Field

The present invention relates to an ozone treatment system for treating a granular organic material with ozone, and to a method of treating a granular organic material with ozone.

Background

Grain, feedstock and other granular organic materials are prone to adulteration by fungal and bacterial growth. Often such granular organic materials are high value, and they are intended for use in human or animal food supply chains. Therefore, damage to a bulk store of such granular organic materials can result in significant financial losses to a manufacturer, supplier or farmer, as well as disruption to a supply chain for important feedstock for human or animal consumption.

There is therefore a need to maintain strict standards of hygiene throughout all stages of material handling, processing and in storage systems for granular organic materials in order to minimise damage to granular organic material.

There is a particular need to maintain granular organic materials dry and within specific temperature ranges in order to prevent bacterial or fungal growth which can spoil the granular organic materials. Often food grains obtained by harvesting crops, such as wheat, are dried in sunshine or driers, before storing to reduce their moisture content.

In general, a higher moisture content in food grains tends to promote the growth of fungi and moulds on the stored grains which damages them. Therefore, as well as drying, it is often necessary to treat such granular organic materials further to prevent them from spoiling.

There is therefore a need for a system, and a method, capable of efficiently treating granular organic materials to prevent them from spoiling and to reduce or to eliminate unwanted biological organisms. The invention arose in order to overcome problems associated with prior art ozone treatment systems.

Prior Art

Canadian patent application CA 2 980 091 (ETIA) discloses a method for the continuous treatment of a product in the form of particulate solids. The product is introduced into a chamber with a pressurised ozone atmosphere. Product is conveyed through the chamber in a continuous by means of a screw conveyor mounted to rotate in the chamber about a given axis.

European patent application EP 2 785 474 (Association de Gestion de I’lnstitut Polytechnique) discloses a system which uses of ozone for the elimination of persistent phytosanitary molecules contained in plant seeds, such as wheat, corn or rape seed. Plant seeds contaminated with persistent phytosanitary molecules are treated in a process in which contaminated seeds are treated in an atmosphere whose humidity is adjusted.

French patent application FR 2 811 745 (ETIA Evaluation Technologique) describes a method of refrigerating particulate solids which involves convectively permanently cooling the centre of mass of particulate on a cold wall which extends in a conveying direction. The mass is simultaneously subjected to a through flow of a cooling gas to fluidize it without use of a condenser. The gas also increases the heat exchange rate of the cold wall.

United States patent application US 2011/0151080 (Kevin Johnson) describes a system for treatment of grain in a storage container using ozone. The system treats grain for toxins, insects, mould, and/or odour. Downdraft methods apply high concentrations of ozone to grain in a storage container without generating ozone-related objectionable odours or with generation of only minimal ozone-related objectionable odours.

The method involves providing a negative air pressure at a bottom of a volume of grain in a storage container. A high ozone concentration is generated in air above an upper surface of the volume of grain. Ozone is drawn down into the volume of grain using the negative pressure for a treatment time sufficient to effectively treat the grain without causing significant ozone-related and/or commercially objectionable foreign odours in the grain.

Chinese utility model CN-U-206547380U (Guangxi Agriculture) describes a system which controls insects which may damage stored grain. The system uses ozone by fumigating insects and larvae. The system has a hollow shaft connected to rotating paddles through which ozone is distributed whilst mixing. It is intended for use in a grain store and appears to require daily usage to treat grain continually.

Chinese utility model CN-U-209807000 (Najing Mengbo Environmental Technology), describes a system whose main object appears to be drying, as well as sterilising grain for storage. The system uses warm air and introduces ozone through paddle wings. Again, no mention is made of a system through which material falls vertically from an upper inlet to exploit the advantage of treating material in free fall as well as the benefits of gravitational mixing.

Chinese utility model CN-U-213281400 (Maoming Hengyu Biotech) describes a system which treats fish meal by disinfection using ozone. The system has a set of rotating arms disposed around a horizontal planes. The arms are hollow and are supplied with ozone from a hollow vertical shaft. Heat is applied with dry steam.

Chinese utility model CN-U-208338803U Li), describes a device which incorporates a rotating helical screw which has an ozone injector. The device is said to improve the sterilization effect as well as prevent ozone from coming into contact with humans. No mention is made of a system through which material falls vertically from an upper inlet to exploit the advantage of treating material in free fall.

Chinese utility model CN-U-212437179U (Li), describes a sterilisation system with a horizontal drum arrangement and a means for injecting ozone and radiating the contents with ultraviolet (UV) light. The system is intended to treat dried or candied fruit for preservation and to extend its shelf life. The system simply tumbles fruit product in a mesh cylinder, exposes fruit to ozone and UV light and removes treated products on a conveyor belt.

It is apparent therefore that there is a need for an improved system which treats grain or granular materials, such as feedstuff for livestock, in an efficient manner in order to remove contaminants.

The invention arose in order to overcome problems associated with existing oxidation systems.

One problem with some types of treatments systems which have angled augers is that the slumping of granular material can occur which can lead to blockages or non-uniform treatment of the granular material. The latter can result in untreated material degrading which in turn can lead to an entire load becoming spoiled.

One object of the invention is therefore to provide a system for treating granular organic material with ozone win a more homogeneous and consistent manner.

Another object of the invention is to provide a system for treating a granular organic material with ozone at a controllable rate across a wide range of throughput volume.

Summary of the Invention

According to a first aspect of the present invention, there is provided a system for treating a granular organic material with ozone comprising: a processing vessel in the form of a substantially cylindrical silo having an upper end and an opposed lower end, the vessel has an inlet located at the upper end, through which the granular organic material is supplied from a delivery system and an outlet is located at the lower end of the vessel, through which outlet treated granular organic material is removed; at least one rotating ozone injector is disposed along a diameter of the cylindrical silo between the inlet and the outlet, the at least one rotating ozone injector is operative to rotate about its axis of rotation and to introduce ozone gas into the granular organic material through apertures formed across its surface as the granular organic material passes across the surface of the at least one rotating ozone injector, characterised in that two baffles are provided within the vessel, the baffles are substantially planar and each baffle extends from an internal surface of the cylindrical silo to an edge which is substantially parallel with the axis of rotation of the at least one rotating ozone injector and a space is defined between the edges of each baffle, either side of the at least one rotating ozone injector, the baffles are dimensioned and arranged to disrupt and spread the passage of the granular organic material falling from the inlet towards the outlet and to provide a continuous supply of the granular organic material by directing it to the at least one rotating ozone injector; and a pressurised supply of ozone gas is arranged to deliver ozone gas to the at least one rotating ozone injector via a rotating gas tight seal.

The system of the present invention therefore provides more efficient oxidation of granular organic material.

The term baffle includes anything which interrupts falling granular organic material to promote tumbling or mixing or causes or promotes a disturbance or disruption in a flow of the granular organic material. Therefore, baffles may be any device which maximises a contact area as a consequence of agitation and/or fluidisation and/or disruption of flow of the granular organic material as it passes through the silo.

Preferably the two baffles are symmetrical. Ideally, as the silo is in a cylindrical form baffles are shaped as pairs of parabolic sheets which are disposed at an angle within the body of the silo. Ideally each baffle has a parabolic edge which is in contact with an inner surface of the cylindrical silo and are hereinafter referred to as butterfly wing baffles as they lie symmetrically about the rotating ozone injector(s) and resemble a butterfly wing.

The, or each, rotating ozone injector preferably comprises at least one paddle wheel and/or at least one auger and/or at least one an Archimedean screw. The, or each, rotating ozone injector rotates about an axis of rotation.

In some embodiments moisture may be introduced in the form of fine spray or mist within the vessel to improve oxidation of a surface of grain. This has been found to promote and activate production of radical hydroxyls, which are potent in organic chemistry, and in combination with ozone gas have been shown to improve the ozone treatment process of the granular organic material.

A deflector may be provided proximal to the inlet and preferably includes angled pieces or sheets of rigid material that define a surface which deflects the granular organic material causing it to scatter laterally. The deflector may take the form of an umbrella or one or more similar curved surfaces.

Preferably a diverter is provided at the outlet. The diverter is operable to discharge selectively treated granular organic material via a discharge port, and thereby remove treated granular organic material from the vessel leaving partially treated or untreated within the vessel for further treatment.

The diverter is also selectively operable to divert partially or untreated granular organic material for recirculation using a re-circulator.

In some embodiment a vibrating means is provided to agitate internal conduits or surfaces, ideally at frequency between 20 Hz to 40 Hz, and more preferably at a frequency of around 30 Hz, to improve throughput, fluid movement of grain or granular material and thereby help prevent clogging or blockages or so-called bridging. A suitable control means enables the vibration frequency to be varied in dependence upon the size and nature of the granular organic material that is being treated.

Optionally means is provided to vary an orientation of baffles to deflect grain according to its density. The choice of deflection of the grain or granular organic material may be selected so as to control and vary throughput of the grain through the silo.

Optionally a lip is provided along straight edges of baffles to ensure a consistent spill over of granular organic material onto the or each one rotating ozone injector. This helps to control the dwell time and feed rate of granular organic material to the, or each, rotating ozone injector.

Optionally in some embodiments two augers may be deployed and extend across a diameter to remove treated grain in two directions. Sensors may be provided to detect the density of grain and to vary speed and intensity of agitation in dependence of density, moisture content and throughput.

Likewise, the speed of rotation of the, or each, rotating ozone injector, the intensity of agitation provided by the vibrating means and the concentration of ozone are all variable according to density, moisture content and desired throughput.

In some embodiments a carbon dioxide (CO2) extinguisher is provided to quench or prevent combustion. This may take the form of a number of injector lines and nozzles directed to regions prone to overheating.

Purge ports may be provided as a safety feature to prevent overprocessing or to enable access to clean regions prone to build-up.

Optionally active purging devices, such as one or more metal or ceramic balls, may be provided inside a portion of a rotating ozone injector so that internal rolling motion of the purging device(s) removes debris which may pass through apertures in the rotating ozone injector and so prevent them from becoming trapped inside a rotating ozone injector. These active purging devices thereby avoid build-up of fine dust or particles and so help to prevent clogging of the apertures through which ozone gas passes.

In addition to providing a more homogenous treatment of the granular organic material than achieved by the Archimedean screw, the embodiment of the rotating ozone injector with the paddle wheel, also prevents build-up of fine granular material because each scoop, between adjacent pair of fins on the paddle wheel, improves control of material flowing through the vessel. Also, because the paddle wheel acts in a similar manner to a dosing wheel, discharging a channel volume each time a paddle moves past the baffle achieves a more consistent treatment of material.

In some embodiments, for example where a CO2 source is optionally to prevent or quench fire, the system may be operable to inject a pulse of gas to a network of ozone delivery tubes. This CO2 pulsing helps maintain ozone nozzles clear of debris/dust which might otherwise form blockages. In an alternative embodiment an existing network of ozone delivery tubes may be deployed in an emergency also to deliver high pressure CO2 to quench fires in addition to the aforementioned dedicated prevention/quenching system.

In some embodiments ozone injection points may include a collar or torus, with omnidirectional holes formed therein in order to direct ozone in different directions. This may be located close to an inlet to subject material to ozone treatment as soon as it enters the silo.

Optionally a torus or toroidal tube may have a diameter of between 10.00 mm to 50.00 mm and extends around the silo with its centre line lying on a circumference of approximately half the diameter of the silo. The torus or toroidal tube may be positioned below a conical scattering surface. This arrangement further exposes granular organic material to ozone for continuous treatment as it falls from the inlet to the rotating ozone injector(s).

Sizes of apertures through which ozone gas passes, ranges from 2.00 mm to around 5.00 mm diameter. The apertures may be arranged in an array across surfaces which contact the granular organic material. The surfaces include the surface of the rotating ozone injector, the aforementioned toroidal tube, (over which granular organic material optionally passes as it travels through the silo); and the deflector plate(s) or the baffles over which the granular organic material flows.

Baffles may be supported on hinges so that they may be raised and lowered within the vessel so that the angle defined by their surfaces either side of the axis of rotation of the rotating ozone injector(s) is variable. Baffles may be moved independently one from another or they may be connected so that they move together. Variation of the angle of inclination of baffles may be used to vary the throughput of granular organic material to be treated.

Optionally a drive means is configured to displace a baffle relative to the vessel. Displacement of the baffle, relative to the vessel, improves disruption of the passage of falling material within the vessel, thereby improving efficiency of mixing and exposure to gaseous treatment of the material and prevents clagging.

The drive means may include a motor associated with the at least one baffle. The drive means is preferably configured to rotate the at least one baffle with respect to the vessel.

In another embodiment, baffles may include a hollow portion through which ozone gas passes and is delivered to an array of small holes formed in the baffle wall leading from its outer surface (skin) to its hollow portion. These holes allow injection of a pressurised gas mix, which ideally includes a proportion of ozone, to agitate the organic granular material as it passes over the external outer surface of the baffle and to expose the material to ozone. When the gas is introduced under pressure, mixing of the granular material also occurs.

Optionally the gas mixture may be warmed, prior to injection, to promote drying or the treated granular organic material.

The granular organic material is typically grain, flour, seeds or human or animal feedstuff.

The vessel comprises a closable outlet providing a discharge point for removing material from the vessel, through which treated material passes for immediate use, for storage or for recirculation.

The system may further comprise a vertical re-circulator or a cyclone, configured to collect and transport material from the outlet of the vessel to the inlet of the vessel.

In a preferred embodiment the combined features of agitation, drying and oxidation help to avoid flocculation of the granular organic material.

In one embodiment, a vertical re-circulator comprises a first end providing an inlet in communication with the outlet of the vessel, and a second opposed end providing an outlet in communication with inlet of the vessel. Treated material is ideally removed from the vessel, via the outlet, and optionally via the vertical re-circulator and transported to the upper inlet, via the outlet of the vertical re-circulator.

The vertical re-circulator may include a blower, or a series of buckets or preferably a delivery system with a motor driven auger which receives material at its lower end and deposits the material at an upper inlet port.

Displacement of baffles may be achieved by application of vibration to the baffles or by raising or lowering portions of the baffles.

In one embodiment, the system comprises a plurality of baffles within the vessel which direct and deflect the material to prevent material from falling vertically from the inlet to the outlet, thereby prolonging the dwell time that material is exposed to gaseous treatment.

Baffles may be movable by actuators which are controlled automatically by a drive means or by a human operator. The drive means may be associated with one or more of a plurality of baffles. In one embodiment, a separate drive means may be associated with each of the baffles.

Mixing may be improved by applying a pressurised fluid source, such as air or a mixture of air with at least one other gas, such as ozone.

The vessel may have any suitable shape and/or dimension. In one embodiment, the vessel comprises a frusto-conical section located at or adjacent the lower end of a generally cylindrical vessel. Typically, the height of the vessel is in excess of 5 metres and preferably in excess of 10 metres.

In a preferred embodiment a gas joint connector has a flexible seal which accommodates movement between and resists shocks and vibration to ensure that ozone is delivered in a safe manner from an ozone supply to the silo without leakage. Ozone gas is delivered via the connector to a static injection port and then to a network of conduits or pipes to various mixing means, such as a rotating paddle wheel or auger, without any loss of gas to the surroundings. This is important to avoid leakage of ozone to the environment which may be dangerous.

Ozone gas is preferably delivered via a silicon hose and a gas tight injection connection. The gas joint connection is ideally mounted on a bearing mounting housing. A dual lip seal ensures there is no ozone leakage. All gas seals are ozone resistant flexible seals and have suitable ozone resistant gaskets.

In the gas joint seal there are small threaded holes. These threaded holes vent any ozone or pressure in that ozone leaks from a rotating seal. This preserves the seal on the bearing itself and avoids harmful deterioration of lubricant leading to bearing failure, overheating or fire.

Pipes that deliver ozone are formed from silicon rubber and all flexible conduits are also formed from silicon rubber.

Optionally a discharge agitator comprises an actuator connected to a frusto-conical section of the vessel, and in which the agitator is displaced with respect to the vessel in a gyrating manner to prevent bridging of flowing material.

The discharge agitator may include a gyrator and/or agitator and/or auger which are also operative to impose shock vibrations to moving granular material and are optimised to prevent blockages of treated material.

The system may further comprise at least one level sensor configured to detect a level of an amount of stored material within the vessel. Systems ideally further comprise a processing means configured to receive a signal from the at least one level sensor, and a controller operative to modify supply of material to the inlet of the vessel in the event of the processing means detecting that the level of material within the vessel has reached a predetermined maximum level for the material. The controller may be configured to receive a command signal from the processing means in dependence on the signal from the at least one level sensor.

The system may further comprise a cyclone for removing particles of material from the vessel.

Preferably, the cyclone is operative to remove particles having a particle size less than a predetermined maximum level, for example the cyclone is configured to remove particles having a particle size of less than 400pm, preferably less than 300pm.

The system may further comprise a dehumidifier operative to extract moisture from within the vessel after material has passed beyond the rotating ozone injector(s).

The system may further comprise at least one agitating plate located in the vessel operative to promote mixing of the material.

The system may further comprise at least one heat transfer means operative to extract heat from the material as it passes through the vessel.

The system may further comprise a monitoring system operative to sense and monitor at least once material characteristic of the material and/or an at least once vessel characteristic of an internal volume of the vessel.

In one embodiment, the monitoring system is operative to sense and monitor an amount of colony forming units (CFU/g) on non-treated and treated material.

The system may further comprise a control system operative to vary at least one of the following factors in dependence upon the material characteristic and/or the vessel characteristic, the factors from the group comprising: average particle size, mass flow of the material through the vessel, dwell time of the material in the vessel, concentration of ozone gas introduced into the vessel, moisture content of the material, humidity within the vessel, temperature of the vessel, temperature of the material exiting the vessel and amount of colony forming units (CFU/g) detected on a sample of the material. At least one sensor provides a signal to a processing means which is configured to operate a controller for modifying the drive to alter the mass flow rate of supply of the granular organic material to the housing.

The controller may be configured to receive an override command signal from the processing means in dependence on the signal from the at least one level sensor.

The system provides a retrofit auger or other form of rotating ozone injector which could be connected from a silo/grain store on a farm to a feed supply, for local use in treating animal feed.

According to a second aspect of the present invention, there is provided a method of operating the system for treating a granular organic material with ozone comprising the steps of: introducing the material into a processing vessel; cascading the material over at least part of a surface of at least one baffle provided within the vessel; and passing ozone through at least one mixer aperture of the at least one rotating ozone injector as the granular organic material falls towards an outlet of the vessel.

Embodiments of the present invention will now be described in detail and with reference to the Figures 1 to 14, in which:

Brief Description of Figures

Figure 1 shows side views of a treatment plant for treating a granular organic material with ozone;

Figure 2 is a schematic illustration of an apparatus comprising a system for treating a granular organic material with ozone which includes a plenum or gas injection collar;

Figure 3 is an external view of an embodiment of the system and shows a silo with pressure closure caps and observation windows;

Figures 4 and 5 show part sectional views of the system in Figure 3 and shows two pairs of butterfly wing baffles, one pair above another pair, for directing granular organic material to rotating ozone injectors; Figures 6 to 8 show various views of an embodiment of the system in which the rotating ozone injectors are augers;

Figure 9 is a part sectional view of an upper part of one embodiment of the system and shows a recycle motor and a recirculator which introduces untreated material for reprocessing;

Figure 10 shows an overall view of a lower part of the silo which shows an exit port, with a gyrator, a flexible coupling and a recirculation valve;

Figure 11 show overall views of the silo corresponding to the side views of Figure 1 and a bag unloader;

Figure 12 is an overall sectional view through one example of a gas joint connector; and

Figures 13 to 15 show different views of an alternative embodiment of the rotating ozone injector which is in the form of an elongate paddle wheel.

Detailed Description of Preferred Embodiments

With reference to Figures 1 to 4, there are shown views of a system 1 for treating a granular organic material with ozone. The system comprises a processing vessel 2. The processing vessel 2 has an upper end 4 and an opposed lower end 6. The vessel 2 comprises a main inlet feed 8 from bulk silo or delivery tank (not shown) located at the upper end 4 of the vessel 2.

It is to be understood that although the illustrated embodiment shows the inlet 8 to be at the upper end 4 of the vessel 2 that the inlet 8 may be located at any location adjacent the upper end 4 of the vessel 2. The inlet 8 is configured to supply material from a delivery system (bulk silo or delivery tank) to the vessel 2 so that the material falls and is distributed evenly towards one or more rotating ozone injectors, as described below. The vessel 2 further comprises an outlet 10 located at the lower end 6 of the vessel 2. Figure 9 shows in greater detail how material to be processed, is introduced via inlet 8 and how recycle motor 68 delivers part treated or untreated material via recirculator 16 for reprocessing.

It is also to be understood that although the illustrated embodiment shows the outlet 10 to be at the lower end 6 of the vessel 2, that the outlet 10 may be located at any location adjacent the lower end 6 of the vessel 2.

Referring briefly to the schematic view in Figure 2, the system 1 , further comprises a pressurised supply of ozone gas 14, configured to pass ozone through apertures (not shown) in the rotating ozone injectors 46, as shown below in Figure 7, to treat the granular organic material with ozone.

Referring to Figure 4, the system 1 further comprises a plurality of pairs of baffles 12 provided within the vessel 2. The baffles 12 are dimensioned and arranged to disrupt the passage of the material falling from the inlet 8 towards the outlet 10. Baffles, shown in detail in Figure 7, are in the form of a butterfly wing and define a surface which deflects and directs granular organic material towards rotating ozone injectors 46.

Material enters through the silo via entry port at upper end 4 of the processor vessel 2 and material is scattered via a dispersing scatterer 38. The scatterer 38 helps promote an even distribution of material so that it is forced sideways across as large an area of the butterfly wing baffles 12 as possible thereby avoiding a build-up or agglomeration of material underneath entrance port and an even feed to the rotating ozone injector(s). The scatterer 38 may include a rotating portion with serrations or ridges which helps to disperse the material over a larger area so that material is distributed more evenly, rather than fall over a smaller area.

Optionally the scatterer 38 has holes through which injection of a pressurised gas, which includes ozone, in order to expose the material to ozone, as well as promote mixing due to convective forces. The outlet 10 is closable and in communication with a vertical re-circulator 16. The outlet 10 is operable to provide a discharge point for removing material from the vessel 2 for storage, or for recirculation via the vertical re-circulator 16.

The vertical re-circulator 16 is configured to collect and transport material from the outlet 10 of the vessel 2 to the inlet 8 of the vessel 2. The vertical re-circulator 16 has a first end 18 providing an inlet 20 in communication with the outlet 10 of vessel 2 and an opposed second end 22 providing an outlet 24 in communication with the inlet 8 of the vessel 2. The vertical re-circulator 16 includes a delivery system with a motor driven auger.

The system 1 optionally comprises a drive means (not shown) associated with each of the baffles which is operable to tip baffles 12 relative to the vessel 2 so as to improve disruption of the passage of the granular organic material falling and thereby improve efficiency of oxidation of the material.

Referring to Figure 2, the lower end of the vessel 2 comprises a frusto-conical section 26. The frusto-conical section 26 having any suitable shape and/or dimensions. The system 1 further comprises a discharge agitator 28 including a gyrator, located towards the lower end 6 of vessel 2. The discharge agitator 28 includes an actuator connected to a frusto-conical section 26 of the vessel 2 and in which the agitator 28 is displaced with respect to the vessel 2.

The system 1 further comprises a level sensor 30 configured to detect a level of material within the vessel 2. The level sensor 30 is located adjacent the upper end 4 of the vessel 2.

The system 1 further comprises a processing means (not shown) configured to receive a signal from the level sensor 30 and a controller (not shown) operative to shut off supply of material to the inlet 8 of the vessel in the event of the processing means detecting that the level of material within the vessel has reached a predetermined maximum level for the material. The system 1 further comprises three spaced apart agitating plates 32 located in the vessel 2 operative to promote mixing of the material.

The system 1 further comprises a monitoring system (not shown) to sense and monitor an amount of colony forming units (CFU/g) on non-treated material and material that has been treated with ozone. The system 1 also comprises a control system operative to vary at least one of the following factors in dependence upon the material characteristic and/or the vessel characteristic, the factors from the group comprising: average particle size, mass flow of the material through the vessel, dwell time of the material in the vessel, concentration of ozone gas introduced into the vessel, moisture content of the material, humidity within the vessel, temperature of the vessel, temperature of the material exiting the vessel and amount of colony forming units (CFU/g) detected on a sample of the material. Ideally, following treatment with ozone, the granular organic material is rendered viable but non culturable (VBNC).

In the system shown schematically in Figure 2, the system 1 may include heat transfer means, in the form of fans 34, operative to extract heat from the material as material passes through the vessel 2. The fans 34 are provided in the frusto-conical section 26 to provide a drying zone.

In the system shown in Figure 5, the ozone is provided via an injection plenum collar 35 located adjacent the upper end 4 of the vessel 2.

As shown in Figure 1 , the system 1 is part of a material processing plant for treating a granular organic material with ozone. The plant comprises a bag unloader 42 in communication with a buffer hopper 44 which in turn is in communication with the system 1 as described above. The bag unloader 42 and buffer hopper 44 ensure continuous supply of granular organic material to system 1 .

In use, granular organic material is provided into vessel 2 via inlet 8 at the upper end 4 of the vessel 2. As the material falls through the vessel 2 from the upper end 4 towards the lower end 6 of the vessel 2, the system 1 material is agitated by the agitating plates 32 and the discharge agitator 28 and exposed to a pressurised supply of ozone provided by an ozone injection means 14.

As material enters the frusto-conical section 26 of the vessel 2, ozone is forced into the vessel 2 by fans 34 and passes through the granular material. The number, combination and location of fans varies depending on the requirements of the vessel and/or granular material. Air flow from the fans 34 is typically within the range of 15 to 20 litres per second per tonne or material. In one embodiment, the air/ozone within the vessel 2 is changed, by the fans 34, every 25 to 50 seconds. Air flow provided by the fans 34 has been found to be between 10 to 15 times greater than that achieved using conventional aeration.

The vessel, and in particular the frusto-conical section of the vessel, is dimensioned to ensure a uniform gas flow is achieved through the granular material. A monitoring system has level sensors 30 and other sensors (now shown) which monitor and sense oxidation of the material such that the control system can vary one or more factors (as discussed above) to optimise oxidation of the material within the vessel 2.

A heat extraction means (not shown) is operated by the control system to ensure that heat is efficiently extracted from the material within the vessel 2. As the material reaches the lower end 6 of the vessel 2 the outlet 10 may be operated to either discharge the material, store the material or recirculate the material using the vertical re-circulator 16 as required and in dependence on factors monitored by the monitoring system.

The monitoring system may for example determine that the amount of treating the material with ozone within the material of the vessel 2 is less than a predetermined minimum level and as such the control system may open the outlet 10 and supply the material to the vertical re-circulator 16 to ensure the material is re-supplied to the vessel 2 for additional exposure to ozone.

Once the monitoring system has determined that the material within the vessel 2 has reached sufficient oxidation levels, the outlet 10 may be opened by the control system to discharge the material from the vessel 2. When the level sensor 30 determines that the volume of material within the vessel 2 has reached or exceeds a predetermined level, the outlet 10 may be opened to discharge material.

Figures 3 and 6 shows an overall view and depicts blast panels, in the form of upper 52 and lower 54 burst hatches, are formed from a relatively weaker material such as polycarbonate serve as safety release dump valves in the event of an explosion, thereby avoiding the entire silo being damaged. As the system operates under pressure closure caps 50 are provided so as to ensure the system is compliant for purposes of safety, especially from a point of view of explosions and ozone contamination.

Figures 8, 9, 10 and 11 show overall views of the silo and a depicts ozone injectors, in the form of cross augurs 46, which ensure even treatment of material and promote recirculation of material and mixing as a consequence of the even supply of material from the angled butterfly wing baffles 12. Each butterfly wing baffle 12 angles and directs the material over a baffle edge 67 into a space 69 occupied by the rotating ozone injector(s) 46 which may be a paddle wheel 96, as shown in Figure 12 to 14 or augers 46. The rotating ozone injector(s) are hollow and inject ozone which they receive via a rotating gas sealed coupler, as described below.

Cross augurs 46 may counter rotate in order to promote mixing of material. Alternatively cross augers 46 may rotate in the same direction so as to ensure material (not shown) flows in a preferred direction through the processing vessel 2.

Upper 46A and lower 46B rotating ozone injectors, for example as shown in Figure 4 may operate at different speeds. However, to avoid depletion or build-up of material it is important that throughput of material passed each rotating ozone injector, from above to below each respective rotating ozone injector 46A, 46B is controlled so that the mass flow of material past each rotating ozone injector is substantially constant. In this sense therefore the lower 46B rotating ozone injector should operate to process a greater volume of material than the upper 46A rotating ozone injector. Butterfly wing baffles 12 may have apertures 36 through which gas flows to improve circulation through the silo. Apertures 36 have been found to improve fluidisation and mixing of the granular organic material and therefore improve overall efficiency of injection of ozone. Apertures 36 may be arranged in a line or offset in a grid or array pattern. The example shown in Figure 8 has six apertures 36 in each butterfly wing baffle.

Examples shown in Figures 9 to 11 have six apertures in each butterfly wing baffle. Apertures 36 in upper and lower butterfly wing baffles 12 may optionally be offset one from another so as to be staggered, to promote mixing and sideways movement of material.

Butterfly wing baffles are spaced apart one above one pair above another pair typically of a distance between 1 m and 4 m. This has been found to promote mixing and to improve gas flow through the silo.

Referring to Figure 10, which shows a more detailed view towards a lower portion of the silo, a gyrator 40 is provided which avoids clumping and coagulation and ensures a fluidic flow of treated product from the lower end 6 of the silo 2.

A re-circulator 24 is provided for material which requires further treatment or post-processing, and this is introduced during the recycling phase at re-circulator entrance port 48.

A diverter valve 58 selects a pathway for direction of treated material, and a sensing system determines whether the material requires further processing or whether it is suitable for use, or storage, or transport. If further treatment is required, the diverter diverts the material to the re-circulator.

In one embodiment only the lower portion of the silo is deployed which may enable upper parts to be accessed for maintenance or repair.

Figure 12 shows a sectional view through a gas joint connector 80. Ozone gas is delivered via the connector to the upper cross auger 46A and Io lower cross auger 46B. Ozone gas is introduced under pressure to the rotating augers 46, at one end thereof, so that the ozone is distributed evenly along the length of the rotating member. Alternatively, a paddle wheel 96, for example of the type shown in Figures 13, 14 and 15 may be used as a rotating ozone injector.

Ozone gas is delivered via a hose and injection port 80 via a rotating gas tight seal in a gas joint connect 80 is mounted on a bearing mounting housing 82. A dual lip seal 92 ensures no ozone leaks from the port during operation. A transfer port 86 provides a pathway from the supply (not shown) to the internal silo. A double row of self-aligning bearings 88 ensure that, irrespective of any weight variation or variations in loading or vibration which are encountered by the silo, the there is no leakage from the delivery port.

Figures 13, 14 and 15 show different views of an alternative embodiment of the rotating ozone injector which is in the form of an elongate paddle wheel 96. Figure 13 is an overall end view of an end support 99 which connects to the gas joint connector 80 shown in Figure 12 and enables ozone to be distributed to each hollow fin 102.

Figure 14 shows hollow fins 102 extending substantially the entire length of the paddle wheel 96. The hollow fins 102 have apertures (not shown) through which ozone gas flows so that granular organic material, that has flowed over the baffles 12, is scooped between adjacent hollow fins 102 and treated with ozone gas as the paddle wheel 96 rotates.

Figure 15 shows different an end view of one example of a rotating port which connects to the gas joint connector 80 so that ozone is continuously fed to the rotating paddle wheel 96.

Untreated granular material is collected below each rotating paddle wheel and retuned , via the recirculate (as shown in Figures 8 and 9) mixed, and ozone injectors may also be provided in a lower portion of the silo between the lower butterfly wing baffles and exit port of the silo 2. It is appreciated that sensors (not shown) are provided in different positions within the silo 2 in order to monitor variables such as humidity and temperature and payload of material. Other sensors may be deployed to detect fire, ozone leaks and to monitor various other critical plant and machinery as part of a monitoring system.

The invention has been described by way of example only and it will be appreciated that variation to the aforementioned embodiments may be made without departing from the scope of invention as defined by the claims.

Parts List

1 system

2 processing vessel or silo

4 upper end

6 lower end

8 main inlet feed from bulk silo

10 outlet

12 butterfly wing baffle

14 pressurised ozone supply

16 vertical recirculator

18 re-circulator first end

20 re-circulator second end

22 opposed second end

24 recirculator

26 frusto-conical section

28 discharge agitator

30 level sensor

32 agitating plates

34 fan

35 injection plenum collar

36 apertures dispersing scatterer gyrator bag unloader buffer hopper A rotating ozone injector (upper cross auger)B rotating ozone injector (lower cross auger) recycling entrance port closure caps upper burst hatch lower burst hatch rotating vertical lift diverter valve sluice valve bin agitator double handed lower mixer baffle edge recycle feed motor space inspection hatch or blast panel flexible coupling load cell a gas joint connector bearing housing mounting threaded hole ozone injector port transfer port self-aligning bearing connector to cross screw dual lip seal retention circlip paddle wheel end support gas inlet hole elongate paddles or fins central aperture

(angled) deflector plate plenum diverter controller cyclone heat transfer system/means monitoring system