Patent Application
20250001475
The technical field generally relates to extraction of a wet fraction from a multiphase waste material, and more particularly to extractor systems and processes for extracting a wet fraction that includes organics from waste materials, such as municipal solid waste (MSW) and source separated organics (SSO), using a press-type extractor.
Extracting organics from MSW and SSO is becoming more common due to stricter regulations on the landfilling of organics and the economics of resource recovery, such as converting organic waste into energy, fertilizer and clean water. Press extractors have been used to compress MSW and SSO to promote separation of the wet organics-rich materials from the solid, undesirable materials such as glass, rocks, metal, and plastics. There are various challenges related to such press extractors, such as providing high yields of organics and high throughput while minimizing undesirable material in the wet fraction. There is a need for technologies that respond to at least some of the challenges that currently exist.
In the context of the present application, in some implementations there is provided an extraction system for processing waste material to form a wet fraction comprising organics and a liquid-depleted fraction, comprising: a barrel; a plunger received within the barrel and configured to displace axially within the barrel; and a perforated chamber having perforations and being connected to a distal end of the barrel, the perforated chamber being configured to receive a load of waste material and a head of the plunger during axial displacement into the perforated chamber to compress the load of waste material to cause wet material to be expelled out of the perforated chamber through the perforations and form the wet fraction, the perforations being sized and configured to have a diameter between 20 mm and 40 mm and to provide a total open area between 10% and 40%.
In some implementations, there is provided an extraction process for treating waste material to form a wet fraction comprising organics and a liquid-depleted fraction, comprising: providing a load of the waste material in a perforated chamber comprising perforations; pressing the load of the waste material within the perforated chamber with a plunger to cause wet material to flow out of the perforated chamber through the perforations and form the wet fraction and a liquid-depleted plug, the perforations being sized and configured to have a diameter between 20 mm and 40 mm and to provide a total open area between 10% and 40%; and removing the plug from the perforated chamber.
In some implementations, there is provided an extraction system for processing waste material to form a wet fraction comprising organics and a liquid-depleted fraction, comprising: a barrel; a plunger received within the barrel and configured to displace axially within the barrel; a perforated chamber having perforations and being connected to a distal end of the barrel, the perforated chamber being configured to receive a load of waste material and a head of the plunger during axial displacement into the perforated chamber to compress the load of waste material to cause wet material to be expelled out of the perforated chamber through the perforations and form the wet fraction; wherein the load of the waste material comprises cellulosic materials, organic-rich liquid materials, and non-organic materials; and wherein the perforations are sized and configured such that at a compression pressure between 60 and 160 bar, the wet fraction and/or liquid-depleted fraction have one or more of the following characteristics: the wet fraction has at least 10 wt %, 15 wt %, or 20 wt % paper; the wet fraction has a paper percentage greater than a paper percentage of the waste material; the wet fraction is composed of at least 5 wt %, 10 wt % or 15 wt % of cellulose-plastic components; the wet fraction has a plastic content between 6 wt % and 10 wt %; the wet fraction has a plastics percentage that is between a quarter and a half of the plastics percentage in the waste material; the wet fraction has an organics yield of at least 70%, at least 80% or at least 90%; the liquid-depleted fraction has at most 15 wt %, 10 wt %, or 5 wt % of the cellulosic materials; the liquid-depleted fraction has a percentage of the cellulosic materials that is lower than the cellulosic materials percentage of the waste material; and/or the liquid-depleted fraction has an organics content below 20 wt %, below 15 wt %, or below 10 wt %.
In some implementations, there is provided an extraction process for treating waste material to form a wet fraction comprising organics and a liquid-depleted fraction, comprising: providing a load of the waste material in a perforated chamber comprising perforations, the load of waste material comprising cellulosic materials, organic-rich liquid materials, and non-organic materials; pressing the load of the waste material within the perforated chamber with a plunger to cause wet material to flow out of the perforated chamber through the perforations and form the wet fraction and a liquid-depleted plug, the perforations being sized and configured to have a diameter and total open area such that the wet fraction and/or liquid-depleted plug have one or more of the following characteristics: the wet fraction has at least 10 wt %, 15 wt %, or 20 wt % paper; the wet fraction has a paper percentage greater than a paper percentage of the waste material; the wet fraction is composed of at least 5 wt %, 10 wt % or 15 wt % of cellulose-plastic components; the wet fraction has a plastic content between 6 wt % and 10 wt %; the wet fraction has a plastics percentage that is between a quarter and a half of the plastics percentage in the waste material; the wet fraction has an organics yield of at least 70%, at least 80% or at least 90%; the liquid-depleted plug has at most 15 wt %, 10 wt %, or 5 wt % of the paper; the liquid-depleted plug has a percentage of paper that is lower than the paper percentage of the waste material; and/or the liquid-depleted plug has an organics content below 20 wt %, below 15 wt %, or below 10 wt %; and removing the plug from the perforated chamber.
In some implementations, there is provided an extraction system for processing waste material to form a wet fraction comprising organics and a liquid-depleted fraction, comprising: a barrel; a plunger received within the barrel and configured to displace axially within the barrel a perforated chamber having perforations and being connected to a distal end of the barrel and configured to receive a load of waste material and to receive a head of the plunger during axial displacement into the perforated chamber to compress the load of waste material to cause wet material to flow out of the perforated chamber through the perforations and form the wet fraction and a liquid-depleted plug; and a control assembly configured to measure a position of the plunger to determine a measured plug thickness of the liquid-depleted plug, and control compression of the load of the waste material at least in part based on a target plug thickness of the liquid-depleted plug within the perforated chamber.
In some implementations, there is provided an extraction process for treating waste material to form a wet fraction comprising organics and a liquid-depleted fraction, comprising: providing a load of the waste material in a perforated chamber comprising perforations; pressing the load of the waste material within the perforated chamber with a plunger to cause wet material to flow out of the perforated chamber through the perforations and form the wet fraction and a liquid-depleted plug; controlling compression of the load based on a target plug thickness of the liquid-depleted plug; and removing the plug from the perforated chamber.
Techniques described herein relate to systems and processes that enhance performance of press extraction of waste materials, such as MSW and SSO, to obtain a wet fraction and a liquid-depleted fraction. When MSW or SSO are processed, the wet fraction is rich in organics and can be converted to biogas, while the liquid-depleted fraction is enriched in solid and non-organic materials. The techniques described herein can include various aspects, such as enlarged perforations for passage of the wet fraction and operating based on plug thickness of the leftover plug of the liquid-depleted material.
For example, the press extraction can be conducted in a press extractor that has relatively large perforations and is designed and/or operated based on plug thickness. The press extractor includes a perforated chamber and a plunger that strokes into the perforated chamber to compress the waste material and thus promote discharge of wet material through perforations while retaining dry material in the form of a compressed plug. In addition, the press extractor can include perforated sections that form the perforated chamber and allow passage of the wet material while retaining the plug of waste material, where the perforations are sized between 20 mm and 40 mm, between 22 mm and 35 mm, or between 25 mm and 30 mm, for example, which is larger than in conventional press extractors. Various other perforation characteristics can be provided in the perforated chamber, as will be discussed in further detail below. The perforated sections with enlarged perforations can be on side walls, a back section and/or a front section of the perforated chamber, where the front section can be defined by the head of the plunger. The press extractor can also be designed and operated based on plug thickness, which can be predetermined as used in process control, and can also be relatively small, such as between 40 mm to 200 mm, 40 mm to 100 mm, or 60 mm to 80 mm and/or which can be about 5% to about 20% of the infeed waste material thickness prior to compression. As will be described in more detail further below, the press extractor can have various configurations to which the techniques described herein can be applied. System and equipment implementations
Referring to
Still referring to
The plunger 10 is then retracted through the barrel 12 so that a subsequent load of waste material can be fed into the barrel 12, and the perforated chamber 18 closed, e.g., by closing the back end section 37. Before retraction, the plunger 10 can be used to push the plug 24 out of the perforated chamber 18 and additional components can be used to cut or remove the plug 24 away from the chamber perforated chamber 18. Retraction of the plunger 10 can be controlled to adjust the quantity of feed material that is provided into the barrel: by retracting more or less, the quantity of the load of waste material fed into the barrel for the next run can be greater or lesser, respectively. The plunger retraction can thus be a variable that is controlled based at least in part on the target and measured plug thickness.
It is noted that
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Another optional feature of the press extractor can be a pre-press assembly that can, for example, include a pre-press and a ram that radially enclose the infeed waste material and also, in the closed configuration, form part of the barrel so that a main axial plunger can compress the waste material within a perforated chamber. Referring to
It is also noted that various additional features can be provided for the press extractor. For example, a single extractor can include multiple perforated chambers associated with one or more plungers for compression of material.
Removal of the plug from the perforated chamber can be achieved in various ways, and can depend on the overall construction of the press extractor. The plug can be removed by advancing a plunger that is used to compress the material, a plunger that is used to advance the material into the chamber, or another component that pushes the plug out of the chamber. For example, in some implementations, the plunger that compressed the material to achieve the PT can be retracted, and then another component can be used to push out the plug. For the radial compression extractor, such as the one shown in
While several possible configurations of the press extractor have been described and illustrated herein, it is noted that other features and configurations are also possible. For instance, the press extractor can have components for feeding waste material, withdrawing waste material, driving and controlling moving parts such as plungers, and providing support and interconnection between the various components. In addition, the press extractor can be configured to not have certain components, such as not having a barrel section that receives waste material such that the waste material is fed directly into the perforated chamber and the plunger can then perform the compression.
In some implementations, the perforations 20 that are present in the side walls of the perforated chamber 18, the back section 37, and/or the head of the plunger 10 are sized and configured to provide enhanced performance in terms of organics yield and/or throughput capacity. For example, the perforations 20 can be sized to have a diameter from 15 mm to 40 mm, from 17 mm to 35 mm, from 20 mm to 30 mm, or from 22 mm to 28 mm, and/or to provide a total open area in one or more perforated regions from 10% to 30%, from 12% to 28%, from 15% to 25%, or from 17% to 23%. In this sense, the perforations are relatively large compared to holes used in conventional equipment which have been in the range of 8 mm. The large perforations can each have a perforation area between about 175 mm2 and 1300 mm2, between 300 mm2 and 800 mm2, or between 600 mm2 to 800 mm2, for example, the perforations 20 can also have a center-to-center spacing of 2 to 3 times the diameter of the perforations, for example. In some implementations, at least 50%, 60%, 70%, 80% or 90% of the perforations through which the wet fraction passes are large having one or more of the size properties mentioned above, with any remaining perforations being sized different (e.g., smaller). In one example implementation, the large perforations 20 are present in the side walls of the perforated chamber 18, the back section 37, and the head of the plunger 10; are circular in shape; each have a diameter between 18 mm and 24 mm or between 20 mm and 22 mm; and the total open area of the perforated regions is approximately 22% to 26%. It is also noted that a given wall of the perforated chamber can include one or more perforated regions, with the other regions being non-perforated and designed for facilitating fastening and assembling the unit together. Most of each wall of the perforated chamber would include perforations, while minor regions would be non-perforated and could include some holes for fasteners.
Referring now to
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In addition, the perforations 20 that are present on each section or location of the perforated chamber can all be the same size and/or shape, or can be different for certain sections or locations. For example, the perforations on the side walls can be different in size compared to the perforations on the back section. In addition, each section can itself include perforations of different sizes. For instance, the perforations at the upstream region of the side walls of the perforated chamber can be different in size compared to the perforations at the downstream region of the side walls. The perforations can be evenly distributed over each section or can have different distributions for different sections and/or within each section. The pattern of the perforations can also take many forms, such staggered or straight, and the shape of the perforations is preferably circular in cross-section but can also be square, hexagonal or another shape. In one example, the side walls of the perforated chamber have smaller perforations (e.g., 20 mm to 30 mm) compared to perforations in the backing plate and/or plunger head (e.g., 25 mm to 40 mm).
Larger perforations can also lead to wet fractions that have higher viscosity materials to flow, such that downstream unit operations can be adapted accordingly. In addition, the press extractor can be mechanically modified to facilitate the use of larger perforations, e.g., stronger and/or thicker materials for the perforated sections and/or greater spacing between the perforations, compared to conventional machines.
Larger perforations also facilitate the use of lower pressures, which can in turn reduce energy use, construction constraints, and processing time. For example, whereas some prior documents have disclosed pressures of up to 300 bars, it was found that 160 bar is acceptable for most MSW while 80-100 bar is acceptable for most SSO with the larger perforation size.
The press extractor can be operated in various ways, some of which will be described below. One method of operation is to include the plug thickness (PT) as a process control parameter that is detected and used to control aspects of the pressing operation.
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Regarding the minimum pressure threshold and multiple cycles, the trigger for performing a second cycle can be if the extractor does not meet the setpoint pressure before arriving within a predetermined end position, which can be for example 30 mm from the door or another predetermined distance that is smaller than the target PT. If the loads have a very high extrudable organics content (e.g., high concentration of fruits or vegetables), the extractor could continue through several cycles without opening the end door as nearly all of the pulp and liquid would pass through the perforations and it is only after adding some solid rejects (e.g., bags, metal, wood, packaging) that the plug would form and need squeezing to the predetermined PT.
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It should be noted that the precision of the control schemes illustrated in
In addition, referring to
In some implementations, the PT can be considered as the thickness of the plug pursuant to the final compression by the plunger 10 or another compression component. Thus, when multiple plungers or compression components are used in certain press extractor designs, as shown in
The plug thickness can be between about 5% and 20%, or between 10% and 15%, of the infeed material thickness within the barrel prior to compression, for example. For MSW feed material, the density of the feed can be between 200 and 500 kg/m3, while for SSO feed material the density can be between 400 and 700 kg/m3, for example. The pressure exerted on the waste material in the perforated chamber can be above 80 bar or 100 bar for SSO, and above 160 bar for MSW, for example. More particularly, for press extractors with one-directional axial compression, the PTAX could be between 5% and 12% of the infeed material thickness within the barrel prior to compression; while for press extractors with two-directional compression the PTAX could be between 10% and 20% of the infeed material thickness within the barrel prior to final compression along the second direction. In addition, the target PT can be between 40 mm and 250 mm depending on the extractor design. For example, for press extractors with one-directional axial compression, the target PT can be between 40 mm and 120 mm, between 50 mm and 100 mm, or between 60 mm and 80 mm; while for press extractors with two-directional compression, the target PT can be between 100 mm and 250 mm or between 150 mm and 200 mm.
The target plug thickness (PT) can be set depending on certain extractor design and operating features. For example, for a given extractor, the target PT can depend on whether or not the plunger head is perforated. When the plunger head is perforated, the target PT is larger compared to when it is not perforated, based on a same target yield of wet fraction for a given run, as a larger load of material can be pressed when the plunger head is perforated. More generally, the more the area of the perforated chamber that includes perforations, the larger the PT can be for a same yield.
In terms of waste materials that can be processed using techniques described herein, the waste material can be MSW or SSO or a combination or fractions thereof. The waste material can be other materials that include organic waste, such as ICI-food waste or non-SSO agricultural waste. In some implementations, the waste material includes putrescible organics and undesirable solid materials, such as plastics, metal, glass, mineral solids such as stones, and the like. The press extractor can be operated to maximize the yield of the putrescible organics in the wet fraction and the overall throughput, while minimizing the concentration of undesirable materials that are entrained in the wet fraction.
In alternative implementations, the waste material can be various pre-consumer food waste or certain industrial waste streams, such as pulp-and-paper streams that include solid and liquid components. For pulp-and-paper applications, the wet fraction can be separated from pulp as part of a dewatering process using the press extractor.
It is also noted that other multiphase materials that include liquid that is shear thinning and flows under pressure and some solids, can be processed using techniques described herein. The multiphase material can be a waste material or a material that is processed to separate fractions thereof. The multiphase material can include extrudable solids that pass through the perforations with the liquid, and/or can include solids that are oversized and do not pass through the perforations. After the separation, the wet fraction and/or the liquid-depleted fraction can be further processed to recover valuable components.
In some implementations, the press extraction can be operated to achieve various benefits, including enhanced organics extraction efficiency using larger perforation sizes, e.g., over 20 mm in diameter; enhanced organics extraction efficiency using plug thickness of 60-80 mm for one-directional press extractor; and enhanced ability to send organics contaminants such as paper and diapers to the organics wet fraction, thereby reducing or avoiding the need for extra cellulose recovery steps from the dry fraction (e.g., pulper after press).
In addition, certain parameters can be adjusted depending on the input characteristics (e.g., MSW vs SSO), such as modifying the control of the axial movement of the plunger to change the target PT based on the feed material. It is also possible to modify parameters, such as target PT, based on the quantity of feed material per load, such that a greater load would result in a greater target PT for that particular cycle.
Therefore, the control assembly can be configured to modify certain setpoints and operating parameters per load, or per a given run time for a given batch of feed material. When operating on a per-load basis, the quantity (e.g., mass and/or volume) of each load can be determined and/or the type of each load (e.g., MSW or SSO) can be determined, and then the target PT for that cycle can be set accordingly along with other parameters like minimum pressure threshold, among others. Alternatively, the target plunger pressure can be obtained for each run and the actual PT can be measured and used with a target PT to control the feed quantity for subsequent runs. The target PT can be established or determined based on predetermined calibration work that relates PT to feed material variables as well as performance parameters like organics yield. Thus, each load can be processed more optimally based at least in part on target PTs. Alternatively, the control method can be generally set for a given run time that includes multiple compression cycles, such that a set PT is predetermined based on the type of material being processed and the target load quantities fed into the extractor. While this method may be less precise than the per-load control method, it can be relatively simple while maintaining advantageous performance.
More particularly, the control assembly can include various components and instrumentation which can be installed and calibrated for the given control process to be implemented. In one example, an operator can control the plunger to stop at a predetermined location (e.g., distance from end door or certain location indicated on the barrel). In another example, the control assembly can be preprogrammed so that the plunger stops at a predetermined distance from the end door. The distance from the end door can be determined in various ways using position sensors. The control method can thus achieve and control defined plug thicknesses for operation of the extractor. In some implementations, position sensor instruments that measure the position of the plunger can be calibrated relative to the alternate face of the chamber, where zero point is the position where the plunger head face touches the opposing back face of the chamber. The control assembly can include a programmable logic controller (PLC) or other programmable controller utilizing the signal (e.g., analogue) from the position sensor to monitor the speed, acceleration, and end position of the plunger. Meanwhile, pressure can be monitored on the hydraulic power system driving the plunger with analog pressure transmitters and sensors. If the hydraulic cylinder coupled to the plunger has a different area compared to the surface area of the plunger, a scaling factor can be used. For control methods that utilize target pressures, as in
Of course, the control assembly can be configured to monitor and control various other aspects of the extractor, such as the pressure and duration of maximal holding pressure without plunger movement, speed of plunger movement, timing for feeding waste material into the extractor, opening and closing of the backing plate and removal of the plug, among other variables. In addition, other parameters of the extraction process can be monitored and correlated to PT to aid in process control. For example, the volume of the wet fraction removed per run can be correlated to the PT, and the maximum pressure can be correlated to PT particularly when the feedstock water material is well known and characterized.
In experimental runs, effects of plug thickness and perforation size were assessed for one-directional and two-directional press extractors. It was found that increasing the perforation size from a more conventional diameter of about 4 to 8 mm to a size of 26 mm to 30 mm reduced the quantity of organics remaining in the liquid-depleted fraction as more material is pressed through the larger holes, but also the amount of paper and cellulosic-plastic components (e.g., diapers) in the wet fraction increased notably while the amount of plastics in the wet fraction did not increase significantly. Since it can be desirable that the wet fraction include cellulosic organic material, such as paper and diapers, while minimizing other materials, such as plastics, the increase in perforation size was able to have a dual advantage of increasing liquid organics yield as well as solid cellulosic organics yield while not significantly increasing unwanted contaminants (e.g., plastic, stones, metal, glass) in the wet fraction.
Larger perforation size can also facilitate reduced blockage of perforations, reduced wear caused by having unnecessarily high internal pressures or small plug thickness when using smaller perforations; reduced processing of reject fraction to remove organics such as paper; reduced downtime that can occur at high pressures as larger perforations and certain plug thickness can facilitate the use of lower pressures.
Experiments that assessed a 200 ton/day press extractor showed that with smaller perforations of 13 mm there were difficulties recovering desirable yields of paper, organics and pulp from diapers. A new set of perforations with 26 mm diameter were installed and it was found that there was a considerable reduction in the organics in reject fraction and more paper in the wet fraction. For extrusion of certain organics, such as paper and diapers and yard waste, larger holes can provide notable performance enhancements. The following Table 1 summarizes effects of increased perforation size on the wet and liquid-depleted fractions:
As shown in Table 1, the TS of the wet fraction stayed relatively unchanged, while the reject TS rose slightly. There was a large decrease in organic content of the rejects, which is positive. In addition, the 37.8% organic content in the reject fraction with the smaller perforations is likely on the lower side compared to typical operations as well, as 49 wt % organics in the rejects have also been observed. The wet fraction shows the following changes: (a) plastics increased by 25% (4.74% to 6% mass yield), (b), paper in the wet fraction increased by 800%, (c) stones increased by 200%, (d) diapers increased by 250%, and (e) yard waste increased by 150%.
In addition, the average plug thickness decreased from 97 mm to 30 mm. Assuming the same plug density as the previous samples, this would decrease the reject yield from the initially measured 19.9% down to 6.15%.
Plug thickness had not been previously studied, as work focused instead on pressure and perforation size. Results have shown that for a given load of waste material, there can be an advantageous window of plug thickness that allows enhancing organics recovery as well as capacity. For instance, with an example one-directional press extractor, optimal plug thickness was 30-150 mm, preferably 60-80 mm. This was found through experimentation. Larger plug thicknesses with all other variables staying constant resulted in wetter reject fractions, especially in the middle portion of the plug, where organics and moisture appeared to be trapped. As observed from experimentation, the relationship defined an inverse hockey stick shape (blade at top left, stick going down), with an initial relatively constant yield with increasing plug thickness followed by a notable decrease in yield with an increase in plug thickness. It appears that a target plug thickness can be determined as the largest PT that achieves the relatively constant high organics yield, as decreasing the PT would result in minimal organics yield increase and increasing the PT would result in a sharper drop-off of organics yield.
The following Table 2 summarizes findings regarding examples of enhanced plug thicknesses for different press extractors:
It was noted that the enhanced PT can be in the approximate range of 5% to 15% or 8% to 12%, compared to the axial length of the perforated chamber where the plug is formed, for one-directional press extractors; with a range of 10% to 25% or 15% to 20% for the two-directional press extractor.
Factors that can have an impact on the PT include (i) the location, number and size of perforations of the perforated chamber, (ii) the feed quantity, (iii) the plunger pressure, and (iv) composition and properties of the waste material. For example, when larger perforations are provided, the wet fraction yield can be increased such that the PT would be lower if all other parameters are kept constant; likewise, when larger perforations are provided, the target PT can be higher for the same wet fraction yield as more feed material can be provided per run. When more sides of the chamber are provided with perforations, the wet fraction yield can be increased and the impact on PT and target PT are similar as described above. Thus, the range of PT between 40 mm and 120 mm for Extractor A is given in Table 2 based on variations that may be made to factors (i) to (iv), for example.
Other parameters, such as change in ram position, internal pressure as a function of time, and hold time at maximal pressure have been studied. It has been observed that maintaining the maximal pressure for an additional 3 seconds can lead to 5% increase in organics recovery. Extrusion pressures have also been studied using a pilot press and the pressure at which extraction yield plateaus have been identified for different kinds of feedstock.
It has also been found that it can be advantageous to feed smaller loads while pressing more quickly and with better efficiency, for instance based on a predetermined plug thickness. Smaller loads in this context can correspond to reduced load sizes for which the response of plug thickness is linear.
The following Table 3 shows a comparison between an extractor with standard perforation sizing compared to an extractor with enlarged perforation sizing, in terms of impacts on output stream compositions.
Effects of perforation size on the composition of the output streams of the press extractor can be framed in various ways. For example, the large perforations can facilitate one or more of the following:
It is noted that the aspects and implementations of the technology described herein should not be viewed as limiting since variations are also possible.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2022/051086 | 7/12/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63203178 | Jul 2021 | US |
