SBC solid / liquid separation unit.

[0059] According to a still further aspect of the present invention, there is provided processing plant comprising: a high temperature high pressure chamber vessel in which an HTC sludge is generated, the HTC sludge being liquid / solid separable to form a product for application to a farm; and a mixer for mixing at least one additive with the HTC sludge prior to the liquid / solid separation.

[0060] Preferably, the at least one additive is at least one of an additive to adjust pH, an ash from pyrolysis, biochar, sludge from an anaerobic digester, and soil thriving bacteria.

[0061] Preferably, the processing plant includes a burner for burning a dry product produced from the HTC sludge afterthe at least one additive has been mixed to produce ash, the at least one additive comprises the ash.

[0062] Preferably, the processing plant includes an anaerobic digester and the at least one additive comprises sludge from the anaerobic digester. Preferably, the additive to adjust pH is calcium carbonate derived from oolitic aragonite.

[0063] Preferably, the processing plant further includes a drying apparatus (3) and an exit temperature of the drying apparatus is between 50-100C.

[0064] According to a still further aspect of the present invention, there is provided an apparatus for performing HTC wherein a continuous flow of biomass sludge is processed through a sludge pump, followed by a steam jacketed screw conveyor, followed by a continuous stirred tank reactor vessel CSTR, followed by a cooling screw conveyor resulting in an HTC sludge.

[0065] Preferably, the rotational speed of the steam jacketed screw conveyor is used to control the temperature of sludge entering the CSTR.

[0066] Preferably, a CSTR outlet gas pressure relief setpoint is a function of the CSTR temperature.

[0067] Preferably, an outlet of the cooling screw conveyor contains a control valve which is used to maintain a sludge level of the CSTR.

[0068] Preferably, the rotational speed of the cooling screw conveyor is used to control a pressure drop across said cooling screw conveyor.

[0069] Preferably, the pH of the HTC sludge is controlled by mixing combustion ashes into the HTC sludge.

[0070] Preferably, the pH of the HTC sludge is controlled by mixing calcium carbonate into the HTC sludge.

[0071] Preferably, the calcium carbonate is derived from oolitic aragonite.

[0072] Preferably, living bacterial biology is added to the HTC sludge.

[0073] Preferably, pyrolytic biochar is added to the HTC sludge. According to a still further aspect of the present invention, there is provided an HTC processing method comprising: generating a first gas stream containing CO2 from a high temperature high pressure chamber vessel, passing at least a portion of CO2 from the first gas stream through a solution containing sodium carbonate to form sodium bicarbonate, whereby at least a part of the portion of the CO2 stream is prevented from being released into the atmosphere, and precipitating and removing said formed sodium bicarbonate from solution.

[0074] According to a still further aspect of the present invention, there is provided an HTC processing method comprising: generating an HTC sludge with a high temperature high pressure chamber vessel, the HTC sludge being liquid / solid separable to form a product for application to a farm; and mixing additives with the HTC sludge prior to the liquid / solid separation in order to adjust the soil pH of the product.

[0075] According to a still further aspect of the present invention, there is provided a farming method comprising using a low carbon soil amendment on predetermined farmland, said soil amendment having been produced by a food processing facility from waste derived from crops grown from said farmland.

[0076] By using a soil amendment on the same farmland from which the organic waste was produced, Scope 3 emissions can be reduced or eliminated.

[0077] The soil amendment need not be used on the same farmland, however.

[0078] Preferably, the soil amendment has been produced by generating an HTC sludge from the waste using a high temperature high pressure chamber vessel; and mixing at least one additive with the HTC sludge; and separating the HTC sludge into liquids and solids.

[0079] Preferably, the at least one additive is at least one of an additive to adjust pH, an ash from pyrolysis, biochar, sludge from an anaerobic digester, and soil thriving bacteria.

[0080] Preferably, the ash has been produced from a dry product from the HTC sludge.

[0081] Preferably, the additive to adjust pH is calcium carbonate derived from oolitic aragonite. According to a still further aspect of the present invention, there is provided a method for performing HTC comprising: causing a continuous flow of biomass sludge to pass through a sludge pump, followed by a steam jacketed screw conveyor, followed by a continuous stirred tank reactor vessel CSTR, followed by a cooling screw conveyor thereby resulting in an HTC sludge.

[0082] This invention can be used to convert organic solid waste streams into valuable products which would otherwise contaminate the air, water, or go to landfills. Primary users of this invention would be large food processing facilities, farm wastes, and sewage treatment, with a primary purpose of reducing the harmful impact of waste on the environment. Valuable products would be the following:

[0083] • Sodium bicarbonate

[0084] • Farm soil amendments

[0085] • Electricity

[0086] • Carbon accounting credit

[0087] Ancillary products could also be produced from this plant using add-on conventional methods which include:

[0088] • Liquified pure CO2

[0089] • Carbon black

[0090] • Inorganic phosphorus fertilizer

[0091] Brief description of the drawings

[0092] Fig. 1 is a schematic view of a chemical production plant according to one embodiment of the present invention.

[0093] Fig. 2 is a schematic view of an HTC reactor apparatus according to another embodiment of the present invention. Description of Invention

[0094] A chemical production plant is described in the following diagram, which includes an HTC sludge processing unit (1 , 9, 2, 3), a CO2 purification unit (5, 6), a sodium bicarbonate (SBC) crystallization unit (7, 8), an anaerobic digestion unit (10), and a combined heat and power unit (4). The diagram shows the way that the major process streams are connected.

[0095] Advantages & Detailed System Description (Figure-1)

[0096] Hydrothermal Carbonization (HTC) Reactor

[0097] The HTC reactor (1) heats the incoming biomass sludge while the sludge is under pressure so that water does not outgas. The higher the temperature that is used, the higher the pressure must be maintained to prevent the water from outgassing. While the sludge is at the high temperature, high pressure condition, other gases, primarily CO2, are released and sent to the gas cleansing unit (5) to remove unwanted gases such as SO2, and NOx. A detailed description of a proposed HTC reactor and subsequent Mixing unit (9) is contained in a later section under Figure-2.

[0098] Heat and power unit description

[0099] The heat and power unit (4) uses dry BioNuggets (D) and Biogas (Q) as fuel. The biogas is used as primary heat for a boiler to turn water into steam, wherein the steam is subsequently used as heat for other areas of the plant (1 ,3,6,8). Excess steam is also used to drive a turbine to generate electricity.

[0100] Heat is also provided by an air combustion chamber where BioNuggets are burned to make the ash required for pH control of the sludge feeding nugget production (9), and to make more heat to increase steam production.

[0101] The heating requirements can be further increased by burning the mixture of gas which evolves from heating BioNuggets in a pyrolysis chamber (not shown) which is used to make Biochar. The gases from the pyrolysis can be combined with the biogas to drive the boiler. A portion of the Biochar can be mixed with the ash that is used to adjust the pH of the BioNuggets. Soh Amendment pH Control

[0102] Critically, the ash from the heat and power unit (4) is used to control the pH of the solid product nuggets from the HTC unit. The sludge / ash mixing component (9) is shown as part of the HTC unit, but may be a separate unit. Preferably, sludge / ash mixing is performed after high temperature (180-250C) and pressure (8 - 40 Bar) is performed in the HTC reactor (1). More ash is added to the mixture when an increase in the pH of the BioSoilNuggets (O) is desired. Likewise, if lower pH is desired, then less ash is added. If nuggets are desired only for energy, then no ash needs to be added to the sludge. An ideal range of the pH of soil amendments can be from pH 6 - 8. It is worth noting that a higher nugget pH will not distract from the energy content.

[0103] If it is desired to use less ash to control the soil pH, or if more pH adjustment is necessary for the target soil (e.g, acid soils), then Calcium Carbonate can be added in addition to or instead of ash. To prevent a higher carbon footprint of the BioSoilNugget, the calcium carbonate can be sourced from sustainable aragonite (Oolitic aragonite).

[0104] CO2 utihzed to make sodium bicarbonate (SBC)

[0105] All of the CO2 sources (F, G) are captured from the generating sources (1 , 4) and are fed first into a gas cleansing unit (5), followed by an optional CO2 concentrating unit (6), and then into an SBC crystallization unit (7) where the pure CO2 (I) is reacted with sodium carbonate (M) to form SBC. After SBC is formed, it is separated from the liquid carrier solution (centrate) and dried as a final crystalline powder product (U).

[0106] A portion of the centrate liquid (L) from the solid / liquid separator and SBC dryer (8) is used as a cleansing agent in a gas cleansing reaction unit (5). Using this liquid saves on chemical costs that would otherwise need to be purchased to cleanse the gas. This stream also serves as a bleed stream to prevent trace element accumulation in the centrate carrier solution. Biomass to produce heat and power

[0107] The plant power and energy requirements can come entirely from its biomass feedstock. Two sources of biomass feed into the heat and power unit (4), which are BioNuggets (D) from the HTC sludge processing unit (1 , 9, 2, 3), and Biogas (Q) from the anaerobic digester (10). All of the energy required to run the plant can be derived from the burning of some of the nuggets, or from burning biogas which comes from the anaerobic digestion unit (10). Normally there will be an excess production of nuggets which can be sold as a soil amendment product (O). In this document, to differentiate the pellets used for fuel from the pellets used as a soil amendment, we will call the first BioBurnNugget, and the second a BioSoilNugget, collectively BioNuggets.

[0108] Since the sodium bicarbonate production process also uses energy, the plant can be fitted with a sodium bicarbonate unit that only uses a portion of the CO2 that is generated. Building a smaller sodium bicarbonate plant will result in a larger ratio of organic material that can be used for BioSoilNuggets.

[0109] Recovery of AD sludge, Combustion ash, and Pyro carbon

[0110] There are three streams downstream of BioNugget production from the HTC that produce solids that have value as a soil amendment if they are recycled and injected into the sludge after the high temperature HTC process and before the HTC sludge is dried.

[0111] Anaerobic digester (AD) sludge (T). In addition to producing biogas, the anaerobic digester will produce a lean effluent (S), and a solid / liquid sludge (T). Both the liquid and solid in the digester are rich in anaerobic and aerobic bacteria, much of which are suitable for soil amendments as they can build up good soil biology in agriculture. When the AD sludge is recycled and inserted into HTC sludge after the high temperature process, but before the solids separations process (9), and further, if the HTC drying temperature (3) is kept below the sterilization temperature (100C), but above the pasteurization temperature (70C), then the living biology of the AD sludge which is not a human pathogen will be preserved and its benefit realized in soil biology.

[0112] Combustion Ash (R). As stated earlier, the combustion ash will contain oxidized minerals, which can increase the pH of the BioSoilNuggets. To control the pH of the BioNuggets, the ash is injected into the HTC sludge in a mixing apparatus (9) after the high temperature / pressure process (1) and before the solid / liquid separation (3). Biochar (not shown). Where the BioBurnNuggets are pyrolyzed to produce biochar, this can be added to the HTC sludge to improve the BioSoilNuggets were desired.

[0113] Inoculation of Soil Amendment

[0114] Biological components that are critical for the health of specific crops can be cultivated independently of the waste recovery and energy systems. These cultivated biological components could be then injected into the sludge to create crop specific BioSoilNuggets. As long as the sludge is dried to form BioNuggets at a temperature that preserves the efficacy of the biology, then the BioSoilNuggets will have superior agricultural performance over other soil amendments. This can be a great benefit when land is converted from one agricultural product to another because it will greatly shorten the time that it takes for the new / different crop to grow.

[0115] Ideally, a separate inoculation apparatus consisting of a bacterial growth unit would provide a high bacteria count solution that would also be injected into the mixing tank prior to solids separations in order to optimize the efficacy of the BioSoilNuggets.

[0116] Plant Sizing Considerations

[0117] A heat and mass balance was developed so that various options for unit sizing could be optimized. The heat and mass balance took into consideration the capital cost of each of the equipment required for each unit. Four different scenarios were run to illustrate a comparison which is shown in the table below:

[0118] In the table, TPD stands for tons per day; ESA for engineered soil amendment (BioSoilNuggets); and HA for hectares.

[0119] Inputs to the heat and mass balance were adjusted to obtain the various sizes of plant. In this example, it was assumed that the plant would use spent grain waste from a brewery with a certain capacity to produce beer (millions of liters per year). Different fractions of BioNugget usage (pyrolysis in pyrolysis chamber (not shown) to make Biochar, combustion in the boiler (4), and soil amendment) were also input parameters. Assumptions were also made about the number of hectares that were used to grow the grain which was shipped to the brewery, and assumptions were made about the quantity of soil amendment that would be needed to sufficiently fertilize the farm acreage. Power requirements, CO2 utilization, Capex, and total revenue were calculated to form a complete business picture.

[0120] It was found that a brewery capacity of 400 ML / yr could produce enough soil amendment to satisfy 100% of its supply chain with a very low carbon organic soil amendment, which would eliminate the majority of the brewers Scope-3 emissions. The soil amendment would be sufficient to fertilize 6,689 HA of farmland. The plant would produce 194 tons per day of BioNuggets from the HTC sludge processing unit (1 , 9, 2, 3) for use in pyrolysis in the pyrolysis chamber, combustion in the boiler (4), and soil amendment. The plant would also produce 175 tons per day of sodium bicarbonate, and would produce enough power (4MW) to drive the entire operation. The net result would be a plant that could produce $25.4M in revenue with an equipment capital cost of $23.4M.

[0121] Continuous HTC Reactor Apparatus (Figure-2)

[0122] A proposed HTC reactor apparatus (1000), which could be used in the chemical production plant in Figure-1 , is provided in Figure-2. As shown, the apparatus includes a Biomass Hopper (101), where the biomass feed material (100A) is introduced. A sludge pump (102) moves the biomass (100B) into a heated screw conveyor (103), and pressurizes the sludge to the operating pressure of the sludge tank (104). The heat to the sludge in the screw conveyor (103) is provided by process steam (100C) in a steam jacket (103A), which substantially envelopes the screw conveyor (103) to provide uniform heating of the sludge (100C) as it moves toward the sludge tank (104). The sludge enters the heated screw conveyor at ambient temperature.

[0123] A combination of screw rotational speed, diameter, screw flight shape, and steam temperature determine the uniformity of the outlet temperature of the sludge (100C). It is desired that the outlet temperature be the same temperature as the temperature of the sludge tank (104), because that will reduce the heat load on the sludge tank (104). The sludge tank (104) is surrounded by a steam jacket (104A) and behaves as a continuously stirred tank reactor (CSTR), whereby the residence time of the sludge in the tank, combined with the temperature of the tank, determines the total amount of hydrothermal carbonization.

[0124] During the process, gases evolve (100D). It is desired to keep the pressure high enough so that water does not evolve as a gas. This is accomplished by only allowing gas to escape from the tank when the pressure is above the water vaporization pressure for the temperature at which the tank is operating. Hence, optimally, the outlet gas flow is controlled by the gas pressure in the headspace above the sludge in the tank using a pressure control (104B), and this set point changes dynamically with the temperature in the tank to prevent water from escaping.

[0125] Once the sludge is cooked, it exits the sludge tank (104) through a cooling screw conveyor (105). The cooling screw conveyor (105) is jacketed with a cooling jacket (105A) filled with cooling water (100E), which brings the temperature of the sludge down rapidly and stops the hydrothermal carbonization. At the exit of the cooling screw conveyor is a control valve (105B), which is adjusted to keep the level of the sludge tank (104) at a predetermined level, which is the primary control of the residence time of the reaction. The rotational speed of the cooling screw conveyor is maintained to keep a near constant pressure across the conveyor (or slight pressure drop depending on the design of the conveyor).

[0126] The processed sludge moves from the cooling screw conveyor (105) and into the mixing tank (106). The tank is operated near ambient pressure and temperature. Additives (100Q, 100R, 100S, 100T) are added to the mixing tank to control the efficacy of the BoiSoilNugget. As stated earlier in the description; • Combustion ash (100T) is added to control the pH of the BioSoilNugget

[0127] • Biochar (100R) is added to improve soil biology and sequester carbon (as specified by recipe)

[0128] • Anaerobic digester sludge (100S) is added to increase solid content and provide primary biology to the BioSoilNugget.

[0129] • Cultivated biology (100Q) is added to provide targeted biology to the BioSoilNugget.

[0130] Sludge pump (107) then pumps out the resulting slurry (1 OOP). BioNuggets can be produced with the slurry (100P) including one or more of these additives in any combination to improve efficacy of BioNugget in the soil.

[0131] In this specification, the term “HTC unit” is a processing unit for processing an organic solid waste sludge by hydrothermal carbonization. The HTC unit preferably includes any one or more, or more preferably all, of the following features:

[0132] • The sludge preferably contains 10 - 40 wt% solids (preferably solids by weight).

[0133] • The sludge is preferably processed through an apparatus consisting of a high temperature high pressure vessel.

[0134] • The temperature is preferably 180 - 250C.

[0135] • The pressure is preferably 8 - 40 Bar.

[0136] • The processing is preferably for a period of 20 minutes to 8 hours.

[0137] • The processing preferably causes the release of a mixture of gas containing greater than 20 wt% CO2.

[0138] • The apparatus is preferably followed by equipment that separates the remaining sludge mixture solids from liquids whereby the solid cake portion is less than 50 wt% moisture.

[0139] • The apparatus and the separating equipment, if included, is preferably followed by a drying apparatus whereby the cake portion is dried to less than 15 wt% moisture content to form an organic substance that we call dry BioNuggets.

[0140] • The liquid portion that is separated preferably contains 4-15 wt% organic liquids.

[0141] The expression “unit” should not be taken to imply a unitary body and the unit may be composed of separate items of equipment / apparatus which may be amalgamated to the extent possible or dispersed / disparate to the extent that the overall function of the unit can still be achieved. Thus, the expression “unit” includes any suitable arrangement of plant / equipment / apparatus.

[0142] In the foregoing description, the term HTC reactor is taken to mean the HTC reactor 1 in Fig. 1 (shown primarily as sludge tank 104 in Fig. 2 but optionally including any one or more components before the mixing tank 106 in Fig. 2); the term HTC reactor apparatus is taken to mean the HTC reactor 1 and the mixer 9 in Fig. 1 (the sludge tank 104 and the mixing tank 106 in Fig. 2 but optionally including any one or more of the other components in Fig. 2); and the term HTC sludge processing unit is taken to mean the HTC reactor 1 , the mixer 9, the separator 2, and the dryer 3 in Fig. 1. The HTC unit described above may be any one of the HTC reactor, the HTC reactor apparatus and the HTC sludge processing unit.

[0143] It should be appreciated that in any case the mixer 9 is not limited to a pH adjust - ash mixer but may mix any one or more suitable additives into the sludge from the HTC reactor 1 , preferably including one or more of biology, biochar, digester sludge and combustion ash as additives.

[0144] Embodiments of the present invention have been described by way of example. However, the invention is not limited to the described embodiments and the skilled addressee will recognise that various modifications can be made within the scope of the invention as defined by the appended claims.

Claims

Claims1 . A processing plant comprising: an HTC unit (1) whereby a first gas stream (F) containing CO2 is generated from a high temperature high pressure chamber vessel (1 , 104), at least a portion of CO2 from the first gas stream being subsequently passed through a solution containing sodium carbonate to form sodium bicarbonate, whereby at least a part of the portion of the CO2 stream is prevented from being released into the atmosphere, and wherein said formed sodium bicarbonate is precipitated and removed from solution.

2. A plant according to claim 1 , wherein liquid from the HTC unit is subsequently passed into an anaerobic digester (10) which produces: biogas (Q), a liquid effluent (S), and a liquid / solid sludge (T); said biogas stream is subsequently burned for its energy content producing a second gas stream containing CO2 and other gases, at least a portion of said second stream containing CO2 is combined with first said gas stream containing CO2; and at least a portion of said combined stream is passed through the solution containing sodium carbonate to form sodium bicarbonate.

3. A plant according to claim 1 or claim 2 wherein a dry product (D) produced by the HTC unit is subsequently pyrolyzed to produce volatile combustible gases and a solid residue that contains >90 wt% biochar; whereby, said volatile combustible gases are burned for their energy content producing a third gas stream containing CO2 and other gases, at least a portion of said third stream containing CO2 is combined with said first stream containing CO2; and at least a portion of said combined stream is passed through the solution containing sodium carbonate to form sodium bicarbonate.

4. A plant according to any one of the preceding claims, wherein a dry product (D) produced by the HTC unit is subsequently burned to produce a non-volatile ash (R) consisting of one or more non-volatile oxidized minerals and a fourth gas stream (G) containing CO2 and other gases,at least a portion of said fourth stream containing CO2 is combined with said first stream containing CO2; and at least a portion of said combined stream is passed through the solution containing sodium carbonate to form sodium bicarbonate.

5. A plant according to claim 4, whereby a portion of the ash (R) produced from burning the dry product (D) is inserted and mixed into sludge of the HTC unit between the high temperature high pressure vessel and a solid / liquid separation apparatus.

6. A plant according to claim 5, whereby the amount of ash inserted into said sludge is sufficient to maintain a pH of the dry product between 6.0 - 8.0.

7. A plant according to claim 3, whereby a portion of the biochar is inserted and mixed into sludge of the HTC unit between the high temperature high pressure vessel and a solid / liquid separation apparatus.

8. A plant according to claim 8, whereby the biochar mass content in the dry product is maintained between 2-20%.

9. A plant according to claim 2, whereby a portion of the solid / liquid sludge stream produced by the anaerobic digester is inserted and mixed into sludge of the HTC unit between the high temperature high pressure vessel and a solid / liquid separation apparatus.

10. A plant according to claim 9, wherein the exit temperature of an HTC drying apparatus (3) is kept between 50 - 100C, preferably less than 80C.

11. A plant according to claim 10, wherein an additional injection of separately cultivated soil thriving bacteria is injected into the sludge stream prior HTC drying.

12. A plant according to any one of claims 2 to 4, wherein said combined streams containing CO2 have a CO2 concentration of 10 wt% or higher.

13. A plant according to the preceding claims, comprising an SBC solid / liquid separation unit (8) for removing said sodium bicarbonate, anda gas cleaner (5) for cleansing the gas stream containing CO2 of impurities by injecting a spray containing a portion of centrate liquid from the SBC solid / liquid separation unit (8).

14. A processing plant comprising: a high temperature high pressure chamber vessel (1 , 104) in which an HTC sludge is generated, the HTC sludge being liquid / solid separable to form a product for application to a farm; and a mixer (9, 106) for mixing at least one additive (R, T; 100Q, 100R, 100S, 100T) with the HTC sludge prior to the liquid / solid separation.

15. A processing plant according claim 14, wherein the at least one additive is at least one of an additive to adjust pH, an ash from pyrolysis, biochar, sludge from an anaerobic digester, and soil thriving bacteria.

16. A processing plant according to claim 15, wherein the processing plant includes a burner (4) for burning a dry product produced from the HTC sludge after the at least one additive has been mixed to produce ash, the at least one additive comprises the ash.

17. A processing plant according to claim 15 or claim 16, wherein the processing plant includes an anaerobic digester (10) and the at least one additive comprises sludge from the anaerobic digester.

18. A processing plant according to any one of claims 15 to 17, wherein the additive to adjust pH is calcium carbonate derived from oolitic aragonite.

19. A processing plant according to any one of claims 14 to 18, wherein the processing plant further includes a drying apparatus (3) and an exit temperature of the drying apparatus (3) is between 50-100C.

20. An apparatus (1000) for performing HTC wherein a continuous flow of biomass sludge is processed through a sludge pump (102), followed by a steam jacketed screw conveyor (103), followed by a continuous stirred tank reactor vessel CSTR (104), followed by a cooling screw conveyor (105) resulting in an HTC sludge.

21. An apparatus according to claim 20, wherein the rotational speed of the steam jacketed screw conveyor (103) is used to control the temperature of sludge entering the CSTR.

22. An apparatus according to claim 20 or claim 21 , wherein a CSTR outlet gas pressure relief setpoint is a function of the CSTR temperature.

23. An apparatus according to any one of claims 20 to 22, wherein an outlet of the cooling screw conveyor (105) contains a control valve (105B) which is used to maintain a sludge level of the CSTR.

24. An apparatus according to any one of claims 20 to 23, wherein the rotational speed of the cooling screw conveyor (105) is used to control a pressure drop across said cooling screw conveyor (105).

25. An apparatus according to any one of claims 20 to 24, wherein the pH of the HTC sludge is controlled by mixing combustion ashes into the HTC sludge.

26. An apparatus according to any one of claims 20 to 25, wherein the pH of the HTC sludge is controlled by mixing calcium carbonate into the HTC sludge.

27. An apparatus of claim 26, wherein the calcium carbonate is derived from oolitic aragonite.

28. An apparatus according to any one of claims 20 to 27, wherein living bacterial biology is added to the HTC sludge.

29. An apparatus according to any one of claims 20 to 28, wherein pyrolytic biochar is added to the HTC sludge.

30. An HTC processing method comprising: generating a first gas stream (F) containing CO2 from a high temperature high pressure chamber vessel (1 , 104),passing at least a portion of CO2 from the first gas stream through a solution containing sodium carbonate to form sodium bicarbonate, whereby at least a part of the portion of the CO2 stream is prevented from being released into the atmosphere, and precipitating and removing said formed sodium bicarbonate from solution.

31. An HTC processing method comprising: generating an HTC sludge with a high temperature high pressure chamber vessel (1 , 104), the HTC sludge being liquid / solid separable to form a product for application to a farm; and mixing additives (R, T; 100Q, 100R, 100S, 100T) with the HTC sludge prior to the liquid / solid separation in order to adjust the soil pH of the product.

32. A farming method comprising using a low carbon soil amendment on predetermined farmland, said soil amendment having been produced by a food processing facility from waste derived from crops grown from said farmland.

33. A farming method according to claim 32, wherein the soil amendment has been produced by generating an HTC sludge from the waste using a high temperature high pressure chamber vessel (1 , 104); and mixing at least one additive (R, T; 100Q, 100R, 100S, 100T) with the HTC sludge; and separating the HTC sludge into liquids and solids.

34. A farming method according to claim 33, wherein the at least one additive is at least one of an additive to adjust pH, an ash from pyrolysis, biochar, sludge from an anaerobic digester, and soil thriving bacteria.

35. A farming method according to claim 34, wherein the ash has been produced from a dry product from the HTC sludge.

36. A processing plant according to any one of claims 34 to 36, wherein the additive to adjust pH is calcium carbonate derived from oolitic aragonite.

37. A method for performing HTC comprising:causing a continuous flow of biomass sludge to pass through a sludge pump (102), followed by a steam jacketed screw conveyor (103), followed by a continuous stirred tank reactor vessel CSTR (104), followed by a cooling screw conveyor (105) thereby resulting in an HTC sludge.

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