Patent Application
20240307888
The present application claims priority to European Application No. 23162483.4 which was filed on Mar. 16, 2023, and the contents of which are hereby incorporated by reference in their entirety.
The present disclosure relates to apparatus for the processing of biohazardous waste. In particular, the disclosure relates to a shredding apparatus for use in the decontamination & processing of waste to prepare it for a recycling process.
Waste generated from various different sources requires different levels of treatment in order for it to be further processed in any one of various known recycling processes. Such recycling processes exist for different materials such as paper, plastics and metals, for example.
Generally, recycling processes are sensitive to contaminants and some degree of cleaning of waste materials may be necessary prior to entering a recycling process. Recycling processes may require relatively small particles in order to process them. In general, in known processes, waste is separated, washed and shredded in the recycling centres before being pelletised.
There exists a need for improved processes and machinery in which waste materials can be disinfected and/or treated and shredded more effectively and efficiently in preparation for further steps in a recycling lifecycle.
One aspect of improvement identified is a novel blade arrangement which can process a vast array waste streams that differ in size, composition, malleability, strength and composition more reliably and efficiently.
According to one aspect, there is provided a shredding assembly comprising any or all of the following features:
The shredding assembly of the present teachings provides a device which can shred waste more flexibly and efficiently. Such a shredding assembly can be incorporated into a waste processing vessel for receiving waste to be shredded and treated. The fixed blade array may be a lower fixed blade array, such that it can be positioned at the bottom of the waste processing vessel where waste is collected in the shredding assembly. This can correspond to a waste processing zone of the waste processing vessel in which waste is continuously shredded for a set period of time. By providing a rotatable blade array configured to rotate relative to the fixed blade array, the advantageous shredding assembly can be provided, for example, by a single rotatable shaft, in contrast to arrangements having a twin shaft of interspersing rotatable blades. An advantageous arrangement may therefore provide a rotatable blade array which has blades arranged to interleave with one or more adjacent fixed blade arrays.
By providing a first cutting face and a second cutting face, the shredding assembly can be operated such that the rotatable blade array can rotate in a first direction or a second, opposite direction in order to shred waste between the rotatable blades and the fixed blades when the rotatable blade array rotates in either direction. Such bidirectionality of the rotatable blade array is advantageous because it allows for an improved shredding process in which the direction of rotation can be reversed periodically, and/or in response to reaching a threshold torque of the rotatable blade array.
The radial extent of the main body can be defined as the maximum radial distance of a radial extremity of the main body from the rotational axis. A maximum width of the main body between the first and second cutting faces may be less than the radial extent of the main body. A maximum width of the main body between the first and second cutting faces may be less than three quarters, preferably less than seven tenths, preferably less than two thirds of the radial extent of the main body. A minimum width of the main body between the first and second cutting faces may be less than one half of the radial extent of the main body. This provides an advantageously dimensioned blade arrangement that efficiently shreds various types of waste.
The shredding assembly may be configured such that at least half, preferably at least three quarters, preferably at least eight tenths of the radial extent of the main body passes through the gap between adjacent fixed blades during rotation of the rotatable blade array. By interspersing the fixed blades with the rotatable blades such that a major portion of the radial extent of the main body passes through a gap between adjacent fixed blades of the fixed blade array, the shredding assembly can be suitable for shredding waste having different dimensions while reducing the chance that the shredding assembly becomes jammed.
Two or more rotatable blades may extend from the rotational axis at different angles relative to one another. The plurality of rotatable blades may comprise a first rotatable blade and a second rotatable blade, which may be located at a position adjacent along the rotational axis to the first rotatable blade. An angular offset between the first rotatable blade and the second rotatable blade may be at least 15 degrees, preferably at least 30 degrees. The angular offset may be an integer multiple of an angle between 15 and 45 degrees. The angular offset may be an integer multiple of 30 degrees. The plurality of rotatable blades may comprise a group of up to twelve rotatable blades. The shredding assembly may comprise any number between 5 and 50 rotatable blades in different implementations. One or more, or each, of the plurality of rotatable blades in the group may be angularly offset from the other rotatable blades. The group may comprise two, preferably four, preferably eight, preferably twelve rotatable blades. For different implementations, any integer number between 3 and 50 may be suitable. The angular offset between select pairs of blades in the array, or between each blade in the array may be an integer multiple of an angle between 5 and 45 degrees, or between 15 and 45 degrees, and may be 30 degrees in certain examples. In this way, the rotatable blade array can be configured such that, during rotation thereof, the passage of rotatable blades through the gaps in the fixed blade array can be staggered. This can be advantageous in reducing peaks in the maximum torque of the rotatable blade array and can help in reducing overall levels of vibration. However, different implementations may require certain blades in the array or group to be in rotational alignment, i.e., having no angular offset with respect to one another. In certain implementations, plural arrays may be provided, each array comprising blades which are in rotational alignment with each other with the respective array being offset from other arrays by the offsets described herein.
Each rotatable blade may comprise a fixing portion configured to engage with a shaft. At least one of the first and second cutting faces may extend linearly in a radial direction from the fixing portion to a tip portion of the blade extending between the first and second cutting faces.
A centreline of the main body may be defined along the radial extent thereof. The first cutting face may extend along the main body at a first angle to the centreline. The second cutting face may extend along the main body at a second angle to the centreline. At least one of the first angle and the second angle may be between 1 and 10 degrees. At least one of the first angle and the second angle may be approximately 5 degrees. A plane defined by the centreline and the rotational axis may be a plane of symmetry between the first and second cutting faces.
At least one of the first and second cutting faces may comprise a plurality of serrations. The plurality of serrations may comprise a first set of serrations on a first side of the rotatable blade. The plurality of serrations may further comprise a second set of serrations on a second side of the rotatable blade. The first side and the second side may define opposite sides of the rotatable blade at different positions along the rotational axis. The first side and the second side may comprise planar side faces of the main body. The planar side faces may be normal to a direction parallel to the rotational axis. The serrations of the first and/or second set of serrations may be substantially pyramidal. The serrations may extend along a respective cutting face between a tip portion of the blade and a region of the blade proximal to the rotational axis (e.g. a region substantially aligned with the rotational axis or substantially aligned with a mounting portion of the blade).
The shredding assembly may further comprise a recess extending at least partially along the radial extent of the first and/or second cutting face. The recess may extend at least partially along the radial extent of the first and/or cutting face so as to define a first cutting surface of the or each respective cutting face on a first side of the rotatable blade, and a second cutting surface of the or each respective cutting face on a second side of the rotatable blade. The first and second sides may define opposite sides of the rotatable blade at different positions along the rotational axis.
The rotatable blade may comprise a tip portion extending between the first and second cutting faces. The tip portion may be configured to define a third cutting surface. The rotatable blade may comprise at least four cutting surfaces. The rotatable blade may comprise at least five cutting surfaces.
At least one of the first and second cutting faces may comprise a first set of serrations on the first cutting surface. At least one of the first and second cutting faces may comprise a second set of serrations on the second cutting surface. A third set of serrations may be provided on the third cutting surface.
The recess may be located between the first set and second set of serrations.
A blade height may be defined as the difference between the smallest radius of the main body about the rotational axis, which may be where the main body is connected to a shaft and the largest radius of the main body, which may be the maximum radial extent of the main body. The blade height may be larger than the lateral distance between the opposing cutting faces. The blade height may be larger than a maximum lateral distance between the opposing cutting faces by at least a quarter, preferably by at least a third, preferably by at least four tenths. The blade height may be larger than a minimum lateral distance between the opposing cutting faces by at least a third, preferably at least four tenths, preferably by at least a half. The minimum lateral distance may be at least half the maximum lateral distance between the opposing cutting faces, preferably at least six tenths, preferably at least three quarters.
The fixed blade array may be an upper fixed blade array provided above and across the rotational axis. The fixed blade array may be a lower fixed blade array provided below the rotational axis.
A fixed blade of the shredding assembly may comprise first and second end regions. The first end region and second end region may have mounting portions for mounting to a fixed body of the shredding assembly, which may be part of a waste processing vessel. The fixed blade may extend between the mounting portions. The fixed blade may extend across the rotatable blade array. The fixed blade may extend transverse to the rotational axis. The fixed blade array may comprise two, preferably three fixed blades.
The fixed blade may further comprise an intermediate portion provided between the first and second end region. The intermediate portion may comprise a cutting face. The cutting face may extend between the first and second end regions. The fixed blade may further comprise end cutting portions. The end cutting portions may be oriented toward a centreline of the intermediate portion. The end cutting portions may be provided on the first and second end regions. The fixed blade may lie in a plane normal to the rotational axis.
The cutting face may be an upper cutting face. The upper cutting face may be oriented away from the rotational axis. The fixed blade may further comprise a lower cutting face. The lower cutting face may extend between the first and second end regions. The lower cutting face may be oriented toward the rotational axis. The lower cutting face may have end cutting portions oriented toward a centreline of the intermediate portion. In this way, the fixed blade can have cutting means on opposite sides thereof such that, when a rotatable blade rotates relative to the fixed blade, waste can be shredded against the upper cutting face on a downward swing of the rotatable blade, and can be shredded against the lower cutting face on an upward swing of the rotatable blade.
The fixed blade may comprise a further face. The further face may be oriented toward the intermediate portion. The further face may be provided between an end region and the upper cutting face. The further face may face toward the upper cutting face. The further face may form a wall of a cut-out portion provided between an end region and the upper cutting face. The cut-out portion may be configured to align with an outer radial edge of the rotatable blade when the rotatable blade rotates relative to the fixed blade.
The cutting face may comprise at least a first spike and a second spike adjacent the first spike. The fixed blade may comprise a first side face and a second side face on the opposite side of the fixed blade to the first side face. The first spike may have a surface that is coplanar with the first side face. The second spike may have a surface that is coplanar with the second side face. The first and/or second spike may be substantially pyramidal. An apex of the first spike may be in the plane of the first side face. An apex of the second spike may be in the plane of the second side face.
The fixed blade array may be a first fixed blade array of the shredding assembly, which may be an upper fixed blade array. The first fixed blade array may be provided above and across the rotational axis. The shredding assembly may further comprise a second fixed blade array. The second fixed blade array may extend from the fixed body of the shredding assembly radially toward the rotational axis. The second fixed blade array may be a lower fixed blade array. The second fixed blade array may be provided below the rotational axis.
The fixed blade array (e.g. the second fixed blade array) may be arranged in a linear array. At least one of the plurality of fixed blades may comprise a substantially triangular portion, which may be truncated in proximity to the rotatable blade array. A fixed blade of the second fixed blade array may comprise a first cutting face and a second cutting face arranged in a similar manner to the first and second cutting faces on the rotatable blade. A first cutting face of the fixed blade may be configured for cutting when the rotatable blade array rotates in its first rotational direction. A second cutting face of the fixed blade may be configured for cutting when the rotatable blade array rotates in its second rotational direction. A main body of the fixed blade may extend from a fixed body of the shredding assembly toward the rotational axis.
At least one of the first and second cutting faces of the fixed blade may comprise a plurality of serrations. The plurality of serrations may comprise a first set of serrations on a first side of the fixed blade. The plurality of serrations may further comprise a second set of serrations on a second side of the fixed blade. The first side and the second side may define opposite sides of the fixed blade at different positions along the rotational axis. The first side and the second side may comprise planar side faces of the main body. The planar side faces may be normal to a direction parallel to the rotational axis.
A recess may extend at least partially along the radial extent of the first and/or cutting face of the fixed blade so as to define a first cutting surface of the or each respective cutting face on a first side of the rotatable blade, and a second cutting surface of the or each respective cutting face on a second side of the rotatable blade. The first and second sides may define opposite sides of the fixed blade. At least one of the first and second cutting faces may comprise a first set of serrations on the first cutting surface, and a second set of serrations on the second cutting surface. The recess may be located between the first and second sets of serrations.
The rotatable blade array may be configured to only have a single blade in a given plane perpendicular to the rotational axis. In other words, the rotatable blade array may be arranged to consist of one rotatable blade at a given position along the rotational axis. This is in contrast to arrangements having multiple blades extending in different directions from a single position along the rotational axis. This arrangement provides more efficient shredding which can be less likely to jam and may reduce vibrations.
The shredding assembly may comprise a shaft. The shredding assembly may comprise a single shaft. The rotatable blade array may be rotatably mounted on the single shaft. Put another way, the shredding assembly may comprise only one shaft upon which the rotatable blade array is mounted (e.g. the rotatable blade array may not be mounted over multiple shafts, or there may not be multiple rotatable blade arrays each mounted to different shafts).
The rotatable blade array may be provided on a shaft. The rotatable blade may comprise a fixing portion configured to engage with, or surround a major portion or the entirety of the angular extent of, the shaft. The fixing portion may comprise an aperture configured to receive a shaft. The aperture may be configured to engage a shaft and prevent rotation between rotatable blade and a shaft to which the rotatable blade is mounted. The fixing portion may comprise a non-circular aperture. The non-circular aperture may define a spline, or may be polygonal in form. The aperture may comprise a plurality of corners, curves and/or flat faces, configured to engage corresponding faces on a shaft to prevent relative rotation therebetween. The aperture may be any polygon, for engaging any corresponding polygonal shaft and in one example, may be a hexagonal aperture, which may be configured to receive a hexagonal shaft. This provides the advantage of increasing the manufacturability of the shredding assembly. The first cutting face may extend at a first tangent from the fixing portion. The second cutting face may extend at a second tangent from the fixing portion.
The width of the main body may taper away from the rotational axis of the rotatable blade. The width of the main body may decrease linearly with increased radial distance from the rotational axis. The angle between the first tangent and the second tangent may be approximately ten degrees. The angle between the centreline and at least one of the first and second tangents may be between four and six degrees; preferably, this angle is approximately five degrees. A first width (perpendicular to the centreline) of the main body between the first and second cutting faces may be defined at a first radial position, and a second width may be defined at a second radial position further from the rotational axis than the first radial position, and the first width may be greater than the second width. The first width may be measured at a base of the main body, that is, proximate to the rotational axis, and the second width may be measured at an end of the main body, that is, distal from the rotational axis. The rotatable blade may be configured such that its centre of mass is offset from the rotational axis. Alternatively or additionally, a maximum order of rotational symmetry of the rotatable blade with respect to the rotational axis may be one.
The shredding assembly may be configured such that, when a rotatable blade passes through the gap between adjacent fixed blades, the separation between the rotatable blade and a fixed blade is no more than 1 mm with respect to a direction parallel to the rotational axis. The separation may additionally or alternatively be no more than two tenths, preferably no more than one tenth, preferably no more than one twentieth of the thickness of the rotatable blade with respect to a direction parallel to the rotational axis. A non-zero and non-negligible separation is provided, so that materials can pass between the adjacent blades within the gap, to reduce the risk of jamming. The separation may therefore be at least a tenth of a millimetre or at least a multiple of a tenth of a millimetre, including all integer multiples of a tenth of a millimetre up to and including the upper bounds defined above for the separation.
There is also provided a rotatable blade array for the shredding assembly as described hereinabove. In other words, there is provided a rotatable blade array separate from the shredding assembly, i.e. without including any fixed blade array.
There is also provided a rotatable blade for the shredding assembly or the rotatable blade array as described hereinabove. In other words, there is provided a single rotatable blade separate from the rotatable blade array.
There is also provided is a fixed blade for the shredding assembly as described hereinabove. In other words, there is provided a fixed blade separate from any rotatable blade array. The fixed blade may be a fixed blade of the first fixed blade array or the second fixed blade array, and may have any of the features described hereinabove.
Further features and advantages of the present disclosure will become apparent from the following description of aspects thereof, presented by way of example only, and by reference to the drawings, in which:
A large amount of biologically hazardous waste is generated from different sources, including clinical facilities, diagnostic laboratories, and research institutes. This waste requires specialised treatment. Such treatment typically occurs off-site and therefore also requires specialised transportation and handling ahead of treatment. Treatment of hazardous waste, and biohazardous waste in particular, often requires energy intensive processes, such as autoclaving or incineration, whose emissions, water and energy usage, and environmental impact can be improved upon.
A particular aspect of biologically hazardous waste is that the risks relating to contaminants present upon the waste need to be handled throughout its processing, until such time as it is considered safe for contact with humans or the environment.
The inventors have identified particular areas for improvement in the processing of waste, in particular contaminated, hazardous or biohazardous waste. In particular, the inventors have identified improved blade arrangements which can effect both mixing and shredding of waste in a more efficient and effective manner.
The disclosed shredding assembly is particularly suited to use with the vast array of different biohazardous waste products that are produced in laboratories. Such waste streams may contain glass, paper, polymers, blood, urine, sharps, PPE, etc. and hence the blade arrangement needs to cope with a range of hard and soft materials, some being pliable and malleable others being hard and brittle. None of these materials can be recycled while they are considered to be of a biohazardous nature. For a system in which the disclosed blade arrangement is implemented to disinfect biohazardous waste, the waste needs to be shredded sufficiently to ensure that a treatment chemical comes into contact with the biohazardous materials. Once the initially biohazardous waste is sufficiently treated to be considered non-hazardous and safe for handling and transportation, it can be sent to recycling facilities for separation and pelletisation. The disclosed system facilitates recycling, as the waste processed in the system can be made safe. Combined disinfection or decontamination and shredding is an advantage to downstream recyclers as they can skip several steps in the usual known processes at recycling plants, with the output from blade arrangements and systems as disclosed herein.
Disclosed herein is a shredding assembly for the mixing and shredding of waste. The shredding assembly can be incorporated into a device for the treatment of biohazardous waste. In particular, the shredding assembly can be incorporated into a receiver, such as a waste processing vessel for waste to be treated. The shredding assembly can form part of a process for treating waste, which may additionally include treating the waste with a fluid or liquid treatment in order to clean, sterilise or disinfect the waste. Such treatment may occur in the waste processing vessel at the same time as the shredding assembly shreds the waste.
The shredding assembly disclosed herein includes a rotatable shaft having a plurality of blades configured to rotate with the shaft. The blades can be spaced at regular intervals along a rotational axis of the shaft and can extend from the shaft at a variety of different angles. Each rotatable blade on the rotatable shaft has a cutting face on opposite sides of the blade such that the cutting faces are substantially perpendicular to the path of rotation of the rotatable blade. The shredding assembly may also include a lower fixed blade array, which can be fixed relative to the waste processing vessel. The lower fixed blade array has a plurality of lower fixed blades configured to intersperse with the rotatable blades so that the rotatable blades will pass through gaps between the lower fixed blades during rotation of the rotatable blades about the rotational axis. The lower fixed blades can have cutting faces on opposite sides thereof in order to co-operate with the cutting faces of the rotatable blades. The rotatable shaft can be configured to rotate in a clockwise or an anti-clockwise direction. In this way, waste in the bottom of the waste processing vessel can be shredded by the action of the rotatable blades passing through the lower fixed blades in either a clockwise or an anti-clockwise direction.
The shredding assembly can also include one or more upper fixed blades. The upper fixed blades can be provided on a top side of the rotatable shaft, that is, on the opposite side of the rotatable shaft to the lower fixed blade array. The upper fixed blades can be configured to facilitate the breaking down and cutting of larger items of waste before such items are further shredded between the rotatable blades and the lower fixed blade array. Therefore, when a bag of hazardous waste-which may include various items of waste made from different materials, such as glass beakers, plastic tubes, fabric laboratory coats, and so on—is placed into the waste processing vessel, rotation of the rotatable blades can begin to break down the waste by crushing and cutting the waste between the cutting faces of the rotatable blade and the upper fixed blade, until the waste is small enough to fall to the bottom of the waste processing vessel, where the waste can be further shredded between the cutting faces of the rotatable blades and the lower fixed blades.
The assembly can advantageously shred waste to a sufficiently small size that the waste can be immersed in treatment fluid in the waste processing vessel. This can be performed for all waste added to the waste processing vessel. One way of achieving this is for the waste to be shredded to a size smaller than a depth of the treatment fluid retained the waste processing vessel, for example so that it fits below an upper level of the fluid. The assembly can also advantageously mix the waste with treatment fluid during and/or after the shredding of the waste by the blades. This can be achieved by continued operation of the blades for a sustained period. An advantage of methods described herein is that no heat energy need necessarily be applied to the waste for the treatment process. This can provide economies in energy consumption.
The arrangement of the blade arrangement in the waste processing vessel is such that it can shred the waste into smaller particles and provide a number of advantageous functions and advantages. These can include exposing the material to the chemical for disinfection, making the waste unrecognisable, for example so that the form or function of the un-shredded waste is unrecognisable, or such that any branding or personal data applied to the waste is unrecognisable. This can be advantageous when handling medical waste which may have this type of data applied. A further function may be to render the waste un-reusable, so that it can no longer perform the function it was manufactured for, for example such that a syringe or sample tube could not be re-used for the same function. It is also relevant that the entire treatment vessel is disinfecting waste regardless of whether or not it is in the liquid area.
An advantage of the system described herein is that both the functions of shredding and of disinfecting are carried out in the same enclosed area. This can be advantageous as compared to systems which may shred waste in a first area or operation and then treat, sterilise or disinfect the waste in a second area or operation. If the functions are separated, in the intermediate phase between shredding and disinfection, there could be a risk of aerosol infection, in particular if intervention for maintenance, for example, is required when a waste processing cycle is incomplete.
An aspect of the apparatus described is that it can apply the treatment fluid from the top down. If performed before the blades are rotated, this can help to provide that the waste is substantially covered in treatment fluid prior to commencing shredding. Subsequently, the shred process may start by rotating the blades at a first speed, which may be a lower speed, while a higher rotation speed may be used later in the cycle. Treatment fluid or diluent may be applied simultaneously with rotation of the blades, at any point during the shredding process, and in particular at the beginning of the shredding process. Applying fluid from the top down during shredding can also help to prevent infectious aerosols propagating from the waste away from the treatment fluid, for example in an upward direction. This risk can be greatest at the beginning of the cycle, when containers are initially broken down and opened, so applying a spray at the early stages can have a particular advantage.
The plurality of rotatable blades 320 may be interspersed with the lower fixed blade array 360 such that, during rotation of the rotatable blade arrangement 310, at least a portion of the radial extent of a rotatable blade 320 passes through a gap between adjacent lower fixed blades of the lower fixed blade array 360. In
The upper fixed blade array 340 can comprise three upper fixed blades 341 distributed along the rotational axis 311. The upper fixed blade array may be configured such that two, preferably three, more preferably four or more rotatable blades 320 are received in the gap provided between an adjacent pair of upper fixed blades 341. In the arrangement shown, four rotatable blades 320 are positioned along the rotational axis 311 between a first upper fixed blade and a second, adjacent upper fixed blade. The blades can be advantageously arranged to provide a scissor-type action between cutting faces of the rotatable blades and the fixed blades. When one or more of the rotatable blades passes adjacent one or more lower blades, an acute angle (i.e. between 0 and 90 degrees) may be formed between their oppositely oriented cutting faces. Providing such a scissor action using an acute angle between opposing cutting faces can improve the cutting action. Providing such acute angles between cutting faces on both sides of the rotatable blades and preferably on both sides of the lower fixed blades, can help to facilitate effective cutting in both directions of rotation of the rotatable blade array. Multiple cutting and shredding locations can be provided by providing such acute angles between one or two or more faces of at least one rotatable blade and any cutting face of the different fixed blades. This can include cutting faces of the upper fixed blades 340 which either face towards or away from the rotational axis 311, and in particular cutting faces 362 of the lower fixed blades oriented in either direction, or preferably two opposing directions, relative to the direction of rotation of the rotatable blade array. The interfaces can all contribute to more effective and efficient shredding, particularly in combination.
The rotatable blade array 310 may comprise a first rotatable blade 320a and a second rotatable blade 320b adjacent to the first rotatable blade 320a along the rotational axis 311. Each of the first rotatable blade 320a and the second rotatable blade 320b comprises a main body extending from the shaft 312 in a radial direction with respect to the rotational axis 311, and a first and a second cutting face configured to cut waste in a circumferential direction with respect to the rotational axis 311. In this respect, the first and second cutting faces can be substantially perpendicular to a path of rotation of the rotatable blade 320, for example between 80 and 100 degrees to the path of rotation.
At least one adjacent pair of rotatable blades 320 may be separated by a spacer 313 provided around the shaft 312. The main body of each rotatable blade 320 may be connected to a fixing portion which surrounds the rotatable shaft 312 in order to facilitate fixing thereto. The fixing portion may be integrally formed with the main body in some arrangements. As will be described later, the main body of the rotatable blade 320 can be substantially planar such that the main body is normal to a direction parallel to the rotational axis 311. The first and second cutting faces of a rotatable blade 320 can be symmetrical with each other with respect to a centreline of the main body.
An angular offset between the first rotatable blade 320a and the second rotatable blade 320b may be a fraction of a turn wherein the fraction is at least one twenty-fourth, or at least one twelfth, one tenth, one eighth, one sixth, or one quarter. The angular offset may be at least a quarter radian, or a half radian, three quarter radians, one radian, or three half radians. An angle between the centreline of the first rotatable blade 320a and the second rotatable blade 320b may be at least 30 degrees, and may be an integer multiple of 30 degrees.
In the arrangement shown, the rotatable blade array 310 comprises a group of twelve rotatable blades 320, labelled 320a to 3201, wherein each of the group of rotatable blades is orientated at a different angle with respect to the rest of the group. The rotatable blade array 310 includes 17 rotatable blades 320a to 320q. Since there are only twelve distinct orientations of rotatable blades 320 under the constraint that each rotatable blade 320 is offset by an integer multiple of 30 degrees in the circumferential direction, the remaining five rotatable blades 320m to 320q may repeat the angular sequence of the rotatable blades 320a to 320e. The relative angle of each of the rotatable blades 320a to 320q with respect to the rotatable blade 320a is provided in the following sequence: 0, 210, 60, 270, 120, 330, 180, 30, 300, 90, 240, 150, 0, 210, 60, 270, 120. It will be appreciated that each of these corresponds to a clockwise direction, for example ‘0 degrees’ corresponds to 12 o'clock, and 210 degrees corresponds to 7 o'clock, and so on.
It will be appreciated that the above sequence illustrates just one arrangement for organising the rotatable blades 320a-320q along the shaft 312, but that many other combinations of angles exist. In the arrangement shown, a first rotatable blade 320a is offset from a second rotatable blade 320b by an angle of 150 degrees. The rotatable blade array 310 may comprise a third rotatable blade 320c, arranged such that the second rotatable blade 320b is provided between the first rotatable blade 320a and the third rotatable blade 320c. The third rotatable blade 320c may be offset from the first rotatable blade 320a by 60 degrees. The rotatable blade array 310 can comprise further rotatable blades provided sequentially in order to provide a fourth rotatable blade 320d, a fifth rotatable blade 320e, a sixth rotatable blade 320f and so on.
In the arrangement shown, the fixing portion 327 comprises a hexagonal aperture configured to receive a corresponding hexagonal shaft 312 (not shown). The hexagonal aperture is shaped as a regular hexagon, that is, each internal angle being 120 degrees, and is oriented such that the centreline perpendicularly bisects two opposite edges of the hexagon. It will be appreciated that six different orientations of the rotatable blade can be achieved on a single hexagonal shaft using the rotatable blade 320 of
The rotatable blade 320 may comprise a first side face 321 and a second side face 322. The first and second side faces can define opposite sides of the main body 323, which may be perpendicular to the first and second cutting faces 331, 332. The first and second side faces 321, 322 may be arranged normal to a direction parallel to the rotational axis 311. At least one of the first and second cutting faces 331, 332 may comprise a recess 334 extending at least partially along the radial extent of the cutting face. The recess 334 defines a first cutting surface 333a and a second cutting surface 333b of the or each of the first and second cutting faces 331, 332. The or each first cutting surface 333a is located on the first side face 321 of the blade 320, and the or each second cutting surface 333b is located on the second side face 322 of blade 320. In this way, the recess 334 provides for two cutting surfaces on the or each cutting face 331, 332.
The rotatable blade 320 may further comprise a tip portion 338. The tip portion 338 may be arcuate between the first and second cutting faces 331, 332. The tip portion 338 may provide a substantially triangular portion, which may be truncated, between the first and second side faces 321, 322. The tip portion 338 may define a third cutting surface 333c. In this way, the combination of the tip portion 338 and the recess 334 results in a blade 320 having at least four cutting surfaces, e.g. first and second cutting surfaces 333a, 333b defined by the recess on one of the first and second cutting faces 331, 332, and the third cutting surface 333c at the tip portion 338. In arrangements where the recess 334 is present along both the first and second cutting faces 331, 332, it will be understood that five cutting surfaces may be present, e.g. first and second cutting surfaces 333a, 333b defined by the recess on each of the first and second cutting faces 331, 332, and the third cutting surface 333c at the tip portion 338.
The cutting surfaces 333a, 333b, 333c may be defined by any suitable cutting means and any combination thereof, e.g. serrations, a sharp edge, a spiked arrangement or the like.
In the figures, the first cutting surface 333a and the second cutting surface 333b on each cutting face 331, 332 include a plurality of serrations. At least one cutting face 331, 332 may comprise a plurality of serrations comprising a first set of serrations 333a which may define part of the first side face 321 and a second set of serrations 333b which may define part of the second side face 322. The first and second sets of serrations 333a, 333b can be disposed on opposite sides of a cutting face 331, 332. In this way, the sets of serrations 333a, 333b can be provided on the rotatable blade 320 at different positions along the rotational axis.
In the arrangement shown, the recess 334 provides a part-cylindrical surface which extends between the first set of serrations 333a and the second set of serrations 333b. The first and second set of serrations 333a, 333b may be scalloped. At least one serration of the first and/or second set of serrations 333a, 333b may be substantially pyramidal. In this way, at least one serration may have a three-dimensional structure defined by four surfaces converging at a vertex. One surface of the pyramid structure may be coplanar with the first and/or second side face 321, 322.
As shown in
A width of the main body between the first and second cutting faces 331, 332 may taper away from the rotational axis 311. In the illustrated arrangement, the first side face 321 defines a first width W1 perpendicular to the centreline 329 between the first cutting face 331 and the second cutting face 332. The first side face 321 also has a second width W2 perpendicular to the centreline 329 between the first cutting face 331 and the second cutting face 332 at a position further from the rotational axis 311 than the first width W1. The first width W1 may be greater than the second width W2. The width of the main body 323 may decrease linearly with increased radial distance from the rotational axis 311.
The lower fixed blade array 360 may comprise four lower fixed blades 361, preferably at least eight, preferably at least twelve, preferably at least 16 lower fixed blades 361. In the arrangement shown in
The lower fixed blades 361 may comprise a cutting face 362 which may be arranged in a similar manner to the cutting faces 331, 332 of the rotatable blade 320 and may have a similar arrangement of recesses and/or cutting surfaces and/or serrations. In the arrangement shown, the first lower fixed blade 361a defines an end of the lower fixed blade array 360 and its cutting faces may only define a first set of serrations, configured to co-operate with a set of serrations on the first rotatable blade 320a during rotation thereof. However, the other lower fixed blades 361b-361d may comprise two sets of serrations similarly to the rotatable blades 320.
The lower fixed blade array 360 may comprise a support structure at a base thereof configured to be connected to the waste processing vessel 120, and a support structure may include spacers 367 configured to separate adjacent lower fixed blades 361. The lower fixed blades 361 may comprise a substantially triangular portion, which may be truncated by a tip portion 365. The tip portion 365 may be provided on an upper end of a lower fixed blade 361 and may comprise a concave shape corresponding to an outer surface of the shaft 312. Although not shown in
At least one of the first and second end regions 341a, 341b may comprise a cutting face which may have a cutting region such as a knife edge 342. The knife edge 342 can be configured to face in a substantially upward direction with respect to the waste processing vessel 120 and can be configured to co-operate with a rotating blade 320 in order to cut waste. The knife edge 342 labelled in
As shown in
With reference to
Unless otherwise stated, each of the integers described may be used in combination with any other integer as would be understood by the person skilled in the art. Further, although all aspects of the disclosure preferably “comprise” the features described in relation to that aspect, it is specifically envisaged that they may “consist” or “consist essentially” of those features outlined in the claims. In addition, all terms, unless specifically defined herein, are intended to be given their commonly understood meaning in the art.
Further, in the discussion of the various examples, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, is to be construed as an implied statement that each intermediate value of said parameter, lying between the smaller and greater of the alternatives, is itself also disclosed as a possible value for the parameter.
In addition, unless otherwise stated, all numerical values appearing in this application are to be understood as being modified by the term “about”. Any means for providing a function in this disclosure may be provided in the form of an apparatus, device or system for performing that function, or configured to provide that function, including the examples specifically described.
Various modifications, whether by way of addition, deletion and/or substitution, may be made to all of the above-described aspects to provide further aspects, any and/or all of which are intended to be encompassed by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2316248304 | Mar 2023 | EP | regional |
