NL2037596B1

NL2037596B1 - System and method for drying bulk material

Info

Publication number: NL2037596B1
Application number: NL2037596A
Authority: NL
Inventors: Chardon Merlijn; Van Wijck Casper
Original assignee: Multiphase Dryers B V
Priority date: 2024-05-01
Filing date: 2024-05-01
Publication date: 2025-11-18
Also published as: WO2025230416A3; WO2025230416A2

Abstract

SYSTEM AND METHOD FOR DRYING BULK MATERIAL System for drying bulk material, comprising at least one elongated drum for holding the bulk material, each of the at least one drum comprising a ﬁrst end and a second end, wherein the system is conﬁgured to rotate each of the at least one elongated drum around its longitudinal axis individually, for setting the bulk material in that drum in motion, wherein the at least one drum forms at least one passage to feed the bulk material through the system, wherein the system is conﬁgured for supplying a carrier ﬂuid to the outside of each of the at least one drum for 10 transferring heat to the bulk material inside the at least one elongated drum. Corresponding uses and methods. [Fig 6]

Description

SYSTEM AND METHOD FOR DRYING BULK MATERIAL

The present description concerns a system and method for drying bulk material.

Many industrial processes create as a by-product in the category of wet granular material, such as brewer’s spent grain, plant fibres, salt slurry, or paper pulp. Another category of materials starts off as pumpable liquid, but can be turned into bulk material by mixing it with already dried matter.

Currently, most of this material is disposed of at an economic and environmental cost as a waste product, or is at best used in a low-grade application, for instance as wet livestock feed. If the bulk material would be dry, it would have a substantially longer shelf life, it would be lighter and easier to transport, and it would be suitable for higher-grade applications, for instance as chipboard particles or biobased fuel (“industry grade”). as a fertilizer, as an ingredient in pet food or dry concentrated feed (“fodder grade™), or as a food ingredient, such as a protein source or binder (“food grade™). This would contribute significantly to establishing circular industrial chains.

In existing processes for drving bulk material, workers put batches of the bulk material into a holding tank of a specially constructed drying installation, or continuously spread over a perforated conveyer belt/plate system. A carrier fluid such as air is then heated and provided to the bulk material. To maximize the effective surface area for power transfer, the carrier fluid may be fed through the holding tank to come into direct contact with the material to be dried. When dried, the batch of bulk material is removed and compensated for by adding new wet product, either in a batchwise, or in a continuous process.

Drying is an energy intensive process by nature. Existing dryers are typically designed to dry using high temperature heat, typically 90 degrees C up to 1200 degrees C, temperatures that have to be generated using fuels or electricity. The high air temperature reduces the drying time and hence increases the drying capacity of the dryer. However, the fuels/or electricity to generate this high temperature heat come at a considerable cost, both economically and environmentally (in terms of carbon emissions). The energy costs of the drying step constrain many circular business cases aiming at valorising byproducts considerably. For example, typical fresh plant fibres have a moisture content of 90%, drying such fibres in a conventional, efficient dryer would require approximately | m* of natural gas per kg of dried product.

As a result, in most cases, the combination of the complex process; the cost of the required installation; the cost of providing heat; and the limited potential for heat recovery, hence limited potential for further efficiency improvements cannot be overcome to make the drying of bulk material economically viable.

It is a problem to at least reduce at least some of these issues, in order to make the drying of bulk material economically viable in more cases.

It is a problem to provide an efficient process for drying bulk material which requires only low-grade surplus heat.

It is a further problem to provide an installation for drying bulk material which has low investment and operating costs and using only low-grade, environmentally friendly heat from residual heat or renewable energy sources.

It is yet a further problem to provide an approach to drying bulk material which is flexible and which is suitable for various heat input grades and material output grades.

In a first aspect, at least one of these problems is solved at least partially in a system for drying bulk material, comprising at least one elongated drum for holding the bulk material, each of the at least one drum comprising a first end and a second end, wherein the system is configured to rotate each of the at least one elongated drum around its longitudinal axis individually, for setting the bulk material in that drum in motion, wherein the at least one drum forms at least one passage to feed the bulk material through the system, wherein the system is configured for supplying a carrier fluid to the outside of each of the at least one drum for transferring heat to the bulk material inside the at least one elongated drum.

The solution is based on the following insights by the applicant.

An alternative to generating heat would be to use surplus heat from industrial processes to dry the bulk material. This approach would be advantageous because such surplus heat is often already being produced near places where the wet bulk material is created. such as at food processing plants, and it would otherwise go to waste. However, industry produces a limited amount of surplus heat of over 100 degrees Celsius (such as in steam). Low-grade surplus heat, for example between 50 and 100 degrees Celsius (such as in wet steam, hot water or moist air), is much more readily available, but evaporation is slowed down considerably at such lower temperatures, limiting the drying capacity of existing dryer designs. Also, dry air as a heat carrier has limitations when operating at low temperatures due to its low specific heat. Large volumes of dry air have to be generated and ducted through the dryer, increasing thermal losses and electricity consumption for fans, filters etc.

Furthermore, many carrier fluids of surplus heat should not be brought into direct contact with the bulk material for reasons of contamination and moisture content. If the heat is carried by a liquid, a liquid-air heat exchanger can be used to generate dry warm air. If the heat is carried by wet or polluted air, air-to-air heat exchangers are required, which by nature either have limited heat exchanging efficiency or high pressure losses (electricity consumption of fans) and in direct heat recovery applications typically only a small portion of the carried surplus (condensation) heat can be recovered. As an alternative, the carrier fluid can be provided to the outside of the holding tank.

However. the effective surface area for thermal conduction will be low. To increase the surface area, the holding tank may be provided with various fins, through-openings, etcetera, but this greatly increases the cost and complexity of the drying installation as well as the cleaning efforts while providing relatively small benefits in terms of spatial efficiency.

In the proposed system, the heat carrier fluid does not come into contact with the bulk material to be dried, allowing for the direct use of wet or contaminated carriers of surplus heat without an intermediate step of conversion or heat transfer, to be able to obtain a high product output grade. An elongated drum has a relatively large surface area compared to other drums with similar capacities, and using the proposed system, bulk material may be spread out in, and fed through an elongated drum to improve heat transfer.

The proposed system may be applied for processing a great variety of bulk materials as well as for materials which behave sufficiently like bulk materials when processing in large quantities, such as textiles. The system may be built at small scale from relatively cheap and simple components which may be recycled, further reducing its environmental burden. It may be embodied in a modular and mobile form, which enables use at a relatively small scale and with low economic barriers to entry. For example, a rental or system as a service business model may be used to operate such a system.

The system may be configured with individual drums or with passages comprising multiple drums. In both cases, it has been determined that such a system may operate efficiently using only low-grade surplus heat. In case of individual drums, the system is particularly simple to construct and maintain. Complex feeding systems and/or coupling members can be omitted. Systems with individual drums are particularly suited for batch-wise application.

In case of passages comprising multiple drums, it is an advantage that a plurality of drums have a much larger surface area than a single drum of similar capacity, further improving heat transfer. Drums with smaller circumferences may have thinner walls while remaining sufficiently strong structurally. again improving heat transfer. such a system is particularly suitable for processing bulk material in a continuous process, which is generally more efficient.

In certain embodiments, each of the at least one elongated drum is oriented at an angle in the range from 0 to 45 degrees relative to the horizontal plane, preferably an angle in the range from 0 to 5 degrees, more preferably an angle in the range from 0.5 to 2 degrees, most preferably an angle of 1 degree.

The horizontal plane refers to a plane which is level with a placement surface of the system, for example of the system housing, because a system will typically be configured to be used and transported while placed on a horizontal surface. Orienting a drum at an angle closer to the horizontal plane than to the vertical plane enables feeding the bulk material through the drum in a predictable and controlled manner. Orienting a drum at a nonzero angle relative to the horizontal plane may help in feeding the bulk material through the drum by rotating that drum and/or otherwise agitating the material.

In certain embodiments, at least one of the at least one elongated drum is oriented substantially horizontally.

Orienting a drum horizontally may save space and makes it easier to configure other components like racks and drives.

In certain embodiments. the at least one elongated drum is arranged in a rack, for instance a rack consisting of stacked drawers, wherein the rack determines the angle at which the at least ong ¢longated drum is oriented.

Arranging drums in a rack allows for the modular use of drums of a relatively simple design. By determining the angle of the drums via the rack, different angles may be used for the processing of different materials at different speeds, depending on specific characteristics affecting the drying of the material, such as grain size, by adjusting the angles of the rack or by using a different rack.

In certain embodiments, each of the at least one elongated drum has a substantially circular

Cross-section.

A substantially circular cross-section is at least substantially rotationally symmetric and leads to more predictable behaviour of bulk material in the drum during rotation, although other cross-section shapes like oval or star shapes may be preferred in specific cases, for example if more agitation is required.

In certain embodiments, agitation strips are attached to the inside of at least one of the at least one elongated drum, wherein the agitation strips are configured to agitate the bulk material in their respective at least one drum during rotation. In certain embodiments, the inside of at least one of the at least one elongated drum is shaped with longitudinal ridges configured to agitate the bulk material in their respective at least one drum during rotation.

Agitation strips and longitudinal ridges are examples of wall shaping elements which change the shape of the inside wall of a drum to cause more agitation of the bulk material during rotation, while a substantially rotationally symmetric shape may be maintained. Such agitation may help mixing of the material, in particular the mixing of wetter and drver parts of the material, to speed up processing.

Agitation strips may be added to an existing drum, while longitudinal ridges are created by changing the shape of the drum itself. Agitation strips may be added and removed at will, contributing to the modularity of the system. A drum with longitudinal ridges may have a locally smooth shape, facilitating cleaning the drum by flushing and/or brushing. A drum with agitation strips may maintain a locally and globally smooth shape, facilitating cleaning the drum by flushing, brushing. and/or scraping when the agitation strips are temporarily removed. Instead of or in additional to longitudinal ridges, other inwardly extending drum wall deformations may be applied with similar advantages. Agitation strips and longitudinal ridges may also be combined.

Longitudinal ridges have other advantages as well. They improve the surface to volume ratio of the drum, and therefore the ratio between drum diameter and amount of material which can be processed in a unit of time. Furthermore, at a constant drum diameter, they reduce the average distance between the material bemg processed and the heat source. 5 Wall shaping elements may be configured parallel to the length of the drum, or may be curved in a helical shape. Curved wall shaping elements can be used to feed the material through the drum, in combination with gravity or even on their own. In certain cases, drums with curved wall shaping elements can be arranged exactly horizontally and still sufficiently feed through the bulk material for processing.

In certain embodiments, a scraper is arranged inside at least one of the at least one elongated drum, wherein the scraper comprises a scraping surface along substantially the whole length of its respective at least one drum, wherein the scraping surface is arranged near the wall of the drum to scrape bulk material sticking to the wall of the drum off that wall.

Using a scraper during processing of the bulk material improves the control and predictability of the feed through speed, in particular if that material is sticky. Using a scraper after processing may aid in cleaning a drum to prepare for future use. A scraper is particularly advantageous in combination with agitation strips or longitudinal ridges arranged in parallel to the length of the drum, or in particular in the cleaning case, with removable agitation strips.

In certain embodiments, the system is configured to rotate each of the at least one elongated drum in place, around an axis lying within that drum, preferably around a central axis of that drum.

Rotating the drums individually in this way is particularly advantageous for feeding through, mixing, or alternatingly exposing bulk material in the drums.

Certain embodiments further comprise at least one drive element, and at least one ring gear around each of the at least one elongated drum, wherein the at least one ring gear is configured to connect to a respective drive element for rotating that elongated drum.

Such a drive configuration is efficient while enabling simple introduction and removal of drums.

In certain embodiments, the system is configured to rotate each of the at least one elongated drum, so as to mix bulk material in that drum and/or so as to vary which granules of the bulk material are exposed to an inside of a wall of the drum and to a fluid in the drum.

Rotating a drum, in particular while also agitating material in that drum, enables the system to generate movement of the bulk material in the drum in particular in a cross-sectional plane of the drum, in order to mix the particles of the material so as to keep the temperature and moisture level of the material homogenous during processing. Furthermore, such movement will alternatingly expose different granules of the bulk material to the drum wall for heating and to a fluid in the drum for giving off moisture.

In certain embodiments, the system is configured to rotate each of the at least one elongated drum so as to feed bulk material in that drum through that drum.

Rotating a drum, in particular while also agitating material in that drum, enables the system to generate movement of the bulk material in the drum in particular in a longitudinal direction of the drum, in order to feed the bulk material through the drum in a predictable and controllable manner appropriate to its moisture level and stickiness.

Certain embodiments are further configured to feed a drying fluid through the at least one passage, to remove moisture from that passage. In some embodiments, the system is configured to feed the drying fluid through the at least one passage in the same direction as the bulk material. In some embodiments, the system is configured to feed the drying fluid through the at least one passage in the opposite direction to the bulk material. In some embodiments, the system is configured to adjust the orientation of the at least one elongated drum relative to the horizontal plane. In some embodiments, the system is configured to adjust the orientation of each of the at least one elongated drum to a same selected angle in the same direction or in opposite directions.

Producing a flow of a drying fluid, such as air or an inert gas such as nitrogen, which is dry relative to the granular material in the drum may assist in carrying off moisture given off by the granular material from the at least one passage. The drying fluid may be fed through the at least one passage in the same direction as the bulk material or in the opposite direction. Feeding the drying fluid through in the same direction as the bulk material may better assist the process of feeding the bulk material through the drum. Feeding the drying fluid through in the opposite direction as the bulk material may result in better heat exchange, and may work best when a drum is oriented at a relatively large angle relative to the horizontal plane, in particular when the bulk material is light and relatively dry. Feeding the drying fluid through in the opposite direction may also be advantageous for cooling the bulk material back down after drying. In that case, cooling may take place in the last drum or a plurality of final drums while heat can be recovered at the same time. The system may be configured to allow a user to set either drying fluid feeding direction alternatingly, for example through a control unit.

In some embodiments, the system is configured to alternatingly feed the bulk material from the first end toward the second end and from the second end toward the first end of the at least one elongated drum, for example by changing the orientation direction and/or rotation direction of the at least one elongated drum.

An rotation direction is an angular direction. An orientation direction is a direction in the horizontal plane toward which an elongated drum is tilted when it is not oriented at a 0 degree angle relative to the horizontal plane. An orientation direction may be changed by continuously changing the orientation of the elongated drum through a 0 degree angle relative to the horizontal plane.

In certain embodiments, each passage formed by the at least one elongated drum comprises one respective elongated drum. In certain embodiments, the at least one elongated drum is a single elongated drum. In certain embodiments, the at least one elongated drum is a plurality of elongated drums, wherein the ends of the plurality of elongated drums are coupled to each other so as to form the at least one passage to feed the bulk material through the system.

Certain embodiments further comprise coupling members comprising two end pieces connected via a chute, wherein the coupling members are configured to be applied to a pair of ends of arespective pair out of the plurality of elongated drums, each end piece fitting over an end of a respective drum.

Such coupling members may be used as the mechanism to couple the drums into at least one passage, by applying an upper end piece of a coupling member to a lower end of a first drum, and applying the lower end piece of that coupling member to an upper end of a second drum, so that bulk material, having been fed through the first drum, will fall via the chute into the second drum to be fed there-through. Using such coupling members enables the use of drums of a simple design.

Certain embodiments further comprise one or two headers, wherein each header contains a plurality of the coupling members, wherein each header is configured to be releasably attached to a respective side of the system, so as to releasably apply each end piece of that plurality of coupling members to a respective end of the plurality of elongated drums.

Such headers may be used on at least one end of a system in order to allow an operator to easily switch the system between a closed processing state wherein all end points are applied to drums to form the at least one passage, and an open state wherein it is possible to access the drums and coupling members for inspection, cleaning, maintenance, and/or replacement. In the closed state, the header may shield the relatively vulnerable coupling members, preventing accidental disruption of the system during processing and energy losses.

In certain embodiments, the at least one passage is a plurality of passages.

A system comprising a plurality of passages may be used to process a larger amount of bulk material in a uniform manner than a system comprising only a single passage. using drums of the same size.

In certain embodiments, the drums of the at least one passage are arranged at different heights while overlapping in the horizontal plane, and/or the ends of the drums of at least one passage are coupled so as to feed bulk material through in alternating directions in the horizontal plane.

Arranging the drums of a passage in such a way results in a system which is compact in the horizontal plane while not becoming impractically large in the vertical direction in practice.

In certain embodiments, the plurality of elongated drums is arranged in a square grid, and/or the openings of the elongated drums are aligned in two vertical planes.

Such an arrangement of the drums allows for a compact system configuration, enables the configuring a header as described above with a relatively simple design, and enables easier access to the drums for inspection, cleaning, maintenance, and/or replacement.

Certain embodiments further comprise a transportable housing around the at least one elongated drum, wherein the housing preferably comprises a shipping container. In some embodiments, the housing is heat-insulating.

A single housing may substantially surround the whole plurality of drums in a cross- sectional plane if the drums are arranged in parallel. Housing subdivisions between sets of drums can be applied to achieve specific drying conditions in subsets of drums or for higher thermal efficiency. A housing preferably also comprises an enclosure for the ends of the plurality of drums, for example at least one of the aforementioned headers, which may be made at least in part out of the ends of a shipping container or may be attached to a housing comprising four sides of a shipping container. A housing may function to regulate the inflow and outflow of heat carrier fluids from around the outside of the drums.

Such a housing may comprise, or may substantially consist of, a shipping container. For efficiency, this may be a refurbished shipping container. This is particularly advantageous for transport and in an outdoors setup of the system. Alternatively or additionally, the outside of the housing may be made of, for example, substantially smoothly finished stainless steel or medium high temperature resistant polymer such as polypropylene. This is particularly advantageous in an indoors setup of the system and for ease of cleaning. A system may be built with a first type of housing for transport and may be transferred to an alternative housing at a setup location. A housing which is structurally suited for convenience and robustness in transport, such as a housing comprising a shipping container, is advantageous for a system-as-a-service business model.

In some embodiments, the housing is moisture-insulating and preferably comprises a drain for condensed moisture.

When a heat carrier fluid contacts the outside of a drum, moisture may condense on the outside of that drum. It is advantageous if the housing comprises a drain for the predictable and controlled removal of condensed moisture. Removing condensed moisture is particularly valuable for preventing or reducing the growth of unwanted organisms. A drain may comprise an outlet to the outside of the housing, a sewer connection, and/or a water collection reservoir. Regularly emptying and/or flushing a water collection reservoir is also valuable for preventing or reducing the growth of unwanted organisms.

In a second aspect, at least one of these problems is solved at least partially in the use of such a system for drying bulk material.

In a third aspect, at least one of these problems is solved at least partially in the use of such a system as a heat exchanger between the carrier fluid and a bulk material.

In a fourth aspect, at least one of these problems is solved at least partially in the use of such a system as a direct heat exchanger between the carrier fluid and a fluid fed through the at least one passage.

In a fifth aspect, at least one of these problems is solved at least partially in a method for drying bulk material, comprising feeding the bulk material into at least one passage comprising at least one elongated drum; rotating each of the at least one elongated drum around its longitudinal axis individually, for setting the bulk material in that drum in motion; and supplying a carrier fluid to the outside of the elongated drums for transferring heat to the bulk material inside the at least one elongated drum.

Certain embodiments comprise performing the feeding, rotating, and supplying in parallel in a substantially continuous drying process. Certain embodiment comprise performing the feeding, rotating. and supplying in a batch-wise drying process.

In certain embodiments, the carrier fluid has a temperature in the range from 40 to 100 degrees Celsius, preferably in the range of 50 to 100 degrees Celsius, more preferably in the range from 60 to 90 degrees Celsius.

Using such a carrier fluid has been determined to result in efficient processing of the bulk material, without requiring a potentially inefficient step of reprocessing the carrier fluid, or transferring heat to a different carrier fluid, in order to concentrate heat into a higher input grade.

In certain embodiments, the carrier fluid is wet steam or moisture-saturated gases.

Wet steam and moisture-saturated gases can carry a lot of condensation heat, using which itis easy to keep the drums at a good processing temperature. Wet steam and moisture-saturated gases are broadly available, for example as a by-product of industrial processes, and their use as carrier fluid in many cases eliminates the need for a potentially inefficient step of transferring heat to a different carrier fluid.

Wet steam is commonly under a pressure substantially higher than atmospheric pressure, such as 1 to 20 bar, or (much) higher. A carrier fluid may be applied that way in the present system, but in contrast to many existing applications, the present system does not require a high- pressure carrier fluid and/or complex, expensive seals. A carrier fluid at the same pressure, or at less than 1 bar, for example 1-10 millibars, higher pressure is sufficient to prevent contamination of the material to be dried by the carrier fluid. In fact, it is preferred that the pressure difference between the outside and the inside of the drums remains relatively small, in order to reduce the strength requirement of walls and complexity of seals.

Certain embodiments comprise back-mixing drier bulk material into the bulk material to be dried which is fed through the at least one passage.

The back-mixing into the wet bulk material of dry bulk material or of bulk material which has been partially dried. and therefore contains significantly less moisture than the input material, is particularly advantageous in case the moisture in the input material causes that material to be too sticky to keep it from forming layers on the drums’ inner wall, altematingly expose granules of it, and/or feed it through a drum in a sufficiently effective, predictable and/or controlled manner in its original state.

Certain embodiments comprise agitating the bulk material in each of the at least one elongated drum using wall shaping elements such as agitation strips and/or longitudinal ridges.

Certain embodiments comprise scraping bulk material sticking to the wall of at least one of the at least one elongated drum of the respective at least one drum, using a scraper arranged inside the respective at least one drum.

Certain embodiments further comprise rotating each of the at least one elongated drum in place, around an axis lying within that drum, preferably around a central axis of that drum.

Certain embodiments comprise mixing the bulk material in each of the at least one elongated drum and/or exposing varying granules of the bulk material to an inside of a wall of the drum and to a fluid in the drum, by setting that bulk material into motion. Certain method comprise feeding the bulk material in each of the at least one elongated drum through that drum, by setting that bulk material into motion.

Certain embodiments further comprise feeding a drying fluid through the at least one passage, to remove moisture from that passage, wherein preferably the drying fluid comprises ambient air or consists of an inert gas like nitrogen.

In certain embodiments, each passage formed by the at least one elongated drum comprises one respective elongated drum. In certain embodiments, the at least one elongated drum is a single elongated drum. In certain embodiments, the at least one elongated drum is a plurality of elongated drums. In certain embodiments, the at least one passage is a plurality of passages.

This method may be performed using any embodiment of the system described above.

The system and method will be described in more detail below, with reference to the following figures.

Figure 1A shows a view in the longitudinal direction of an embodiment of an elongated drum comprising longitudinal ridges. Figure 1B shows a view in the longitudinal direction of an embodiment of an elongated drum comprising agitation strips. Figure 1C shows a view in the longitudinal direction of an embodiment of an elongated drum comprising helical wall shaping elements. Figure 1D shows a view in the longitudinal direction of an embodiment of an elongated drum in which a scraper is arranged.

Figure 2 shows a perspective view of part of an embodiment of a svstem for drying bulk material comprising elongated drums in a rack.

Figure 3 shows a perspective view of part of an embodiment of a system for drying bulk material comprising a housing and coupling members.

Figure 4A shows a side view of part of an embodiment of a system for drying bulk material comprising elongated drums arranged in a rack, and feed-through directions for bulk material. Figure 4B shows a side view of an end of an elongated drum with an inner cover and an end piece. Figure 4C shows a side view of an end of an elongated drum with an inner cover and an end piece. Figure 4D shows a front view of elongated drums with ring gears. Figure 4E shows a top view of elongated drums with a drive element.

Figure 5 shows a perspective view of an embodiment of a system for drying bulk material comprising a housing, elongated drums, and headers.

Figure 6 shows an openwork perspective view of an embodiment of a system for drying bulk material comprising elongated drums in a rack, with arrows indicating material and carrier fluid flows in a method of drying bulk material.

Figure 7 shows a perspective view of part of an embodiment of a system for drying bulk material batch-wise. the system comprising single-drum passages.

Figures 8A and 8B show a perspective view of part of an embodiment of another system for drying bulk material batch-wise, the system comprising single-drum passages.

Figure 9 shows an embodiment of a method for drying bulk material.

Figures 1A, IB. and IC each show a view of a rotatable drum 10 for a system 1 for drying bulk material. The diameter of a drum 10 for drymg bulk material is preferably in the range from 10 to 50 cm, more preferably in the range from 20 to 30 cm, for example in the range from 22 to 25 cm, for a good balance between the amount of feed-through volume and the size of the contact surface. Other diameters are also possible and may be advantageous in case of particular materials to be dried. The length of a drum 10 is preferably in the range from 2 to 10 meters. In a preferred embodiment, drum 10 length is chosen to fit into a standard shipping container, for example 5 meters for a 20 foot container or 10 meters for a 40 foot container.

The use of longer drums is advantageous to limit the ratio of header components to drum 10 length. Optionally, a drum 10 comprises two or more drum sections connected to each other by flanges or similar means. The longer a drum 10 is, the greater the vertical extension will be if the drum 10 is positioned at an angle relative to the horizontal plane, so in particular for long drums 10 a small angle or a horizontal placement is preferred to ease positioning of the drums 10 in a housing 37.

A drum 10 may comprise, or may substantially consist of, a drum wall 11. The drum wall 11 may comprise plastic or preferably metal, for example aluminium or more preferably stainless steel. A drum wall is suitably structurally strong at thicknesses of 0.5-1 mm, for example 0.75-1 mm, in particular 0.8 mm, as well as being suitably resistant to moisture and heat. In order to obtain a good balance between strength and heat transfer, the drum wall preferably has a thickness in the range from 1/25 to 1/60 of the drum diameter, more preferably between 1/30 and 1/50 of the drum diameter, most preferably 1/40 of the drum diameter. The drum wall may be built up out of longitudinal sections.

A drum 10 preferably has a substantially circular cross-section. Being substantially circular on its radial outside enables easy handling and compact placement. Being substantially circular on its inside makes the movement of the bulk material in the drum 10 more predictable when the drum 10 is rotated. Other drum 10 shapes such as oval, polygonal, or irregular cross-sections may also work and may have the advantage of agitating the bulk material in the drum 10.

In case the drum wall 11 comprises metal, the drum 10 having a substantially circular cross-section may mean that most of the drum wall 11 is circular up to manufacturing tolerances, while substantial irregularities may exist near a welding seam. A thicker drum wall 11 may be manufactured with fewer irregularities due to its greater structural strength, but at the price of reduced heat conduction. Alternatively, structural strengthening profiles may be applied to the outside of the drum to reduce unintended deformation during transport, placement, and/or use.

Figure 1A shows a view in the longitudinal direction of an embodiment of an elongated drum 10 comprising longitudinal ridges 13, which are an example of wall shaping elements. The drum 10 has a first opening 12 on one end, shown in front, and a second opening 12 on the opposite end, shown in the back.

The inside of the depicted drum wall 11 has a shape comprising longitudinal ridges 13 such that when the drum 10 is rotated, bulk material in the drum 10 cannot slide along the drum wall 11 in the direction of rotation but will be agitated. A drum wall 11 with such ridges 14 may be manufactured for example by using a sheet of corrugated metal as a basis.

The depicted ridge 13 configuration, with sixteen straight, continuous ridges 13 wherein the inwardly protruding part 13A of the ridge 13 nearer to the radial centre of the drum 10 is narrower than the more outward part 13B, is suitable for cleaning, mixing, and exposing.

Other ridge 13 shapes may also be used. as long as the sliding of material along the drum wall 11 is interrupted at least once, preferably multiple times, per rotation of the drum 10 along substantially the whole length of the drum 10. For example, one may apply more or fewer ridges 13 than shown, broader or narrower ridges 13, irregularly shaped ridges 13, ridges 13 with a inwardly protruding part 13A broader than the more outward part 13B, longitudinally shorter ridges 13 which are staggered along the length of the drum 10, or blade-like ridges 13 which are slightly curved to shift along the longitudinal direction of the drum 10.

Also shown is a ring gear 14 radially surrounding the drum 10. The ring gear 14 may serve as a point of contact for a drive element 46 (described below with reference to figure 4C) to impart a rotating motion on the drum 10. A ring gear 14 is particularly easy to fix in its circumferential position to a drum 10 with longitudinal ridges 13. but may be applied to other drum wall 11 shapes aswell. A ring gear 13 may comprise for example metal, plastic, or a mix of materials.

Using the ring gear 14 or another suitable mechanism, the system 1 may be configured to impart a rotating motion on each of its drums 10 individually around a respective axis of rotation of that drum 10, preferably along an axis running along the radial centre of that drum 10. This way all drums 10 of the system 1 may be rotated at substantially the same angle and speed. while remaining in place.

A rotating motion, ¢ither alone or in combination with an element for agitating the drum 10, may cause the granules of the bulk material in the drum 10 to mix and/or may cause the granules of the bulk material to be exposed at one time to the inside of the drum wall 11 and at another time to a fluid such as air inside the drum 10.

Alternatively or additionally, a rotating motion, either alone or in combination with an element for agitating the drum 10, may disperse local piles of the bulk material in the drum 10 to spread out more evenly in the drum 10. Particularly in combination with placing the drum 10 at an angle (to be described below with reference to figure 2 and onward), this may have the effect of moving the bulk material along the length of the drum 10, so as to gradually feed the bulk material through the drum 10 from one opening 12 to the other.

Figure 1B shows a view in the longitudinal direction of an embodiment of an elongated drum 10 comprising agitation strips 18, which are another example of wall shaping elements.

The depicted embodiment has a drum wall 11 with a substantially circular cross-section. A plurality of agitation strips 18 has been applied to the inside of the drum wall 11 such that when the drum 10 is rotated, bulk material in the drum 10 cannot slide along the drum wall 11 in the direction of rotation but will be agitated. The agitation strips 18 need not manufactured in one piece with the drum 10 or fixedly attached to the drum 10, but may be separate element removably and/or adjustably attached to the drum 10.

The agitation strips 18 may be thin strips of metal positioned upright or at an angle of for example 45 degrees relative to the drum wall 11 in order to interrupt the sliding of bulk material along the drum wall 11. Each agitation strips 18 may be strung across the entire length of the drum 10 between two positioning elements 19 such as protrusions fixed to either end of the drum 10 at regular circumferential intervals. Placement of the agitation strips 18 may involve first fixing positioning elements 19 to the drum 10 and then stringing agitation strips 18 between the ends of the drum 10, and removal may involve removing these in the opposite order.

The application of agitation strips 18 has the advantage that the inside of the drum wall 11 can be changed to be more suitable for scraping or more suitable for agitation at will, for example between processing and cleaning, or between the processing of two different types of bulk material.

Figure 1C shows a view in the longitudinal direction of an embodiment of an elongated drum comprising helical wall shaping elements. The drum 10 and a drum wall 11, opening 12. and ring gear 14 are indicated.

An elongated drum 10 may be provided with helical wall shaping elements. In the depicted embodiment the wall shaping elements are agitation strips 18, although alternatively, longitudinal ridges 13 may be formed in a helical shape as helical wall shaping elements.

Helical wall shaping elements may help in spreading bulk material out over the length of an elongated drum 10 and/or feeding bulk material through an elongated drum 10, when that drum 10 is rotated. This approach may be combined with orienting the drum at an angle relative to the horizontal plane.

Figure 1D shows a view in the longitudinal direction of an embodiment of an elongated drum 10 in which a scraper 15 is arranged.

Processing relatively sticky bulk material may require measures to prevent the bulk material from becoming immobilized by sticking to the drum wall 11 or for removing material already stuck. A system 1 may be provided with at least one scraper 15 fixedly or removably positioned in at least one of the at least one elongated drum 10. A scraper 15 may be used for cleaning the corresponding drum 10 when no processing is taking place and/or for better processing relatively sticky bulk material. Altematively or additionally, drier bulk material may be back-mixed into the input stream of bulk material to lower the stickiness of the bulk material to a workable level.

A scraper 15 may be arranged inside a drum 10 along part or all of the length of that drum 10, and along all or part of the inner circumference of that drum 10, in order to scrape bulk material sticking to the inside of the drum wall 11 off that drum wall 11.

A scraper 15 may be a tangential scraper 15 configured to scrape tangentially to the drum wall, or a longitudinal scraper 15 configured to scrape longitudinally to the drum wall.

The depicted scraper 15 is tangential. It is preferred that a tangential scraper 10 is dimensioned to run along the length of the drum. The system 1 may be configured to rotate the tangential scraper 15 and the corresponding drum 10 relative to each other, by holding the scraper steady while rotating the drum 10, by rotating the scraper 15 in a stationary drum 10, or by rotating both at different speeds or in different directions.

A longitudinal scraper 15, the system 1 is configured to move the scraper in a longitudinal direction through the corresponding elongated drum 10 and is particularly suited to be combined with wall shaping elements. In case of a longitudinal scraper 15, it is preferred that the system is configured to hold a longitudinal scraper 15 and the corresponding drum 10 stationary relative to each other and/or to allow a longitudinal scraper 15 and the corresponding drum 10 to rotate freely relative to each other, for example to allow a longitudinal scraper to be guided to rotate by helical wall shaping elements.

A scraper 15 may be configured to be inserted into the drum 10 and removed from the drum 10 at will so that the scraper 15 may be used only during processing, or only during cleaning. or both, or neither, as circumstances require. A scraper may be positioned in the drum 15 without being attached to that drum 15, while being positioned fixedly relative to the housing 37 by being attached to a header 51 or to the housing 37.

A scraper 15 may comprise at least one rider 16. A rider may comprise an arm with a flexible, smooth, and/or rotating contact element such as a wheel or a sliding carrier for keeping the distance of the scraper 15 relative to the drum wall 11 within a predetermined range. A contact element is preferably positioned against a support point of the drum 10 such as a ring gear 14. A scraper 15 comprises at least one scraping element 17 comprising an arm 171 with a fixedly or flexible attached scraping surface 172 arranged close to the inside of the drum wall 11. The scraping surface 172 may be positioned close to the inside of the drum wall 11 by suitably selecting the relative size and positioning of the riders 16 and the scraping element 17, which positioning may be adjustable. It is important that a scraper 15, in particular a scraping element 17, is configured to prevent releasing contaminants as a result of wear, for example by being produced from a suitable material. Preferably, a scraper 15 is configured to be easy to remove and clean.

The fewer irregularities the drum wall 11 contains, and the closer the shape of the drum wall 11 is to circular, the more precisely the scraping element 17 can be positioned relative to that drum wall 11 and the more effective the scraping will be. Preferably, a rider 16 and/or a scraping element 17 is attached in a sufficiently flexible manner to follow the local drum wall 11 geometry.

This allows the scraper 15 to better cooperate with a drum 10 which 1s manufactured with limited wall geometry precision, which allows for thinner drum walls and may be far cheaper to produce.

The system 1 may combine scrapers 15 and wall shaping elements in all or part of the drums 10 of a passage. For example, the first drum 10 or a plurality of initial drums 10 of a passage may comprise only a scraper 15 and/or only wall shaping elements, while the remaining drums 10 of that passage may be provided with both, as the stickiness of the bulk material will be reduced in later drums 10.

Figure 2 shows a perspective view of part of an embodiment of a system 1 for drying bulk material comprising elongated drums 10 in a rack 20.

The rack 20 may comprise metal, for example steel or aluminium strips or bars, and may comprise two or more sections, in particular lengthwise sections, which may or may not be configured to be structurally connected to each other. A rack 20 defines a number of positions at which drums 10 can be placed, wherein each position is configured to hold a drum 10 ata respective predetermined angle relative to the surface on which the rack 20 is placed, which is typically the ground and which may be considered the horizontal plane. As an example, the depicted embodiment holds 36 drums.

Orienting the drums 10 at an angle relative to the horizontal plane assists in feeding bulk material through the drum 10 when that drum 10 is rotated and/or when the bulk material in the drum 10 1s agitated. Suitable angles for predictable and controlled feed through speeds are between 0 and 45 degrees. To leave sufficient time for processing, the angle is preferably in the range from 0 to 5 degrees. more preferably in the range from 0.5 to 2 degrees. most preferably 1 degree.

For convenience of insertion and removal of the drums 10, the rack 20 may comprise a plurality of drawers 21 configured to be inserted and removed from the rack 20 as a whole, and configured to each hold a plurality of drums 10 which are to be positioned at the same predetermined angle and in the same direction. The depicted embodiment comprises nine drawers of four drums each.

A rack 20 may comprise a lower surface or supports to rest on the bottom of the housing 37, and one or multiple internal surfaces or supports to hold racks 21 and/or drums 10. A drawer 21 may have a lower surface or supports to rest on the bottom of the housing 37 and/or to be held by the rack 20, an internal surface or supports to hold a drum 10, and an upper surface or supports to hold a further drawer 21 and/or to engage with the rack 20.

There are various ways to ensure that the drums 10 in the rack 20 are held at a predetermined angle relative to the surface on which the rack 20 is placed, for example, by suitable selecting the angles between the relevant surfaces and/or supports of the rack 20 and/or drawers 21.

In the depicted embodiment, the internal surfaces or supports of the rack 20 are configured to hold drawers 21 at the predetermined angle relative to lower surface or support of the rack, and the internal surfaces or supports of the drawers 21 are configured to hold drums 10 level with the drawer 21. In other embodiments, the internal surfaces or supports of the rack 20 are configured to hold drawers 21 level relative to the lower surface or support of the rack 20, and the internal surfaces or supports of the drawers 21 are configured to hold the drums 10 at the predetermined angle relative to the drawer 21. In vet other embodiments, the rack 20 and drawers 21 are configured such that the rack 20, drawers 21, and drums 10 are all level with each other, and the system is configured with means such as a winch for changing the orientation of the rack 20 as a whole.

In certain embodiments, the rack 20 substantially consists of a plurality of drawers 21. One or multiple stacks of drawers 21 alone may form the rack 20, with no further structural elements. In that case, in order to hold the drums 10 at the predetermined angle relative to the ground, the drawers 21 may for example be configured to be stacked such that the lower surface or supports of each drawer 21 are level with the surface on which the drawer 21 below is placed, while the internal surfaces or supports of the drawers 21 are configured to hold the drums 10 at the predetermined angle.

Each position of the rack 20 is configured to hold drums 10 in a certain predetermined direction. The rack 20 may be configured to hold all drums 10 substantially in parallel, in which case a longitudinal direction L of the rack 20 may be exactly the same as the longitudinal directions of the drums 10.

In the depicted embodiment, the rack 20 is configured to hold different drums 10 angled in opposite directions. This is achieved by configuring each drawer 21 to hold different drums 10 angled in a predetermined, opposite direction. As an altemative, for example, cach drawer 21 may be configured to hold all its drums 10 angled in the same predetermined direction, while the drawers 21 are configured to be stacked alternatingly in opposite directions.

In either case, the openings 12 of the plurality of drums 10 may at least approximately align in two vertical planes. This is the case in the depicted embodiment.

The rack 20 may be configured to hold a plurality of drums 10 in rows in a width direction

W across the rack 20. The depicted embodiment holds three drawers 21 to a row, totalling six drums 10 to a row. Similarly, the rack 20 may be configured to hold drums 10 at a plurality of levels in the vertical direction V. The depicted embodiment holds three stacked rows of drawers 21, totalling six stacked rows of drums 10. When combining these configurations, the drums 10 are arranged in a square grid, in this case a grid of three by three drawers 21 totalling six by six drums 10.

Figure 3 shows a perspective view of part of an embodiment of a system 1 for drying bulk material comprising a housing 37 and coupling members 33.

Coupling members 33 are configured to couple openings 12 of two drums 10 to each other on the same side of the system 1. The depicted coupling members 33 each comprise two end pieces 31 and a chute 34. In this embodiment, the end pieces 31 are a first end piece 31A and a second end piece 31B, respectively. An end piece 31 is configured to fit over the end of a drum 10. In embodiments wherein a chute 34 is present, an end piece is configured to connect to the chute 34.

End pieces 31 and/or chutes 34 may comprise metal, or plastic, for example polypropylene, and/or some other material. A first end piece 31A of the coupling member 33 comprises an upper chute connection 48 (see figure 4C below) for connecting the lower side of the first end piece 31A to the upper side of a chute 34, to allow bulk material from a connected drum 10 to fall into the chute 34, and a second end piece 31B of the coupling member 33 comprises a lower chute connection 44 (see figure 4B below) for connecting the upper side of the second end piece 3 1B to the lower side of a chute 34, to allow bulk material to fall from the chute 34 into a connected drum 10. The end pieces 31 may be coupled or couplable to the chute 34 via a clamped connector and/or gasket connector, such as a tri-clamp coupling.

Using such coupling members 33, the elongated drums 10 may be coupled to each other so as to form a passage configured for the system 1 to feed bulk material through. In the depicted embodiment, a plurality of passages has been formed, and each drum 10 is part of one passage. In this case, twelve passages of three drums 10 each have been formed. but passages may alternatively consist of two, four, or other numbers of drums 10. Preferably, all passages of a system 1 comprise the same number of drums 10.

In the depicted embodiment, the drums 10 of a passage have been coupled in alternating directions in the horizontal plane, for the system | to feed bulk material through the drums 10 in alternating directions. In the depicted embodiment, the drums 10 of each passage are arranged at different heights while overlapping in the horizontal plane.

Furthermore, in the depicted embodiment, the drums 10 of two different passages are arranged in at least approximately the same location in the horizontal plane, and the openings 12 of the respective drums 10 of the two passages are connected alternatingly in an inside bend 35 and an outside bend 36. The drums 10 of the one passage are arranged further toward one longitudinal end than the drums 10 of the other passage, for example 10-30 cm, preferably 10-15 cm further. At that longitudinal end of the system 1, the drums 10 of that one passage form an outside bend 36 and the drums of the other passage form an inside bend 35. while on the other longitudinal side of the system 1 the bends are reversed. This has been determined to be a particularly space-efficient manner of arranging the passages.

In such an inside bend 35 — outside bend 36 configuration, the two drums 10 of the one passage which forms the outside bend 36 on a certain side of the system 1 (the outside passage) are arranged on the vertical outside of the two drums 10 of the other passage which forms the inside bend at that side of the system 1 (the inside passage). The first end piece 31A connected to the upper drum 10 of the outside passage is located higher than the first end piece 31A connected to the upper drum of the inside passage, while the second end piece 31B connected to the lower drum 10 of the outside passage is located lower than the second end piece 31B connected to the lower drum 10 of the inside passage. The chute 34 which forms part of the outside bend 36 is longer than the chute 34 which forms part of the inside bend 35, so that the bulk material being fed through the outside bend 36 follows a longer path than the bulk material being fed through the inside bend 35. at that side of the system 1.

In the depicted embodiment, the mitial openings 12A of all passages are located at the same longitudinal side of the system 1, so that all bulk material enters the system 1 at the same side, and the final openings 12B of all passages are located at the other longitudinal side of the system 1, so that all bulk material exits the system 1 at the other longitudinal side of the system 1, but this need not be the case. For example, in an embodiment wherein each passages comprises an even number of parallel drums 10, the initial openings 12A and final openings 12B of the passages may be on the same side of the system 1, so that all bulk material both enters and exits the system 1 at the same longitudinal side.

Some example configurations are as follows. A system 1 may comprise at least one passage comprising three drums 10 wherein the initial opening 12A of the at least one passage is positioned at the opposite longitudinal end of the system 1 to the final opening 12B. A system 1 may comprise at least one passage comprising four drums 10 wherein the initial opening 12A of the at least one passage is positioned at the same longitudinal end of the system 1 as the final opening 12B. Such a system, with an inside bend 35 — outside bend 36 configuration, may comprise a housing 37 comprising a high cube type shipping container. A system 1 may comprise at least one passage comprising an even number of drums 10 wherein the initial opening 12A of the at least one passage is positioned at the same longitudinal end of the system 1 as the final opening 12B. Such a system 1 may easily be provided with a back-feeding means, such as a passage and pump, for feeding processed bulk material back from the final opening 12B back into the initial opening 12A for further processing, optionally as part of a back-mixing arrangement with new wet bulk material. Many other configurations are possible.

Figure 3 depicts the side of the system 1 where the bulk material exits the system 1. In the depicted embodiment, the twelve openings 12 the two lower rows are the final openings 12B of twelve distinct passages.

The initial openings 12A and/or final openings 12B of a passage may or may not be covered by an initial end piece 41 or final end piece 42, respectively (see figure 4A), which may or may not be connected to a chute 34. An initial end piece 41 and/or a chute 34 may be used to connect the initial openings 12A to a central input element 61 (see figure 6) for feeding bulk material into the system 1. A final end piece 42 and/or a chute 34 may be used to connect the final openings 12B to a central output element for outputting bulk material from the system 1. A final end piece 42 may comprise a width-oriented conveyor screw to collect bulk material from the final openings 12B, and a second conveyor screw to convey the collected bulk material from the system 1, for example upwards. A transport screw may be configured as a closed environment, to separate dried bulk material from the potentially humid or contaminating carrier fluid.

In the depicted embodiment, the housing 37 surrounds the drums 10 and the rack 20 radially. It is preferred to include a cover to shield at least electrical parts and/or drives from the carrier fluid in the system 1. In the depicted embodiment, the housing also surrounds the drums 10 and the rack 20 in the longitudinal direction L with inner covers 38 which may comprise a sheet of for example plastic across an entire longitudinal end of the rack 10, to shield all components in the corresponding header 51.

A housing 37 may be configured to protect the drums 10 and/or other components of the system 1 from damage. may be configured to allow the system 1 to be picked up, transported, and placed as one piece, and/or may be configured to regulate the flow of a heat carrier fluid and condensed moisture. To drain condensed moisture, the housing 37 may comprise a drain (not depicted) on its bottom side.

Figure 4A shows a side view of part of an embodiment of a system 1 for drying bulk material comprising elongated drums 10 arranged in a rack 20, and feed-through directions for bulk material.

In the depicted embodiment, it can be seen particularly well that the drums 10 are each arranged at a certain predetermined angle. In this case the angle is the same for each drum 10. End pieces 31 are depicted without chutes 34 for clarity. Instead, arrows indicate feed-through directions for bulk material. The depicted embodiment of a system 1 is configured to feed the bulk material through the passages in alternating horizontal directions starting in initial end pieces 41 in the upper two layers of drums 10 and ending in final end pieces 42 in the lower two layers of drums 10.

Preferably, the drum walls 11 are substantially closed to liquids, moisture and gases. In particular, it is preferred if the drums 10 are sufficiently closed to allow the system to induce a flow of a drying fluid through the passages, such as a gas or gas mixture, in particular air which is relatively dry compared to the bulk material fed into the system 1. A drying fluid may carry off moisture which is given off by the bulk material in the drums 10 in response to heat. A system may be configured to induce a flow of drying fluid through the passages in the feed-through direction of the bulk material, or in the opposite direction, or either.

It is particularly advantageous to induce a flow of drying fluid in the feed-through direction, because this contributes to feeding the bulk material through the passages and/or reduces the extent to which bulk material gets stuck in the passages, for example in an end piece 31.

Figure 4B shows a side view of an end of an elongated drum 10 with an inner cover and an end piece 31B.

The end piece 31B comprises a drying fluid connection 39 and a lower chute connection 44. The depicted drum 10 comprises longitudinal ridges 13.

The depicted end piece 31B concerns a second end piece 31B of a coupling member 33 and comprise a lower chute connection 44. The lower chute connection 44 may comprise a tube extending into the drum 10 at an angle toward the longitudinal inside of the system 1 and may be configured so as to urge bulk material falling from a connected chute 34 into the connected drum 10. The depicted drying fluid connection 39 is particularly suitable for feeding drying fluid through the drum 10 in the same direction as the bulk material. The opening of the drying fluid connection 39 is located further toward the end of the drum 10 than the opening of the lower chute connection 44, so that bulk material fed into and through the drum 10 will tend to not pass the opening. The opening may be below the lower chute connection 44. The drying fluid connection 39 may comprise a tube from the opening toward the outside of the drum 10, preferably extending in the longitudinal direction of the drum 10.

Figure 4C shows a side view of an end of an elongated drum 10 with an inner cover 38 and an end piece 31A.

The end piece comprises a drying fluid connection 39 and an upper chute connection 48.

The depicted drum 10 comprises longitudinal ridges 13.

The depicted end piece 31A concerns a first end pieces 31A of a coupling member 33 and comprise an upper chute connection 48. The upper chute connection 48 may comprise an opening over substantially the whole bottom of the end piece 31A and may be configured to allow bulk material reaching the end of the drum 10 to fall into a connected chute 34. The end pieces 31A fit over the ends of the respective drums 10.

The depicted drying fluid connection 39 is particularly suitable for feeding drymg fluid through the drum 1 in the same direction as the bulk material. In this case, too, the drying fluid connection 39 comprises an opening for letting drying fluid into or out of the drum 10. The opening is located relatively high in the drum 10, above the upper chute connection 48, so that bulk material fed through and out of the drum 10 will tend to pass below the opening. Preferably, the opening of the drying fluid connection 39 has a large surface area, which may be achieved by cutting a tube diagonally. This allows for the addition of a mesh in the opening to prevent bulk material from escaping the drum 10 via the drving fluid connection 39 while preventing clogging of the mesh by sticky and/or fibrous material. Alternatively or additionally, a cyclone or bag-filter may be operatively connected to the drying fluid connection, for example downstream of the opening for letting drying fluid into or out of the drum 10, to intercept escaping bulk material.

End pieces 31 may be comprised in a header 51 (see figure 5) and may be configured to be coupled to the rest of the system 1 in a horizontally suspended manner. To this end the end pieces 31 may comprise, for example. leaf springs and parallel guides or spiral springs with straight guidance. Spiral springs are preferably shielded for safety and cleanliness. Any parts which are to be coupled to a drum 10 and are not fixedly attached to said drum 10, for example end pieces 31 or drying fluid connections 39, may comprise a radial flange or another suitable receiving surface to receive suspension forces.

In the embodiments of figures 4B and 4C, the end pieces 31 lay against the inner cover 38.

Preferably, the end pieces 31A are tensioned to push lightly against the inner cover to seal the inside of the system 1.

Figure 4D shows a front view of elongated drums with ring gears.

Between the drums 10 is a drive element 46 configured to impart a rotating motion on the drums 10 via the ring gears 14 (depicted schematically). Preferably, the drive element 46 is a drive gear engaging with at least one ring gear 14. For example, in the situation wherein a drawer 21 is in place in a rack 20, one central drive gear engages with the ring gears 14 of all drums 10 in the rack, and the system 1 is configured to drive the drive gear to impart a rotating motion on these drums 10.

At least one of the elongated drums 10 may be further supported by at least one support wheel 52. A support wheel 52 may be configured to freely rotate with the corresponding elongated drum 10 so as to limit friction and may in turn be supported by a corresponding rack 20 or drawer 21 or by the housing 37.

Figure 4E shows a top view of elongated drums with a drive element. The elongated drums 10 are placed in a housing 37.

A drive element 46 may be configured to be driven via a first connector 47, such as a drive shaft, which is in turn coupled to a second connector 48 of a drive 49 mounted in or coupled to a header 51. Each header 51 may comprise one or more drives 49 or second connectors 48, wherein gach drive 49 or second connector 48 is configured to drive at least one drive element 46, preferably a plurality of drive elements 46, for example all drive elements 46 positioned at the same horizontal or vertical position in a rack 20.

Figure 5 shows a perspective view of an embodiment of a system 1 for drying bulk material comprising a housing 37, end pieces 31, and headers 51.

The system 1 is shown from the longitudinal side where the initial openings 12A are located.

In the depicted embodiment, the end pieces 31 and chutes 34 (left out for clarity) of the coupling members 33 are comprised in two headers 51 separate from the housing 37, one at each longitudinal side of the system 1. Including a single header 51 on only one side of the system 1 is also possible. Preferably, any components required for inducing a flow of drying fluid through passages are also comprised in the header or headers.

A header 51 is structurally separate from the housing 37. and may be alternately moved against the housing 37 or away from the housing 37 to provide an operator with access to the drums 10. In the depicted embodiment, the header is connected via a vertical hinge 53 on one side in the width direction W and may be moved against the housing 37 and releasably attached to the housing 37 via a secure attachment point 54. Alternatively, a header 51 may be provided with rails and configured to be rolled away from the housing 37. This is particularly advantageous in combination with end pieces 31 which are configured to overlap with a longitudinal portion of the drums 62. End pieces 31 may be dimensioned to fit snugly over or into the corresponding ends of the drums 62. Regardless of whether a header 51 is configured to be moved against the housing 37 by rotation or by linear movement, the header 51 and housing 37 may be provided with a plurality of mutually connectable coupling elements (not indicated) for uniformly placing and optionally securing the header 51 to the housing 37.

A header 51 may be configured such that, when that header 51 is moved against the housing 37, the end pieces 31 comprised in that header 51 are applied to respective drums 10 of the system 1, to cover openings 12 of these drums 10 so as to create passages.

A number of feed openings 81 is depicted. The carrier fluid may be fed into the space inside the housing 37 and may surround the drums 10 there. To this end, one or both of the lateral sides of the housing 37 may be provided with one or more feed openings 81, preferably a plurality of feed openings 81 distributed over the lateral sides of the housing 37. The feed openings 81 may be configured to be connected to a respective carrier fluid infeed or outfeed. For transport and modularity, it is advantageous if the sides of the housing 37 comprise no active components. It is also advantageous if the only one side of the housing 37 comprises feed openings 81.

In the depicted embodiment, four openings 81 are provided. All openings 81 are provided in the same lateral side of the housing 37. One opening 81 is provided near each corner of the lateral side. Certain openings 37 are distributed over the height of the housing 37 near one longitudinal end of the lateral side and are configured to receive a carrier fluid. Certain other openings are distributed over the height of the housing 37 near the opposite longitudinal end of the lateral side and are configured to output a carrier fluid. In such a configuration, the system 1 may feed a carrier fluid through the housing 37 from one longitudinal side to the other. Many other configurations of openings and different uses of openings as infeeds and outfeeds are possible.

Heat may be transferred from the carrier fluid to the bulk material via condensation of moisture from the carrier fluid on the outside of the drums 10. Condensed moisture may drip or flow to the bottom of the housing 37 in the form of clean or contaminated water, and the housing 37 is preferably provided with a drain configured to drain such moisture in a controllable and predictable manner.

Figure 6 shows an openwork perspective view of an embodiment of a system 1 for drying bulk material comprising elongated drums 10 in a rack 20, with arrows indicating material and carrier fluid flows.

The depicted embodiment comprises passages of three drums 10 each which are not positioned in the same horizontal position as the drums 10 of other passages and therefore also do not form inside bends 35 and outside bends 36. Two headers 51 are depicted in a closed manner, while the housing 37 is depicted in an openwork manner.

A first set of arrows A1 indicates the horizontally alternating and vertically descending directions of bulk material being fed through the drums 10 in the longitudinal direction of the system 1, and a second set of arrows A2 indicates the flow of a heat carrier fluid across the system

I in the width direction at one or more vertical positions.

A central input element 61 comprising a funnel is depicted on top of one of the headers 51.

A central output element may also be provided. Various feeding devices for input, output, or feed-through may be connected to the system. For example, a central input element 61, initial opening 12A, central output element, and/or final opening 12B may be provided with a controllable lid or funnel.

One or more input devices for one or more streams of bulk material may be connected to the system, such as for separate streams of relatively dry material and relatively wet material or separate streams for back-mixed material and new material. Feeding devices for carrier fluid and/or drying fluid may be connected to the system. The system may comprise sensors such as optical sensors, load sensors, temperature sensors, and/or humidity sensors.

A control unit 62 is depicted. The control unit 62 may comprise an electronic control unit (ECU) comprising a processor and a memory. The depicted control unit 62 is attached to a header 51, but alternatively a control unit 62 may be attached to the housing 37, and/or the control unit 62 may comprise one or more internal components and/or one or more external devices, over which its functionality is distributed.

The control unit 62 may be configured to control the system based on a processing plan which is stored in its memory and executed by its processor. The control unit 62 may comprise sensors for observing the processing by the system and may control the system based on sensor data in a feedback loop, in order to stabilize certain properties of the processing, such as the amount of bulk material present in the system and/or the temperature and/or humidity in certain parts of the system. Based on processing a certain bulk material for a certain minimum period of time and collecting sensor data, a control unit 62 may determine one or more calibration variables to improve its current processing plan or to adjust permanent settings.

The control unit 62 may be configured to receive input and/or provide output via a panel such as a touch screen, from an external wired or wireless input device such as a controller provided with the system 1 (not depicted), and/or from an external computer system running compatible software. The control unit 62 may comprise components for receiving input from and/or for providing output to a human user, such as a touch screen. The control unit 62 may comprise components for receiving input from and/or providing output to an external computer system, such as a wired or wireless network connector. The external computer system may be, for example, a local workstation, factory automation system, or a cloud interface. The control unit 62 may be configured to include an external computer system into its feedback loop of controlling the system based on sensor data. External computer systems may be connected to a plurality of systems 1 for collecting and analysing outputs, and/or may hold information on optimum settings for different types of bulk materials.

The received input may comprise a processing plan to be executed and/or may comprise control instructions for directly controlling the system. The provided output may comprise sensor data and/or may comprise information about the progress of a processing plan, such as a log.

A control unit 62 may be configured to control the system as a whole, components of the system, and/or devices connected to the system. For example, the control unit 26 may be configured to control activities and settings of all drums at a time. or of individual drums.

Controlling may comprise starting or stopping activities and/or adjusting settings.

For example, the control unit 62 may be configured to start or stop rotation or to control the rotation speed of the drums 10. The control unit 62 may be configured to control the orientation and/or direction of the drums 10. The control unit 62 may be configured to start or stop feeding or to control the volumes of bulk material let into the drums 10. The control unit 62 may be configured to control the fractions of various streams of bulk material, for example by starting or stopping the feeding of various fractions. The control unit 62 may be configured to control the volume and/or direction of drving fluid fed through the drums 10. The control unit 62 may be configured to control the temperature and/or flow speed of the carrier fluid.

Figure 7 shows a perspective view of part of an embodiment of a system for drying bulk material batch-wise, the system comprising single-drum passages. This embodiment contains a number of simplifications compared to the embodiments discussed above.

In a simple embodiment, a system | may comprise one or more elongated drums 10 with a first end and a second end, in a housing 37. The at least one elongated drum 10 may rest in a rack 20 or in recesses of the housing.

At least one of the ends of each of the at least one elongated drum 10, for example the first end, has an opening 12 for feeding bulk material into and out of the drum 10. The other end of the same drum 10 may also be provided with an opening 12, for ease of cleaning the drum 10, but this is not necessary.

An opening 12 may be provided with a corresponding removable end piece 31 which is not part of a chute connection 33 and therefore does not contain a coupling member. No chute is required. An end piece 31 may be configured to rotate with the corresponding drum 10, and may be provided with a centrally positioned drying fluid inlet. The drying fluid inlet is preferably not attached to the drum 10 at a fixed rotational orientation and configured to rotate with the drum 10.

The system may be configured to rotate the at least one elongated drum 10 using a drive, for example a drive 49 as described above. The at least one elongated drum 10 may be provided with wall shaping elements. but this is not necessary.

The system may be configured to spread bulk material over the length of the elongated drum 10 and/or to empty the bulk material from across the length of the elongated drum 10, for example in that wall shaping elements are helical and the system 1 is configured to alternatingly rotate the elongated drum in either direction, or in that the orientation of the elongated drums 10 may be adjusted manually or via a further drive.

For example, the system may be configured to adjust the orientation of the elongated drums 10 to be oriented at a predetermined nonzero angle relative to the horizontal plane in a first direction or to be horizontal, by lifting and lowering and end of the drums 10 using for example a winch. Furthermore, the system may be configured to adjust the orientation of the elongated drums 10 to the same or a different angle relative to the horizontal plane in an opposite direction. An orientation in a first direction or a horizontal orientation may be used when feeding bulk material into the drums 10, and an orientation in an opposite direction or a horizontal orientation may be used when feeding bulk material out of the drums 10. The first direction may be a direction such that an end comprising an opening 12 is oriented upward. and the opposite direction may be a direction such that an end comprising an opening 12, preferably the same end, is oriented downward. It is advantageous if a drive 49 is configured such that its orientation may be adjusted together with the corresponding drum 10 or drums 10, or such that its operative connection to the corresponding drum 10 or drums 10 is robust to predetermined changes in orientation.

In contrast to the system 1 embodiment of figure 5, the embodiment of figure 7 comprises areservoir 82 at the bottom of the housing 37. The reservoir 82 is configured to receive the carrier fluid and comprises heating means (not depicted) configured to generate or introduce heat and transfer said heat to the carrier fluid. The transferred heat will cause the carrier fluid to rise, transferring its heat to the at least one drum 10 before falling back into the reservoir 82. It is also possible to combine the embodiment of figure 7 with different types of carrier fluid feed, such as one with feed openings 81 as described earlier.

Figures 8A and 8B show a perspective view of part of an embodiment of another system for drying bulk material batch-wise, the system comprising single-drum passages. This embodiment contains a number of alternative features relative to the embodiments discussed above. It will be clear to the skilled person that features of the various embodiments can generally be interchanged.

Figure 8A depicts an embodiment of a system 1 comprising a housing 37 comprising lateral openings 81. The housing 37 comprises feet 37 configured to raise the housing 37 above the ground. Raising the housing 37 above the ground improves heat insulation.

Figures 8A and 8B show at least four drums 10. The drums are stacked vertically. Each depicted drum may represent a row of drums 10, for example a row of two drums 10, in which case the total number of drums is eight. Other numbers of drums 10, rows, and columns, as well as other ways of organizing drums 10 in the cross-section of the system 1 are possible.

On both sides, the drums 10 are provided with end pieces 31. The end pieces 31 may be provided with openings for drying fluid connections 39. Preferably, these openings are central.

That way, if the end pieces 31 are connected to their respective drums 10 to rotate with these drums 10 in a fixed relative orientation, the drying fluid connections 39 may be configured to remain stationary and to be relatively easily connected to an external system and/or to the respective header 51 of the system 1. An advantage of attaching end pieces 31 to the drums 10 at fixed rotational orientations while connecting drving fluid connections 39 in a way which allows rotation is that the connecting surfaces between rotating and stationary parts are smaller than in the case of stationary end pieces 31, which reduces friction and dust buildup.

In a system 1 for batch-wise processing, it is advantageous to configure one side of the system 37 as a driving side D for driving the drums 10 and another side as a feeding side F for feeding bulk material into and out of the drums 10. On the driving side, the system 1 may be provided with a drive 49 and may be provided with a winch or other orientation changing means (not depicted). The header 51 and end pieces 31 on the driving side D may be configured to be removed only when cleaning or maintenance are required, while the header and end pieces on the feeding side F may be configured to be removed at each batch feed-in or feed-out step.

As an example, bulk material may be fed into drums 10 of the system 1 via the feeding opening 12 manually while the drums 10 are horizontal and still, and the bulk material may be fed out of the drums into a receptacle by rotating the drums while they are oriented such that the end comprising the feeding opening 81 is oriented downward. Keeping the drums 10 still during feeding is advantageous for worker safety.

Figure 9 shows an embodiment of a method for drying bulk material. The method 70 for drying bulk material may be performed using an embodiment of the system as described above.

In a first step, a heat source provides 71 heat carried by a heat carrier fluid. The heat source may be an enclosure of an industrial processing installation. Preferably the heat carrier fluid contains moisture. For example, the heat carrier fluid may comprise wet steam or moisture- saturated gases which may or may not be contaminated with non-condensing gases such as the outside air. This allows moisture from the heat carrier fluid to condense on the outside of the drum housing 11, transferring heat to the drums 10 and indirectly to the bulk material in the drums 10.

The described system 1 and method 70 are most suitable for use with heat carrier fluid with a temperature in the range from 40 to 100 degrees Celsius, preferably in the range of 50 to 100 degrees Celsius, more preferably in the range from 60 to 90 degrees Celsius, for example in the range from 70 to 80 degrees Celsius.

In an optional step, in case the original heat carrier fluid originating from the heat source is not suitable for direct use in the described system 1 and/or method 70, the original heat carrier fluid may be preprocessed 72 to produce a suitable heat carrier fluid. In a preprocessing installation, a heat carrier fluid may be turned into a lower grade or a higher grade of concentration of heat, or a proportion of a liquid component such as water may be increased or reduced.

For example, an original heat carrier fluid with a temperature over 100 degrees Celsius may be used, but may require preprocessing to a lower temperature. An original heat carrier fluid of a temperature which is lower than preferred may be used after reprocessing it to a higher temperature. An original heat carrier fluid may contain too little moisture, or may have the form of a liquid in cases wherein a gas or a mixed state is preferred. In such cases, the original heat carrier fluid may be preprocessed into, for instance, wet steam or moisture-saturated air.

At least one of the step of providing heat 71 and the step of preprocessing 72 the original heat carrier fluid may be performed by separate systems.

In a further step, bulk material is fed 73 into at least one passage of a system | comprising at least one elongated drum 10.

In a further step, each of the at least one elongated drum 10 is rotated 74 around its longitudinal axis individually, for setting the bulk material in that drum 10 in motion.

In a further step, a carrier fluid is supplied 75 to the outside of the at least one elongated drum 10 for transferring heat to the bulk material inside the at least one elongated drum 10, preferably all drums at the same time.

The steps of the method may be performed substantially in parallel as a continuous process. Bulk material may be continually fed into and out of the system 1, or the step of feeding 73 bulk material into the svstem may be performed batch-wise, while the other steps of the method may be performed substantially in parallel to process each batch in turn.

The system described above may alternatively be used as a pure heat exchanger between the carrier fluid and the bulk material, for example for pasteurization of the bulk product, with drying not being a required outcome. In that case, providing a drying fluid is not required, and therefore providing the associated components is not required either.

Furthermore, the system may be used to heat a fluid, for example a liquid, by feeding that fluid through the at least one passage analogously to the drying fluid, without requiring the presence of bulk material. In case no bulk material is present, rotation of the drums may not be required either.

The svstem described above may be manufactured using standardized and/or recycled parts. The system may therefore be implemented in a relatively cheap and environmentally friendly manner. The modular and scalable nature of the system allows for efficient and flexible operation.

The description above, while generally referring to embodiments of a system, additionally describes a method for drying bulk material which, it will be clear to the skilled person, may be performed with the use of different systems.

The system and method have been described with reference to embodiments. The scope of this document is determined by the claims, within the scope of which many different variations are possible. For example, the system may comprise further components beyond those described, and a method may comprise further processing steps.

Claims

CONCLUSIONS

1. A system for drying bulk material, comprising: at least one elongate drum for holding the bulk material, each of the at least one drum comprising a first end and a second end, the system being adapted to rotate each of the at least one elongate drum individually about its longitudinal axis to agitate the bulk material within that drum, the at least one drum defining at least one passageway for conveying the bulk material through the system, the system being adapted to supply a carrier fluid to the exterior of each of the at least one drum to transfer heat to the bulk material within the at least one elongate drum.

A system according to claim 1, wherein each of the at least one elongated drum is oriented at an angle in the range of 0 to 45 degrees relative to the horizontal plane, preferably at an angle in the range of 0 to 5 degrees, more preferably at an angle in the range of 0.5 to 2 degrees, most preferably at an angle of 1 degree.

The system of claim 2, wherein at least one of the at least one elongated drum is oriented substantially horizontally.

A system according to any preceding claim, wherein the at least one elongated drum is placed in a rack, for example a rack consisting of stacked drawers, the rack determining the angle at which the at least one elongated drum is oriented.

5. A system as claimed in any preceding claim, wherein each of the at least one elongated drum has a substantially circular cross-section.

6. A system as claimed in any preceding claim, wherein agitation strips are attached to the interior of at least one of the at least one elongated drum, the agitation strips being adapted to agitate the bulk material in their respective at least one drum during rotation.

7. A system as claimed in any preceding claim, wherein the interior of at least one of the at least one elongated drum is formed with elongated ridges adapted to agitate the bulk material in their respective at least one drum during rotation.

A system as claimed in any preceding claim, wherein a scraper is disposed in at least one of the at least one elongated drum, the scraper comprising a scraping surface along substantially the entire length of its respective at least one drum, the scraping surface being disposed proximate the wall of the drum for scraping bulk material adhering to the wall of the drum from that wall.

9. A system according to any preceding claim, wherein the system is arranged to rotate each of the at least one drum in place about an axis located within that drum, preferably about a central axis of that drum.

The system of claim 9 further comprising at least one drive member and at least one ring gear about each of said at least one elongate drum, said at least one ring gear configured to engage said at least one respective drive member for rotating said elongate drum.

11. A system as claimed in any preceding claim, wherein the system is arranged to rotate each of the at least one elongated drum, to mix bulk material in that drum and/or to vary which granules of the bulk material are exposed to an inside of a wall of the drum and to a fluid in the drum.

A system as claimed in any preceding claim, wherein the system is adapted to rotate each of the at least one elongate drum to feed bulk material in that drum through that drum.

A system as claimed in any preceding claim and further configured to pass a drying fluid through the at least one passage to remove moisture from said passage.

14. A system as claimed in claim 13, wherein the system is configured to convey the drying fluid through the at least one passage in the same direction as the bulk material.

A system according to claim 13 or 14, wherein the system is arranged to feed the drying fluid in the opposite direction to the bulk material through the at least one passage.

16. A system as claimed in any preceding claim and further configured to adjust the orientation of the at least one elongated drum relative to the horizontal plane.

A system as claimed in any preceding claim and further configured to adjust the orientation of each of the at least one elongated drums to the same selected angle or in the same direction or in opposite directions.

18. A system according to any preceding claim and further arranged to alternately feed the bulk material from the first end towards the second end and from the second end towards the first end of the at least one elongated drum, for example by changing the orientation angle and/or orientation direction of the at least one elongated drum.

A system according to any preceding claim, wherein each passage formed by the at least one elongated drum comprises one respective drum.

20. The system of claim 19, wherein the at least one elongated drum is a single elongated drum.

21. A system as claimed in any preceding claim, wherein the at least one elongate drum is a plurality of elongate drums, the ends of the plurality of elongate drums being coupled together to form the at least one passageway for conveying bulk material through the system.

22. The system of claim 21 and further comprising coupling members comprising two end portions connected by a chute, the coupling members adapted to be mounted to a pair of ends of a respective pair of the plurality of elongated drums, each end portion fitting over an end of a respective drum.

23. The system of claim 21 or 22 further comprising one or two head members, each head member including a plurality of said coupling members, each head member being adapted to be releasably connected at a respective side of the system for mounting each end portion of said plurality of coupling members to a respective end of said plurality of elongate drums.

24. A system according to any one of claims 21 to 23, wherein the at least one passage is a plurality of passages.

A system according to any one of claims 21 to 24, wherein the drums of the at least one passage are disposed at different heights while overlapping in the horizontal plane, and/or wherein the ends of the drums of the at least one passage are coupled to pass bulk material in alternating directions in the horizontal plane.

26. A system as claimed in any preceding claim, wherein the plurality of elongated drums are arranged in a square grid, and/or the ends of the elongated drums are aligned in two vertical planes.

27. A system as claimed in any preceding claim, further comprising a transportable housing around the at least one elongated drum, the housing preferably enclosing a transport container.

28. System according to claim 27, wherein the housing is heat-insulating.

29. System according to any of claims 27 to 28, wherein the housing is moisture-insulating and preferably comprises a drain for condensed moisture.

30. Use of a system according to any of the preceding claims for drying bulk material.

31. Use of a system according to any of claims 1-29 as a heat exchanger between the carrier fluid and a bulk material.

32. Use of a system according to any of claims 1 to 29 as a direct heat exchanger between the carrier fluid and a fluid passed through the at least one passage.

33. A method for drying bulk material, comprising: feeding the bulk material into at least one passage comprising at least one elongate drum; rotating each of the at least one elongate drums individually about its longitudinal axis to set the bulk material in motion; and supplying a carrier fluid to the exterior of the at least one elongate drum for transferring heat to the bulk material in the at least one elongate drum.

34. A method according to claim 33, comprising performing the feeding, turning, and supplying in parallel in a substantially continuous drying process.

35. The method of claim 33 comprising performing the feeding, turning, and feeding in a batch drying process.

36. A method according to any one of claims 33 to 35, wherein the carrier fluid has a temperature in the range of 40 to 100 degrees Celsius, preferably in the range of 50 to 100 degrees Celsius, more preferably in the range of 60 to 90 degrees Celsius.

37. A method according to any one of claims 33 to 36, wherein the carrier fluid is wet steam or moisture-saturated gases.

38. A method according to any one of claims 33 to 37, comprising mixing drier bulk material back into the wet bulk material to be dried passed through the at least one passage.

39. A method according to any one of claims 33 to 38, comprising agitating the bulk material in each of the at least one elongated drum using wall-forming elements such as agitation strips and/or elongated ridges.

40. A method according to any one of claims 33 to 39, comprising scraping bulk material adhering to the wall of at least one of the at least one elongated drums from the respective debris using a scraper disposed in the respective at least one drum.

41. A method as claimed in any one of claims 33 to 40, further comprising rotating each of the at least one drum in place about an axis within said drum, preferably about a central axis of said drum.

A method according to any one of claims 33 to 41, further comprising mixing the bulk material in each of the at least one elongated drum and/or exposing varying granules of the bulk material to an interior of a wall of the drum and to a fluid in the drum by agitating said bulk material.

43. A method according to any one of claims 33 to 42, comprising feeding the bulk material into each of the at least one elongated drum through said drum by setting said bulk material in motion.

A method according to any one of claims 33 to 43, further comprising passing a drying fluid through the at least one passage to remove moisture from said passage, preferably wherein the drying fluid comprises ambient air or consists of an inert gas such as nitrogen.

45. The method of claim 44 further comprising passing the drying fluid through the at least one passage in the same direction as the bulk material.

46. The method of claim 44 further comprising passing the drying fluid through the at least one passage in the opposite direction to the bulk material.

47. A method according to any one of claims 33 to 46, wherein each passage formed by the at least one elongate drum comprises one respective elongate drum.

48. The method of claim 47, wherein the at least one elongated drum is a single elongated drum.

49. A method according to any one of claims 33 to 47, wherein the at least one elongated drum is a plurality of elongated drums.

50. The method of claim 49, wherein the at least one pass is a plurality of passes.

51. A method according to any one of claims 33 to 50, using a system according to any one of claims 1 to 29.