System for combustible material and corresponding methods

Abstract

A system comprising a two-stage cooling process where a solid free-flowing carbonaceous material 140 produced from waste material during a thermochemical process is fed into a first cooling stage 110

Description

Field The present disclosure relates to a system for reducing the self-ignitability of combustible material. Such combustible material may take the form of free-flowing material, such as a byproduct free-flowing carbonaceous material from a waste disposal process, such as Biochar. Also provided are corresponding methods for use with such combustible / free-flowing materials. Background In the context of existing waste disposal processes (also described as thermal treatment processes), which turn waste (such as household waste / rubbish, or other general rubbish), e.g. via pyrolysis or some other thermal decomposition method, into various different byproducts, problems arise in terms of what to do with these by-products once they are formed. One such by-product, which often forms, is free-flowing material in the form of Biochar, which collects in the process, and which is thus a by-product that needs to be exhausted from the waste disposal process to ensure the waste disposal process can continue to run effectively. Mindful of the above, existing waste disposal systems may typically dump the by-product free-flowing material, for example via a chute, into an open-topped skip or other open-topped container. Once this container is then full, the container with its filled by-product free-flowing material can then be taken away for further processing, as required. However, noting the byproduct free-flowing material may leave the waste disposal process at a suitably elevated temperature, such that it may be described as a combustible material, there is the risk that this combustible material may ignite as it is delivered into, or is cooling inside, the open-topped container, thus posing a fire risk. Mindful of the above, it has been found that there is a need to provide for an improved mechanism to collect this combustible material from the waste disposal process, in a way which significantly reduces the likelihood of this combustible material from igniting as it is delivered to, or whilst it is located, inside this end / downstream container. As used herein, the term ‘free-flowing material’ may be understood as comprising solid particles which are of, or are capable of being in, a flowing or running consistency, and which may have an element of granularity - such as in respect of the textures / consistencies of flour; grain; sugar; sand; or other similar granulated, potentially courser, material - e.g. those where each granule might comprise a maximum dimension of up to 50mm, such as in respect of clumps of Bichar which may be up to 50mm wide. By the term ‘maximum dimension’ here, this may be understood as meaning that each granule / component from the free-flowing material may comprise a maximum length / width / height that are each no more than the quoted amount in millimetres. For completeness as well, the term ‘combustible material’ as used herein may be understood as meaning material that has the potential to ignite if exposed to suitably oxygen rich environments, such as atmospheric air. Such combustible material may take the form of free-flowing material described above, such as Biochar, which is at a suitably elevated temperature above atmospheric conditions such that the material may ignite if exposed to suitably oxygen rich environments. Summary According to a first aspect of certain embodiments there is provided a system for reducing the ignitability of a combustible material, the system comprising a first, cooling, stage and a second, wetting, stage: wherein the first stage is configured to receive the combustible material, and comprises a conveyor configured to cool the combustible material to a temperature which is no greater than a first predetermined temperature; and wherein the second stage is configured to receive the combustible material from the first stage, and wherein the second stage comprises a wetting unit configured to increase a moisture content of the combustible material as the combustible material passes through the wetting unit. According to a second aspect of certain embodiments there is provided a method of reducing the ignitability of combustible material, using a system comprising a first; cooling; stage and a second; wetting; stage, the method comprising: delivering the combustible material to the first stage; conveying the combustible material through the first stage using a conveyor, wherein the combustible material is cooled as it is conveyed by the conveyor such that the combustible material leaves the first stage at a temperature which is no greater than a first predetermined temperature; and delivering the combustible material, which has passed from the first stage of the system, into a wetting unit from the second stage, wherein the wetting unit is configured to increase a moisture content of the combustible material as the combustible material passes through the wetting unit. It will be appreciated that features and aspects of the invention described above in relation to the various aspects of the invention are equally applicable to, and may be combined with, embodiments of the invention according to other aspects of the invention as appropriate, and not just in the specific combinations described herein. Brief Description of the Drawings Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 represents a schematic view of a system for reducing the ignitability of a combustible material, such as free-flowing material in the form of Biochar, wherein the system comprises a first, cooling, stage; a second, wetting, stage; and an optional isolating portion, which is located between the first stage and the second stage, in accordance with certain embodiments of the disclosure; Figure 2 represents a schematic view of the first, cooling, stage from Figure 1, in accordance with certain embodiments of the disclosure; Figure 3 represents a schematic view of the second, wetting, stage from Figure 1, in accordance with certain embodiments of the disclosure; and Figure 4 represents a schematic view of the optional isolating portion from Figure 1, which is functionally located between the first stage and the second stage, in accordance with certain embodiments of the disclosure. Detailed Description Aspects and features of certain examples and embodiments are discussed I described herein. Some aspects and features of certain examples and embodiments may be implemented conventionally and these are not discussed / described in detail in the interests of brevity. It will thus be appreciated that aspects and features of apparatus and methods discussed herein which are not described in detail may be implemented in accordance with any conventional techniques for implementing such aspects and features. The present disclosure relates to a system for reducing the ignitability of a combustible material. An example of a system 100 according to the present disclosure is shown in the Figures. Referring to Figure 1, the system 100 comprises a first, cooling, stage 110 and a second, wetting, stage 130. As will be described in due course, in some embodiments the system 100 may include an optional intermediary stage 120, wherein the intermediary stage 120 is configured to receive combustible material 140 from the first stage 110 and provide the material to the second stage 130. In other embodiments, the second stage 130 is configured to receive combustible material 140 directly from the first stage 110. The first stage 110 is shown in more detail in Figure 2. The first stage 110 is configured to receive the combustible material 140, and in general terms is configured to cool combustible material 140 which is delivered to the first stage 110 at a relatively high temperature, for instance because it originates from a waste disposal process 2 which is operated at elevated temperatures. The first stage 110 is therefore configured to cool this [hot] combustible material to a lower temperature, such to provide an initial mechanism for reducing the ignitability of the combustible material. Mindful of this general functioning, it may be seen that the first stage 110 comprises a conveyor 150 configured to cool the combustible material 140 to a temperature which is no greater than a first predetermined temperature. Cooling the combustible material 140 to a temperature no greater than a first predetermined temperature allows moisture to be more conveniently introduced into the combustible material 140 when it passes to the second, wetting, stage 130. Specifically, if the temperature of the combustible material 140 is too high when it passes to the second stage 130, the combustible material 140 cannot be sufficiently wetted, as the moisture presented to the combustible material would immediately evaporate following its contact onto the [still sufficiently hot] combustible material. Therefore, the first stage 110 cools the combustible material 140 to a temperature no greater than a first predetermined temperature, allowing the moisture content to be increased as it passes through the wetting unit in the second stage 130. Noting this general function of the first stage, it may be appreciated that the first predetermined temperature may be set depending on the intended operating conditions, and the type (and evaporation temperature) of the cooling fluid, which is intended to be used as part of the wetting unit. For example, where the cooling fluid used in the wetting unit comprises water, it would be desirable to set the first predetermined temperature to be no more than 100°C, such to reduce evaporation of such cooling fluid when the combustible material 140 reaches the wetting unit. Appreciably though, where the cooling fluid comprises a lower temperature at which evaporation will occur, or where a colder temperature is required in the wetting unit, the first predetermined temperature may be lowered accordingly. For instance, it is envisaged in some embodiments that the conveyor may be configured to cool the combustible material to a temperature which is no greater than a first predetermined temperature, wherein the first predetermined temperature is set to no more than any of 80°C; 60°C; 50°C; 45°C; 40°C; and / or 35°C. For completeness, with reference to cooling the combustible material to a temperature, this may be interpreted as meaning an average, mean, temperature for the combustible material as a whole, in so far as the combustible material, due to its inherently clumpy nature, will always have some small inherent internal portions, or other small flecks / regions / smuts, which are hotter than this average / mean temperature. In all though, the fact that the temperature for the combustible material may be considered as an average means that its resultant effects of reducing evaporation of the cooling fluid when the combustible material 140 reaches the wetting unit may still be achieved to some extent, even if such small internal portions, or other small flecks / regions / smuts, of the combustible material may [unavoidably] otherwise have a temperature which is above the average, mean, temperature. Concerning the cooling conveyor 150, as shown in Figure 2, in accordance with the embodiments of this disclosure, the combustible material 140 may be configured to pass through the cooling conveyor 150. This allows a continuous flow of combustible material 140 to be cooled as it passes through to the second stage 130, allowing the system 100 to support a continuous process. The cooling conveyor 150 may comprise an auger 157 for pushing the combustible material 140 passing through the cooling conveyor 150. The use of an auger 157 also encourages more of the combustible material 140 to be exposed to the cooling process as it passes through the cooling conveyor 160, and may also break up the combustible material 140 into smaller pieces, increasing the surface area of the material to be exposed to the cooling process and facilitating effective cooling of the combustible material 140. As mentioned above, the first predetermined temperature may be set dependent on the intended cooling fluid intended for the second stage 130, and / or the temperatures intended for use in the downstream wetting unit. For instance, some embodiments may employ the first predetermined temperature as being 100°C or 70°C, which would be particularly suited in embodiments where the cooling fluid for the wetting unit comprises water. That being said other predetermined temperatures are envisaged, as noted above. For helping to contain the combustible material, the cooling conveyor 150 in some embodiments may comprise a tubular channel 151 for receiving the combustible material 140, and at least one conduit 152a; 152b configured to receive cooling fluid 170 for cooling the combustible material 140 passing through the tubular channel 151. Cooling the combustible material 140 via a tubular channel 151 comprising a conduit 152a; 152b allows the combustible material to be cooled without directly contacting the cooling fluid 170. This prevents the combustible material 140 from getting wet, and thus clumping together and causing blockages in the system 100 and / or the first stage 1101 conveyor 150. In some embodiments, the at least one conduit 152a; 152b comprises a first conduit 152a, and a second conduit 152b which at least partially surrounds the first conduit 152a, as shown in Figure 2. For example, the second conduit 152b may extend around the tubular channel 151. This allows the combustible material 140 to be cooled from multiple directions, further facilitating the cooling process. In some embodiments, the second conduit 152b may be annular, which even further facilitates the cooling process by providing cooling from all angles. Where the cooling conveyor 150 comprises a first and second conduit 152a; 152b, the first conduit 152a may extend through the tubular channel 151 (and / or the auger 157, where employed), as shown in Figure 2. This advantageously provides cooling through the central / inner portions of the tubular channel 151, increasing the surface area of the combustible material 140 that is exposed to the conduits 152a-b, which further facilitates the cooling process. Figure 3 shows an example of the second stage 130. The second stage 130 is configured to receive the combustible material 140 from the first stage 110, and comprises a wetting unit 160 configured to increase a moisture content of the combustible material 140 as the combustible material 140 passes through the wetting unit 160. By increasing the moisture content of the combustible material 140, the self-ignitability of the combustible material 140 is reduced. This therefore better prevents the combustible material 140 from catching fire, improving the safety of the combustible material collection process. As alluded to already, it is envisaged in some embodiments that the combustible material 140 may comprise a free-flowing material, such as Biochar for example. That being said, any other type of free-flowing material is also compatible with the teachings described herein. In the context of Figure 3, the wetting unit 160 may be configured to supply a cooling fluid 170 onto the combustible material 140 as it passes through the wetting unit 160. The cooling fluid 170 may provide further cooling to the combustible material 140, as well as increase the moisture content of the combustible material 140 at the same time. The cooling fluid 170 may therefore allow the combustible material 140 to be cooled to a desirable temperature before it enters the end open-topped container / skip 4 into which the combustible material 140 is configured to be ultimately collected, as shown in Figure 1 for example. To assist with this cooling, the wetting unit 160 may be configured to deliver the cooling fluid 170 into the wetting unit 160 at a sufficiently low temperature, such as for example a temperature of no more than any of 60°C; 50°C; 40°C; 30°C or 25°C. Appreciably, lower temperatures may provide a faster rate of cooling, but the temperature of the cooling fluid 170 which is delivered into the wetting unit 160 may in some instances be related to the first predetermined temperature, which will have an impact on the temperature of the combustible material entering into the wetting unit 160, for instance to better avoid the possibility of evaporation of the cooling fluid from it otherwise contacting combustible material which is too hot. In so far as the wetting unit is configured to supply a cooling fluid 170, the wetting unit 160 may in some embodiments comprise at least one spray nozzle 180a; 180b; 180c for spraying the cooling fluid 170 onto the combustible material 140 as it passes through the wetting unit 160. Spray nozzle 180a-c provides a simple mechanism that allows combustible material 140 to receive an even distribution of cooling fluid 170. Other mechanisms for introducing moisture content to the combustible material are also compatible with the embodiments of this disclosure, for example a hose or a tap. As an alternative, or alongside, the use of any spray nozzle 180a; 180b; 180c for spraying the cooling fluid 170 onto the combustible material 140, the wetting unit 160 could be configured to increase the moisture content of the combustible material as the combustible material passes through the wetting unit, via use of a quenching process. Put differently, in some embodiments the wetting unit 160 may be described as a quenching unit which is configured to increase the moisture content of the combustible material as the combustible material passes through [and is quenched in] the wetting unit. Where such quenching is configured to occur, it may be appreciated in such embodiments that the wetting / quenching unit 160 may comprise a tank 177 containing cooling fluid 170;170a, into which the combustible material is configured to be quenched. In this way, the quenching of the combustible material may serve to both cool the combustible material, and also increase its moisture content, per the intent of the wetting unit 160. To help prevent any excess cooling fluid 170 from escaping the wetting unit 160 alongside the combustible material, in some embodiments the wetting unit may further comprise a weir 178 for reducing the escape / egress of cooling fluid 170, from the wetting unit 160, via an outlet 179 of the wetting unit through which the combustible material 140 is configured to pass. This weir is shown in Figure 3, where the weir 179 is shown at a downstream end of the wetting unit 160. Regardless of whether quenching is employed or not, and turning to the cooling fluid 170 which may be utilised in the wetting unit 160, one potential cooling fluid 170 which may be employed is water. Water is an effective coolant due its high heat capacity; low cost; and ease of availability. Although not necessarily required, the second stage 130 may comprise an agitation portion 190, for instance located within the wetting unit, for agitating the combustible material 140 passing through the wetting unit 160. An example of an agitation portion is shown in Figure 3, such as the agitation portion comprising a plurality of vanes 191 for agitating the combustible material 140 passing through the wetting unit 160. That being said, other forms of agitation portions are appreciably equally compatible with the embodiments of this disclosure. For example, an auger or a screw conveyor may be used to help provide the agitation effect. In this way, and in so far as an agitation portion 190 may be employed, this may facilitate the mixing of the the combustible material 140 as it passes through the wetting unit 160, allowing the moisture content of the combustible material 140 to be increased evenly across the material flow, and encouraging more of the combustible material 140 to be exposed to the wetting process as it passes through the wetting unit 160. In some particular embodiments from those where the second stage comprises an agitation portion 190, the agitation portion 190 may further be configured to pulverise combustible material 140 passing through the wetting unit 160. This may serve to break up the combustible material 140 into smaller pieces, increasing the surface area of the material to be exposed to the wetting process, allowing the moisture content to be effectively increased. This may also reduce the individual pieces of the combustible material into a desirable size for entering the open-topped container / skip 4, for merchandising, or for enabling the breaking down of larger contaminates such as stone, tile or glass that may otherwise be present in the combustible material. The wetting unit 160 as described herein may additionally or alternatively define an interior volume 161 through which the combustible material 140 is configured to pass, wherein the composition of the interior volume 161 which is inert and / or comprises an oxygen content of a sufficiently low oxygen content, for example which may be no more than 2% by mass; no more than 1% by mass; and / or no more than 0.5% by mass. Through reducing the oxygen content of this interior volume, this may further assist in reducing the ignitability of the combustible material 140. For completeness, to the extent such low oxygen containing environment is provided in the interior volume of the wetting unit, it may be appreciated that such an environment may be expanded to also be present in other (or all) parts of the system 100, such as for example the first stage 110 or the intermediary stage 120, as required. Although not necessarily required, as shown in Figure 4, the system 100 may further comprise an isolating portion 200, which is located between the first stage 110 and the second stage 130. At a general level, the isolating portion 200 is configured to help isolate the first stage 110 and the second stage 130 from each other, such that if combustible material from either stage ignites, the isolating portion 200 can help prevent any fires from this stage being transmitted to the other of the two stages. In other words, the isolating portion can be configured to act as a fire-break, for preventing any fire in one of the two stages from being transmitted to the other of the two stages. To help achieve this function, the isolating portion 200 may comprise an inlet 220 which is operable to receive combustible material 140 from the first stage 110, and an outlet 230 which is operable to deliver combustible material 140 towards the second stage 130. The isolating portion 200 may then also comprise one or more chambers 240 which are moveable for transferring combustible material 140 from the inlet 220 to the outlet 230. In this way, the isolating portion 200 may be configured such that at any given time, there is no chamber from the one or more chambers 240 which is simultaneously in fluid communication with both the inlet 220 and the outlet 230. This allows the environment within the first stage 110 and the second stage 130 to be controlled, and isolated from each other. For example, isolating portion 200 may prevent oxygen and / or a fire from the first stage 110 from entering the second stage 130, and vice versa, hence acting as the safety measure just described. Where the system 100 comprises an isolating portion 200, the one or more chambers 240 may be rotatable for transferring the combustible material 140 from the inlet 220 to the outlet 230. This allows smaterial to be passed from the inlet 220 to the outlet 230 without the inlet 220 and the outlet 230 being in fluid communication with one another. In some embodiments, the isolating portion 200 may comprise a rotary seal. Mindful of the above remarks, it may be seen that the present disclosure may additionally provide for a method of reducing the ignitability of combustible material 140, using a system 100 comprising a first cooling stage 110 and a second wetting stage 130. The method comprises delivering the combustible material 140 to the first stage 110, conveying the combustible material 140 through the first stage 110 using a conveyor 150, wherein the combustible material 140 is cooled as it is conveyed by the conveyor 150 such that the combustible material 140 leaves the first stage 110 at a temperature which is no greater than a first predetermined temperature. The combustible material 140, which has passed from the first stage 110 of the system, is delivered into a wetting unit 160 from the second stage 130, wherein the wetting unit 160 is configured to increase a moisture content of the combustible material 140 as the combustible material 140 passes through the wetting unit 160. The first stage 110 of cooling the combustible material 140, to a temperature which is no greater than a first predetermined temperature, facilitates moisture to be introduced into the combustible material 140 in the second stage 130. Increasing the moisture content of the combustible material 140 reduces the risk of self-ignition of the combustible material, reducing the likelihood of the combustible material 140 from catching fire and therefore increasing the safety of the combustible material collection process as a whole. In some instances, the method may further comprise using the wetting unit 160 to increase the moisture content of the combustible material 140, relative towhen the combustible material 140 initially entered the wetting unit 160, by at least any of 5%; 7%; 10%; or 15% by mass. For completeness, this moisture content percentage by mass may be derived as being equal to 100 multiplied by (mass of the [wetted] combustible material 140 as it leaves the wetting unit 160 post-wetting, minus the mass of the combustible material 140 as it initially enters the wetting unit 160), all divided by the mass of the combustible material 140 as it initially enters the wetting unit. Through the addition of this moisture content, this has been found to reduce the ignitibility of the combustible material. In addition or alternatively, the method may comprise using the wetting unit 160 to increase the moisture content of the combustible material 140, relative to when the combustible material 140 initially entered the wetting unit, by no more than 25% by mass. A moisture content of no more than 25% by mass better prevents the combustible material 140 from being overly saturated with moisture, which may otherwise hamper the performance and desirability of the combustible material 140 in the context of future processing; transportation; or sale, once it is located in the skip / open-topped container 4 as shown in Figure 1. In accordance with some embodiments, it is envisaged that the combustible material 140 may be delivered to the first stage 110 of the system 100 at a temperature of between 120°C -600°C. This may be the case, for example, where the temperature of the combustible material 140 correlates to its temperature when the combustible material has left a waste disposal process 2. Again, to be clear, the temperature here may be construed as an average, mean, temperature for the combustible material delivered to the first stage as a whole, in so far as the combustible material, due to its inherently clumpy nature, will always have some inherent internal portions, or other small flecks / regions / smuts, which are hotter or potentially colder than this average temperature In some aspects, the method may further comprise pulverising the combustible material 140, for breaking the combustible material 140 into smaller pieces, as the combustible material 140 passes through the wetting unit 160. As described above, this increases the surface area of the combustible material 140 that is exposed to the wetting process, which facilitates increasing the moisture content of the combustible material 140 in the second stage 130. Breaking up the material into smaller pieces may also be more desirable for subsequent processing; transporting; or merchandising and may allow contaminates to be removed more easily. Turning to the first cooling stage 110, the method may further comprise the combustible material 140 being cooled, as the combustible material 140 is conveyed by the conveyor 150, by a cooling fluid 170 that is delivered into the conveyor 150. The cooling fluid 170 may be water, but other cooling fluids are also compatible with the embodiments of this disclosure, as alluded to previously. As described above, cooling the combustible material 140 as it is conveyed by the conveyor allows a continuous flow of combustible material 140 to be cooled as it passes through to the second stage 130, allowing the system 100 to support a continuous process. In this embodiment, the cooling fluid 170 may not directly contact the combustible material 140. Put differently, the combustible material 140 may be described as not being wetted as the combustible material 140 is conveyed by the conveyor. This better prevents the combustible material 140 from clumping together and causing blockages in the system 100 and / or as the combustible material 140 passes through the first stage 110 or the cooling conveyor 150. Returning to the wetting unit 160, in some aspects the wetting unit 160 may be further configured to cool the combustible material 140 to a temperature which is no greater than a second predetermined temperature, wherein the second predetermined temperature is no greater than 30°C. Again, the wetting unit 160 being configured to cool the combustible material 140 to a temperature may be construed as an average, mean, temperature, as discussed previously. This allows the combustible material 140 to be cooled to a temperature that is no more than most ambient / environmental temperatures before it enters the skip 4, or end container 4, that is configured to collect the combustible material 140 at the end of the process. In this way, such temperatures again reduce the likelihood of the combustible material igniting whilst it is located / being stored in this skip / container when exposed to environmental oxygen / air conditions 5 therein. In accordance with the embodiments of this disclosure, the system 100 may comprise a volumetric capacity in the range of delivering 20 kg / hour to 4000kg / hr of combustible material through the system. Additionally or alternatively, the method according to embodiments of this disclosure may be operable to run continuously for a predetermined of time, which is at least 3 hours, which may be achieved to the extent a sufficiently large end container, or transport system, is arranged at the end of the system to accommodate such throughputs of combustible material. In other embodiments, the method may run as a batch process, activating for example between 1 to 16 times per hour. The system 100 and method as disclosed herein can therefore be scaled for a wide range of throughputs and operating times, making it suitable for a many different types of combustible material collection processes. As described herein, it is noted that the combustible material 140 delivered to the first stage 110 in accordance with the embodiments of this disclosure may be a by-product from a waste disposal process 2. As discussed above, the combustible material delivered to the first stage may additionally or alternatively be a free flowing material, or may be Biochar. That being said, and for completeness, it is envisaged that the systems, processes, and methods herein described may notionally be applicable to any form of combustible material 140 which requires a degree of cooling / wetting before to make it safer, and less combustible, as a whole. Appreciating the foregoing, there has accordingly been described a system for reducing the ignitability of a combustible material, the system comprising a first, cooling, stage and a second, wetting, stage: wherein the first stage is configured to receive the combustible material, and comprises a conveyor configured to cool the combustible material to a temperature which is no greater than a first predetermined temperature; and wherein the second stage is configured to receive the combustible material from the first stage, and wherein the second stage comprises a wetting unit configured to increase a moisture content to a predetermined level of the combustible material as the combustible material passes through the wetting unit. There has also been described a method of reducing the ignitability of combustible material, using a system comprising a first; cooling; stage and a second; wetting; stage, the method comprising: delivering the combustible material to the first stage; conveying the combustible material through the first stage using a conveyor, wherein the combustible material is cooled as it is conveyed by the conveyor such that the combustible material leaves the first stage at a temperature which is no greater than a first predetermined temperature; and delivering the combustible material, which has passed from the first stage of the system, into a wetting unit from the second stage, wherein the wetting unit is configured to increase a moisture content of the combustible material as the combustible material passes through the wetting unit. There has also been described system (100) for reducing the ignitability of a combustible material (140), such as a free-flowing material in the form of Biochar. The system (100) comprises a first, cooling, stage (110) configured to receive the combustible material (140), and which comprises a conveyor (150) configured to cool the combustible material to a temperature suited for allowing the combustible material (140) to enter into a second, wetting, stage (130) from the system (100). The second stage (200) receives the combustible material (140), from the first stage (110), and comprises a wetting unit (160) for increasing a moisture content of the combustible material (140) as the combustible material passes through the wetting unit (160). The cooled / wetted combustible material may consequentially be delivered from the system (100) to a container (4), for disposing of, in a state that renders this combustible material (140) much less likely to ignite when exposed to environmental oxygen / air conditions (5) as a result of its cooled / wetted state. In order to address various issues and advance the art, this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and / or exclusive. They are presented only to assist in understanding and to teach the claimed invention(s). It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects of the disclosure are not to be 5 considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope of the claims. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. other than those specifically described herein, 10 and it will thus be appreciated that features of the dependent claims may be combined with features of the independent claims in combinations other than those explicitly set out in the claims. For instance, any of the dependent claims relating to independent claim 1 (or other independent claims) may correspondingly be employed as corresponding features in any of the related independent claims listed in the claims, as required. Appreciably as well, the disclosure may include other 15 inventions not presently claimed, but which may be claimed in future.

Claims

1. A system for reducing the ignitability of a combustible material, from a waste disposal process, the system comprising a first, cooling, stage and a second, wetting, stage:5 wherein the first stage is configured to receive the combustible material from the wastedisposal process, and comprises a conveyor configured to cool the combustible material to a temperature which is no greater than a first predetermined temperature, wherein the combustible material is configured to pass through the conveyor and is configured to be cooled by a cooling fluid that is delivered into the conveyor, wherein the cooling fluid is configured to10 not directly contact the combustible material; andwherein the second stage is configured to receive the combustible material from the first stage, and wherein the second stage comprises a wetting unit configured to increase a moisture content of the combustible material as the combustible material passes through the wetting unit;15 wherein the conveyor comprises a tubular channel for receiving the combustiblematerial, and wherein the conveyor further comprises at least one conduit configured to receive cooling fluid for cooling the combustible material passing through the tubular channel; wherein the at least one conduit comprises a first conduit, and a second conduit which at least partially surrounds the first conduit; wherein the first conduit extends through the tubular20 channel; and wherein the second conduit extends around the tubular channel.

2. The system according to claim 1, wherein the combustible material comprises a free-flowing material.25 3. The system according to any preceding claim, wherein the wetting unit is configuredto supply cooling fluid onto the combustible material as it passes through the wetting unit.

4. The system according to claim 3, wherein the wetting unit comprises at least one spray nozzle for spraying the cooling fluid onto the combustible material as it passes through the30 wetting unit.

5. The system according to claim 3 or 4, wherein the cooling fluid comprises water.

6. The system according to any of claims 3-5, wherein the wetting unit is configured to35 deliver the cooling fluid into the wetting unit at a temperature of no more than 50°C.10 04 257. The system according to any preceding claim, wherein the second stage further comprises an agitation portion for agitating combustible material passing through the wetting unit.5 8. The system according to claim 7, wherein the agitation portion is located within thewetting unit.

9. The system according to claim 7 or 8, wherein the agitation portion is further configured to pulverise combustible material passing through the wetting unit.1010. The system according to any preceding claim, wherein the wetting unit defines an interior volume through which the combustible material is configured to pass, wherein the composition of the interior volume comprises an oxygen content which is no more than 2% by mass.1511. The system according to any preceding claim, wherein the conveyor comprises an auger for pushing the combustible material passing through the conveyor.

12. The system according to any preceding claim, wherein the first predetermined 20 temperature is 100°C.

13. The system according to any preceding claim, wherein the first predetermined temperature is 70°C.25 14. The system according to any preceding claim, wherein the system further comprisesan isolating portion, which is located between the first stage and the second stage, wherein the isolating portion comprises:an inlet which is operable to receive combustible material from the first stage;an outlet which is operable to deliver combustible material towards the second stage;30 andone or more chambers which are moveable for transferring combustible material from the inlet to the outlet, wherein the isolating portion is configured such that at any given time, there is no chamber from the one or more chambers which is simultaneously in fluid communication with both the inlet and the outlet.

15. The system according to claim 14, wherein the one or more chambers are rotatable for transferring the combustible material from the inlet to the outlet.10 04 2516. The system according to claim 14 or 15, wherein the isolating portion comprises a rotary seal.5 17. A method of reducing the ignitability of combustible material from a waste disposalprocess, using a system comprising a first; cooling; stage and a second; wetting; stage, the method comprising:delivering the combustible material from the waste disposal process to the first stage;conveying the combustible material through the first stage using a conveyor, wherein10 the combustible material is cooled, as it is conveyed through a tubular channel of the conveyor, by a cooling fluid that is delivered into at least one conduit of the conveyor, and wherein the cooling fluid does not directly contact the combustible material, such that the combustible material leaves the first stage at a temperature which is no greater than a first predetermined temperature; and15 delivering the combustible material, which has passed from the first stage of thesystem, into a wetting unit from the second stage, wherein the wetting unit is configured to increase a moisture content of the combustible material as the combustible material passes through the wetting unit;wherein the at least one conduit comprises a first conduit, and a second conduit which20 at least partially surrounds the first conduit; wherein the first conduit extends through the tubular channel; and wherein the second conduit extends around the tubular channel.

18. The method according to claim 17, wherein the method further comprises: using the wetting unit to increase the moisture content of the combustible material,25 relative to when the combustible material initially entered the wetting unit, by at least 5%.

19. The method according to claim 17 or 18, wherein the method further comprises: using the wetting unit to increase the moisture content of the combustible material, relative to when the combustible material initially entered the wetting unit, by no more than30 25%.

20. The method according to any of claims 17-19, wherein the combustible material is delivered to the first stage of the system at a temperature of between 120°C - 600°C.35 21. The method according to any of claims 17-20, wherein the method further comprises:pulverising the combustible material, for breaking the combustible material into smaller pieces, as the combustible material passes through the wetting unit.

22. The method according to any of claims 17-21, wherein the wetting unit is further configured to cool the combustible material to a temperature which is no greater than a second predetermined temperature, wherein the second predetermined temperature is no greater 5 than 30°C.

23. The method according to any of claims 17-22, wherein the combustible material delivered to the first stage is a free flowing material.10 24. The method according to any of claims 17-23, wherein the combustible materialdelivered to the first stage comprises Biochar.LDCM

Images