A system and method for processing waste material

Abstract

Embodiments of the present invention relate to a system and method for processing waste material. The system comprises a pyrolysis unit for heating the waste material for a predetermined period of time to convert the waste material into at least a gas component and a particulate component, at least one dry scrubbing unit connected to the pyrolysis unit, and at least one at least one condensing unit connected to the at least one dry scrubbing unit.

Description

A system and method for processing waste materialTechnical Field

[0001] The present invention relates to a system and method for processing waste material. In particular, the present invention relates to a system and method for processing plastic material using pyrolysis.Background

[0002] There is a growing need to process waste material and transforming the material into resources that can be utilised in various ways. This will ultimately decrease dependency on landfill and have significant advantages to the environment. Processing waste material, in particular waste material that includes plastics, is a challenging process due to a number of factors, such as the composition of the material to be recycled, the different chemical compositions of the plastic material, and the longevity of the plastic material. Still today, a large portion of plastic material is improperly discarded in landfill as with conventional methods, only very few types of plastic materials can be recycled.

[0003] It would be advantageous if at least an embodiment of the present invention overcame some problems of conventional recycling methods or at least provided a workable alternative.

[0004] Any discussion of documents, acts, materials, devices, articles or the like which have been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

[0005] Throughout the specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.Summary

[0006] Embodiments of the present invention relate to a system for processing waste material, the system comprising: a pyrolysis unit for heating the waste material for a predetermined period of time to convert the waste material into at least a gas component and a particulate component; at least one dry scrubbing unit connected to the pyrolysis unit to process a flow of the gas component, the at least one dry scrubbing unit comprising a particulate material and being configured to cause turbulences in the flow of the gas component such that the gas component reacts with the particulate material to remove harmful gases and / or particulate matter from the gas component; and at least one condensing unit connected to the at least one dry scrubbing unit, the at least one condensing unit being configured to reduce a temperature of the gas component to convert the gas component into oil and a non-condensable gas component.

[0007] Embodiments of the present invention provide significant advantages. In particular, in accordance with an embodiment of the present invention, different types of plastic waste material can be processed using the same system. By configuring the system as a modular, portable unit, waste material can be processed at the location where the waste material is generated, thereby saving transportation costs and reducing the associated negative effects on the environment.

[0008] In accordance with embodiments of the present invention, the waste material comprises plastic. Exemplary waste material includes soft plastic material, e-waste that includes plastic components and industrial plastic material.

[0009] In an embodiment, the pyrolysis unit heats the waste material to a temperature in the range between about 250°C to 600°C. A temperature of the pyrolysis unit may be selected depending on the type of the waste material. For example, soft plastic material may require a lower temperature than industrial plastic material.

[0010] In an embodiment, the system is portable. For example, the system may comprise a container for housing at least some components of the system. In one specific example, the container may be a sea shipping container. This has the significant advantage that the system can bedecentralised and accordingly transported to any desired location, including remote areas. In this way, waste material can be processed at the location where the waste is generated. One particular example relates to dwellings in remote areas that would conventionally need to transport waste material to the next larger dwelling or dispose the waste material in landfill. This is associated with high transport costs and / or a negative impact to the environment. Another example relates to waste material that is generated at mining and exploration sites which are typically located in remote areas.

[0011] In an embodiment of the present invention, the system may comprise modular units that can be connected to each other, and exchanged if necessary. For example, depending on the requirements of processing the waste material, a further dry scrubbing unit may be added to the system, or a fixed bed reactor may be replaced by an auger reactor.

[0012] In one specific embodiment, the pyrolysis unit comprises a fixed bed reactor. Alternatively, the pyrolysis unit may comprise an auger reactor.

[0013] The system in accordance with embodiments of the present invention may be configured to heat the waste material in the pyrolysis unit until a majority of the waste material is converted to the gas component and the particulate component. For example, the pyrolysis unit may heat the waste material to a temperature in the range from about 250°C to about 600°C, depending on the type of the waste material. The waste material is heated within the pyrolysis unit until about 80%, or about 85%, or about 90%, or about 95% of the waste material is converted to the gas component and the particulate component. The particulate component typically is a fine particulate powder that may be referred to as black carbon (pure carbon in several linked forms).

[0014] In an embodiment, a temperature of the pyrolysis unit is set depending on a type of waste material to be processed. For example, residential soft plastics may require a lower temperature than industrial plastics. The temperature may be set manually. However, it is envisaged that setting of the temperature of the pyrolysis unit may be automated, for example, if the system can automatically identify a type of waste material to be processed.

[0015] The system in accordance with embodiments of the present invention may operate at an operating pressure of less than about 3 bar. For example, the system may operate at an operating pressure of about 1 bar. The system may be configured such that a difference in pressure within the system causes the gas component to naturally flow through the system. Specifically, the pyrolysis unitwould typically operate at a maximum pressure, whereas pressures at other units that follow, such as the dry scrubbing unit and the condensing unit will be lower.

[0016] In some embodiments, the system may comprise at least one pressure sensor for detecting a pressure within the system. The at least one pressure sensor functions as a safety measure to avoid an increase in pressure due to unforeseen circumstances, such as a malfunction of the system.

[0017] In an embodiment, the at least one dry scrubbing unit comprises a tube for receiving the flow of the gas component of the waste material. The tube may be configured in the form of a spiral. However, a person skilled in the art will appreciate that other forms and shapes are envisaged.

[0018] The particulate material of the at least one dry scrubbing unit may be selected and arranged within the at least one dry scrubbing unit to interact with the gas component to remove harmful gas and / or particulate matter. In one specific example, the particulate material may be selected to remove at least chlorine from the gas component. In particular, the particulate material may be selected to react with the gas component to absorb chlorine from the gas component. In one example, the particulate material is in the form of a plurality of solid bodies that are arranged such that the gas component can flow through the plurality of solid bodies to react with the material of the solid bodies. In a specific example, the particulate material is in the form of a plurality of substantially round, solid bodies, such as pellets.

[0019] In a specific example, the particulate material may be located within the tube of the at least one dry scrubbing unit. In the example of the pellets, a bed of pellets may be provided in the tube that the gas component can flow through. The tube may be in spiral form. The inventor of the present invention has found that the spiral shape of the tube increases the surface area interaction of the gas component with the particulate material due to the introduction of turbulences.

[0020] The pellets may have a diameter of approximately 3-4 mm.

[0021] In one embodiment, the particulate material may comprise a composition of calcium hydroxide and sand, such as clay. Specifically, the particulate material may consist of about 70% clay and about 30% calcium hydroxide. However, a person skilled in the art will appreciate that other compositions are envisaged, including but not limited to about 80% clay and about 20% calcium hydroxide, or about 75% clay and about 25% calcium hydroxide, or about 65% clay and about 35% calcium hydroxide, or about 60% clay and about 40% calcium hydroxide. The at least one dry scrubbingunit may be configured such that when the gas component of the waste material flows through the particulate material, for example, a bed of pellets within a spiral tube, chlorine and / or other harmful gases and particulate matter can be absorbed by the particulate material. The inventor of the present invention has found that including the at least one dry scrubbing unit to remove chlorine from the gas component of the waste material has significant advantages in processing chlorine containing plastics, such as PVC plastics. Conventionally, the presence of chlorine within PVC plastics has been associated with difficulties to process this type of plastics material.

[0022] In an embodiment, the system comprises a plurality of dry scrubbing units that are arranged in series. For example, the system may comprise two or three dry scrubbing units.

[0023] In one embodiment, the condensing unit may comprise at least one condensing tube for receiving the gas component from the at least one dry scrubbing unit, wherein the at least one condensing tube is connected to a source of cooling water for cooling the condensing tube. Thus, when the gas component flows through the at least one condensing tube, at least a portion of the gas component condenses at the inner walls of the condensing tube, thereby converting into its liquid state in the form of oil.

[0024] The source of cooling water may comprise cooling water of a temperature that is sufficiently cold such that a majority of the condensable gas component is converted into oil and the noncondensable gas component. For example, the temperature may be less than about 20°C, or less than about 15°C, or less than about 10°C. In a specific example, the cooling water in the source of cooling water is approximately 7°C.

[0025] A length of the at least one condensing tube may be in the range of from about 1 and about 15 metres, for example, between about 2 and about 12 metres, or between about 3 and about 10 metres, or of at least approximately 4m, 5m, 6m, 7m, 8m, 9m, 10m, 11m, or 12m. The length of the at least one condensing tube is selected such that a majority of the condensable gas component is converted into oil and the non-condensable gas component.

[0026] The at least one condensing tube of the condensing unit may be configured at an angle to maintain a flow of the gas component. For example, the at least one condensing unit may be configured to ensure a flow rate of the gas component of at least 20m3 / hour, such as in the range of from about 20 to about 30m3 / hour. The angle of the at least one condensing tube may range between about l°and about 5°, or approximately about 2°, about 3°, or about 4°.

[0027] The condensing unit may comprise a plurality of condensing tubes. In a particular example, the condensing unit comprises a first condensing tube and a second condensing tube that are arranged in series.

[0028] In one specific example, the condensing unit comprises a pair of condensing tubes, each having a length of about 6m and being arranged at an angle of about 3°. The inventor of the present invention has found that this configuration results in a flow rate of the gas component of approximately 25m3 / hour.

[0029] In an embodiment, the system may comprise a shredding unit that processes the waste material prior to feeding the waste material into the pyrolysis unit. The shredding unit may be configured to reduce a size of individual parts of the waste material. Specifically, the shredding unit may be configured to process the waste material to fragments of a pre-determined size, such as having a maximum diameter of about 50mm, or about 40mm, or about 30mm, or about 20mm, or about 10mm. In one particular example, the shredding unit is configured to process the waste material into fragments having a maximum diameter of about 20mm. The size of the fragments is selected to be sufficiently small so that the majority of waste material is converted in the pyrolysis unit.

[0030] In some embodiments, the system may comprise a gravity feeder for feeding waste material into the pyrolysis unit using gravity. The gravity feeder may comprise a hopper for feeding waste material to the pyrolysis unit, wherein the hopper is connected to the pyrolysis unit by a one-way valve. The hopper may taper towards a bottom portion where the one-way valve is positioned.

[0031] In one embodiment, the gravity feeder is configured to pre-heat the waste material in the hopper to dry the waste material thereby removing oxygen from the material. In one example, the gravity feeder is configured to pre-heat the material to a temperature in the range of from about 60 to about 70°C. However, a person skilled in the art will appreciate that other temperatures are envisaged that sufficiently dry the waste material.

[0032] The system in accordance with embodiments of the present invention is configured to feed waste material to the pyrolysis unit in pre-determined batches, for example, batches of a predetermined volume or weight. In this regard, the gravity feeder may comprise a scale for determining a weight of waste material that is located within the gravity feeder. The system may be configured such that when the scale determines that the waste material that is located within the gravity feedermeets the pre-determined weight, the system automatically opens the one-way valve such that a batch of waste material having the pre-determined weight is provided into the pyrolysis unit.

[0033] The system may be configured as an airtight system.

[0034] Some embodiments of the present invention may require a continuous processing of waste material. For these embodiments, the system may comprise a compressor for compressing the waste material, in particular the shredded waste material having a pre-determined particle size. Utilising a compressor may be advantageous if the pyrolysis unit comprises an auger reactor. Furthermore, by compressing the waste material, oxygen can be removed without the need for pre-heating the material or purging the pyrolysis reactor.

[0035] In an embodiment, the system may comprise at least one wet scrubbing unit, wherein the wet scrubbing unit comprises a container for holding a water solution. The water solution may be configured to remove pollutants and other reactants from the gas component by flowing through the water solution.

[0036] In an embodiment, the system is configured as a closed loop system that utilises the resulting gas component to assist in heating the pyrolysis unit.

[0037] Embodiments of the present invention relate to a method of processing waste material, the method comprising: heating, using pyrolysis, the waste material for a predetermined period of time to convert the waste material into at least a gas component and a particulate component; processing a flow of the gas component by causing turbulences within the flow of the gas component and directing the gas component through a particulate material such that the gas component reacts with a surface area of the particulate material to remove harmful gases and / or particulate matter from the gas component; thereafter, gradually cooling the flow of the gas component to convert the gas component into a liquid component and a non-condensable gas component.

[0038] The waste material may be heated to a temperature between about 250°C and about 600°C. The temperature may be selected based on the type of waste material. In some embodiments, the waste material comprises plastic.

[0039] In an embodiment, the method may comprise a step of removing oxygen from the waste material prior to processing. For example, the method may comprise a step of pre-heating the waste material. Additionally or alternatively, the method may comprise a step of providing an inert gas for purging oxygen from the waste material.

[0040] The method may further comprise feeding the pre-heated waste material into a pyrolysis unit where the waste material is heated to a temperature between about 250°C and about 600°C. In addition, the method may comprise weighing the pre-heated waste material and automatically feeding the waste material into the pyrolysis unit when a pre-determined weight has been detected.

[0041] In an embodiment, the method may comprise shredding the waste material into smaller particles, such as having a maximum diameter of about 50mm, or about 40mm, or about 30mm, or about 20mm, or about 10mm.

[0042] In an embodiment, the method may comprise gradually heating the waste material by moving the waste material through sections of increasing temperatures. For example, an auger reactor may be provided having a plurality of sections that can be set at different temperatures. In this regard, the method may comprise rotating a screw within the reactor to move the waste material along the auger reactor.

[0043] In an embodiment, the method may comprise identifying a type of waste material and heating the waste material to a temperature that is selected based on the identified type of waste material.

[0044] In some embodiments, the method may comprise directing the non-condensable gas component through a water solution configured to remove pollutants and other reactants from the gas component.

[0045] It will be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the invention as shown in the specific embodiments and / or aspects without departing from the spirit or scope of the invention as broadly described. For example, it willbe apparent that certain features of the invention can be combined to form further embodiments. The present embodiments and aspects are, therefore, to be considered in all respects as illustrative and not restrictive. Several embodiments are described above with reference to the drawings. These drawings illustrate certain details of specific embodiments that implement the systems and methods and programs of the present invention. However, describing the invention with drawings should not be construed as imposing on the invention any limitations associated with features shown in the drawings.Brief Description of Drawings

[0046] Certain exemplary embodiments of the present invention will now be described, by example only, with reference to the accompanying drawings in which:

[0047] Figure 1 is a schematic representation of a system in accordance with an embodiment of the present invention;

[0048] Figure 2 is a schematic representation of a gravity feeder of the system of Figure 1;

[0049] Figure 3 is a schematic representation of a dry scrubbing unit of the system of Figure 1;

[0050] Figure 4 is a schematic representation of an auger reactor of a system in accordance with an alternative embodiment of the present invention;

[0051] Figure 5 is a schematic representation of a system in accordance with a further embodiment of the present invention; and

[0052] Figure 6 is a flow chart illustrating a method of processing waste material in accordance with an embodiment of the present invention.Description of Embodiments

[0053] Embodiments of the present invention generally relate to a system and a method for processing waste material, such as plastic waste material, using pyrolysis. The system comprises a pyrolysis unit for heating the waste material for a predetermined period of time. The pyrolysis unit may be in the form of a fixed bed reactor or an auger reactor. A temperature of the pyrolysis unit may be set in a range between about 250°C to about 600°C. In some embodiments, the system may be configured in a modular manner so that units of the system can be changed, replaced or added. For example, a specific type of reactor may be selected and connected to the remaining units of the system depending on the requirements of waste material to be processed. The pyrolysis unit is configured to process the waste material such that the waste material converts to at least a gas component and a particulate component, such as carbon black.

[0054] The system further comprises at least one dry scrubbing unit connected to the pyrolysis unit and configured to process a flow of the gas component of the waste material that is received from the pyrolysis unit. The at least one dry scrubbing unit comprises a particulate material and is configured to cause turbulences in the flow of the gas component such that the gas component reacts with the surface of the particulate material. The particulate material is selected such that the surface interaction causes harmful gases, such as chlorine, and / or particulate matter from the gas component to be absorbed by the particulate material. In some embodiments of the present invention, this may be achieved by the gas component flowing through a bed of calcium hydroxide and clay pellets as will be described in further detail below.

[0055] The system further comprises at least one condensing unit connected to the at least one dry scrubbing unit, wherein the at least one condensing unit is configured to reduce a temperature of the gas component to convert the gas component into a liquid component, i.e. oil and a non-condensable gas component.

[0056] Embodiments of the present invention find application in the processing of various waste material, including consumer plastic materials, industrial plastic materials, ocean plastic materials, agriculture plastic materials, medical plastic materials and e-waste which typically refers to discarded electric and electronic devices that most commonly contain a mixture of metals and precious metals and plastic material.

[0057] The system and method according to embodiments of the present invention is configured as a closed, airtight system in which oxygen is not present or has been removed prior to the waste material being loaded into the pyrolysis unit. As such, various plastic materials can be processed, including mixed polymer materials. Exemplary materials include but are not limited to polyolefins - typically polyethylene and polypropylene - polyvinylchlorides, and polystyrenes. Plastics, such as PET (polyethylene terephthalate) cannot be processed by the present invention due to its presence of oxygen within the material which would be released in the pyrolysis step.

[0058] The system and method according to embodiments of the present invention is modular and comprises a plurality of units that allow for coupling, decoupling, and exchanging of individual units based on specific requirements, such as the volume and type of waste material to be processed.

[0059] In a specific embodiment, the system may be implemented as a decentralised system which is portable. For example, the system may comprise a housing in the form of a sea shipping container that can be transported to any desired location. This enables the system to process the waste material at the location where the waste is generated. This has significant advantages, including reducing transporting costs, times and resources of the waste material.

[0060] Embodiments of the present invention aim to overcome problems in traditional waste management by providing a viable system and method to process and ultimately recycle waste material, in particular plastic waste material. Problems with traditional waste management include but are not limited to the following:• lack of viable recycling solutions, in particular for challenging waste material, such as mixed plastics, WEEE waste, contaminated plastics, and hard-to-recover plastics - these types of waste materials are often disposed in landfill,• environmental impact due to improper disposal of plastic waste material - this has a severe impact on environment due to slow degradation time, soil and water contamination and disruption to eco-systems,• resource depletion due to majority of plastics material being produced from valuable resources, such as petroleum, substantial energy consumption to produce new plastics material, and• proliferation of plastic waste in oceans and other systems due to improper disposal of waste material.

[0061] Referring initially to Figure 1 of the accompanying drawings, there is shown a system 100 for processing a waste material, in this particular example of plastic waste material, in accordance with an embodiment of the present invention. The system 100 is configured to process pre-processed waste material. Pre-processing of the waste material may include one or more of the following: manual separation of PET plastic material, sorting of different types of waste material, washing of waste material and / or shredding of waste material. Some exemplary pre-processing units and method steps will be described in further detail below. Other units and method steps relating to the preprocessing of waste material are well known to the person skilled in the art and will not further be described.Pyrolysis unit

[0062] The system 100 comprises a pyrolysis unit 102. The pyrolysis unit 102 may be implemented as a fixed bed reactor 102 as shown in Figure 1, or alternatively as an auger reactor 400 illustrated in Figure 4. One of the differences between fixed bed reactors and auger reactors is that waste material in a fixed bed reactor is stationary, while the waste material is moved through an auger reactor which may be more advantageous in certain applications as will be described below.

[0063] In the pyrolysis unit 102, a batch of waste material 104 is heated up to a maximum temperature of about 600°C in the absence of oxygen. In this regard, the pyrolysis unit 102 may be connected to an inert gas source 106, such as nitrogen 108, that flows into the chamber of the pyrolysis unit 102 to purge oxygen within the pyrolysis unit 102. In this example, nitrogen 108 is used as a carrier gas throughout the system 100 to make the atmosphere inert inside the pyrolysis unit 102. However, a person skilled in the art will appreciate that other suitable gasses are envisaged.

[0064] A temperature of the pyrolysis unit 102 is set depending on a type of waste material 104 to be processed. In this example, the temperature of the pyrolysis unit 102 is manually set to approximately 400°C for processing industrial waste material. Exemplary temperature settings are set out below:About 250 - 300°C for soft plastics,About 450 to 500°C for e-waste, andAbout 300 - 450°C for industrial plastic materials.

[0065] However, a person skilled in the art will appreciate that other temperature ranges are envisaged. Further, the system 100 may be configured to set the temperature of the pyrolysis unit 102 automatically, for example, if a type of waste material is automatically identified through a camera system or the like. In this way, batches of different types of waste material may be automatically processed in the same system.

[0066] In the system 100 shown in Figure 1, the waste material 104 is processed within the pyrolysis unit 102 for approximately 1 hr. However, a person skilled in the art will appreciate that the time for processing the waste material 104 will depend on various factors, including but not limited to the type of waste material, a volume and weight of the waste material to be processed, and a size of particles of the waste material. In the chamber of the pyrolysis unit 102, the waste material 104 is heated up for a predetermined time such that the waste material 104 is substantially converted into at least the following components: a gas component 110 and a particulate material 112, such as black carbon. Black carbon 112 is a byproduct of the pyrolysis process in the pyrolysis unit 102 which is collected in a container (not shown). The black carbon 112 typically is in powder form of carbon particles, and may be further processed in various applications, for example, to produce rubber, tyres, road surfaces or other industrial applications.

[0067] The system 100 is configured as a closed system which is airtight. This is important as the presence of oxygen in the system 100 is undesired. The system 100 is configured such that a pressure within the system 100 does not exceed about 3 bars. In this regard, the system 100 may comprise one or more pressure sensors (not shown) to detect a pressure at one or more units of the system 100 to ensure that a pressure of 3 bar is not exceeded. The highest pressure typically occurs at the pyrolysis unit 102. The gradient in pressure within the system 100 allows for a natural flow of gas 110 within the system 100 without the need for an additional pump.

[0068] In the embodiment shown in Figure 1, the pyrolysis unit 102 comprises a fixed bed pyrolysis reactor with a heating coil 114. Due to the use of a fixed bed reactor, waste material 104 to be processed in the pyrolysis unit 102 is provided to the pyrolysis unit 102 in pre-determined batches, in this embodiment in batches that weigh 250kg. However, a person skilled in the art will appreciate that any weight and volume of batches are envisaged, giving the possibility of upscaling or downscaling the system 100.

[0069] In this embodiment, the pyrolysis unit 102 is connected to a gravity feeder 200 illustrated in Figure 2 of the accompanying drawings. The gravity feeder 200 is configured to feed waste material to the pyrolysis unit 102 in pre-determined batches. The gravity feeder 200 may be configured such that waste material may be pre-heated before moving into the pyrolysis unit 102 under gravity. In this regard, the gravity feeder 200 comprises a hopper 202 for receiving waste material. The gravity feeder 200 further comprises a batch weighing hopper 204 that tapers towards a bottom portion where a one-way valve 206 is provided that connects the gravity feeder 400 with the pyrolysis unit 102. The one-way valve 206 may preferably be a high temperature pneumatic one-way valve to withstand the temperatures of the pyrolysis unit 102.

[0070] Material within the gravity feeder may be heated to approximately 60 - 70°C. Pre-heating the waste material has the function of drying the waste material, thereby removing oxygen from the material. In this example, the batch weighing hopper 204 includes a scale that detects a weight of the waste material within the hopper 204. The gravity feeder 200 may be configured such that the oneway valve 206 automatically opens once the scale determines that the batch weighing hopper 204 holds the required weight of the pre-determined batch, such as 250kg. While a batch is processed in the pyrolysis unit 102 for a pre-determined time period, in this embodiment for approximately 1 hour, a further batch may be pre-processed in the gravity feeder 200. In an alternative example (not shown), a separate pre-heating unit may be provided such that already pre-heated waste material is provided into the gravity feeder 200.

[0071] The gravity feeder 200 may further be connected to a shredding unit that in this example is configured to provide shredded waste material to the gravity feeder 200. The shredding unit is configured to shred plastics material to flakes having a maximum diameter of 20 mm. However, a person skilled in the art will appreciate that other particle dimensions are envisaged, including but not limited to maximum diameters of 15mm, 10mm, or 5mm. In this embodiment, the shredding unit is configured to blow the shredded material into an open top portion of the hopper 202.

[0072] In this embodiment, the provision of continuous batches is fully automated as the one-way valve 206 automatically opens once the batch weighing hopper 204 holds the pre-determined weight of a batch. The system in accordance with this embodiment is configured such that when the gravity feeder unit 400 releases a batch into the pyrolysis unit 102, no oxygen is present in the batch and there is no need to supply an inert gas to the pyrolysis unit 102. However, if a batch is released to the pyrolysis unit 102 that is less than the pre-determined weight of a batch, an inert gas is automatically supplied into the chamber of the pyrolysis unit 102 to purge any oxygen present within the material.

[0073] In an alternative embodiment of the present invention, the pyrolysis unit is implemented as an auger reactor. An example of an auger reactor 400 is illustrated in Figure 4 of the accompanying drawings. Given the modular configuration of the system 100, the fixed bed pyrolysis unit 102 of the system 100 may be replaced by an auger reactor, such as auger reactor 400 that is then connected to the remaining units of the system 100, such as the at least one dry scrubbing unit 116.

[0074] In this alternative embodiment shown in Figure 4 in which the pyrolysis unit comprises an auger reactor 400, the system comprises a compressing unit 402 that is connected to the pyrolysis unit 400.

[0075] In this regard, a continuous feed of waste material 406 may be provided to the pyrolysis unit 400. In this example, this is achieved by a gravity feed hopper 408 that is connected to the compressing unit 402. The compressing unit 402 is composed of a screw 410 that is driven by a motor 412 to move and compress the material 406 within the compressing unit 402. In this example, the compressing unit 402 also incorporates a pre-heater 414 in the form of a band heater 414 that gradually increases a temperature of the waste material 406 within the compressing unit 402 to remove moisture from the waste material 406. The compressing unit 402 is connected to the auger pyrolysis reactor 400 to provide the waste material 412 into the pyrolysis unit.

[0076] The auger pyrolysis reactor 400 comprises a housing 414 and a screw 416 that is rotatable within the housing 414, driven by a motor 417. Thus, by rotating the screw 416, the waste material 406 is moved through the auger reactor 400, typically in a substantially horizontal direction. However, a person skilled in the art will appreciate that other configurations of the auger reactor are envisaged, for example, where waste material is moved vertically, such as upwards. As described above, the pyrolysis unit in accordance with embodiments of the present invention is operated at different temperatures depending on the type of material to be processed. In this particular embodiment, the auger pyrolysis reactor 400 comprises a plurality of sections extending along the housing 414, each section being set to operate at a different temperature thereby increasing the temperature of the waste material 406 along the auger reactor 400. In this example, this is implemented by a ceramic band heater 418. For example, a first section of the housing where the waste material is fed into the auger reactor may be set to a temperature of approximately 250°C. A second section that follows after the first section may be set to a temperature of about 300°C. A third section may be set to a temperature of about 350°C and so on. Thus, waste material 406 moving through the auger reactor 400 may gradually be heated up. A person skilled in the art will appreciate that any suitable number of sections are envisaged so that the temperature incrementally increases along a length of thehousing of the pyrolysis reactor. For example, the auger pyrolysis reactor may be configured to allow heating of the material to up to about 600°C along the length of the reactor. In this way, the pyrolysis unit may be able to process different types of material, including e-waste.

[0077] Having a plurality of sections set at increasing temperatures has the advantage that depending on the type of waste material, some waste material may only need to move to the second section, whereas other types of waste material may need to move to the fourth section. For example, if only residential, household plastic material is to be processed, the waste material may only need to be heated up to about 300°C. Thus, referring to the example above, the material may only need to be heated up to the second section and then moved through the remaining sections without further heating. This significantly reduces the time for the material to move through the auger reactor 400. If industrial plastics are to be processed, the waste material requires to be heated up to approximately 450°C. In this case, the material requires to stay in the auger reactor 400 for a longer period as the waste material needs to be heated to a further section within the housing. Thus, the inventor of the present invention has found that an auger reactor may be particularly advantageous if different types of waste materials are to be processed in the same system.Dry scrubbing unit

[0078] Referring back to the system 100 shown in Figure 1, the system 100 further comprises at least one dry scrubbing unit 116. While the system 100 only comprises one dry scrubbing unit 116, the system in accordance with embodiments of the present invention may comprise a plurality of dry scrubbing units, such as three dry scrubbing units that are configured in series. An example of a dry scrubbing unit 116 is illustrated in further detail in Figure 3.

[0079] In the example shown in Figure 3, the at least one dry scrubbing unit 116 comprises a particulate material 302 to interact with the flow of the gas component 110. In this particular example, the particulate material 302 is in the form of a plurality of solid, round bodies, such as pellets with a diameter of approximately 3-4mm.

[0080] The particulate material 302 comprises a composition of calcium hydroxide and sand, such as clay. Specifically, the particulate material 302 may consist of about 70% clay and about 30% calcium hydroxide. However, a person skilled in the art will appreciate that other compositions are envisaged. The at least one dry scrubbing unit 116 may be configured such that when the gas component 110 of the waste material flows through the particulate material 302, for example a bed of pellets, the gascomponent 110 interacts with a surface area of the particulate material 302 such that chlorine within the gas component 110 is absorbed by the particulate material 302. In this example, the material of the particulate material 302 is selected to remove at least chlorine from the gas component 110 of the waste material. This has the significant advantage that PVC plastics may be processed by the system 100. Conventionally, the presence of chlorine within PVC plastics has been associated with difficulties to process this type of plastics material.

[0081] Referring back to Figure 3, the dry scrubbing unit 116 comprises a tube 304 for holding the plurality of pellets 302. The tube 304 in this example is arranged in a shape of a spiral. The inventor of the present invention has found that providing a tube 304 in the shape of a spiral causes turbulences within the flow of the gas component 110 which increases the surface area interaction of the gas component 110 with the particulate material 302 in the dry scrubbing unit 116.

[0082] The dry scrubbing unit 116 may be heated, in this example by virtue of a heating coil 117. In this example, the heating coil 117 is configured to heat the dry scrubbing unit 116 to approximately 250°C which ensures that chlorine in the gas component 110 stays in its gas form. The inventor of the present invention has found that chlorine in its gas form reacts better with the particulate material 302 in the dry scrubbing unit.

[0083] While the gas component 110 of the waste material 104 flows through the at least one dry scrubbing unit 116, a temperature of the gas component 110 is gradually reduced from approximately 400°C to approximately 200°C.

[0084] Once the gas component 110 of the waste material 104 has flown through the at least one dry scrubbing unit 116, the processed gas component 110 flows from the at least one dry scrubbing unit 116 to a condensing unit 118. The chlorine that has been removed from the gas component is absorbed by the pellets 302 in the at least one dry scrubbing unit 116 which need to be replaced or washed after prolonged use of the system 100. The inventor of the present invention has found that the pellets 302 of the dry scrubbing unit 116 of the system 100 may need replacing or washing after 3 years of operation of the system 100.

[0085] As a result of the gas component 110 flowing through the dry scrubbing unit 116, further dry carbon black 112 may be separated from the gas component 110 which is collected in a container 119 as shown in Figure 1.Condensing unit

[0086] Referring back to Figure 1, the system 100 further comprises a condensing unit 118. Specifically, following on from the at least one dry scrubbing unit 116, the processed gas component 110 of the waste material 104 is received at a condensing unit 118. In the condensing unit 118, a temperature of the gas component 110 is gradually reduced, in this example from approximately 200°C to 40°C. By gradually reducing the temperature of the gas component 110, the gas component 110 is converted into a liquid component, in this example oil 120, and a non-condensable gas component 122.

[0087] The condensing unit 118 of the system 100 shown in Figure 1 comprises at least one condensing tube, in this example, a first condensing tube 124 and a second condensing tube 126. A function of the first condensing tube 124 is to condense the gas component 110 exiting from the dry scrubbing unit 116, facilitating the heat and mass transfer to separate the gas component 110 into oil 120 and gas phases. A function of the second condensing tube 126 is to condense the maximum amount of the gas component exiting from the primary condensing tube 124 to increase overall oil yield.

[0088] Both condensing tubes 124, 126 are connected to a source of cooling water 128 which flows through a wall of each condensing tube 124, 126 thereby cooling the flow of the gas component within the condensing tubes 124, 126. In this particular example, the cooling water 128 has a temperature of approximately 7°C which results in the gas component to be cooled to approximately 40°C when the gas component exits the second condensing tube 126. However, a person skilled in the art will appreciate that other temperature ranges are envisaged. The cooling water circulates through the wall sections of each tube 124, 126 to the cooling unit where a temperature of the water is reduced again to 7°C.

[0089] The condensing tubes 124, 126 of the condensing unit 118 are arranged in series and each have a length of approximately 6m. Each tube 124, 126 is further configured at an angle of 3° which results in a flow rate of 25m3 / hour. The inventor of the present invention has found that the length of 6 m for each tube 124, 126 at an angle of 3° provides for a good result in processing the waste material 104 and obtaining the oil 120. However, a person skilled in the art will appreciate that other dimensions and configurations of the condensing tubes 124, 126 are envisaged.

[0090] By flowing through the condensing unit 118, any condensable component of the gas component turns into liquid state. The resulting liquid oil 120 is captured in an oil storage 130. The liquid oil 120 may be further processed, for example, in a distillation unit to refine the liquid oil that can be used to create recycled plastic materials.

[0091] A component of non-condensable gas 122 is further processed in the next unit of the system 100.Wet scrubber / Bubbler

[0092] The system 100 further comprises a wet scrubbing unit 132 that receives the non- condensable gas component 122 from the condensing unit 118.

[0093] The wet scrubbing unit 132 comprises a container 134 for holding a water composition 136 of water and sodium hydroxide. In the example illustrated in Figure 1, the proportion of water to sodium hydroxide is II water to 100g sodium hydroxide. The container 134 comprises a gas inlet at a bottom portion of the container for feeding the non-condensable gas component 112 into the wet scrubbing unit 132 where the non-condensable gas 112 rises through the water composition 136 thereby reacting with the sodium hydroxide. In this way, pollutants and harmful gases can be removed from the non-condensable gas component 122. Wet scrubbing units are well known to a person skilled in the art and only described in some detail in the present description.Gas storage

[0094] Following the wet scrubbing unit 132, the cleaned non-condensable gas 138 exits the wet scrubbing unit 132 through a gas outlet that is positioned at a top portion of the container 134. There are several options for the further processing of the cleaned non-condensable gas 138. In one embodiment, the cleaned non-condensable gas 138 may be released from the system 100 into the atmosphere. In another example which is illustrated in Figure 1, the cleaned non-condensable gas 138, which may also be referred to as Syngas, is stored in a gas storage tank 140. A pump 142 is provided to direct the cleaned non-condensable gas 138 into the gas storage tank 140 where the cleaned non- condensable gas 138 is compressed by a compressor 144. In this particular example, the cleaned non- condensable gas 138 is compressed to a pressure of 5 bar.Closed loop

[0095] The system 100 as shown in Figure 1 is configured as a closed loop system. In this regard, the cleaned non-condensable gas 138 flows through a second wet bubbling unit 146 and is subsequently directed into a combustion unit 148 in which the cleaned non-condensable gas 138 where the cleaned non-condensable gas 138 is utilised to heat the pyrolysis unit 102. The water composition within the second wet bubbling unit 146 also comprises water and sodium hydroxide, with a ratio of 1:10.

[0096] An exhaust 150 may be provided to release any remaining gas from the system 100.

[0097] Figure 5 of the accompanying drawings shows a further embodiment of a system 500 for processing a waste material. The system 500 is implemented as a decentralised, portable system 500. The system 500 comprises a housing in the form of a shipping container 502 that can be transported to any desired location on a load bearing vehicle, such as truck 504.

[0098] The system 500 comprises some of the units of system 100 shown in Figure 1, in particular the pyrolysis unit 102, the dry scrubbing unit 118, the condensing unit 118 and the wet scrubbing unit 134. However, a person skilled in the art will appreciate that any suitable unit of the system in accordance with embodiments of the present invention may be incorporated in the system 500, including but not limited to the auger reactor 400.

[0099] In addition to these units, the system 500 comprises a conveying and sorting module 506, a cleaning unit 508, a shredding and granulating unit 510, and mechanical recovery unit 512.

[0100] Referring now to Figure 6 of the accompanying drawings, there is shown a flowchart illustrating a method 600 of processing a waste material in accordance with an embodiment of the present invention. The method 600 may be applied to a system for processing waste material, such as system 100 described with reference to Figure 1.

[0101] The method 600 in accordance with an embodiment of the present invention comprises an initial step of pre-heating 602 a waste material to a temperature between about 60°C and about 70°C. The waste material typically is provided in small fragments, and may be shredded prior to being preheated. As described with reference to the system 100 above, the pre-heating step is optional andmay be replaced by compressing the waste material. The main function of pre-heating the waste material is to remove a majority of oxygen within the material.

[0102] In a further step, the pre-heated waste material is heated 604, using pyrolysis, to a temperature between about 250°C and 600°C for a predetermined period of time to convert the waste material into at least a gas component and a particulate component. The particulate material may be removed and further processed.

[0103] The gas component is further processed 606 by generating turbulences within the flow of the gas component and directing the gas component through a particulate material such that the gas component reacts with a surface area of the particulate material to remove at least chlorine from the gas component. Thereafter, the method 600 comprises a step 608 of gradually cooling the flow of the gas component to convert the gas component into a liquid component and a non-condensable gas component.

[0104] Following the condensing step, the non-condensable gas component may be directed 610 through a water solution configured to remove pollutants and other reactants from the gas component.

[0105] In some examples, the method may further comprise a step of feeding the pre-heated waste material into a pyrolysis unit where the waste material is heated to a temperature between about 250°C and about 600°C. In addition, the method may comprise weighing the pre-heated waste material and automatically feeding the waste material into the pyrolysis unit when a pre-determined weight has been detected.

[0106] In an embodiment, the step of heating the waste material to a temperature between about 250°C and about 600°C may be conducted gradually, for example, by moving the waste material through sections of increasing temperatures.

[0107] In specific example, the method may comprise identifying a type of waste material and heating the waste material to a temperature that is selected based on the identified type of waste material.

[0108] It will be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the invention as shown in the specific embodiments and / or aspectswithout departing from the spirit or scope of the invention as broadly described. For example, it will be apparent that certain features of the invention can be combined to form further embodiments. The present embodiments and aspects are, therefore, to be considered in all respects as illustrative and not restrictive. Several embodiments are described above with reference to the drawings. These drawings illustrate certain details of specific embodiments that implement the systems and methods and programs of the present invention. However, describing the invention with drawings should not be construed as imposing on the invention any limitations associated with features shown in the drawings.

Claims

Claims1. A system for processing waste material, the system comprising: a pyrolysis unit for heating the waste material for a predetermined period of time to convert the waste material into at least a gas component and a particulate component; at least one dry scrubbing unit connected to the pyrolysis unit to process a flow of the gas component of the converted waste material, the at least one dry scrubbing unit comprising a particulate material and being configured to cause turbulences in the flow of the gas component such that the gas component reacts with a surface area of the particulate material to remove harmful gases and / or particulate matter from the gas component; and at least one condensing unit connected to the at least one dry scrubbing unit, the at least one condensing unit being configured to reduce a temperature of the gas component received from the at least one dry scrubbing unit to convert the gas component into a liquid component and a noncondensable gas component.

2. The system of claim 1, wherein the pyrolysis unit is configured to heat the waste material to a temperature in the range from about 250°C to about 600°C.

3. The system of claim 1, wherein the system is arranged to process waste material comprising plastic.

4. The system of claim 1, being decentralised and portable, wherein the system comprises a housing in the form of a sea shipping container.

5. The system of claim 1, wherein the pyrolysis unit comprises a fixed bed reactor.

6. The system of claim 1, wherein the pyrolysis unit comprises an auger reactor.

7. The system of claim 1, being configured such that an operating pressure within the system does not exceed 3 bar.

8. The system of claim 1, being configured such that a gradient in operating pressure within the system causes a natural flow of the gas component from the pyrolysis unit via the at least one dry scrubbing unit to the at least one condensing unit.

9. The system of claim 1, where the at least one dry scrubbing unit comprises a tube for receiving the flow of the gas component, the tube comprising the particulate material and being shaped to cause the turbulences within the flow of the gas component.

10. The system of claim 9, wherein the tube is in a form of a spiral.

11. The system of claim 1, wherein the particulate material of the at least one dry scrubbing unit is selected such that at least chlorine is removed from the gas component.

12. The system of claim 11, wherein the particulate material of the at least one dry scrubbing unit comprises a composition of calcium hydroxide and sand.

13. The system of claim 1, wherein the particulate material of the at least one dry scrubbing unit is in the form of a plurality of pellets, each having a diameter of approximately 3-4 mm.

14. The system of claim 1, wherein the condensing unit comprises at least one condensing tube for receiving the gas component from the at least one dry scrubbing unit, the at least one condensing tube is connected to a source of cooling water of for cooling the condensing tube.

15. The system of claim 14, wherein the condensing unit comprises a pair of condensing tubes, each having a length between about lm and about 6m and being arranged at an angle ranging between about l°and about 5°.

16. The system of claim 1, comprising a shredding unit that processes the waste material prior to feeding the waste material into the pyrolysis unit.

17. The system of claim 16, wherein the shredding unit is configured to reduce a size of individual parts of the waste material having a diameter between about 10mm and about 50mm.

18. The system of claim 1, comprising a gravity feeder for feeding material into the pyrolysis unit using gravity.

19. The system of claim 18, wherein the gravity feeder comprises a pre-heating unit for preheating the waste material to a temperature between about 60-70°C.

20. The system of claim 18, wherein the gravity feeder comprises a scale for detecting a weight of waste material in the gravity feeder and a one-way valve that connects the gravity feeder with the pyrolysis unit, the system being configured such that when the gravity feeder holds a predetermined weight of waste material, the one-way valve automatically opens to provide the waste material from the gravity feeder to the pyrolysis unit.

21. The system of claim 1, comprising a compressing unit for compressing the waste material prior to feeding the waste material into the pyrolysis unit.

22. The system of claim 1, comprising at least one wet scrubbing unit, wherein the at least one wet scrubbing unit comprises a container for holding a water solution and being configured such that the non-condensable gas component exiting the at least one condensing unit flows through the at least one wet scrubbing unit thereby removing pollutants and other reactants from the non- condensable gas component.

23. The system of claim 1, being configured as a closed loop system that utilises the resulting gas component to assist in heating the pyrolysis unit.

24. A method of processing waste material, the method comprising: heating, using pyrolysis, the waste material for a predetermined period of time to convert the waste material into at least a gas component and a particulate component; processing a flow of the gas component by causing turbulences within the flow of the gas component and directing the gas component through a particulate material such that the gas component reacts with a surface area of the particulate material to remove harmful gases and / or particulate matter from the gas component; thereafter, gradually cooling the flow of the gas component to convert the gas component into a liquid component and a non-condensable gas component.

25. The method of claim 24, wherein the waste material is heated to a temperature in the range from about 250°C to about 600°C.

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