Screw conveyor for pyrolysis system

Abstract

The present invention relates to a two-way screw conveyor (112) for a processing chamber of a pyrolysis plant. The two-way screw conveyor (112) comprises an axle (A) with a peripheral surface extending in a longitudinal direction and having an inlet end (IE) and an outlet end (OE), a first helical blade (HB), the helical blade positioned around a portion of the peripheral surface of the axle and adapted to flight a portion of the mixed waste stream in a first direction between the inlet end and the outlet end of the axle (A); and a second helical blade (HB'), the second helical blade (HB') positioned around a portion of the peripheral surface of the axle (A) and adapted to flight a portion of the mixed waste stream in a second, substantially opposite direction between the inlet end (IE) and the outlet end (OE) of the axle (A), wherein, by rotating the axle, the two-way screw conveyor is configured to convey portions of the mixed waste stream in opposite directions, so as to ensure sufficient mixing and heating of the mixed waste stream, increased degassing of volatile gasses and increased output of upcycled material from said mixed waste stream.

Description

[0001] SCREW CONVEYOR FOR PYROLYSIS SYSTEM

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a two-way screw conveyor configured to, upon rotation, mix and convey a material in both a first and a second direction. The invention further relates to systems and methods comprising the two-way screw conveyor.

[0004] BACKGROUND OF THE INVENTION

[0005] In one or more stages of pyrolysis, wherein a waste material is processed or upcycled into e.g. oil and / or gas products, the waste material is heated and / or mixed in order for said processes to occur.

[0006] In some pyrolysis systems, advanced or complex means for mixing and heating the waste materials has been devised. The more complex the means for mixing, the higher risk of failure or need for maintenance. Other known methods require prolonged time of flight of the waste material, higher energy expenditure on heating or long conveying paths, which requires more space and materials for construction for said conveying paths.

[0007] Hence, it is an object of the present invention to provide a two-way screw conveyor for mixing waste material in both a first and second direction simultaneously.

[0008] SUMMARY OF THE INVENTION

[0009] Thus, the above described object and several other objects are intended to be obtained in a first aspect of the invention by providing a two-way screw conveyor for a pyrolysis system adapted to upcycle a mixed waste stream, the two-way screw conveyor comprising :

[0010] -an axle with a peripheral surface extending in a longitudinal direction and having an inlet end and an outlet end,

[0011] -a first and second segment, the axle extending through said first and second segment, the first segment comprising : -a first helical blade, the helical blade positioned around a portion of the peripheral surface of the axle and adapted to flight a portion of the mixed waste stream in a first direction between the inlet end and the outlet end of the axle, and

[0012] -a second helical blade, the second helical blade positioned around a portion of the peripheral surface of the axle and adapted to flight a portion of the mixed waste stream in a second, substantially opposite direction between the inlet end and the outlet end of the axle, wherein, by rotating the axle, the first segment is configured to convey portions of the mixed waste stream in opposite directions,

[0013] -the second segment comprising a third helical blade adapted to flight a portion of the mixed waste stream in the first or second direction,

[0014] -a substantially cylindrical disc comprising a wall section extending in a radial direction, the cylindrical disc positioned on the periphery of the axle, between the first and second segment.

[0015] In an alternative aspect, the invention relates to a two-way screw conveyor for a pyrolysis system adapted to upcycle a mixed waste stream, the two-way screw conveyor comprising:

[0016] -an axle with a peripheral surface extending in a longitudinal direction and having an inlet end and an outlet end,

[0017] -a first helical blade, the helical blade positioned around a portion of the peripheral surface of the axle and adapted to flight a portion of the mixed waste stream in a first direction between the inlet end and the outlet end of the axle, and

[0018] -a second helical blade, the second helical blade positioned around a portion of the peripheral surface of the axle and adapted to flight a portion of the mixed waste stream in a second, substantially opposite direction between the inlet end and the outlet end of the axle, wherein, by rotating the axle, the two-way screw conveyor is configured to convey portions of the mixed waste stream in opposite directions.

[0019] The invention is particularly, but not exclusively, advantageous for obtaining an improved mixing and heating of the mixed waste stream during processing. In particular, the invention is advantageous for ensuring a uniform heating of the mixed waste stream. Further, the invention may be advantageous for increasing the homogeneity of the mixed waste stream, with a processing chamber of reduced dimensions, relative to known chambers and screw conveyors. Even further, the invention may be advantageous to ensure an increased degassing of volatile gasses from a processing chamber, by increasing the mixing and / or heating of the mixed waste stream.

[0020] Further, The invention may be advantageous to ensure blending of mixed-waste and activating supplemental pH regulating additives, to ensure optimal conditions for pyrolysis and the upcycling the mixed waste, such as upcycling at least a portion of plastic waste into an oil product.

[0021] The two-way screw conveyor is designed to convey material in two directions. It is used in applications where material, such as mixed waste material or plastic waste needs to be conveyed back and forth between two locations within e.g. a degasser. The two-way screw conveyor can also be used as a feeder or discharger. The de-gas chamber is used in pyrolysis systems to remove volatile organic compounds (VOCs) from the process gas stream. The VOCs are typically burned in an afterburner or thermal oxidizer. The two-way screw conveyor of the de-gas chamber is designed to convey material back and forth between two locations within the chamber. This allows for more efficient removal of VOCs from the process gas stream and improved mixing of the mixed waste stream during heating.

[0022] In the context of the present invention, pyrolysis is to be understood as a process of thermal decomposition of materials at elevated temperatures in an inert atmosphere. It is used to break down organic or synthetic materials into smaller molecules, producing e.g. volatile products and leaving char, a carbon-rich solid residue as a final waste product.

[0023] In the context of the present invention, upcycle is to be understood as the process of reusing waste materials to create a product of higher quality or value than the original. In particular, organic or synthetic waste, such as plastic waste may be processed into oil products, such as fuel oil. In the context of the present invention, screw conveyor is to be understood as a mechanism that uses a rotating helical screw blade, called a flighting, usually within a tube, typically to move liquid or granular materials.

[0024] In the context of the present invention, mixed waste stream is to be understood as a waste product of e.g. organic or synthetic origin or a mix of both. In particular, a mixed waste stream may be understood as a mix of plastic waste with different mechanical or chemical properties.

[0025] In the context of the present invention, convey is to be understood transport of a mixed waste stream or a material from said mixed waste stream. In the context of the present invention, convey and flight may be used interchangeably, when relating to screw conveyors.

[0026] In a preferred embodiment the invention further comprises a substantially cylindrical disc positioned on the periphery of the axle at or near the outlet end of the axle, the disc comprising a wall section extending in a radial direction. This embodiment is particularly advantageous for ensuring, that at least solid portion of the mixed waste stream does not pass on to a next stage of processing, if not suitable for a next processing step. It is to be understood, that the cylindrical disc may serve as a barrier within a chamber, between one section and a second section of a processing plant, in particular, a pyrolysis plant.

[0027] In another preferred embodiment of the invention, the cylindrical disc further comprising a cut-out section in said wall section, wherein the cut-out section enables for a portion of the mixed waste stream to pass through the cut-out section upon rotation of the axle. This embodiment is particularly advantageous for ensuring, that only portions of the mixed waste stream, such as portions with a predetermined temperature and / or viscosity will pass through said cut-outs. In other embodiments, the cut-outs enables for gasses to pass through unhindered, while keeping solids and / or liquids back. It is to be understood, that the cylindrical disc may have a plurality of cut-outs or one single cut-out. In some embodiments, the cut-outs have specific geometric shapes, such as droplet shapes, triangular shapes, round shapes or square shapes, depending on e.g. viscosity of the mixed waste stream and / or temperature of the mixed waste streams. It is further to be understood, that when processing plastic waste, temperature and viscosity may co-dependent or be linear in relationship.

[0028] In yet another preferred embodiment of the invention, a ratio, R, between an area, AW, of the wall section of the cylindrical disc and an area, AC, of the cut-out section in said wall section, is defined as R=AW / AC, and wherein R is between 20 and 1, preferably between 15 and 2, more preferably between 10 and 3, even more preferably between 8 and 4 and most preferably between 6 and 4.5. It is to be understood, that these ratios may have particular advantages depending on the properties of the mixed waste stream to be flighted through the two-way screw conveyor and through the cut-outs of the cylindrical disc.

[0029] In an advantageous embodiment of the invention, a height, HFB, of the first helical blade is different than a height, HSB, of the second helical blade. This embodiment of the invention is particularly advantageous for adjusting the amount of mixed waste material to be conveyed in a first direction relative to a second direction. It is to be understood, that by providing two helical blades with opposite or substantially opposite flights, the mixed waste stream will be churned in both directions, and by adjusting flight of a first helical blade relative to a second helical blade, the mixed waste stream will move substantially in one of the first and second direction based on e.g. viscosity of the mixed waste stream.

[0030] In another advantageous embodiment of the invention, the height, HFB, of the first helical blade is greater than the height HSB of the second helical blade. In some embodiment, a height of at least one of the first and second helical blades may be 300 mm, such as 200 mm, or such as 100 mm. In a preferred embodiment, a height of at least one of the first and second helical blades may be 90 mm, such as 80 mm or such as 70 mm. In other embodiments, a height of at least one of the first and second helical blades may be below 70 mm, such as 60 to 20 mm. It is to be understood, that by providing two helical blades with opposite or substantially opposite flights, the mixed waste stream will be churned in both directions, and by adjusting a height of a first helical blade relative to a height of a second helical blade, the mixed waste stream will move substantially in one of the first and second direction based on e.g. viscosity of the mixed waste stream. It is further to be understood, that the blade height may be dependent on the diameter of the axle. In a preferred embodiment, the diameter of the axle is between 50 and 500 mm, more preferred between 80 and 400 mm, even more preferred between 100 and 200 mm, such as approximately 170 mm. It is to be understood, that the dimensions of the two-way screw conveyor is adapted to the chamber or vessel in which to flight material. In a preferred embodiment of the invention, the ratio between inner chamber / vessel diameter and axle diameter is in the range between 2 and 10, between 3 and 9, such as between 4 and 8, more preferred between 5 and 7, such as 6x. Thus it is to be understood, that if the chamber / vessel diameter is 1040 mm, the axle diameter may be 168 mm.

[0031] In other advantageous embodiments, the height, HFB, of the first helical blade is less than the height HSB of the second helical blade. In a specific embodiment of the invention, the height, HFB, of the first helical blade is between 60 and 200 mm, such as between 70 and 150 mm, preferably between 80 and 130 mm, such as approximately 110 mm; and the height HSB of the second helical blade is between 100 and 250 mm, such as between 120 and 200 mm, preferably between 140 and 180 mm, such as approximately 160 mm. It is to be understood, that the volumetric displacement of volume of mixed waste being flighted in a first flight direction, i.e. from an inlet end towards and outlet end, is greater than volume going in an opposite direction. In the context of the present invention, a relationship between an area of one of the first and second helical blade relative to an area of the other of the first and second helical blade should be greater than 1, in order to have a % resulting volumetric motion of material towards the outlet end. In a preferred embodiment of the invention, said relationship should be between 1.1 and 4, such as between 1.2 and 3, most preferred approximately 2, i.e. wherein the area of the helical blade flighting the mixed waste towards the outlet end is 2x that of the area of the helical blade flighting the mixed waste in the opposite direction.

[0032] In yet another advantageous embodiment of the invention, a pitch of flight of the first helical blade is higher than a pitch of flight of the second helical blade. It is to be understood that within the field, pitch or pitch of flight is to be understood as a ratio between the diameter of the blade and the angle of the pitch, i.e. wherein a 1: 1 ratio determines that one rotation of the helical blade moves material in between adjacent winding of the helical blade, one winding further forwards; and a 1: 5 pitch determines that five rotations of the helical blade moves material in between adjacent winding of the helical blade, one winding further forwards. In other words, pitch refers to the distance between adjacent screw flights. The flight is the helical screw blade that rotates and moves materials along the conveyor, wherein 1 rotation of helical blade moves material 1 diameter of said helical blade in a flight direction. The pitch of the flight is the distance between the tips of two adjacent flights, measured parallel to the axis of the screw conveyor. In preferred embodiments, the pitch of one of the first and second helical blade is between 1:0.5 and 1:20, more preferred between 1: 1 and 1: 10, even more preferred between 1: 1 and 1: 5, such as 1:4.

[0033] In a preferred embodiment of the invention, a volume of mixed waste stream moved by the first helical blade per RPM of the axle is a higher than the volume of mixed waste stream moved by the second helical blade per RPM of the axle. This embodiment of the invention is particularly advantageous for adjusting the amount of mixed waste material to be conveyed in a first direction relative to a second direction. It is to be understood, that by providing two helical blades with opposite or substantially opposite flights, the mixed waste stream will be churned in both directions, and by adjusting flight of a first helical blade relative to a second helical blade, the mixed waste stream will move substantially in one of the first and second direction based on e.g. viscosity of the mixed waste stream.

[0034] In another preferred embodiment of the invention, a volume of mixed waste stream moved in a direction from the inlet end to the outlet end, by the third helical blade, per RPM of the axle, is higher than the volume of mixed waste stream moved in the direction from the inlet end to the outlet end, by the first and second helical blades, per RPM of the axle.

[0035] It is to be understood, that in preferred embodiments, the first, second and third helical blades are fixed to the axle, thus rotating at identical RPM's. It is further to be understood, that the pitch of the helical blades are adapted so at to provide a higher flight rate, i.e. conveyance of mixed waste stream per rotation of the axle, by the third helical blade relative to the first and second helical blades. This embodiment is particularly advantageous for preventing a build-up of the mixed waste stream in between the first and second segments of the two-way screw conveyor.

[0036] In another preferred embodiment of the invention, the axle comprises interchanging sections of first and second helical blades along the peripheral surface of said axle, such as a first section with the first helical blade at or near the inlet end, a second section with a second helical blade adjacent to the first helical blade at the inlet end, a third section with a first helical blade between the second section and a fourth section, the fourth section with a second helical blade at or near the outlet end. This embodiment may be particularly advantageous for churning the mixed waste stream in a first and second direction interchangeably, and only forwarding the mixed waste stream when sufficiently mixed and heated and wherein e.g. volatile gasses has been sufficiently removed from the heated, mixed waste stream.

[0037] In yet another preferred embodiment of the invention, the first and second helical blades extend substantially along the peripheral surface of the axle, the helical blades intersecting as a double helix, with substantially opposite pitches of flight. This embodiment may be particularly advantageous for providing a rigid structure, reducing the need for material to stiffen e.g. the axle and / or helical blades by increasing diameter of said axle and / or using more rigid and possibly expensive materials for the screw conveyor.

[0038] In an advantageous embodiment of the invention, the geometry of the first and second helical blade is configured to mix and convey the mixed waste stream in a first and second direction, based on at least one of the solid mass, liquid mass, texture, viscosity, and porosity of the mixed waste stream. It is to be understood, that the pitch of flight and height of the first and second helical blades respectively, may be based on initial mechanical properties of the mixed waste stream and / or a target temperature of said mixed waste stream.

[0039] In a preferred embodiment of the invention, the first segment is at the inlet end of the axle and the second segment is at the outlet end of the axle. This embodiment is particularly advantageous for providing sufficient mixing of the mixed waste stream at the inlet by the first and second helical blades, prior to being subjected to a more uniform and effective conveyance by the third helical blade.

[0040] In another preferred embodiment of the invention, the first and second helical blades are adapted to flight the mixed waste stream towards the outlet end at a first flight velocity and the third helical blade is adapted to flight the mixed waste stream at a second flight velocity. This embodiment is particularly advantageous for providing a non-uniform conveance between the first mixing, heating and conveyance segment of the two-way screw conveyor and the second, heating and conveyance segment of the two-way screw conveyor. It is further to be understood, that the mixed waste stream may be further mixed in the second segment, while continuously conveyed / flighted towards the outlet end of the axle.

[0041] In yet another preferred embodiment, the second flight velocity is greater than the first flight velocity.

[0042] In the context of the present invention, flight and conveyance may be used interchangeably, and to be construed as the provision of transport of the mixed waste stream by rotating the axle.

[0043] This embodiment is particularly advantageous for preventing build-up of the mixed waste stream, between the first and second segment of the two-way screw conveyor.

[0044] In another advantageous embodiment of the invention, at least one of the first and second helical blades has an adjustable pitch. This embodiment may be particularly advantageous to continuously adapt the uniform mixing and heating of the mixed waste stream.

[0045] In yet another preferred embodiment, the third helical blade has an adjustable pitch. This embodiment may be particularly advantageous for adjusting and preventing build-up of the mixed waste stream between the first and second segment of the two-way screw conveyor. In yet another preferred embodiment, the third helical blade has a varied pitch along a length of the axle. This embodiment is particularly advantageous for ensuring sufficient flight of the mixed waste stream during heating and / or mixing, where a change of viscosity is expected, due to said heating and / or mixing.

[0046] In yet another advantageous embodiment, the invention further comprises one or more sensors adapted to measure one or more of strain, temperature, force and RPM of the blades or axle. It is to be understood, that sensors may be adapted to control one or more of heat applied to the two-way screw conveyor from associated heating means, such as induction heaters or other suitable heating devices, to control RPM of the axle and thus the two-way screw conveyor; or to control a variable pitch of the first and / or second helical blades. This embodiment may be particularly advantageous to continuously adapt the uniform mixing and heating of the mixed waste stream and to ensure sufficient degassing of the mixed waste stream prior to said waste stream entering e.g. a reactor chamber of a pyrolysis plant.

[0047] In a preferred embodiment of the present invention, the axle extends beyond the first and second helical blades at the outlet end, and wherein a third helical blade is positioned around the extended portion of the of the axle and adapted to flight a portion of the mixed waste stream in a first or second direction. In some embodiments, the first and second helical blades may be separated from the third helical blade by the cylindrical disc. This embodiment may be advantageous for ensuring a continuous flow of the mixed waste stream to an associated stage of a pyrolysis plant.

[0048] In the context of the present invention, it is to be understood, that pyrolysis plant and pyrolysis system may be used interchangeably.

[0049] In another preferred embodiment of the invention, at least one of the first and second helical blades have a varied pitch along a length of the axle. In some embodiments, the pitch of one of the first and second helical blades may vary from e.g. 1: 1 to 1: 5 along the length of the axle. In other embodiments, the pitch of one of the first and second helical blades may vary from e.g. 1: 5 to 1: 1 along the length of the axle. Thus, it is to be understood, that in some embodiments, the pitch of one or both of the first and second helical blades may increase or decrease from the inlet end of the axle to the outlet end of the axle. This embodiment may be particularly advantageous for ensuring sufficient flight of the mixed waste stream during heating, where a change of viscosity is expected, due to said heating.

[0050] In a second aspect, the invention relates to a processing chamber, the processing chamber adapted to be a section, in a multi-section pyrolysis system for upcycling mixed waste streams, the processing chamber comprising:

[0051] -the two-way screw conveyor according to the first aspect of the invention, -an inlet and an outlet, said inlet and outlet connected to respective associated sections of the multi-section pyrolysis system, wherein the two-way screw conveyor is adapted to convey the mixed waste stream through said processing chamber, and to an associated section of the multi-section pyrolysis system when a target selected from the following : temperature, processing time, texture, viscosity or porosity; of the mixed waste stream is reached.

[0052] It is to be understood, that a multi-section pyrolysis system is to be understood as a pyrolysis plant, such as the plant described in FIG. 1, and wherein the processing chamber according to the second aspect is a chamber of said plant.

[0053] In a preferred embodiment, the invention further comprises one or more heating elements arranged in or on said chamber, the heating elements adapted to heat the mixed waste stream. This embodiment is particularly advantageous for ensuring proper heating of the mixed waste stream either during a degassing step or during a reaction step, wherein portions of the mixed waste stream is upcycled into e.g. an oil product or a gas, such as a fuel gas.

[0054] In another preferred embodiment, the invention further comprises one or more sensors adapted to measure one or more of temperature, texture, viscosity or porosity of the mixed waste stream. It is to be understood, that said sensors may be adapted to control one or more of heat applied to the two-way screw conveyor from associated heating means, such as induction heaters or other suitable heating devices, to control RPM of the axle and thus the two-way screw conveyor; or to control a variable pitch of the first and / or second helical blades. This embodiment may be particularly advantageous to continuously adapt the uniform mixing and heating of the mixed waste stream and to ensure sufficient degassing of the mixed waste stream prior to said waste stream entering e.g. a reactor chamber of a pyrolysis plant.

[0055] In an advantageous embodiment of the invention, the processing chamber is a de-gasser adapted to de-gas a mixed waste stream during heating and / or mixing. This embodiment is particularly advantageous for ensuring sufficient degassing of e.g. volatile gasses or reactive gasses prohibiting or reducing reactions intended to occur at a later stage of the pyrolysis plant, thus ensuring a high output of upcycled material from the mixed waste stream.

[0056] In another advantageous embodiment, the processing chamber further comprises an additive canal adapted to provide an additive to the mixed waste stream within the processing chamber. This embodiment is particularly advantageous for the provision of an adjusted stream of additives to the mixed waste stream during mixing, such as to regulate pH.

[0057] In yet another advantageous embodiment, the additive canal further comprises a one-way valve or valve system. Thus embodiment ensures that the processing chamber may be maintained within a certain pressure range, while allowing for the provision of additives to the mixed waste stream within the processing chamber.

[0058] In preferred embodiments, the additive canal is located near the inlet or near the first segment of the two-way screw conveyor, thus providing the additive during the most efficient mixing stage.

[0059] It is to be understood, that the additive canal, when the processing chamber is a de-gasser, is interchangeable with the inlet 132 of FIG. 1.

[0060] In another advantageous embodiment, the invention further comprises a motor adapted to rotate at least the axle of the two-way screw conveyor. In some embodiments, the motor is adapted to vary the revolutions per minute (RPM), based on e.g. sensor measurements, such as temperature or viscosity or other relevant measurements. In some embodiments, the motor is further adapted to measure torque as an indication of viscosity of the mixed waste stream being flighted within the processing chamber. In some embodiments of the invention, the two-way screw conveyor is adapted to operate at between 0.1 and 10 RPM. In preferred embodiments of the invention, the two-way screw conveyor is adapted to operate at between 0.3 and 8 RPM. In a more preferred embodiment of the invention, the two-way screw conveyor is adapted to operate at between 0.6 and 5 RPM. In an even more preferred embodiment of the invention, the two-way screw conveyor is adapted to operate at between 0.8 and 3 RPM. In an advantageous embodiment of the invention, the two-way screw conveyor is adapted to operate at between 0.8 and 1.5 RPM, such as approximately at 1 RPM.

[0061] In yet another advantageous embodiment of the invention, the processing chamber has a length of between 20 and 2 meters, preferably between 15 and 3 meters, more preferably between 10 and 4 meters, even more preferably between 8 and 5 meters. In an advantageous embodiment of the invention, the processing chamber is approximately 6 meters in length, measured parallel to a longitudinal axis of the axle of the two-way screw conveyor.

[0062] In a third aspect, the invention relates to a pyrolysis system for upcycling mixed waste streams, the system comprising the two-way screw conveyor according to the first aspect of the invention or the processing chamber according to the second aspect of the invention, the system further comprising:

[0063] -a densifier

[0064] -a pyrolysis reactor, wherein at least the densifier and pyrolysis reactor are directly or indirectly fluidically connected.

[0065] In a preferred embodiment of the invention, the two-way screw is adapted as a conveyor and mixing mechanism within at least one of a de-gasser and a processing chamber of a multi-section pyrolysis system. This embodiment is particularly advantageous for ensuring sufficient heating and / or mixing of a mixed waste stream, to ensure proper degassing of volatile gasses and to ensure a high output of upcycled material from said mixed waste stream.

[0066] In a fourth aspect, the invention relates to a method of heating and mixing a stream of mixed waste stream in a pyrolysis system, the method comprising: -providing a two-way screw conveyor according to the first aspect of the invention or a processing chamber according to the second aspect of the invention,

[0067] -feeding the mixed waste stream at the inlet or inlet end,

[0068] -rotating the axle, and

[0069] -conveying the mixed waste stream to an associated section of the pyrolysis system, when a target selected from the following: temperature, processing time, texture or porosity; of the mixed waste stream is reached.

[0070] In a preferred embodiment, the method further comprises the following steps: -separating solids from liquids within the mixed waste stream, and -providing an upcycled material from the mixed waste stream, such as oil or gas, preferably such as fuel oil or fuel gas.

[0071] In a fifth aspect, the invention relates to use of the two-way screw conveyor according to the first aspect for the upcycling of a mixed waste stream into an upcycled material, such as oil or gas, preferably such as fuel oil or fuel gas.

[0072] The first, second, third, fourth and fifth aspect of the present invention may each be combined with any of the other aspects. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0073] BRIEF DESCRIPTION OF THE FIGURES

[0074] The two-way screw conveyor according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set. FIG. 1 is a schematic view of an embodiment of a pyrolysis plant for recycling of plastics making use of the present invention;

[0075] FIG. 2 shows a trimetric view of the two-way screw conveyor, according to an embodiment of the invention;

[0076] FIG. 3 shows a side view of a section of the two-way screw conveyor, according to an embodiment of the invention;

[0077] FIG. 4 shows a side view of a section of the two-way screw conveyor, according to an embodiment of the invention;

[0078] FIG.5 shows a frontal view of the cylindrical disc, according to an embodiment of the invention;

[0079] FIG. 6 shows a side view of the two-way screw conveyor, according to another embodiment of the invention;

[0080] FIG. 7 is a flow-chart of a method according to the invention;

[0081] FIG. 8 shows a trimetric view of the two-way screw conveyor, according to another embodiment of the invention;

[0082] FIG. 9 shows a side view of the two-way screw conveyor, according to another embodiment of the invention.

[0083] DETAILED DESCRIPTION OF AN EMBODIMENT

[0084] In FIG. 1, a schematic diagram of a pyrolysis plant for recycling of plastics making use of the present invention is shown.

[0085] In this pyrolysis plant, a residual polymer product (also referred to as waste plastic or mixed waste stream) is fed to a densifier 101 wherein the product is compressed, preferably at a ratio of 2-3.5, by screw conveyors 111. A vapour outlet 121 is provided to release water vapour released from the residual polymer products being compressed. By removing the water vapour, vapour explosions in the system may be avoided as well as it is avoided that the pyrolysis oil produced is being oxidized. The compressed residual polymer product is forwarded through a de-gas feeder 101a, where a pH regulating additive, preferably Calcium Oxide (CaO), is added through an inlet 132 at the entry region in the de-gas feeder 101a. The Calcium Oxide is then mixed with the residual polymer product quickly in the de-gas feeder 101a. During the travel through the de-gas feeder the residual polymer product is heated in a heatable pipe 131. In a first section 102a the product is heated to 180-220°C and in a second section 102b, 102c further heated to approx. 200-280°C. The residual polymer product is then fed into the de-gasser 102. In the de-gasser 102 the residual polymer product is moved substantially horizontally by the two-way screw conveyor 112, through three heating zones 102a, 102b and 102c. In the de-gasser 102, the zones heat the media, i.e. the residual polymer product, up to max. 240°C in the first zone 102a and heat the media up to max. 260°C in the second zone 102b and up to max. 280°C in the third zone 102c. A gas outlet 122b is provided above at least the zones 102b and 102c as shown in the FIG. 1. Inside the de-gasser 102 the pressure is within the range of 0.1 to 1 bar, such as 0.2-0.45 bar.

[0086] The residual polymer product, also referred to as the media or plastic pulp is then transferred to the pyrolysis reactor 103 through a pipe conveyor 150 containing a transport screw conveyor. The de-gasser, which is horizontally oriented, and the pyrolysis reactor, which is tilted upwards, are connected so there is a fluid communication between the outlet 122a at the bottom of the de-gasser 102 and the inlet 123a at the lowermost region of the tilted pyrolysis reactor 103. As indicated in FIG. 1 the liquid level 191 is about the same as in the de-gasser 102.

[0087] The pyrolysis reactor 103 preferably comprises two screw conveyors 113, preferably arranged in parallel hence only one is shown in FIG. 1. The screw conveyors 113 are conveying the residual polymer product and mixing the product whilst lifting upwards and out of the liquid level towards a black carbon outlet 123b at the top of the reactor 103. The pyrolysis liquid in the reactor 103 is heated by a heater, such as an electrical heater, for heating the residual polymer product to a temperature of up to max. 500 °C to generate pyrolysis vapour. The heating can be arranged in heating zones. The pressure inside the pyrolysis reactor 103 is similar to the pressure of the de-gasser, i.e. 0.1 to 1 bar, such as 0.2-0.45 bar.

[0088] The pyrolysis vapour is released from the reactor 103 via a reactor vapour outlet 123c. The reactor vapour outlet 123c is away from the dry portion of the reactor to avoid dripping of any condensed vapour onto the dried black carbon. Towards the end of the reactor screw conveyors 113 substantially all of the residual polymer product will have been decomposed and a solid fraction comprising black carbon residue will leave the process in the end of the reactor 103. The black carbon is transported out of the reactor 103 via the black carbon outlet 123b placed in the reactor to receive the black carbon. At the outlet 123b a black carbon screw conveyor 133 may be arranged in extension of the black carbon outlet 123b for transferring the black carbon to a container. Advantageously, also a gas lock valve (not shown) may be provided to ensure that no gases escape through the black carbon outlet 123b.

[0089] The pyrolysis vapour released from the reactor 103 via a reactor vapour outlet 123c is fed into the oil reactor 104. The oil reactor 104 functions as a vapourliquid separator. The reactor vapour outlet pipe 123c is positioned in the oil reactor 104 such that the pipe exit 123d is below the liquid level 104d in the oil reactor 104. The oil reactor 104 may be heated in three zones 104a, 104b and 104c as indicated in FIG. 1. In each zone the pyrolysis vapour product is heated to max. 450 °C. The pyrolysis vapour is released into the oil reactor 104 below the liquid level as shown in the FIG. 1. If the product liquefies in the oil reactor 104 and fall to the bottom thereon, this heavy oil and any solid particles is returned to the pyrolysis reactor 103 via the pipe 124c for further decomposition in the pyrolysis reactor 103.

[0090] In the top of the oil reactor 104 two outlets 124a, 124b are provided for transferring vapour components to the two reflux condensers 105a, 105b. All the pyrolysis vapour enters at the bottom of each of the reflux condensers 105 and exits at the top of the reflux condensers 105a, 105b with a temperature of max. 260°C. From the top of the reflux condensers 105a, 105b, the pyrolysis vapour is led to the raw pyrolysis oil (RPO) condensers 106a and 106b, where the vapour is condensed to heavy products (Raw Pyrolysis Oil or RPO) with an outlet temperature of approx. 150-180°C. Furthermore, pyrolysis vapours are transferred to the Nafta Pyrolysis Oil condenser 107, in which the vapours are condensed and chilled and exits as a light product at a temperature of 10-35°C.

[0091] The transfer of the product from the de-gasser 102 through the pipe conveyor 150 and the transfer of the black carbon in carbon screw conveyor 133 from the reactor 103 are both shown schematically to be in line with the de-gasser 102 and the reactor 103, respectively. However, it is found of preference to provide the pipe conveyor 150 at an angle to the de-gasser and also to provide the carbon screw conveyor 133 at an angle to the reactor 103.

[0092] FIG. 2 shows a trimetric view of the two-way screw conveyor 112, according to an embodiment of the invention.

[0093] In FIG. 2, the two-way screw conveyor 112 is shown, with a central axle A extending in a longitudinal direction and having an inlet end IE and an outlet end OE, opposite the inlet end IE. Around the axle A, is arranged a first helical blade HB, adapted to flight a portion of a mixed waste stream (not shown) in a first direction between the inlet end IE and the outlet end OE of the axle A. Further, a second helical blade HB' is arranged around the axle A and adapted to flight a portion of the mixed waste stream (not shown) in a second, substantially opposite direction between the inlet end IE and the outlet end OE of the axle A. It is to be understood, that by rotating the axle A, the two-way screw conveyor 112 is configured to convey portions of the mixed waste stream (not shown) in opposite directions, i.e. towards the inlet end IE and the outlet end OE, respectively. At or near the outlet end OE, a cylindrical disc is arranged around the axle A. From FIG. 2 it can be seen, that the cylindrical disc CD constitutes a wall section extending in a radial direction from the axle A and outwards. Further, it can be seen, that the cylindrical disc further comprises a plurality of cut-out sections CO in said wall section, wherein the cut-out sections CO enables for a portion of the mixed waste stream (not shown) to pass through said cut-out sections CO upon rotation of the axle A. It is to be understood, that one, two or more cut-out sections CO may be arranged on the wall section of the cylindrical disc CD.

[0094] FIG. 3 shows a side view of a section of the two-way screw conveyor 112, according to an embodiment of the invention.

[0095] In FIG. 3, the two-way screw conveyor 112 is shown, with a central axle A extending in a longitudinal direction. Around the axle A, is arranged a first helical blade HB, adapted to flight a portion of a mixed waste stream (not shown) in a first direction. Further, a second helical blade HB' is arranged around the axle A and adapted to flight a portion of the mixed waste stream (not shown) in a second, substantially opposite direction. It is to be understood, that by rotating the axle A, the two-way screw conveyor 112 is configured to convey portions of the mixed waste stream (not shown) in opposite directions. From FIG. 3 it can be seen, that the first helical blade HB has a height HFB, measured in a substantially radial direction. Further, it can be seen, that the second helical blade HB' has a height HSB, measured in a substantially radial direction. It should be noted, that in FIG. 3, the height HSB is greater than the height HFB. It is to be understood, that the respective heights may be different than what is shown. In particular, the height HFB may be greater than the height HSB, in some preferred embodiments.

[0096] FIG. 4 shows a side view of a section of the two-way screw conveyor 112, according to an embodiment of the invention.

[0097] In FIG. 4, the two-way screw conveyor 112 is shown, with a central axle A extending in a longitudinal direction. Around the axle A, is arranged a first helical blade HB, adapted to flight a portion of a mixed waste stream (not shown) in a first direction. Further, a second helical blade HB' is arranged around the axle A and adapted to flight a portion of the mixed waste stream (not shown) in a second, substantially opposite direction. It is to be understood, that by rotating the axle A, the two-way screw conveyor 112 is configured to convey portions of the mixed waste stream (not shown) in opposite directions. From FIG. 4 it can be seen, that a pitch of flight POF' of the second helical blade HB' has a higher angle of inclination p than the angle of inclination a, of the pitch of flight POF, of the first helical blade HB, relative to a horizontal axis HA.

[0098] It is to be understood, that the respective pitch of flights POF, POF' may be different than what is shown in FIG. 4. In particular, the pitch of flight POF of the first helical blade HB may be greater than the pitch of flight POF', of the second helical blade HSB, in some preferred embodiments.

[0099] FIG.5 shows a frontal view of the cylindrical disc CD, according to an embodiment of the invention. From FIG. 5 it can be seen, that the cylindrical disc CD constitutes a wall section WS extending in a radial direction from the axle A and outwards. Further, it can be seen, that the cylindrical disc CD further comprises a plurality of cut-out sections CO in said wall section WS, wherein the cut-out sections CO enables for a portion of the mixed waste stream (not shown) to pass through said cut-out sections CO upon rotation of the axle A. It is to be understood, that one, two or more cut-out sections CO may be arranged on the wall section of the cylindrical disc CD. In Fig. 5, the total area of the cut out sections CO, is approximately 20 % of the area of the cylindrical disc. In other embodiments, the total area of the cut out sections CO relative to the area of the cylindrical disc may be between 5% and 50%, preferably between 10% and 30% most preferably between 15% and 25%.

[0100] FIG. 6 shows a side view of the two-way screw conveyor 112, according to another embodiment of the invention.

[0101] In FIG. 6, the two-way screw conveyor 112 is shown, with a central axle A extending in a longitudinal direction and having an inlet end IE and an outlet end OE, opposite the inlet end IE. Around the axle A, is arranged a first helical blade HB, adapted to flight a portion of a mixed waste stream (not shown) in a first direction between the inlet end IE and the outlet end OE of the axle A. Further, a second helical blade HB' is arranged around the axle A and adapted to flight a portion of the mixed waste stream (not shown) in a second, substantially opposite direction between the inlet end IE and the outlet end OE of the axle A. It is to be understood, that by rotating the axle A, the two-way screw conveyor 112 is configured to convey portions of the mixed waste stream (not shown) in opposite directions, i.e. towards the inlet end IE and the outlet end OE, respectively. In FIG. 6, a third helical blade HB" is further positioned around the axle, and wherein the cylindrical disc CD, separates the first and second helical blades HB, HB' from said third helical blade HB". From FIG. 6 it can be seen, that the cylindrical disc CD constitutes a wall section extending in a radial direction from the axle A and outwards to chamber walls CW. The cylindrical disc CD further comprises a plurality of cut-out sections (not visible) in said wall section, wherein the cut-out sections CO enables for a portion of the mixed waste stream (not shown) to pass through said cut-out sections CO upon rotation of the axle A, thus moving from the first and second helical blades HB, HB' to the third helical blade HB" through said cut-out sections. In some embodiments, the first and second helical blades HB, HB' extends along between 10% - 60% of the total length of the axle A. In a preferred embodiment, the first and second helical blades HB, HB' extends along between 20% - 50% of the total length of the axle A. In another preferred embodiment, the first and second helical blades HB, HB' extends along between 25% - 45% of the total length of the axle A. In yet another preferred embodiment, the first and second helical blades HB, HB' extends along between 30% - 40% of the total length of the axle A. In an advantageous embodiment, the first and second helical blades HB, HB' extends along between 31% - 38% of the total length of the axle A.

[0102] FIG. 7 is a flow-chart of a method of heating and mixing a stream of mixed waste material in a pyrolysis system, according to an embodiment of the invention, the method comprising the following steps:

[0103] SI: providing a two-way screw according to the first aspect of the invention or a processing chamber according to the second aspect of the invention, S2: feeding the mixed waste material at the inlet or inlet end, S3: rotating the axle, and

[0104] S4: conveying the mixed waste stream to an associated section of the pyrolysis system, when a target selected from the following: temperature, processing time, texture or porosity; of the mixed waste stream is reached.

[0105] FIG. 8 shows a trimetric view of the two-way screw conveyor 112, according to another embodiment of the invention.

[0106] In FIG. 8, the two-way screw conveyor 112 is shown, with a central axle A extending in a longitudinal direction and having an inlet end IE and an outlet end OE, opposite the inlet end IE. Around the axle A, in a first segment, is arranged a first helical blade HB, adapted to flight a portion of a mixed waste stream (not shown) in a first direction between the inlet end IE and the outlet end OE of the axle A. Further, a second helical blade HB' is arranged around the axle A, at the first segment, and adapted to flight a portion of the mixed waste stream (not shown) in a second, substantially opposite direction between the inlet end IE and the outlet end OE of the axle A. It is to be understood, that by rotating the axle A, the two-way screw conveyor 112 is configured to convey portions of the mixed waste stream (not shown) in opposite directions, i.e. towards the inlet end IE and the outlet end OE, respectively. In FIG. 8, at a second segment, a third helical blade HB" is further positioned around the axle, and wherein the cylindrical disc CD, separates the first and second helical blades HB, HB' at the first segment from the third helical blade HB" at the second segment of the two-way screw conveyor. From FIG. 8 it can be seen, that the cylindrical disc CD constitutes a wall section extending in a radial direction from the axle A and outwards. The cylindrical disc CD further comprises a plurality of cut-out sections CO in said wall section, wherein the cut-out sections CO enables for a portion of the mixed waste stream (not shown) to pass through said cut-out sections CO, from the first to the second segment, upon rotation of the axle A, thus moving from the first and second helical blades HB, HB' to the third helical blade HB" through said cut-out sections. See FIG. 5 for further details regarding the cylindrical disc CD.

[0107] FIG. 9 shows a side view of the two-way screw conveyor 112, according to another embodiment of the invention.

[0108] In FIG. 9, the two-way screw conveyor 112 is shown, with a central axle A extending in a longitudinal direction and having an inlet end IE and an outlet end OE, opposite the inlet end IE. Around the axle A, in a first segment, is arranged a first helical blade HB, adapted to flight a portion of a mixed waste stream (not shown) in a first direction between the inlet end IE and the outlet end OE of the axle A. Further, a second helical blade HB' is arranged around the axle A, at the first segment, and adapted to flight a portion of the mixed waste stream (not shown) in a second, substantially opposite direction between the inlet end IE and the outlet end OE of the axle A. It is to be understood, that by rotating the axle A, the two-way screw conveyor 112 is configured to convey portions of the mixed waste stream (not shown) in opposite directions, i.e. towards the inlet end IE and the outlet end OE, respectively. In FIG. 9, a third helical blade HB" is further positioned around the axle, and wherein the cylindrical disc CD, separates the first and second helical blades HB, HB' at the first segment, from the third helical blade HB" at the second segment of the two-way screw conveyor 112. From FIG. 9 it can be seen, that the cylindrical disc CD constitutes a wall section extending in a radial direction from the axle A and outwards to chamber walls CW. The cylindrical disc CD further comprises a plurality of cut-out sections (not visible) in said wall section, wherein the cut-out sections CO enables for a portion of the mixed waste stream (not shown) to pass through said cut-out sections CO upon rotation of the axle A, thus moving from the first and second helical blades HB, HB' to the third helical blade HB" through said cut-out sections. See FIG. 5 for further details regarding the cylindrical disc CD.

[0109] In short, the present invention relates to a two-way screw conveyor 112 for a processing chamber of a pyrolysis plant. The two-way screw conveyor 112 comprises an axle A with a peripheral surface extending in a longitudinal direction and having an inlet end IE and an outlet end OE, a first helical blade HB, the helical blade positioned around a portion of the peripheral surface of the axle and adapted to flight a portion of the mixed waste stream in a first direction between the inlet end and the outlet end of the axle A; and a second helical blade HB', the second helical blade HB' positioned around a portion of the peripheral surface of the axle A and adapted to flight a portion of the mixed waste stream in a second, substantially opposite direction between the inlet end IE and the outlet end OE of the axle A, wherein, by rotating the axle, the two-way screw conveyor is configured to convey portions of the mixed waste stream in opposite directions, so as to ensure sufficient mixing and heating of the mixed waste stream, increased degassing of volatile gasses and increased output of upcycled material from said mixed waste stream.

[0110] The following is a list of Items, according to the invention:

[0111] 1.1. A two-way screw conveyor 112 for a pyrolysis system adapted to upcycle a mixed waste stream, the two-way screw conveyor comprising:

[0112] -an axle A with a peripheral surface extending in a longitudinal direction and having an inlet end IE and an outlet end OE,

[0113] -a first helical blade HB, the helical blade positioned around a portion of the peripheral surface of the axle and adapted to flight a portion of the mixed waste stream in a first direction between the inlet end and the outlet end of the axle, and

[0114] -a second helical blade HB', the second helical blade positioned around a portion of the peripheral surface of the axle and adapted to flight a portion of the mixed waste stream in a second, substantially opposite direction between the inlet end and the outlet end of the axle, wherein, by rotating the axle, the two-way screw conveyor is configured to convey portions of the mixed waste stream in opposite directions.

[0115] 1.2. The two-way screw according to 1.1, further comprising a substantially cylindrical disc CD positioned on the periphery of the axle at or near the outlet end of the axle, the disc comprising a wall section WS extending in a radial direction. 1.3. The two-way screw according to 1.2, the cylindrical disc further comprising a cut-out section CO in said wall section, wherein the cut-out section enables for a portion of the mixed waste stream to pass through the cut-out section upon rotation of the axle.

[0116] 1.4. The two-way screw according to 1.3, wherein a ratio, R, between an area, AW, of the wall section WS of the cylindrical disc CD and an area, AC, of the cut-out section in said wall section, is defined as R=AW / AC, and wherein R is between 20 and 1, preferably between 15 and 2, more preferably between 10 and 3, even more preferably between 8 and 4 and most preferably between 6 and 4.5.

[0117] 1.5. The two-way screw according to any of the preceding Items, wherein a height HFB of the first helical blade is different than a height HSB of the second helical blade.

[0118] 1.6. The two-way screw according to any of the preceding Items, wherein the height HFB of the first helical blade is greater than the height HSB of the second helical blade.

[0119] 1.7. The two-way screw according to any of the preceding Items, wherein a pitch of flight of the first helical blade is a higher than a pitch of flight of the second helical blade.

[0120] 1.8. The two-way screw according to any of the preceding Items, wherein a volume of mixed waste stream moved by the first helical blade per RPM of the axle is higher than the volume of mixed waste stream moved by the second helical blade per RPM of the axle.

[0121] 1.9. The two-way screw according to any of the preceding Items, the axle comprising interchanging sections of first and second helical blades along the peripheral surface of said axle, such as a first section with the first helical blade at or near the inlet end, a second section with a second helical blade adjacent to the first helical blade at the inlet end, a third section with a first helical blade between the second section and a fourth section, the fourth section with a second helical blade at or near the outlet end. 1.10. The two-way screw according to any of Items 1 to 8, wherein the first and second helical blades extend substantially along the peripheral surface of the axle, the helical blades intersecting as a double helix, with substantially opposite pitches of flight.

[0122] 1.11. The two-way screw according to any of the preceding Items, wherein the geometry of the first and second helical blade is configured to mix and convey the mixed waste stream in a first and second direction, based on at least one of the solid mass, liquid mass, texture, viscosity, and porosity of the mixed waste stream.

[0123] 1.12. The two-way screw according to any of the preceding Items, wherein at least one of the first and second helical blades has an adjustable pitch.

[0124] 1.13. The two-way screw according to any of the preceding Items further comprising one or more sensors adapted to measure one or more of strain, temperature, force and RPM of the blades or axle.

[0125] 1.14. The two-way screw according to any of the preceding Items, wherein the axle extends beyond the first and second helical blades at the outlet end, and wherein a third helical blade HB" is positioned around the extended portion of the of the axle and adapted to flight a portion of the mixed waste stream in a first or second direction.

[0126] 1.15. The two-way screw according to any of the preceding Items, wherein at least one of the first and second helical blades have a varied pitch along a length of the axle.

[0127] 1.16. A processing chamber, the processing chamber adapted to be a section, in a multi-section pyrolysis system for upcycling mixed waste streams, the processing chamber comprising:

[0128] -the two-way screw according to any of Items 1 to 15,

[0129] -an inlet and an outlet, said inlet and outlet connected to respective associated sections of the multi-section pyrolysis system, wherein the two-way screw is adapted to convey the mixed waste stream through said processing chamber, and to an associated section of the multisection pyrolysis system when a target selected from the following : temperature, processing time, texture, viscosity or porosity; of the mixed waste stream is reached.

[0130] 1.17. The processing chamber according to Item 16, further comprising one or more heating elements arranged in or on said chamber, the heating elements adapted to heat the mixed waste stream.

[0131] 1.18. The processing chamber according to Item 16 or 17 further comprising one or more sensors adapted to measure one or more of temperature, texture, viscosity or porosity of the mixed waste stream.

[0132] 1.18. The processing chamber according to any of Items 16 to 18, wherein the processing chamber is a de-gasser adapted to de-gas a mixed waste stream during heating and / or mixing.

[0133] 1.19. The processing chamber according to any of Items 16 to 19 further comprising a motor adapted to rotate at least the axle of the two-way screw conveyor.

[0134] 1.20. A pyrolysis system for upcycling mixed waste streams, the system comprising the two-way screw according to any of Items 1 to 15 or the processing chamber according to any of Items 16 to 20, the system further comprising:

[0135] -a densifier

[0136] -a pyrolysis reactor, wherein at least the densifier and pyrolysis reactor are directly or indirectly fluidically connected.

[0137] 1.21. The pyrolysis system according to Item 20 when dependent on any of Items 1 to 15, wherein the two-way screw is adapted as a conveyor and mixing mechanism within at least one of a de-gasser and a processing chamber of a multi-section pyrolysis system. 1.22. A method of heating and mixing a stream of mixed waste material in a pyrolysis system, the method comprising:

[0138] -providing a two-way screw according to any of Items 1 to 15 or a processing chamber according to any of Items 16 to 20, -feeding the mixed waste material at the inlet or inlet end, -rotating the axle, and

[0139] -conveying the mixed waste stream to an associated section of the pyrolysis system, when a target selected from the following: temperature, processing time, texture or porosity; of the mixed waste stream is reached.

[0140] 1.23. Use of a two-way screw conveyor according to any of Items 1 to 15, for the upcycling of a mixed waste stream into an upcycled material or product, such as an oil or gas product, preferably such as a fuel oil or fuel gas.

[0141] 1.24. A method of manufacturing an upcycled material, such as oil, from a mixed waste stream, the method comprising the following steps:

[0142] -providing a pyrolysis system according to claim 21,

[0143] -providing a mixed waste stream,

[0144] -processing the mixed waste stream through the pyrolysis system, and -providing oil from the mixed waste stream, wherein at least a portion of the mixed waste stream is processed into ash or black carbon.

[0145] Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.

Claims

CLAIMS1. A two-way screw conveyor (112) for a pyrolysis system adapted to upcycle a mixed waste stream, the two-way screw conveyor comprising:-an axle (A) with a peripheral surface extending in a longitudinal direction and having an inlet end (IE) and an outlet end (OE),-a first and second segment, the axle extending through said first and second segment, the first segment comprising:-a first helical blade (HB), the helical blade positioned around a portion of the peripheral surface of the axle and adapted to flight a portion of the mixed waste stream in a first direction between the inlet end and the outlet end of the axle, and-a second helical blade (HB'), the second helical blade positioned around a portion of the peripheral surface of the axle and adapted to flight a portion of the mixed waste stream in a second, substantially opposite direction between the inlet end and the outlet end of the axle, wherein, by rotating the axle, the first segment is configured to convey portions of the mixed waste stream in opposite directions,-the second segment comprising a third helical blade (HB") adapted to flight a portion of the mixed waste stream in the first or second direction, -a substantially cylindrical disc (CD) comprising a wall section extending in a radial direction, the cylindrical disc positioned on the periphery of the axle, between the first and second segment.

2. The two-way screw according to claim 1, the cylindrical disc further comprising a cut-out section (CO) in said wall section, wherein the cut-out section enables for a portion of the mixed waste stream to pass through the cut-out section upon rotation of the axle.

3. The two-way screw according to claim 1 or 2, wherein a ratio, R, between an area, AW, of the wall section of the cylindrical disc and an area, AC, of the cutout section in said wall section, is defined as R=AW / AC, and wherein R is between 20 and 1, preferably between 15 and 2, more preferably between 10and 3, even more preferably between 8 and 4 and most preferably between 6 and 4.5.

4. The two-way screw according to any of the preceding claims, wherein a height (HFB) of the first helical blade is different than a height (HSB) of the second helical blade, such as wherein the height (HFB) of the first helical blade is greater than the height (HSB) of the second helical blade.

5. The two-way screw according to any of the preceding claims, wherein a pitch of flight of the first helical blade is a higher than a pitch of flight of the second helical blade.

6. The two-way screw according to any of the preceding claims, wherein a volume of mixed waste stream moved by the first helical blade per RPM of the axle is a higher than the volume of mixed waste stream moved by the second helical blade per RPM of the axle.

7. The two-way screw according to any of the preceding claims, wherein a volume of mixed waste stream moved in a direction from the inlet end to the outlet end, by the third helical blade, per RPM of the axle, is higher than the volume of mixed waste stream moved in the direction from the inlet end to the outlet end, by the first and second helical blades, per RPM of the axle.

8. The two-way screw according to any of claims 1 to 7, wherein the first and second helical blades extend substantially along the peripheral surface of the axle, the helical blades intersecting as a double helix, with substantially opposite pitches of flight.

9. The two-way screw according to any of the preceding claims, wherein at least one of the first and second helical blades have a varied pitch along a length of the axle.

10. The two-way screw according to any of the preceding claims, wherein at least one of the first and second helical blades has an adjustable pitch.

11. The two-way screw according to any of the preceding claims, wherein the third helical blade has an adjustable pitch.

12. The two-way screw according to any of the preceding claims, wherein the third helical blade has a varied pitch along a length of the axle.

13. The two-way screw according to any of the preceding claims, wherein the geometry of the first and second helical blade is configured to mix and convey the mixed waste stream in a first and second direction, based on at least one of the solid mass, liquid mass, texture, viscosity, and porosity of the mixed waste stream.

14. The two-way screw according to any of the preceding claims, wherein the first segment is at the inlet end of the axle and the second segment is at the outlet end of the axle.

15. The two-way screw according to any of the preceding claims, wherein the first and second helical blades are adapted to flight the mixed waste stream towards the outlet end at a first flight velocity and the third helical blade is adapted to flight the mixed waste stream at a second flight velocity.

16. The two-way screw according to claim 15, wherein the second flight velocity is greater than the first flight velocity.

17. The two-way screw according to any of the preceding claims further comprising one or more sensors adapted to measure one or more of strain, temperature, force and RPM of the blades or axle.

18. A processing chamber, the processing chamber adapted to be a section, in a multi-section pyrolysis system for upcycling mixed waste streams, the processing chamber comprising:-the two-way screw according to any of claims 1 to 17,-an inlet and an outlet, said inlet and outlet connected to respective associated sections of the multi-section pyrolysis system, wherein the two-way screw is adapted to convey the mixed waste stream through said processing chamber, and to an associated section of the multisection pyrolysis system when a target selected from the following : temperature, processing time, texture, viscosity or porosity; of the mixed waste stream is reached.

19. The processing chamber according to claim 18, further comprising one or more heating elements arranged in or on said chamber, the heating elements adapted to heat the mixed waste stream.

20. The processing chamber according to claim 18 or 19 further comprising one or more sensors adapted to measure one or more of temperature, texture, viscosity or porosity of the mixed waste stream.

21. The processing chamber according to any of claims 18to 20 further comprising a motor adapted to rotate at least the axle of the two-way screw conveyor.

22. The processing chamber according to any of claims 18 to 21, the processing chamber being a de-gasser adapted to flight and mix the mixed waste stream.

23. The processing chamber according to any of claims 18 to 22 further comprising an additive canal adapted to provide an additive to the mixed waste stream within the processing chamber.

24. The processing chamber according to claim 23, the additive canal further comprising a one-way valve or valve system.

25. A pyrolysis system for upcycling mixed waste streams, the system comprising the two-way screw according to any of claims 1 to 17 or the processing chamber according to any of claims 18 to 24, the system further comprising:-a densifier-a pyrolysis reactor,wherein at least the densifier and pyrolysis reactor are directly or indirectly fluidically connected.

26. The pyrolysis system according to claim 25 when dependent on any of claims 1 to 17, wherein the two-way screw is adapted as a conveyor and mixing mechanism within at least one of a de-gasser and a processing chamber of a multi-section pyrolysis system.

27. A method of heating and mixing a stream of mixed waste material in a pyrolysis system, the method comprising:-providing a two-way screw according to any of claims 1 to 17 or a processing chamber according to any of claims 18 to 24, -feeding the mixed waste material at the inlet or inlet end, -rotating the axle, and-conveying the mixed waste stream to an associated section of the pyrolysis system, when a target selected from the following: temperature, processing time, texture or porosity; of the mixed waste stream is reached.

28. Use of a two-way screw conveyor according to any of claims 1 to 17, for the upcycling of a mixed waste stream into an upcycled material or product, such as an oil or gas product, preferably such as a fuel oil or fuel gas.

29. A method of manufacturing an upcycled material, such as oil, from a mixed waste stream, the method comprising the following steps:-providing a pyrolysis system according to claim 25 or 26,-providing a mixed waste stream,-processing the mixed waste stream through the pyrolysis system, and -providing oil from the mixed waste stream, wherein at least a portion of the mixed waste stream is processed into ash or black carbon.

Images