System and process for treating one or more gas mixtures containing at least one combustible gas

Abstract

The present disclosure provides processes and systems for efficiently reducing polluting gases such as methane from biowaste stores. The system comprises a manifold that collects gasses from slurry tanks, slurry lagoons and / or landfill wells, processes it into a combustible gas and efficiently combusts the waste gases to produce less polluting products. The system is designed to run constantly, allowing efficient reduction in the environmental impact caused by slurry tanks and other biowaste storage containers such as landfill wells. Advantageously, embodiments of the system provide a means for reducing methane and other harmful-gas pollution, e.g., output from biowaste decomposition, with an easy-to-operate, low maintenance, and high efficiency system.

Description

[0001] SYSTEM AND PROCESS FOR TREATING ONE OR MORE GAS MIXTURES CONTAINING AT LEAST ONE COMBUSTIBLE GAS

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to processes for treating gas mixtures, and in particular gas mixtures obtained from biowaste, as well as systems for processing the same.

[0004] BACKGROUND

[0005] Slurry tanks and lagoons are used in agriculture to store animal waste (manure) and, often, other unusable organic matter as a slurried mixture. The natural decomposition of the organic materials typically leads to emission of mixtures of combustible gasses, as well as carbon dioxide, to the atmosphere.

[0006] The collection and storage of biowaste typically is not focussed on collecting the potent polluting (and often climate-impacting) gases released. The composition of gas mixtures resulting from slurry tank decomposition tends to be difficult to predict, varying significantly based on many factors such as slurry level in tanks, outside temperature, time of day, slurry composition, etc.. A similar issue arises with the slow eluting gases that are emitted by decommissioned landfill sites that contain biowaste where there may be a requirement to collect and / or process any methane gas emissions that may occur. Specifically designed equipment for dealing with the byproducts of biowaste decomposition tends to be costly and complex to operate and maintain.

[0007] The present inventors have realised that there exists a need for systems and processes which alleviate these issues. In particular, the present inventors have realised that it would be advantageous to provide systems and processes for treating a gas mixture released from biowaste, in particular in a manner which reduces with methane emissions flexibly, and with a high degree of safety, simplicity, and operational efficiency.

[0008] SUMMARY OF THE DISCLOSURE

[0009] In a first aspect there is provided a process for treating, within a system, one or more gas mixtures containing at least one combustible gas. The process comprises receiving, via a manifold of the system, the one or more gas mixtures. The one or more gas mixtures may be received from a respective one or more biowaste stores. The process further comprises combining, within the manifold, each of the one or more gas mixtures, thereby to produce a processable gas mixture. The process further comprises compressing, by a compressor of the system, the processable gas mixture.

[0010] The receiving may occur due the gas being drawn to the manifold due to an under pressure, or the gas may be forced to the manifold due to an over pressure.

[0011] For instance, the conduit connecting the biowaste store to the manifold may comprise a pump that forces the processable gas mixture to the manifold. Alternatively, a pump within the manifold may create a reduced pressure which draws the processable gas to the manifold. This configuration is preferred, as the risk of leakage of the processable gas prior to reaching the manifold is reduced. Any defects or leaks in the conduit will simply draw in atmospheric air, rather than force processable gas out to the atmosphere.

[0012] The combining may occur prior to or after compression of the gas. Typically, the gas streams are combined and then compressed, as this requires only a single compression unit.

[0013] The process further comprises combining the processable gas mixture with an oxygencontaining gas, such as atmospheric gas, to provide a combustible gas mixture.

[0014] The combustible gas mixture may be provided at above atmospheric pressure. This may be achieved by the pressure from the processable gas mixture, or both the processable gas mixture and the oxygen-containing gas that may itself be compressed.

[0015] The process further comprises conveying the combustible gas mixture to a reaction chamber, and oxidising the combustible gas mixture.

[0016] The reaction chamber may be a bioreactor, and the oxidising the combustible gas mixture comprises consuming the combustible gas mixture as a feedstock within the bioreactor. This type of configuration is particularly suitable for very low concentrations of combustible gas in the processable gas mixture. In such cases, the system collects and processes the combustible gas so that it is in a form suitable for metabolising as a feedstock within the bioreactor. Preferably, the process comprises combusting the combustible gas mixture.

[0017] The combustion may be via a flare, such that the process merely converts the combustible gas to a less polluting form (for instance converting methane to carbon dioxide and thereby reducing climate impact by a factor of 28, according to IPCC AR5). The energy released from the combustion may also be captured, for instance by using the combustion as a heat source, such as in a heating system connected to a building.

[0018] The reaction chamber may be a chimney.

[0019] The combustible gas mixture may be conveyed to the reaction chamber via a nozzle.

[0020] A base of the chimney may be sealed around the nozzle such that the only inlet to the chimney is via the nozzle.

[0021] When oxidising the gas via combustion, combining the processable gas mixture with an oxygen-containing gas (such as atmospheric gas) to provide a combustible gas mixture may comprise conveying, from the manifold into a mixing chamber of the system, the processable gas mixture. Combining the processable gas mixture with an oxygen-containing gas (such as atmospheric gas) to provide a combustible gas mixture may further comprise introducing oxygen-containing gas (such as atmospheric gas) into the processable gas mixture within the mixing chamber to produce a combustible gas mixture within the mixing chamber.

[0022] Conveying the combustible gas mixture to a reaction chamber may comprise conveying the combustible gas mixture from the mixing chamber into a combustion region of the system, the combustion region being a region defined within the chimney of the system.

[0023] Oxidising the combustible gas mixture may comprise combusting, in the combustion region, the combustible gas mixture.

[0024] The process may further comprise controlling one or more parameters of the process. The one or more parameters comprises at least one of: rate or volume of the water vapour removed from the processable gas mixture; a flow rate or volume of the oxygen-containing gas introduced into the gas mixture; a flow rate or volume of the combustible gas mixture conveyed into the combustion region; a flow rate or volume of the one or more gas mixtures into the manifold; a pressure of the combustible gas mixture; and / or a temperature within the combustion region. Controlling one or more of these parameters may allow control of the oxygen content (e.g. the oxygen volume or oxygen concentration) within the combustion region to ensure high efficiency combustion.

[0025] The one or more biowaste stores may comprise one or more slurry tanks or one or more slurry lagoons. Optionally, the one or more biowaste stores may comprise at least one of: one or more slurry tanks, one or more slurry lagoons or one or more landfill wells. The at least one combustible gas may be methane.

[0026] The one or more slurry tanks, one or more slurry lagoons or one or more landfill wells may be sealed and configured to output the one or more gas mixtures to the manifold via one or more ports.

[0027] By "landfill wells" is meant landfill deposits that contain biowaste, preferably decommissioned landfill deposits having a ventilation outlet. Typically, these decommissioned landfill deposits have been covered, with ventilation outlets provided to allow gases to vent to the atmosphere where it is usually collected and / or processed. For instance, organic waste has been banned in landfills in the EU since 1997. However, older landfill deposits may still contain organic waste, and once decommissioned the landfill deposits act as a source of combustible gas that, according to EU regulations, must be collected and / or processed to avoid polluting emissions being released into the atmosphere.

[0028] The process may further comprise storing biowaste in, and / or adding biowaste to, the one or more biowaste stores. Biowaste may, for instance, be added to (sealed) slurry tanks or slurry lagoons via one or more access openings, such as a door or hatch.

[0029] The manifold may be configured to receive each of the one or more gas mixtures from a respective one or more gas stores. The at least one combustible gas may be methane, ethane, or propane, or butane, or another carbon-containing gas.

[0030] The process may further comprise obtaining one or more data associated with the combustion. The one or more data comprises data indicative of at least one of: a combustibility of the combustible gas mixture; a characteristic of a flame generated during the combusting; a composition of a gas mixture within the system, the gas mixture being the one or more gas mixtures, or the processable gas mixture, or the combustible gas mixture; and an oxygen volume and / or an oxygen concentration within an exhaust gas mixture within the chimney.

[0031] In some examples, the one or more data comprises data indicative of at least the oxygen volume and / or the oxygen concentration within the exhaust gas mixture within the chimney. This may provide a direct indication of the combustion efficiency.

[0032] Controlling one or more parameters of the process may include controlling the one or more parameters of the process based on the obtained one or more data. The process may further comprise repeating steps (i)-(vii) in accordance with the controlled parameter. Repeating steps (i)-(vii) in accordance with the controlled parameter may, for example, facilitate continuous operation of the system.

[0033] The process may further comprise adjusting the one or more parameters of the process based on the obtained one or more data. The process may further comprise repeating some or all of the steps above in accordance with the adjusted parameter. The process may further comprise controlling or adjusting a further one or more parameters of the process based on the obtained one or more data. The process may further comprise repeating some or all of the steps above in accordance with the controlled or adjusted parameter. The further one or more parameters may comprise at least one of: a flow rate or volume of the water vapour removed from the processable gas mixture; a flow rate or volume of the oxygen-containing gas introduced into the gas mixture; a flow rate or volume of the combustible gas mixture conveyed into the combustion region; a flow rate or volume of the one or more gas mixtures into the manifold; a pressure of the combustible gas mixture; and / or a temperature within the combustion region.

[0034] Adjusting one or more parameters of the process based on the obtained one or more data may be done with the aim of, for example, improving the position and / or size and / or quality of the flame.

[0035] The introducing oxygen-containing gas into the processable gas mixture may include introducing atmospheric gas into the processable gas mixture.

[0036] The obtaining one or more data may include obtaining, by one or more sensors of the system, data indicative of one or more conditions associated with the combustion. The one or more conditions may include one or more of: a position of the flame within the combustion region; a size of the flame within the combustion region; a quality of the flame; a temperature of the flame; and an oxygen volume or concentration in an exhaust gas mixture within the chimney.

[0037] In some examples, the one or more conditions may include at least the oxygen volume or concentration in the exhaust gas mixture within the chimney. This may provide a direct indication of the combustion efficiency.

[0038] The one or more sensors may be positioned and oriented to detect radiation and / or a gas emitted during the (vii) combustion. The one or more sensors may comprise one or more of: an ultra-violet sensor; an infra-red sensor; a temperature sensor; and / or an oxygen detector configured to detect oxygen present in an exhaust gas mixture during and / or after the combustion.

[0039] In some examples, the one or more sensors may comprise at least the oxygen detector configured to detect oxygen present in the exhaust gas mixture during and / or after the combustion. This may allow sensing data providing a direct indication of the combustion efficiency.

[0040] The torch may comprise a cone disposed within the chimney and separated from the chimney by an air gap. The combustion may occur within the cone. The conveying the combustible gas mixture from the mixing chamber into the combustion region may include conveying the combustible gas mixture into the cone via the nozzle. The one or more parameters of the process may include a temperature of the cone.

[0041] The obtained one or more data associated with the combustion may comprise data indicative of a position of the flame above a base of the combustion region. The method may further comprise iterating some or all of the above steps until the obtained one or more data is indicative of a position of the flame above a base of the combustion region being about 1 cm to 40 cm, for instance about 2 cm to about 10 cm.

[0042] The system may comprise one or more baffles disposed within the mixing chamber. The conveying the combustible gas mixture from the mixing chamber into the combustion region of the system may include conveying the combustible gas mixture along a tortuous, convoluted, or turbulent path defined by the one or more baffles.

[0043] The process may further comprise exhausting combustion products from the combustion unit. A time from the combusting to the exhausting of gases from the combustion unit may be at least about 0.3 seconds.

[0044] The conveying the combustible gas mixture from the mixing chamber into a combustion region of the system may include passing the combustible gas mixture through a diffusion plate.

[0045] The obtained one or more data associated with the combustion may comprise a ratio between oxygen and one or more other gases in the combustible gas mixture or the processable gas mixture.

[0046] The process may further comprise removing one or more carbon-containing or polluting gases produced by the combusting. The removing the one or more carbon-containing or polluting gases may occur before the exhausting the combustion products.

[0047] In a further aspect, there is provided a system for treating one or more gas mixtures containing at least one combustible gas. The system further comprises a manifold. The system further comprises a pressurising means. The system further comprises a pre-combustion unit comprising a mixing chamber and an oxygen-containing gas introduction means. The system further comprises a combustion unit comprising a chimney, defining therewithin a combustion region, and a combustion means. The system optionally further comprises a control means. The manifold is configured to receive each of the one or more gas mixtures, combine the one or more gas mixtures thereby to produce a processable gas mixture, and convey the processable gas mixture into the mixing chamber. The pressurising means is configured to pressurise the processable gas mixture and, optionally, remove water vapour from the processable gas mixture. The oxygen-containing gas introduction means is configured to introduce oxygen-containing gas into the processable gas mixture within the mixing chamber, thereby to produce a combustible gas mixture within the mixing chamber. The mixing chamber is configured to convey the combustible gas mixture into the combustion region. The combustion means is configured to combust the combustible gas mixture within the combustion region. The control means is configured to control one or more parameters of the system. The one or more parameters comprises at least one of: a flow rate or volume of the water vapour removed from the processable gas mixture; a flow rate or volume of the oxygen-containing gas introduced into the gas mixture; a flow rate or volume of the combustible gas mixture conveyed into the combustion region; a flow rate or volume of the one or more gas mixtures into the manifold; a pressure of the combustible gas mixture; and / or a temperature within the combustion region.

[0048] The manifold may be configured to receive each of the one or more gas mixtures from a respective one or more biowaste stores.

[0049] The one or more biowaste stores may comprise one or more slurry tanks or one or more slurry lagoons. Optionally, the one or more biowaste stores may comprise at least one of: one or more slurry tanks, one or more slurry lagoons or one or more landfill wells. The at least one combustible gas may be methane.

[0050] The one or more slurry tanks or one or more slurry lagoons may be sealed and configured to output the one or more gas mixtures to the system via one or more ports.

[0051] The manifold may be configured to receive each of the one or more gas mixtures from a respective one or more gas stores. The at least one combustible gas may be methane, ethane, or propane, or butane, or another carbon-containing gas.

[0052] The system may further comprise a monitoring means configured to obtain one or more data associated with the combustion. The one or more data comprises data indicative of at least one of: a combustibility of the combustible gas mixture; a characteristic of the flame during the combusting; a composition of a gas mixture within the system, the gas mixture being the one or more gas mixtures, or the processable gas mixture, or the combustible gas mixture; and an oxygen volume and / or an oxygen concentration within an exhaust gas mixture within the chimney.

[0053] The one or more data comprises data indicative of at least the oxygen volume and / or the oxygen concentration within the exhaust gas mixture within the chimney

[0054] The control means may be configured to control the one or more parameters based on the obtained one or more data. The control means may be configured to adjust the one or more parameters based on the obtained one or more data. The control means may be configured to control or adjust a further one or more parameters based on the obtained one or more data. The further one or more parameters comprises at least one of: a flow rate or volume of the water vapour removed from the processable gas mixture; a flow rate or volume of the oxygen-containing gas introduced into the gas mixture; a flow rate or volume of the combustible gas mixture conveyed into the combustion region; a flow rate or volume of the one or more gas mixtures into the manifold; a pressure of the combustible gas mixture; and / or a temperature within the combustion region.

[0055] The oxygen-containing gas introduction means may be configured to introduce atmospheric gas into the processable gas mixture.

[0056] The monitoring means may include one or more sensors. The one or more data may be indicative of one or more conditions associated with the combustion. The one or more conditions may include one or more of: a position of the flame within the combustion region; a size of the flame within the combustion region; a quality of the flame; a temperature of the flame; and an oxygen volume or concentration in an exhaust gas mixture within the chimney.

[0057] In some examples, the one or more conditions may include at least the oxygen volume or concentration in the exhaust gas mixture within the chimney

[0058] The one or more sensors may be positioned and oriented to detect radiation and / or a gas emitted during the combustion. The one or more sensors may comprise one or more of: an ultra-violet sensor; an infra-red sensor; a temperature sensor; and / or an oxygen detector configured to detect oxygen present in an exhaust gas mixture during and / or after the combustion.

[0059] In some examples, the one or more sensors may comprise at least the oxygen detector configured to detect oxygen present in the exhaust gas mixture during and / or after the combustion.

[0060] The torch may comprise a cone disposed within the chimney and separated from the chimney by an air gap. The combustion may occur within the cone, and mixing chamber may be configured to convey the combustible gas mixture into the cone via a nozzle. A base of the chimney may be sealed around the nozzle such that the only inlet to the chimney is via the nozzle. The one or more parameters of the process may include a temperature of the cone.

[0061] The one or more data associated with the combustion may comprise data indicative of a ratio of oxygen to combustible gas within the combustible gas mixture. The system may be configured to iterate the conveying, combusting, and controlling and / or adjusting the one or more parameters until the one or more data obtained is indicative of a ratio of oxygen to combustible gas (methane) within the combustible gas mixture of at least about 2: 1 (oxygen: methane), preferably above 2.1 : 1, such as above 2.3: 1, more preferably above 2.5: 1.

[0062] The obtained one or more data associated with the combustion may comprise data indicative of a position of the flame above a base of the combustion region. The system may be configured to iterate the conveying, combusting, and controlling and / or adjusting the one or more parameters until the one or more data obtained is indicative of a position of the flame above a base of the combustion region being about 2 cm to about 10 cm.

[0063] The system may comprise one or more baffles disposed within the mixing chamber and configured to define a tortuous, convoluted, or turbulent path for the combustible gas mixture being conveyed into the combustion region.

[0064] The system may further comprise an exhaust configured to exhaust the combustion products from the combustion unit.

[0065] The combustion unit may be configured such that a time from the combusting to the exhausting of gases from the combustion unit is at least about 0.3 seconds.

[0066] The system may further comprise a diffusion plate configured to deliver the combustible gas mixture from the mixing chamber into the combustion region.

[0067] The obtained one or more data associated with the combustion may comprise a ratio between oxygen and one or more other gases in the combustible gas mixture or the processable gas mixture.

[0068] The system may further comprise means for removing one or more carbon-containing or polluting gases produced by the combustion. The means for removing one or more carbon-containing or polluting gases produced by the combustion may be configured to remove the one or more carbon-containing or polluting gases before exhausting the combustion products.

[0069] The system may be a system in accordance with any preceding aspect.

[0070] In a yet further aspect, there is provided a combustion unit. The combustion unit comprises a chimney defined by an outer wall. The combustion unit further comprises a cone disposed within the chimney, the cone at least partially defining therewithin a combustion region. The combustion unit further comprises an inlet configured to introduce a combustible gas to the combustion region. The outer wall of the chimney surrounds the cone and extends beyond an open end of the cone, defining a gap between the cone and the outer wall, thereby to limit an airflow and / or a heat exchange between an exterior of the outer wall and the combustion region. The chimney is closed from receiving fluids other than through the inlet.

[0071] The combustion unit may further comprise one or more sensors positioned and oriented to detect radiation and / or a gas emitted during the combustion. The one or more sensors may comprise one or more of: an ultra-violet sensor; an infra-red sensor; a temperature sensor; and / or an oxygen detector configured to detect oxygen present in an exhaust gas mixture during and / or after the combustion.

[0072] In some examples, the one or more sensors may comprise at least the oxygen detector configured to detect oxygen present in the exhaust gas mixture during and / or after the combustion.

[0073] A diffusion plate may be between the inlet and the combustion region.

[0074] The inlet may be provided with a nozzle configured to deliver the combustible gas into the combustion region.

[0075] A base of the chimney may be sealed around a nozzle such that the only inlet to the chimney is via the nozzle.

[0076] The one or more parameters of the process may include a temperature of the cone.

[0077] BRIEF DESCRIPTION OF THE FIGURES

[0078] Examples of the present disclosure are described below with reference to the accompanying drawings, in which:

[0079] Figure 1 is a schematic illustration depicting a perspective view of a system for treating gas mixtures released from biowaste;

[0080] Figure 2 is a schematic illustration depicting a side view of the system for treating gas mixtures released from biowaste; Figure 3 is a schematic illustration depicting the system for treating gas mixtures released from biowaste; and

[0081] Figure 4 is a process flow diagram depicting steps of a process for treating gas mixtures released from biowaste.

[0082] DETAILED DESCRIPTION OF THE INVENTION

[0083] Prior to outlining the system and process of the present disclosure in more detail, a set of terms and conventions is first defined.

[0084] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0085] Slurry tank

[0086] In the present context, the term "slurry tank" refers to a structure for gathering and storing biowaste, including (but not limited to) animal (e.g., cow, pig, chicken, etc.) excrement, other animal (e.g., cow, pig, chicken, etc.) waste products, and other organic (e.g., plant) matter such as waste food and substances (e.g. straw bedding) washed from the enclosures housing animals. Slurry tanks are, in the present context, understood to be for storing biowaste prior to or during decomposition, such that decomposition gas mixtures may be collected from respective outputs of the slurry tanks, e.g., via a manifold. One or more slurry tanks may form a part of a gas mixture treatment system or be isolated (i.e., separated) from a gas mixture treatment system.

[0087] In the context of the present disclosure, the slurry tank may be a free standing (above ground) structure such as a silo or tank, or may be a structure formed in the ground, such as a lagoon, pond or reservoir. From a technical perspective, these different structures are considered equivalent and may be used interchangeably, provided they are adapted to collect and direct the gasses emitted in a suitable way.

[0088] Preferably, the slurry tank and / or slurry lagoon contains manure (i.e. animal excrement typically used for fertilising land).

[0089] Torch In the present context, the term "torch", also known as a "combustion torch" or "flare", is an industrial flame burner for combusting a gas mixture in treatment systems, such as the gas mixtures produced by biowaste decomposition and described herein.

[0090] Chimney

[0091] In the present context, the term "chimney" is an industrial architectural ventilation for isolating gases, and specifically those produced by combustion of the gas mixtures produced by biowaste decomposition as described herein.

[0092] Cone

[0093] In the present context, the term "cone" refers to a structure for heating and / or preheating a gas mixture within a chimney, prior to the mixture's combustion by a torch. In particular, the cone may be configured to insulate, e.g., keep warm, a combustion region, thereby to provide an optimal environment for stable combustion. In some instances, a cone configured in this way allows for the methane concentration of combusted gas mixtures to be lowered once a combustion is stable, while maintaining flame quality. Unless specified otherwise, the cone may be of any geometry or volume, e.g., conical, prismatic, rectangular prismatic, rectangular parallel piped, cuboidal, pyramidal, frustrum-shaped, etc. A cone as described herein has a geometry selected principally for functional purposes, taking into account, e.g., gas mixture composition, combustion efficiency, chimney geometry, etc.

[0094] Atmospheric gas

[0095] In the present context, the term "atmospheric gas", refers to a gas mixture comprising predominantly nitrogen and oxygen, in relative concentrations typical of the Earth's atmosphere at ground level (for instance at sea level). Unless specified otherwise, reference to "atmospheric gas", in the present context, encompasses reference to any volume of gas which can be collected and stored from the atmosphere without the need for further treatment or processing (e.g., adding, combusting, or removing gaseous components).

[0096] About

[0097] Wherever the term "about" is employed herein in the context of amounts, for example absolute amounts, such as numbers, purities, concentrations, weights, sizes, etc., or relative amounts (e.g. percentages, equivalents or ratios), timeframes, and parameters such as temperatures, pressure, etc., it will be appreciated that such variables are approximate and as such may vary by ±10%, for example ± 5% and preferably ± 2% (e.g. ± 1%) from the actual numbers specified. This is the case even if such numbers are presented as percentages in the first place (for example 'about 10%' may mean ± 10% about the number 10, which is anything between 9% and 11%).

[0098] System for treating gas mixtures released from biowaste

[0099] Figure 1 depicts a system 100 for treating a gas mixture released from biowaste.

[0100] The system 100 comprises a manifold unit 102 comprising a manifold (not shown) having a plurality of conduits, each conduit being configured to receive a respective gas mixture from a respective slurry tank (not shown) containing decomposing biowaste.

[0101] The conduits are typically attached to the upper region of the roof of a slurry tank, such that they extract the gasses formed and transport them to the manifold unit 102.

[0102] Flow of a respective gas mixture through each conduit of the plurality of conduits may be independently controlled, e.g., via a respective one or more valves disposed in each conduit, thereby to provide relative control of gas mixtures flowing into the manifold. By way of example, a first gas mixture released from a first slurry tank may differ substantially in relative gas composition from a second gas mixture released from a second slurry tank, owing to, e.g., biowaste composition, decomposition conditions, age of biowaste, etc. The combined gas mixture formed in the manifold, resulting from the mixing of respective gas mixtures received into the manifold via the plurality of conduits, is hereinafter referred to as the "processable gas mixture", unless otherwise specified.

[0103] Respective flow rates of the gas mixtures through the plurality of conduits are controlled by respective pumps of a plurality of pumps. In this embodiment, each pump (not shown) of the plurality of pumps is controllable and housed within the manifold unit 102, housed externally (not shown) to the manifold unit 102, or a combination of these. Preferably, each pump of the plurality of pumps is housed within the manifold unit 102.

[0104] Locating the pumps within the manifold is preferred, as this creates a reduced pressure in the conduits that draws processable gas from the biowaste store. The reduced pressure decreases the likelihood of leakage of processable gas through any defects in the conduit. However, optionally it is possible to include pumps in the conduits to force the processable gas to the manifold.

[0105] The respective gas mixtures flowing through the conduits are typically processed to reduce the water content prior to entering the manifold. This may be via one or more water removal means positioned in each respective conduit between the slurry tank and the manifold.

[0106] Such water removal means may be, or comprise, a water trap to remove water that condenses within the conduit. Water condensation can occur as the gas mixture is typically warm when leaving the slurry tank, and may cool when passing through the conduit to the manifold. This cooling may cause precipitation of water from the humid gas stream, which can be collected via a water trap.

[0107] Alternatively or additionally, each of the one or more conduits may contain a water condenser that processes the gas mixture to remove water prior to the gas mixture entering the manifold.

[0108] Since the gas compositions received via the plurality of conduits may differ significantly in (at least) oxygen and / or combustible gas content, adjusting the relative flow rates of the gas mixtures may be considered a first means of adjusting an oxygen and / or combustible gas content of a gas mixture (specifically, the processable gas mixture) in the system 100.

[0109] A flow rate of the processable gas mixture through a main conduit of the manifold is controlled by one or more main pumps (not shown) housed within the manifold unit 102.

[0110] In some embodiments, the system further comprises a water vapour removal means (not shown) disposed in the manifold unit 102. The water vapour removal means is configured to remove a first volume of water vapour from the processable gas mixture flowing through the manifold.

[0111] The water vapour removal means may comprise, e.g., a water compressor which compresses the gas leading to condensation of the water, such that it may be removed. The processable gas mixture having been removed of the first volume of water vapour is hereinafter referred to as the "dry gas mixture". Preferably, the system 100 comprises, in place of or in addition to the water removal means, a pressurising means (e.g., a compressor), which may be integral with any suitable pump of the system 100 described herein (or a further pump of the system not explicitly disclosed herein). The pressurising means (not shown) may lower a humidity or vapour content of the processable gas mixture by pressurisation, and, in embodiments where the pressurising means is in place of the water vapour removal means, may thus itself be considered a water vapour removal means, irrespective of whether a volume of water is strictly removed from the system.

[0112] Optionally, a water trap may be disposed in the manifold, e.g., in the main conduit 206. A further optional water trap or further water vapour removal means may be provided within the pressurising means, to further reduce humidity and further remove condensation if necessary. The pressurising means (e.g., a compressor) may be disposed within a suitable pump of the system, e.g., in the main pump of the manifold unit 102, or in a backup pump, or in a dedicated pump for pressurising and / or water vapour removal.

[0113] Removal of water vapour (even if only by pressurisation to reduce humidity) within the manifold provides a gas mixture with increased combustibility and ensures a more consistent and efficient burn. Removal of water prior to the manifold (i.e. in the one or more conduits) is not essential, but may be helpful in preventing excess condensation build up within the manifold as it processes the processable gas mixture thereby to produce the dry gas mixture.

[0114] The term "dry gas mixture" may, here and hereinafter, refer to the processable gas mixture having been pressurised (and, e.g., thereby dehumidified) irrespective of whether a volume of water has strictly been removed from the processable gas mixture. A "dry gas mixture" may therefore still contain water and is characterised by the lower humidity than the processable gas mixture.

[0115] Preferably, the processable gas mixture is pressurised in the manifold unit 102 by a pressurising means (not shown).

[0116] The manifold unit 102 comprises an output 104 configured to output the dry gas mixture having been removed of the first volume of water vapour.

[0117] The system 100 further comprises a pre-combustion unit 106. The pre-combustion unit 106 comprises an input 108 configured to receive the dry gas mixture from the output 104 of the manifold unit 102. The pre-combustion unit 106 further comprises a dry gas mixture conduit 109 configured to convey the received dry gas mixture into a mixing chamber 110 of the pre-combustion unit 106. Fluid connection of the output 104 of the manifold unit 102 and the input 108 of the pre-combustion unit 106 may be provided by a conduit (not shown).

[0118] The pre-combustion unit 106 comprises an oxygen-containing gas conduit 112 configured to introduce oxygen-containing gas, conveyed from an oxygen-containing gas source (not shown), into the mixing chamber 110 of the pre-combustion unit 106. A blow back (check) valve is disposed along the oxygen-containing gas conduit 112 to ensure that oxygen-containing gas entering the pre-combustion unit 106 cannot back- flow away from the mixing chamber 110.

[0119] The oxygen-containing gas received via the oxygen-containing gas conduit 112 mixes with the dry gas mixture received via the input 108 in the mixing chamber 110. Flow of oxygen-containing gas into the mixing chamber 110 from the oxygen-containing gas source may be considered a second means of adjusting an oxygen and / or combustible gas content of a gas mixture (specifically, the dry gas mixture) in the system 100. A controllable oxygen-containing gas pump 114 of the system 100 is configured to control a flow rate of the oxygen-containing gas into the mixing chamber 110.

[0120] Preferably, the oxygen-containing gas is atmospheric gas. Thus, the oxygencontaining gas source may simply be the atmosphere surrounding the pre-combustion unit, which is drawn in an pressurised by the oxygen-containing gas pump (i.e. oxygencontaining gas pump).

[0121] The gas mixture present in the mixing chamber 110 is hereinafter referred to as the "combustible gas mixture".

[0122] The combustibility of the combustible gas mixture may be controlled by adjusting the oxygemcombustible gas molar / molecular ratio.

[0123] For methane, the preferred ratio is above 2: 1 (oxygen: methane), preferably above 2.1: 1, such as above 2.3: 1, more preferably above 2.5: 1.

[0124] When the oxygen :combustible gas (e.g. methane) ratio is controlled in this way, the combustibility of the combustible gas mixture may be increased, ultimately increasing the efficiency of the system. At typical atmospheric gas compositions and conditions, a threshold oxygen: methane ratio of 2: 1 tends to be provided by a corresponding ratio of atmospheric gas:methane of about 9.5: 1.

[0125] The oxygen detector in the chimney 118 configured to measure excess oxygen in exhaust gases forms a part of an active control system of the system 100, as will be described in more detail below.

[0126] The system 100 further comprises a combustion unit 116 comprising a chimney 118. The mixing chamber 110 is fluidly connected to the chimney 118 via a nozzle (not shown). In operation of the system 100, the combustible gas mixture passes from the mixing chamber 110 into the chimney 118 of the combustion unit 116. The combustible gas mixture may be drawn by a pressure differential from the mixing chamber 110 into the combustion unit 116. A pump (not shown) may be provided in the system 100 to controllably draw the combustible gas mixture from the mixing chamber 110 into the combustion unit 116.

[0127] The chimney 118 houses a combustion means, namely a torch (not shown), for combusting the combustible gas mixture. One or more combustion products (e.g., carbon dioxide gas and water vapour) of the combustion are expelled from an exhaust 120 of the chimney 118.

[0128] Figure 2 depicts a side view of the system 100, showing the manifold unit 102, the pre-combustion unit 106 and the combustion unit 116.

[0129] As illustrated in Figure 2, the mixing chamber 110 comprises a plurality of baffles 200 which together disrupt the path of the combustible gas mixture into the combustion unit 116. The combustible gas mixture is thus forced to follow a turbulent (e.g., indirect or tortuous) path, thereby to more effectively mix the gases within the combustible gas mixture such that the gas mixture entering the combustion unit 116 undergoes efficient (and chemically complete) combustion. In some embodiments, the plurality of baffles 200 is configured such that the combustible gas mixture is forced to follow a convoluted or lengthened path.

[0130] As illustrated in Figure 2, a diffusion plate 202 is disposed at an opening of the nozzle 204 such that the combustible gas mixture passes through the diffusion plate 202 to enter an interior of the chimney 118 from the mixing chamber 110 situated below. The diffusion plate 202 delivers the combustible gas mixture to a cone 206 of the torch, the cone being disposed within the chimney 118. The cone is configured to pre-heat the combustible gas mixture prior to combustion. Pre-heating the cone provides for more efficient (and chemically complete) combustion.

[0131] The cone need not be configured with a heating element, and preferably it is not. Rather, the cone is heated by the flame in the combustion region, and once combustion is occurring the heat of the cone acts to pre-heat the combustible gas mixture prior to combustion as it enters the combustion region.

[0132] The cone part-bounds a combustion region for the combustible gas mixture, the combustion region being defined within the cone. Advantageously, an air gap is provided between the cone 206 and the chimney 118, so as to insulate the cone from the effects of the external air on the outer wall of the chimney. The cone therefore positions the flame optimally within the chimney and protects the combustion process from, e.g., the effects of weather and / or temperature conditions external to the chimney 118. The risk of flame-out during the combustion process, or of inefficient (or chemically incomplete) combustion, is thereby mitigated. The air gap may therefore be considered to restrict an airflow and / or a heat exchange between an exterior of the chimney and the combustion region.

[0133] Preferably, the base of the chimney 118 is sealed around the nozzle 204, such that the only inlet to the chimney is via the nozzle. In this way, the combustion region is closed from receiving fluids at any inlet other than the mixing chamber, such that only the combustible gas mixture received into the combustion region combusts during the combusting. This improves the control over the combustion process, and creates relatively still air around the cone to improve thermal insulation and maintain temperature regulation in the combustion region.

[0134] Preferably, the flame during combustion occupies a volume within the combustion region (or the base of the flame starts at) approximately 1 cm - 40 cm, e.g., 2 cm - 20 cm, or 2 cm - 10 cm, or 3 cm - 6 cm, above the diffusion plate 202.

[0135] When above the diffusion plate in this way, the flame is able to consume a steady supply of pre-heated combustible gas and burn efficiently. If too close to the diffusion plate, the risk of blow back increases. If too far above the diffusion plate, the benefit of even controlled gas flow through the diffusion plate may be lost. A height of the cone 206 may be from about 5 to 100 cm, for instance from about 5 to 60 cm, for instance from about 15 to 45 cm, and preferably from about 25 to 35 cm.

[0136] A diameter of the cone 206 may be from about 5 to 75 cm, for instance from about 5 to 50 cm, for instance from about 10 cm to 25 cm , and preferably from about 13 to about 20 cm.

[0137] A height of the chimney 118 may be from about 50 to 1500 cm, for instance from about 50 to 800 cm, for instance from 100 cm to 500 cm, and preferably from about 200 to about 400 cm, such as about 300 cm.

[0138] A diameter of the chimney 118 may be from about 8 to 120 cm, for instance from about 8 to 80cm, for instance from about 15 to about 50 cm, preferably from about 20 to about 40 cm, such as about 30 cm.

[0139] A width of the air gap defined between the chimney 118 and the cone 206 may be from about 1 to about 30 cm, for instance from about 1 to 20 cm, for instance from about 3 cm to about 10 cm, such as from about 4 cm to about 8 cm, and preferably about 6 cm.

[0140] The combustion unit 116 further comprises a sensor 208 configured to obtain data associated with the flame during combustion. As illustrated in Figure 2, the sensor 208 is configured (e.g., angled) to detect electromagnetic radiation directly from combustion region. The electromagnetic radiation detected by the sensor 208 is indicative of a position and / or size and / or quality of the flame within the combustion region. For example, the sensor 208 may be an ultra-violet or infra-red sensor configured to indicate a maximum signal when data received comprises electromagnetic radiation indicative that the flame is of optimal size, optimal temperature, and / or positioning above the diffusion plate 202).

[0141] The sensor 208 may, in some embodiments, be, or include, a temperature sensor configured to detect the temperature of the flame, the temperature of the combustible gas, the temperature of the exhaust gas, or any combination thereof.

[0142] The sensor 208 may, in some embodiments, be, or include, an oxygen detector configured to detect oxygen present in an exhaust gas mixture during and / or after the combustion. The sensor 208 may form a component of an active control system further comprising the oxygen-containing gas feed pump 114. The active control system may be configured to control the oxygen-containing gas feed pump 114, thereby to control / adjust a flow rate of the combustible gas mixture into the chimney 118 of the combustion unit 116. Data received by the sensor 208 indicative of a position and / or size and / or quality of the flame within the combustion region, and / or indicative of an oxygen volume and / or an oxygen concentration within the chimney, can thereby be used to adjust a composition of the combustible gas mixture in real-time (e.g., in continuous operation of the system 100). Thus, the position and / or size and / or quality of the flame may be improved, and this improvement monitored and maintained in real-time by the sensor 208 and active control system. It is desirable to maintain a pre-determined, calculated, or predicted oxygen excess within exhaust gases in the chimney 118, thereby maintaining a minimum quality of combustion within the combustion region. Data received by the sensor 208 indicative of the oxygen volume and / or the oxygen concentration within the chimney may be particularly beneficial in this regard.

[0143] In this manner, the second means of adjusting an oxygen and / or combustible gas (e.g. methane) content of a gas mixture (specifically, the combustible gas mixture) in the system 100 may thus be controlled via the active control system.

[0144] In some embodiments, one or more manifold sensors (not shown) may be provided in the system 100 (e.g., within one or more conduits within the plurality of conduits) and configured to obtain data indicative of the respective composition(s) of gas mixture(s) received from one or more of the slurry tanks. The one or more manifold sensors may form a further component of the active control system, as will now be explained.

[0145] The data obtained from the one or more manifold sensors may be used to control / adjust a flow rate of the combustible gas mixture into the chimney 118 of the combustion unit 116 by control of the oxygen-containing gas feed pump 114. Data received by the one or more manifold sensors indicative of the respective composition(s) of gas mixture(s) received from one or more of the slurry tanks can thereby be used to adjust a composition of the combustible gas mixture in real-time (e.g., in continuous operation of the system 100).

[0146] For example, if it is determined, based on the data obtained by the one or more manifold sensors, that a slurry tank is providing a relatively methane-rich gas mixture into the processable gas mixture (thereby resulting in a correspondingly methane-rich combustible gas mixture), a downstream flow rate of atmospheric gas into the mixing chamber 110 can be adjusted accordingly.

[0147] In this manner, the second means of adjusting an oxygen and / or combustible gas (e.g. methane) content of a gas mixture (specifically, the combustible gas mixture) in the system 100 may thus be further controlled via the active control system.

[0148] One or more pumps of the plurality of pumps configured to control the flow rates of the gas mixtures may form a further component(s) of the active control system, as will now be explained.

[0149] The data obtained from the one or more manifold sensors may, additionally or alternatively, be used to control / adjust one or more respective flow rates of the gas mixtures through the plurality of conduits in the manifold unit 102, by control of a corresponding one or more pumps of the plurality of pumps. Data received by the one or more manifold sensors indicative of the respective composition(s) of gas mixture(s) received from one or more of the slurry tanks may thereby be used to adjust a composition of the processable gas mixture in real-time (e.g., in continuous operation of the system 100).

[0150] For example, if it is determined, based on the data obtained by the one or more manifold sensors, that a slurry tank is providing a relatively methane-rich gas mixture into the processable gas mixture (thereby resulting in a correspondingly methane-rich combustible gas mixture), a flow rate of the methane-rich gas mixture into the main conduit of the manifold unit 102 may be adjusted accordingly, and / or one or more flow rates of other gas mixtures along the other conduits into the main conduit of the manifold 102 may be adjusted accordingly.

[0151] In this manner, the first means of adjusting an oxygen and / or combustible gas (e.g. methane) content of a gas mixture (specifically, the processable gas mixture) in the system 100 may thus be controlled via the active control system.

[0152] In some embodiments, a further manifold sensor (not shown) may be provided in the main conduit of the manifold unit 102 and configured to obtain data indicative of the composition of the processable gas mixture before it is conveyed to the pre-combustion unit 106. The further manifold sensor may form a yet further component of the active control system, as will now be explained. The data obtained from the further manifold sensor may be used to control / adjust a flow rate of the combustible gas mixture into the chimney 118 of the combustion unit 116 by control of the oxygen-containing gas feed pump 114. Data received by the further manifold sensor indicative of the composition of the processable gas mixture may thereby be used to adjust a composition of the combustible gas mixture in realtime (e.g., in continuous operation of the system 100). For example, if it is determined, based on the data obtained by the further manifold sensor, that the processable gas mixture in the main conduit of the manifold unit 102 is methane-rich (corresponding to a methane-rich combustible gas mixture), a downstream flow rate of atmospheric gas into the mixing chamber 110 can be adjusted accordingly.

[0153] In this manner, the second means of adjusting an oxygen and / or combustible gas (e.g. methane) content of a gas mixture (specifically, the combustible gas mixture) in the system 100 may thus be further controlled via the active control system.

[0154] The data obtained from the further manifold sensor may, additionally or alternatively, be used to control / adjust a flow rate of the processable gas mixture through the main conduit of the manifold unit 102, by control of the one or more main pumps. Data received by the further manifold sensor indicative of the composition of the processable gas mixture may thereby be used to adjust the rate of provision of combustible gas mixture to the combustion unit (e.g., in continuous operation of the system 100).

[0155] For example, if it is determined, based on the data obtained by the further manifold sensor, that the processable gas mixture in the main conduit of the manifold unit 102 is methane-rich (corresponding to a methane-rich combustible gas mixture), a flow rate of a methane-rich gas mixture into the main conduit of the manifold unit 102 may be adjusted accordingly, and / or one or more flow rates of other gas mixtures along the other conduits into the main conduit of the manifold unit 102 may be adjusted accordingly.

[0156] In this manner, the first means of adjusting an oxygen and / or combustible gas (e.g. methane) content of a gas mixture (specifically, the processable gas mixture) in the system 100 may thus be further controlled via the active control system.

[0157] By way of further example, if it is determined, based on the data obtained by the further manifold sensor, that the processable gas mixture in the main conduit of the manifold unit 102 is methane-rich (corresponding to a methane-rich combustible gas mixture), a flow rate of the processable gas mixture from the manifold unit 102 into the mixing chamber 110 may be adjusted accordingly.

[0158] In this manner, a combustion rate of the combustible gas mixture in the combustion unit 106 may thus be further controlled via the active control system.

[0159] Figure 3 depicts a schematic block diagram representing the system 100.

[0160] Gas mixtures received from the plurality of slurry tanks 300 along the plurality of conduits 302 are drawn by respective pumps of the plurality of pumps 304 into the main conduit 306 of the manifold unit 102, where the processable gas mixture is formed. In this embodiment, each pump 304 is independently controllable.

[0161] The water vapour removal means 308 of the system 100 removes a volume of water vapour from the processable gas mixture. In some embodiments, one or more further water vapour removal means may be disposed in the system 100, e.g., upstream of the manifold unit 102, and / or in the manifold unit 102, and / or between the manifold unit 102 and the pre-combustion unit 106, and / or in the pre-combustion unit 106, thereby to remove a further volume of water vapour from the processable gas mixture and / or dry gas mixture and / or combustible gas mixture.

[0162] The manifold unit 102 may be provided with one or more manifold sensors 310, as described above. In this embodiment, and as illustrated in Figure 3, each conduit of the plurality of conduits 302 is provided with a respective sensor 310. In some embodiments, only one or some of the plurality of conduits 302 are provided with a respective sensor 310, or no sensor 310 is present.

[0163] In this embodiment, the main conduit 306 is provided with the further manifold sensor 312. In some embodiments, the further manifold sensor 312 is disposed in another conduit in the manifold unit not depicted in Figure 3, or is absent.

[0164] The one or more main pumps 314 draw the processable gas mixture along the main conduit 306 and dry gas conduit 109 to the mixing chamber 110, via the outlet 104 of the manifold unit 102 and the inlet 108 of the pre-combustion unit 106.

[0165] The oxygen-containing gas pump 114 of the system 100 draws oxygen-containing gas from the oxygen-containing gas source 316 (most typically, this is atmospheric gas) into the mixing chamber 110, thereby to produce the combustible gas mixture. The combustible gas mixture is drawn (e.g., by a pressure differential which may be established by one or more further pumps not depicted in Figure 3) through the mixing chamber in a tortuous or turbulent path created by the plurality of baffles 200. The combustible gas mixture is thus effectively mixed during its passage through the mixing chamber 110.

[0166] The combustible gas mixture is passed from the pre-combustion unit 106 into the combustion unit 116 via the nozzle 204 and the diffusion plate 202, and into the combustion region defined by the cone 206.

[0167] Sensor 208 is configured to monitor the position and / or size and / or quality of the flame, and / or an oxygen volume or concentration in an exhaust gas mixture within the chimney as described above. The sensor 208, and, optionally, one or more of the sensors 310, 312 in the manifold unit 102, may, as components of the active control system, obtain data based on which the oxygen-containing gas pump 114 and, optionally, one or more of the pumps 304, 314 in the manifold unit 102, are control led / adjusted.

[0168] In this manner, the active control system of the system 100 ensures efficient and safe combustion by monitoring and controlling the flow rate of the combustible gas mixture into the combustion region and / or the combustible gas (e.g. methane) concentration of the combustible gas mixture introduced into the combustion region and / or the oxygen concentration of the combustible gas mixture introduced into the combustion region.

[0169] In some embodiments, a temperature of the cone is also controllable, e.g., based on at least some of the data obtained by the active control system. This provides further flexibility of flame position and / or size and / or quality, and further mitigates the risk of flame-outs or the detrimental impact of unfavourable chimney conditions (e.g., weather).

[0170] The system 100 may further comprise one or more pressurising means (not shown) for pressurising one or more of the respective gas mixtures received by the manifold 102, and / or the processable gas mixture, and / or the dry gas mixture, and / or the atmospheric gas, and / or the combustible gas mixture. The one or more pressurising means, if present, may form a further component of the active control system. That is, operation of the one or more pressurising means may be controlled based on some or all of the data obtained by the active control system. Improved flexibility, safety, and combustion efficiency may thus be provided.

[0171] The system 100 may further comprise a further water vapour removal means (not shown), e.g., upstream of the manifold unit 102, and / or in the manifold unit 102, and / or between the manifold unit 102 and the pre-combustion unit 106, and / or in the pre-combustion unit 106, thereby to remove a further volume of water vapour from the respective gas mixtures, and / or the processable gas mixture, and / or the dry gas mixture, and / or the combustible gas mixture.

[0172] As described above, the system 100 may comprise, in addition to or instead of the water vapour removal means and / or further water vapour removal means, a pressurising means (or a plurality of pressurising means), e.g., a compressor. The pressurising means may provide the function, or this function may be provided separately by a distinct water vapour removal means and / or, if present, further water vapour removal means.

[0173] In some embodiments, a mixture of combustible gases may be present in the combustible gas mixture, including hydrocarbons such as methane, ethane, propane and butane.

[0174] The exact composition of the combustible gas will depend on the source. For instance, in some embodiments, the source of combustible gas may be an overflow from propane or butane storage tanks, such that the system of the disclosure acts as a safety measure and reduced environmental impact of gas leaching by converting the combustible gas to combustion products.

[0175] Preferably, the combustible gas is methane.

[0176] Preferably, the one or more gas mixtures received by the system are received from one or more slurry tanks, and each contain predominantly or solely methane as the combustible gas.

[0177] In this embodiment, the one or more slurry tanks may be connected to the manifold unit of the system via a respective one or more conduits. The one or more slurry tanks (and / or one or more slurry lagoons and / or one or more landfill wells) may be substantially sealed and configured to output the one or more gas mixtures to the system via one or more ports.

[0178] Thus, a system for treating gas mixtures released from biowaste is provided.

[0179] Advantageously, embodiments of the above-described system provide a means for reducing methane and other harmful-gas pollution, e.g., output from biowaste decomposition, with an easy-to-operate, low maintenance, and high efficiency system. Advantageously, embodiments of the above-described system allow the efficient combustion even when processing gas sources containing relatively low methane concentrations (e.g., 5% by volume within the combustible gas mixture, and sometimes even lower) by providing a combustion region which is optimally configured. For example, the cone, diffuser, and air gap, and, in some embodiments, the active control system tasked with maintaining, e.g., combustion quality, contribute to an environment which is conducive to maintaining high combustion quality, ensuring efficient conversion of highly polluting methane gas to combustion products such as carbon dioxide and water.

[0180] In some embodiments, the combustible gas mixture is pre-heated, e.g., by, or in addition to being heated by, the cone. For example, in some embodiments, the combustible gas mixture may be heated to about 500 degrees Celsius prior to the point of ignition within the combustion region. For instance, the combustible gas mixture may be heated to a temperature of from about 200 to about 500 °C, for instance from 300 to 500 °C.

[0181] The systems shown in Figure 1, Figure 2 and Figure 3 relate to the preferred configuration wherein the reaction chamber is a chimney, and the oxidation occurs via combustion. However, the manifold and combustion unit as depicted in the figures (excluding the chimney) may be utilised in the alternative configurations of the system and process, such as those where the reaction chamber is a bioreactor.

[0182] Thus, collection and processing of the gas mixtures to form a processable gas mixture, and subsequent combination of this processable gas mixture with an oxygen-containing gas mixture optionally in a mixing chamber may occur prior to conveying the combustible gas mixture to a bioreactor. Thereafter, oxidation of the combustible gas mixture comprises consuming the combustible gas mixture as a feedstock within the bioreactor. Suitable bioreactors are known and typically contain methanotrophs, bacteria and archaea that oxidize methane. Typically, removal of methane from atmospheric air using a bioreactor is challenging, as the low levels of methane found in atmospheric air cannot usually sustain the microorganisms in the reactor. However, using the system of the disclosure, the combustible gas mixture may be configured to provide a suitable input to the bioreactor, ensuring its efficient and sustained use.

[0183] This configuration is particularly advantageous when the biowaste stores produce very low levels of combustible gases such as methane. Typically, the process will include a step of removing toxic gases prior to processing the combustible gas in the reaction chamber. Toxic gases that may be removed include hydrogen sulphide and / or ammonia, which may not be tolerated by the organisms in the bioreactor.

[0184] Likewise, rather than consuming the combustible gas mixture in a flare, the heat from the combustion may be used to another purpose, such as in a heating system connected to a building. The heating system may comprise heating water which is circulated within the building.

[0185] Process for treating gas mixtures released from biowaste

[0186] Figure 4 depicts a process 400 for treating, by the system 100, gas mixtures released from biowaste, and particularly the steps involved when the process is used for combustion.

[0187] The process 400 includes, at step s402, receiving, into the main conduit 306 of the manifold unit 102, the plurality of gas mixtures from the plurality of slurry tanks 300 via the plurality of conduits 302.

[0188] In this embodiment, step s402 includes operating one or more (e.g., all) of the plurality of pumps 304, thereby to draw the plurality of gas mixtures into the main conduit 306.

[0189] The process 400 includes, at step s404, removing, by the water vapour removal means 308, a volume of water vapour from the processable gas mixture produced at step s402. The process 400 includes, at step s406, conveying, by the one or more main pumps 314, the dry gas mixture resulting produced at step s404 out of the manifold unit 102 and into a mixing chamber of the pre-combustion unit 106.

[0190] The process 400 includes, at step s408, introducing, by the oxygen-containing gas pump 114, a volume of atmospheric gas into the mixing chamber 110, thereby to mix the dry gas mixture with the volume of atmospheric gas to produce the combustible gas mixture.

[0191] The process 400 includes, at step s410, conveying the combustible gas mixture through the mixing chamber 110, via the plurality of baffles 200, and into the combustion region of the torch via the nozzle 204.

[0192] In this embodiment, step s402 includes passing the combustible gas mixture through the diffusion plate 202, thereby to better (e.g., more homogeneously) diffuse the combustion reagents within the combustion region and thus improve flame quality. In other embodiments, however, the diffusion plate 202 may be omitted from the system 100.

[0193] The process 400 includes, at step s412, combusting, in a combustion region of the torch, the combustible gas mixture.

[0194] In this embodiment, step s412 includes combusting the combustible gas mixture in the cone, thereby to provide improved flame position and / or size and / or quality, and mitigating the risk of flame-outs or the detrimental impact of unfavourable chimney conditions (e.g., weather). In other embodiments, however, the cone may not be heated, or may be omitted altogether.

[0195] In this embodiment, the cone is housed within and separated from the chimney by an air gap, thereby to position the flame optimally within the chimney and protect the combustion process from, e.g., the effects of weather and / or temperature conditions further up the chimney 118. The risk of flame-out during the combustion process, or of inefficient (or chemically incomplete) combustion, is thereby mitigated.

[0196] The process 400 may include, at step s414, obtaining data associated with the flame during combustion. In this embodiment, the data associated with the flame may include electromagnetic radiation detected by the sensor 208 and indicative of a position and / or size and / or quality of the flame within the combustion region. Additionally, or alternatively, the data associated with the flame may be the oxygen content of the exhaust gas, wherein the chimney comprises an oxygen sensor. An absence of oxygen usually indicates incomplete combustion and if detected, the system can adjust the conditions until a desired level of oxygen is detected the exhaust gas.

[0197] The process 400 may include, at step s416, controlling, based on the data obtained at step s414, one or more of:

[0198] • a rate of operation of the oxygen-containing gas pump 114, thereby to control a flow rate of the atmospheric gas into the mixing chamber 110;

[0199] • a rate of operation of the one or more main pumps 314, thereby to control a flow rate of the processable gas mixture and / or dry gas mixture through the main conduit 306 and / or the dry gas conduit 109;

[0200] • one or more rates of operation of one or more of the plurality of pumps 304, thereby to control one or more flow rates of a respective one or more gas mixtures through respective conduits of the plurality of conduits 302;

[0201] • a flow rate of the one or more further pumps, thereby to control a flow rate of the combustible gas mixture through the mixing chamber 110;

[0202] • an operation of the pressurising means, thereby to control a pressure of the atmospheric gas, and / or the processable gas mixture, and / or the dry gas mixture, and / or the combustible gas mixture;

[0203] • an operation of the water removal means 308 and / or, if present, the further water removal means;

[0204] • the temperature of the cone within the torch of the combustion unit 116; and / or

[0205] • an oxygen volume or concentration in an exhaust gas mixture within the chimney 118.

[0206] As described with reference to embodiments above, execution of step s416 may be considered performance of active system control based on the data obtained at step s416.

[0207] The process 400 may further include, at step s418, obtaining data indicative of a composition of one or more of the gas mixtures within the system 100. The one or more gas mixtures may be, e.g. : one or more of the respective gas mixtures received from the slurry tanks 300; the processable gas mixture within the main conduit 306; the dry gas mixture within the main conduit 306 or the dry gas conduit 109; and / or the combustible gas mixture within the mixing chamber 110.

[0208] The data indicative of a composition of the one or more of the gas mixtures may be data indicative of a combustible gas (e.g. methane) concentration and / or an oxygen concentration and / or a water vapour concentration.

[0209] The process 400 may further include, at step 420, controlling, based on the data obtained at step s418, one or more of:

[0210] • a rate of operation of the oxygen-containing gas pump 114, thereby to control a flow rate of the atmospheric gas into the mixing chamber 110;

[0211] • a rate of operation of the one or more main pumps 314, thereby to control a flow rate of the processable gas mixture and / or dry gas mixture through the main conduit 306 and / or the dry gas conduit 109;

[0212] • one or more rates of operation of one or more of the plurality of pumps 304, thereby to control one or more flow rates of a respective one or more gas mixtures through respective conduits of the plurality of conduits 302;

[0213] • a flow rate of the one or more further pumps, thereby to control a flow rate of the combustible gas mixture through the mixing chamber 110;

[0214] • an operation of the pressurising means, thereby to control a pressure of the atmospheric gas, and / or the processable gas mixture, and / or the dry gas mixture, and / or the combustible gas mixture;

[0215] • an operation of the water removal means 308 and / or, if present, the further water removal means; and / or

[0216] • the temperature of the cone within the torch of the combustion unit 116.

[0217] As described with reference to embodiments above, execution of step s416 may be considered performance of active system control based on the data obtained at step s418.

[0218] Thus, a process for treating gas mixtures released from biowaste is provided.

[0219] In the above embodiments, a plurality of gas mixtures is received into the manifold unit from a plurality of slurry tanks or lagoons, the plurality of gas mixtures combining in the manifold unit to produce a processable gas mixture. In other embodiments, however, only a single gas mixture may be received into the manifold unit, and only a single conduit and single pump is required to convey the gas mixture (i.e., the processable gas mixture) through the manifold unit.

[0220] For example, in some embodiments, a gas mixture may be received from one or more (for instance one, or two, or three, or four, or five, or six, or more) slurry tanks or lagoons.

[0221] The system of the disclosure is thus able to overcome the challenges with the variable gasses emitted from slurry tanks. Even when the concentration of combustible gas is low, the system is able, via a combination of pressurisation and ensuring the correct oxygemcombustible gas ratios, to achieve high levels of efficiency of combustion of the combustible gas. Moreover, these efficiencies can be maintained even when high levels of combustible gas are present, or other gasses that may typically be problematic to combustion such as carbon dioxide. The high efficiency is achieved and maintained by the interacting combination of features described herein, particularly the control and feedback loop that ensures the combustible gas is delivered to the combustion region in a suitable form, and the combustion unit described herein that advantageously provides a combustion region that can be maintained due to the insulation from conditions external to the chimney, and which can be monitored by suitably positioned sensors.

[0222] Advantageously, embodiments of the above-described process provide a means for reducing methane and other harmful-gas pollution, e.g., output from biowaste decomposition, with an easy-to-operate, low maintenance, and high efficiency system.

[0223] Advantageously, embodiments of the above-described process tend to compensate, energetically speaking, for a relatively low methane concentration (e.g., 5% or even lower by volume within the combustible gas mixture) by providing a combustion region which is optimally configured. For example, the cone, diffuser, and air gap, and, in some embodiments, the active control system tasked with maintaining, e.g., combustion quality, contribute to an environment which is conducive to maintaining high combustion quality.

Claims

CLAIMS1. A process for treating, within a system, one or more gas mixtures containing at least one combustible gas, the process comprising:(i) receiving, via a manifold of the system, the one or more gas mixtures from a respective one or more biowaste stores, and processing said one or more gas mixtures to provide a processable gas mixture at above atmospheric pressure;(ii) combining the processable gas mixture with an oxygen-containing gas (such as atmospheric gas) to provide a combustible gas mixture optionally at above atmospheric pressure;(iii) conveying the combustible gas mixture to a reaction chamber; and(iv) oxidising the combustible gas mixture.

2. The process of claim 1, wherein: the one or more biowaste stores comprises one or more slurry tanks and / or one or more slurry lagoons and / or one or more landfill wells; and the at least one combustible gas is methane.

3. The process of any preceding claim, wherein the oxidising comprises combustion of the combustible gas mixture.

4. The process of claim 3, wherein the reaction chamber is a chimney.

5. The process of claim 4, wherein the combustible gas mixture is conveyed to the reaction chamber via a nozzle.

6. The process of claim 5, wherein a base of the chimney is sealed around the nozzle such that the only inlet to the chimney is via the nozzle.

7. The process of any preceding claim, wherein steps (ii), (iii) and (iv) comprise:(ii) conveying, from the manifold into a mixing chamber of the system, the processable gas mixture; introducing oxygen-containing gas (such as atmospheric gas) into the processable gas mixture within the mixing chamber to produce a combustible gas mixture within the mixing chamber; and(iii) conveying the combustible gas mixture from the mixing chamber into a combustion region of the system, the combustion region being a region defined within a chimney of the system; and(iv) combusting, in the combustion region, the combustible gas mixture.

8. The process of claim 7 when dependent on claim 5, wherein: the combustion region comprises a cone disposed within the chimney and separated from the chimney by an air gap; the (iv) combustion occurs within the cone, and the (iii) conveying the combustible gas mixture from the mixing chamber into the combustion region includes conveying the combustible gas mixture into the cone via the nozzle.

9. The process of any preceding claim, wherein: the process further comprises (v) obtaining one or more data associated with the combustion, wherein the one or more data comprises data indicative of at least one of: a combustibility of the combustible gas mixture; a characteristic of a flame generated during the combusting; a composition of a gas mixture within the system, the gas mixture being the one or more gas mixtures, or the processable gas mixture, or the combustible gas mixture; and / or an oxygen volume and / or an oxygen concentration within an exhaust gas mixture within the chimney; and(vi) based on the one or more data obtained, controlling one or more parameters of the process, wherein the one or more parameters comprises at least one of: a flow rate or volume of the water vapour removed from the processable gas mixture; a flow rate or volume of the oxygen-containing gas introduced into the gas mixture; a flow rate or volume of the combustible gas mixture conveyed into the combustion region; a flow rate or volume of the one or more gas mixtures into the manifold; a pressure of the combustible gas mixture; and / or a temperature within the combustion region.

10. The process of claim 9, wherein:the process further comprises repeating steps (i)-(iv) in accordance with the controlled parameter.

11. The process of claim 9 or claim 10, further comprising:(vii) adjusting the one or more parameters of the process based on the obtained one or more data, and, optionally, repeating steps (i)-(iv) in accordance with the adjusted parameter; and / or(viii) controlling or adjusting a further one or more parameters of the process based on the obtained one or more data, and, optionally, repeating steps (i)-(iv) in accordance with the controlled or adjusted parameter, wherein the further one or more parameters comprises at least one of: a flow rate or volume of the water vapour removed from the processable gas mixture; a flow rate or volume of the oxygen-containing gas introduced into the gas mixture; a flow rate or volume of the combustible gas mixture conveyed into the combustion region; a flow rate or volume of the one or more gas mixtures into the manifold; a pressure of the combustible gas mixture; and / or a temperature within the combustion region.

12. The process of any preceding claim, wherein the oxygen-containing gas includes (or consists of) atmospheric gas.

13. The process of claim 9 or any claim dependent on claim 9, wherein the (v) obtaining one or more data includes obtaining, by one or more sensors of the system, data indicative of one or more conditions associated with the (iv) combustion, the one or more conditions including one or more of: a position of the flame within the combustion region; a size of the flame within the combustion region; a quality of the flame; a temperature of the flame; and / or an oxygen volume or concentration in an exhaust gas mixture within the chimney.

14. The process of claim 13, wherein the one or more sensors is positioned and oriented to detect radiation and / or a gas emitted during the (vii) combustion, and the one or more sensors comprises one or more of:an ultra-violet sensor; an infra-red sensor; a temperature sensor; and / or an oxygen detector configured to detect oxygen present in an exhaust gas mixture during and / or after the (vii) combustion.

15. The process of claim 9 or any claim dependent on claim 9, wherein: the obtained one or more data associated with the combustion comprises data indicative of a ratio of oxygen to combustible gas within the combustible gas mixture; and the process further comprises iterating at least steps (i)-(iv) until the obtained one or more data is indicative of a ratio of oxygen to combustible gas within the combustible gas mixture of at least 2: 1.

16. The process of claim 9 or any claim dependent on claim 9, wherein: the obtained one or more data associated with the combustion comprises data indicative of a position of the flame above a base of the combustion region; and the method further comprises iterating at least steps (i)-(iv) until the obtained one or more data is indicative of a position of the flame above a base of the combustion region being about 2 cm to about 10 cm.

17. The process of any preceding claim, wherein the (i) receiving and processing comprises receiving one or more gas mixtures from a respective one or more biowaste stores, combining the one or more gas mixtures, and compressing, via a compressor, the one or more gas mixtures to form a processable gas mixture.

18. The process of claim 1 or claim 2, wherein the reaction chamber is a bioreactor, and the oxidising the combustible gas mixture comprises consuming the combustible gas mixture as a feedstock within the bioreactor.

19. A system for treating one or more gas mixtures containing at least one combustible gas, the system comprising: one or more biowaste stores; a manifold; a pressurising means; a pre-combustion unit comprising: a mixing chamber; and an oxygen-containing gas introduction means;a combustion unit comprising: a chimney defining therewithin a combustion region; and a combustion means; wherein the manifold is configured to receive each of the one or more gas mixtures from the respective one or more biowaste stores, combine the one or more gas mixtures thereby to produce a processable gas mixture, and convey the processable gas mixture into the mixing chamber; the pressurising means is configured to pressurise the processable gas mixture and, optionally, remove water vapour from the processable gas mixture; and the oxygen-containing gas introduction means is configured to introduce oxygen-containing gas into the processable gas mixture within the mixing chamber, thereby to produce a combustible gas mixture within the mixing chamber; the mixing chamber is configured to convey the combustible gas mixture into the combustion region; and the combustion means is configured to combust the combustible gas mixture within the combustion region.

20. The system of claim 19, wherein: the system further comprises a control means and a monitoring means, the monitoring means configured to obtain one or more data associated with the combustion, wherein the one or more data comprises data indicative of at least one of: a combustibility of the combustible gas mixture; a characteristic of the flame during the combusting; a composition of a gas mixture within the system, the gas mixture being the one or more gas mixtures, or the processable gas mixture, or the combustible gas mixture; and / or an oxygen volume and / or an oxygen concentration within an exhaust gas mixture within the chimney; and wherein the control means is configured to: control the one or more parameters based on the obtained one or more data; and / or adjust the one or more parameters based on the obtained one or more data; and / or control or adjust a further one or more parameters based on the obtained one or more data, the further one or more parameters comprising at least one of:a flow rate or volume of the water vapour removed from the processable gas mixture; a flow rate or volume of the oxygen-containing gas introduced into the gas mixture; a flow rate or volume of the combustible gas mixture conveyed into the combustion region; a flow rate or volume of the one or more gas mixtures into the manifold; a pressure of the combustible gas mixture; and / or a temperature within the combustion region21. The system of claim 19 or claim 20, wherein the one or more biowaste stores comprises one or more slurry tanks and / or one or more slurry lagoons and / or one or more landfill wells that are sealed and configured to output the one or more gas mixtures to the manifold via one or more ports.

22. A combustion unit comprising: a chimney defined by an outer wall; a cone disposed within the chimney, the cone at least partially defining therewithin a combustion region; and an inlet configured to introduce a combustible gas to the combustion region; wherein the outer wall of the chimney surrounds the cone and extends beyond an open end of the cone, defining a gap between the cone and the outer wall, thereby to limit an airflow and / or a heat exchange between an exterior of the outer wall and the combustion region; and the chimney is closed from receiving fluids other than through the inlet.

23. The combustion unit of claim 22, wherein the chimney further comprises one or more sensors positioned and oriented to detect radiation and / or a gas emitted during combustion that occurs within the combustion region, the one or more sensors comprising one or more of: an ultra-violet sensor; an infra-red sensor; a temperature sensor; and / or an oxygen detector configured to detect oxygen present in an exhaust gas mixture during and / or after the combustion.

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