Biodrying of biomass

Abstract

A system for biodrying biomass comprising an area to receive biomass material and an air sparge system comprising one or more sparge pipes. In one example, the system includes a slab 102 defining mult

Description

FIELD

[0001] The application relates to processes for increasing the dryness of biomass. BACKGROUND

[0002] Municipal wastewater treatment plants produce solids that require utilization or disposal. Prior to utilization or disposal, it is common to dewater the solids into cake using, for example, belt filter presses, centrifuges or similar, for ease of subsequent handling. The cake may be dried for further enhancement to its handling characteristics or for preparation for further processing such as carbonization or incineration. Typical drying processes include, for example, belt dryers, drum driers, drying beds and greenhouse dryers. However, these processes are often energy intensive or require large areas relative to their throughput. SUMMARY

[0003] In examples, a system for biodrying biomass material includes a slab defining multiple bays to receive biomass material, and an air sparge system associated with the slab and configured to supply air to the bays, the air sparge system including one or more sparge pipes. The one or more sparge pipes may be movable to accommodate emptying and subsequent refilling of the bays of the biomass material.

[0004] Optionally, the one or more sparge pipes are withdrawable from the slab to accommodate emptying the bays of the biomass material.

[0005] Optionally, the air sparge system includes separate air sparge subsystems associated with each bay, each air sparge subsystem including a blower and a piping system.

[0006] Optionally, the system includes channels defined in or above the slab, wherein the sparge pipes extend within the channels.

[0007] Optionally, the sparge pipes include removable ends configured to selectively allow air to blow loose biomass material out of the sparge pipes.

[0008] Optionally, the sparge pipes include downward facing holes to supply air to the biomass material.

[0009] Optionally, the air sparge system includes a manifold, wherein the one or more sparge pipes are releasably coupled to the manifold.

[0010] Optionally, the bays include a first set of bays adjacent one another and a second set of bays adjacent one another, wherein a gap is defined between the first set of bays and the 1 second set of bays to allow vehicular access. The system may be embodied in a building including an entry and an exit, wherein the gap aligns with the entry and the exit to define a straight passthrough.

[0011] Optionally, the multiple bays are separated by retaining walls.

[0012] Optionally, the slab includes a heated floor configured to assist drying of the biomass material.

[0013] Optionally, the air sparge system is configured to preheat the air supplied to the bays.

[0014] Optionally, the biomass material includes treated or untreated dewatered sewage sludge.

[0015] In examples, a system for biodrying biomass material includes an enclosure defining a volume to receive biomass material, and an air sparge system including one or more sparge pipes located in the volume and configured to supply air to a bottom of the enclosure. The one or more sparge pipes may be configured to limit an intrusion of the biomass material.

[0016] Optionally, the enclosure includes a silo and a cover, wherein the cover comprises one or more filling or extraction ports. The silo may be positioned above ground to define an equipment access beneath the silo. The system may be configured for continuous drying of the biomass material in the silo through continuous fill and emptying of the silo. The system may be configured to create a downward flow of the biomass material in the silo. The silo may include a live bottom, wherein the live bottom includes a first port and a second port. The first port may be configured for unloading dried biomass material into transport equipment. The second port may be configured for unloading dried biomass material onto a material return conveyor. The system may include a mixer configured to blend the dried biomass material with fresh biomass material to produce blended biomass material. The blended biomass material may be fed into the top of the silo.

[0017] Optionally, the one or more sparge pipes have an aerofoil shaped cross-section.

[0018] Optionally, the one or more sparge pipes include an underside and holes on the underside.

[0019] Optionally, the one or more sparge pipes are movable to limit a bridging of the biomass material across the one or more sparge pipes.

[0020] Optionally, the air sparge system includes a blower coupled to the one or more sparge pipes.

[0021] Features from any of the disclosed embodiments may be used in combination with one another, without limitation. In addition, other features and advantages of the present disclosure will become apparent to those of ordinary skill in the art through consideration of the following detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings illustrate several embodiments of the present disclosure, wherein identical reference numerals refer to identical or similar elements or features in different views or embodiments shown in the drawings.

[0023] FIG. 1 illustrates an example floor-based reactor for biodrying biomass.

[0024] FIG. 2 illustrates the reactor of FIG. 1, with portions shown transparent for illustration purposes.

[0025] FIG. 3 illustrates an example air sparge system, such as for use in the reactor of FIG. 1.

[0026] FIG. 4 illustrates an example silo-based reactor for biodrying biomass.

[0027] FIG. 5 illustrates a side view of the reactor of FIG. 4.

[0028] FIG. 6 illustrates another example air sparge system, such as for use in the reactor of FIG. 4.

[0029] FIG. 7 illustrates a bottom view of the air sparge system of FIG. 6.

[0030] FIG. 8 is a flow diagram of a method for biodrying wastewater solids. DETAILED DESCRIPTION

[0031] Embodiments disclosed herein are related to assemblies, systems, and methods of using a system for biodrying biomass, such as sewage sludge or wastewater solids, among other biomass feedstocks For example, the assemblies, systems, and methods of using a system for biodrying biomass may be configured and designed to increase the solids content of dewatered sludge, whether raw or treated, or any appropriate feedstock biomass utilizing a biological drying process without the addition of external chemicals. FLOOR-BASED REACTOR

[0032] FIGS. 1-3 illustrate an example floor-based reactor 100 for biodrying biomass. The biomass may include cake solids, such as dewatered anaerobically digested cake solids. The biomass may include treated or untreated (e.g., raw) dewatered sewage sludge, wastewater screenings, anaerobic wastewater treatment lagoon scum, organic waste, bagasse, sugar beet 3 waste, rice waste, seaweed, etc., without intent to limit. In some embodiments, the biomass may include about 20 percent to about 35 percent solid material.

[0033] In some embodiments, the biomass may be biodried in an aeration system described in more detail below. The biodried solids may be recycled from the output of the reactor 100 (e.g., recycled back into the biodrying system) or may be stored and used in a future time.

[0034] Referring to FIGS. 1-2, the reactor 100 may include or take the form of a hard slab 102 (e.g., concrete or other structure having a hard surface). In examples, the slab 102 may be covered by an overhead structure 106 (e.g., a roof or other covering), such as to protect the reactor 100 from one or more elements (e.g., sun, precipitation, wind, debris, falling objects, etc.). As a result, the reactor 100 may define or be part of a building 110. Referring FIG. 1, the building 110 may include outer walls 114, such as along the perimeter of the slab 102.

[0035] The reactor 100 may be placed under an open cover, such as within a Dutch barn structure, under a roof, or within a poly tunnel or other cover. For example, columns 116 may extend from the slab 102 and / or outer walls 114 to support the overhead structure 106. In examples, the building 110 may be an open air building having no exterior walls, or at least openings defined between the outer walls 114 and the overhead structure 106, such as to promote airflow and ventilation (e.g., to control odor emissions).

[0036] The reactor 100 or building 110 may be configured to facilitate importing and exporting of material. For example, the reactor 100 may include an entry 120 and an exit 122. In some examples, the entry 120 may be located on one side of the reactor 100 and the exit 122 located on another side (e.g., opposite the entry 120). In other examples, the reactor 100 may include a single entrance / exit (e.g., the entry 120 and exit 122 at the same location). The entry 120 may be sized to allow importing of material (e.g., fresh cake material), such as via a front loader or other equipment. Once dried, the material may be removed from the reactor 100 via the exit 122, such as using a front loader or other equipment. As shown, the entry 120 and exit 122 may be aligned, such as defining a straight passthrough through the building 110 or reactor 100.

[0037] Referring to FIG. 2, the slab 102 may be divided into bays 130. As one example arrangement, eight bays 130 may be arranged on the slab 102, such as four bays 130 arranged in a first row 132 along one side of the slab 102 and another four bays 130 arranged in a second row 134 along an opposite side of the slab 102. A gap 138 may be defined between the first and second rows 132, 134 of bays 130, such as to allow vehicular or equipment access, although other configurations are contemplated. The gap 138 may align with the entry 120 and the exit 122, defining the straight passthrough through the building 110 or reactor 4 100. In examples, the bays 130 may be set off or defined by retaining walls 140. However, the retaining walls 140 may be omitted should the biodrying process be easier to operate with no internal walls (e.g., based on scale). Without retaining walls 140, the bays 130 may form logical or imaginary divisions within the process, such as for the purpose of controlling aeration rate and retention time (e.g., each forming a separate aeration zone controlled by a single controller). Each bay 130 may receive or hold a pile 142 of biomass (e.g., wastewater solids, municipal sludge, raw sewer sludge, digested sludge, etc.), such as to biodry the material in the pile 142.

[0038] If process emissions are required to be captured (e.g., due to the nature of the feedstock), the bays 130 may be provided with a closure device (e.g., a roller shutter similar to a smoke shutter), which shall be closed by the operator prior to the drying process startup to enclose the bay 130. In such examples, the bays 130 may include one or more extraction ports for venting (e.g., connected to an air extraction system). Alternatively, the process may be placed within a poly tunnel or similar cover, with extraction of the process air from the polytunnel. In some examples, the extraction may be through the sludge or biomass itself (e.g., negative aeration downwards through the biomass to extraction pipes having a negative pressure). In examples, the bays 130 may be configured to be retrofittable with roller shutters or another sealing / ventilation system. If process emissions are not required to be captured, forced or passive ventilation may be provided (e.g., by high-level vents, openings, etc.) to limit excessive buildup of moisture in the working environment within the building 110.

[0039] Referring to FIGS. 1-3, the reactor 100 may include an air sparge system 146. The air sparge system 146 may be configured to supply air to the bays 130 (e.g., for biodrying biomass placed in the bays 130). For example, the air sparge system 146 may include one or more blowers 148 and a piping system 150 to deliver air from the blower(s) 148 to the pile(s) 142. In some embodiments, individual air systems or subsystems may be provided for each bay 130. For instance, each bay 130 may include a separate air sparge subsystem 152 including an individual blower 148 and an individual piping system 150 for each bay 130 (e.g., each bay 130 may be served by a separate blower 148 and piping system 150). The piping system 150 may include a manifold 156 and one or more sparge pipes 158 coupled to the manifold 156. The blowers 148 may provide a desired volume of air to the piles 142, such as to provide variable aeration rates through variable speed drives. The sparge pipes 158 may be placed on the slab 102, or the sparge pipes 158 may be set into the slab 102.

[0040] In examples, the blowers 148 may be positioned outside the building 110, with the sparge pipes 158 extending from outside the building 110 to within the building 110 and into 5 the bays 130 (e.g., passing through the outer walls 114). Each sparge pipe may be releasable from the manifold 156 or blower 148. In such embodiments, the sparge pipes 158 may be withdrawn from the reactor 100, such as being withdrawable from outside the building 110 for maintenance purposes, to drag the sparge pipes 158 out from under the piles 142, to facilitate emptying and subsequent refilling of the bays 130, etc. To facilitate removal, each sparge pipe 158 may be provided with a strap, eyebolt, or other feature for simple connection (e.g., to a front loader, tractor, or other pulling machine). Additionally, or alternatively, the sparge pipes 158 may be configured to be raised and lowered from the slab 102, such as to facilitate emptying and subsequent refilling of the bays 130.

[0041] Referring to FIG. 3, the sparge pipes 158 may be configured to deliver air to the piles 142 and limit blockage of air delivery. For instance, each sparge pipe may include holes 164 to deliver air to the pile 142 of material. In some examples, the holes 164 may be downward facing or generally downward facing, such as to limit blockage. In other examples, the sparge pipes 158 may extend within channels 168 defined in or above the slab 102. The channels 168 may be U-shaped, such as defined by U-channel, although other configurations are contemplated. In some examples, removable covers may be provided to seal the sparge pipes 158 within the channels 168 (e.g., U-channel). In other examples, the holes 164 may be relatively large to allow loose material to fall into the holes 164 and sparge pipes 158. In such embodiments, the sparge pipes 158 may include a removable end 172, such as to allow air to blow the loose material out of the sparge pipes 158. For example, an operator may clear the holes 164, remove the removable end 172, and purge the sparge pipes 158 at the end of each drying batch. The air may be preheated (e.g., the air sparge system 146 configured to preheat the air), or the slab 102 may be heated (e.g., include a heated floor), to assist drying of the biomaterial. In other examples, waste heat may be recycled into the process to assist drying of the biomaterial.

[0042] In applications for treated biomass, the sparge pipes 158 may deliver air to the bottom of the piles 142 and pass to the top. Such configurations may reduce tendency for the sparge pipes 158 to block, provide no re-wetting of cake through condensation because the driest cake has airflow first (e.g., the bay 130 is first filled with dry product material, biodried biosolid from a previous process has been left at the bottom of the bay 130, etc.), and increase scope for deeper piles 142 due to the ability to further increase air pressure compared to negative aeration.

[0043] In applications for untreated biomass, the sparge pipes 158 may deliver air to the top or bottom of the piles 142. If air enters at the bottom, then emissions capture may be 6 provided for, such as by having roller shutter doors as noted above. If air enters at the top, then emissions capture systems may not be needed. In either application, air can be made to flow in other directions, such as horizontally, by using proper constraints to the pile 142.

[0044] If air is to be extracted, the air may be vented to a location above and typically downwind of the reactor 100 to limit recirculation of moist air. Additionally, or alternatively, treatment of process air may be provided. The air intake may be approximately at grade and typically upwind of the reactor 100.

[0045] In examples, the reactor 100 may include one or multiple sensors for monitoring operations. For instance, monitors may be provided to measure the process air temperature in and out of the process, the surface temperature of the pile 142, the bulk temperature of the pile 142, and the oxygen, methane, nitrogen, and / or carbon monoxide content of outgoing process air or off gas. In some examples, sensors may be provided to monitor a level or characteristic (e.g., height, weight, etc.) of the pile 142, the amount of material added and / or removed from the process, or the like. The sensors may be used as inputs to adjust operations. For instance, process control may maintain a material temperature of at least 40°C and no more than 55°C, ensure dry solids of at least 60% at exit, ensure a desired amount of material for each pile 142 or within the process, and the like.

[0046] In examples, a control system may be configured to adjust the airflow immediately and / or on a programmed basis, depending on previous performance, for example using timers and variable speed controllers. Dry solids may be manually sampled before and after processing. Alternatively, the control system may monitor the temperature of the piles 142.

[0047] An example material handling process using the reactor 100 of FIGS. 1-3 will now be described. To facilitate loading, the reactor 100 should be located close to the source of biomass cake or feedstocka. Loading of the reactor 100 should be by a method allowing a sufficiently high stack of material (e.g., in piles 142), such as by a front loader 176, a material stacker 178 (e.g., a grain stacker), other handling equipment, or any combination thereof. In one example, the material stacker 178 is located in or close to the most recently completed area of the reactor 100, with an unloading end above the empty area to be loaded. The material stacker 178 may be loaded (e.g., by the front loader 176) alternately with dry cake followed by fresh cake until the bay 130 is full. The action of alternately loading dried and fresh cake may produce a sufficient mixing effect for the process. The grain handler may be moved during loading, such as to ensure a roughly even load to the area of the aeration floor (e.g., slab 102) being loaded.

[0048] Before unloading the bays 130, the sparge pipes 158 may be released from the manifold 156 and dragged out from under the piles 142 (e.g., by the front loader 176 or some other method). The sparge pipes 158 may be placed out of the way, such as into the next bay 130 and connected to the manifold 156 there ready for the next bay 130 to be loaded. Alternatively, once the completed bay 130 is empty, the sparge pipes 158 may be returned to the bay 130 ready for the next filling operation. In examples, the unloading operation may leave some of the dry cake in the completed bay 130, which may be required for the filling of the next bay 130 in operation. Fresh cake may be stacked or mixed with the leftover dried cake. The product material unloaded may be either loaded directly to a vehicle for removal from site, or moved to an open dried cake store, among other locations. If the system uses recessed sparge pipes 158, the sparge pipes 158 may be cleaned after unloading. For example, an operator may dislodge cake from the holes 164 and run the blowers 148 to purge the sparge pipes 158 through the removable end 172, as described above. SILO-BASED REACTOR

[0049] FIGS. 4-7 illustrate an example silo-based reactor 400 for biodrying biomass. Referring to FIGS. 4-5, the reactor 400 may be or include a cylindrical silo 402 (e.g., similar to a cake reception silo), although other silo shapes are contemplated, with cylindrical possibly being more efficient. The silo 402 may be sized for maximum cost efficiency, noting that the silo 402 may be concurrently loaded and unloaded (e.g., operated in a continuous mode). The biomass towards the bottom of the silo 402 may be driest with a steady rise in moisture content through the reactor 400, hence the freshly added material at the top will be the wettest. The silo 402 may be provided in a standard size, such as to allow modularization, to match current silos, and the like.

[0050] The silo 402 may include nozzles 406 for passing sparge pipes 410 therethrough. In examples, the nozzles 406 are placed approximately 300mm from the floor, although other configurations are contemplated. Irrespective of their position, the nozzles 406 must not affect the structural integrity of the silo 402. As shown, the silo 402 may be located above ground, with lorry, truck, or other equipment access beneath the silo 402 for unloading.

[0051] Referring to FIG. 6, the reactor 400 or silo floor may include a live bottom 414 to facilitate emptying. The live bottom 414 may include a twin screw or spiral conveyor arrangement with a sliding frame above. In examples, the live bottom 414 may include two unloading ports, which can be operated independently. For example, referring to FIG. 4, a first unloading port 418 may be configured for unloading product into transport equipment 8 for export. A second unloading port 422 may be configured to open onto a material return conveyor 424 for return to a mixer 426, such as to facilitate a batch mixing process. For instance, the mixer 426 may receive wet cake from a storage tank 430 and mix the wet cake with the dry material received from the silo 402. After mixing, the blended biomass may be fed into the top of the silo 402 via a reactor feed 432. The unloading ports 418, 422 may be equipped with seals to limit excessive process air from escaping.

[0052] Referring to FIG. 6, the reactor 400 may include an air sparge system 446. The air sparge system 446 may be configured to supply air into the process (e.g., for biodrying biomass placed in the silo 402). For example, the air sparge system 446 may include sparge pipes 410 connected to a blower 448. The sparge pipes 410 may be spaced at regular intervals across the silo 402 (e.g., at a height of approximately 0.3m above the base as noted above).

[0053] The sparge pipes 410 may be shaped to limit blockage or material intrusion. For instance, referring to FIG. 7, the sparge pipes 410 may include holes 464 on the underside to limit blockage. In some examples, the sparge pipes 410 may include a streamlined crosssection, such as an aerofoil, oval, or elongated rectangle, among other shapes. In some examples, the sparge pipes 410 may be equipped with angled tops to limit or prevent material being stuck above them. In some examples, the sparge pipes 410 may be placed sufficiently far apart such that material does not bridge between adjacent pipes. In some examples, the sparge pipes 410 may be rotatable or shakable to allow bridging material to be disturbed. In some examples, the sparge pipes 410 may be inserted into the silo 402 beneath a protective cover (e.g., a half pipe). In such embodiments, the covers may be utilized to break up material bridging across adjacent pipes (e.g., when the silo 402 is being emptied). For instance, the covers may be attached to a spring (e.g., via support wire) to allow oscillating or other movement. In examples, the sparge pipes 410 may be withdrawn from the silo 402, such as to allow bridge breaking in sequence, to allow unhindered emptying of the silo 402, to replace the pipes, or for other purposes.

[0054] The reactor 400 may include one or more features for material management or control. For instance, the weight of biomass within the silo 402 may be measured and displayed, such as through strain gauges or load cells. In some examples, the silo 402 may include horizontal load bars spanning the inside of the silo 402, such as to relieve material pressure towards the bottom. In such embodiments, the load bars may be provided with an oscillating or other movement to limit material bridging (e.g., when the silo 402 is being emptied). In some examples, the inside surfaces of the silo 402 may include a coating to limit corrosion and / or sticking of material.

[0055] Referring to FIG. 4, the reactor 400 may include a cover 470. The cover 470 may act as an extraction hood. In examples, the cover 470 may be fitted with filling ports 472, fresh air intakes 474, and extraction ports 476. The filling ports 472 may facilitate even filling of material. The fresh air intakes 474 may facilitate maintaining negative pressure in the freeboard of the reactor 400. The extraction ports 476 may allow gases to be removed and transferred for treatment. In examples, the reactor 400 may not be airtight, such as to prevent falling foul of pressure vessel regulations and to prevent buildup of gases in the event of ventilation failure.

[0056] In examples, the reactor 400 may include one or multiple sensors for monitoring operations. For instance, monitors may be provided to measure the process air temperature in and out of the process, the weight of material in the silo 402, the bulk temperature of the material in the silo 402, the surface temperature of the silo 402, the height of the material in the silo 402 and the oxygen, methane, and carbon monoxide content of outgoing process air. The sensors may be used as inputs to adjust operations. For instance, process control may maintain a material temperature of at least 40°C and no more than 55 °C, ensure dry solids of at least 60% at exit, and the like. A control system may adjust airflow, screw speed, and screw direction, among other process parameters.

[0057] An example material handling process using the reactor 400 of FIGS. 4-7 will now be described. Depending on the application, biomass cake may be mixed and shredded prior to entry 120 to the reactor 400. Pre-shredding may facilitate material transfer, such as allowing unloading of the reactor 400 and loading of transport equipment in the same step, with no de-clumping necessary. Process efficiency within the reactor 400 may also improve with smaller particle size. In some examples, pre-processed biomass cake may be placed in buffer storage (e.g., storage tank 430), such as to facilitate batch mixing with a semi-continuous reactor.

[0058] The reactor 400 or silo 402 may be loaded through the cover 470, such as via suitably designed ports and / or distributors (e.g., filling ports 472) to facilitate even filling of the reactor 400. Preferably, the reactor 400 or silo 402 may be loaded via pneumatic conveyance, although other configurations are contemplated, including screws or conveyors.

[0059] Air may enter the bottom of the reactor 400 (through the sparge pipes 410) and pass to the top. Such configurations may reduce tendency for the sparge pipes 410 to block, provide no re-wetting of cake through condensation because the driest cake has airflow first, and increase scope for deeper piles due to the ability to further increase air pressure compared to negative aeration. The air may be preheated, or the sparge pipes 410 may be heated, to 10 assist drying of the biomaterial. Additionally, or alternatively, the biomaterial within the silo 402 may be mixed (e.g., continuous slow mixing) during the process to assist drying, which may be static or dynamic mixing. Air may be extracted to a location above and typically downwind of the reactor 400 to limit recirculation of moist air. Additionally, or alternatively, treatment of process air may be provided, such as through biofilter, wet scrubber, thermal oxidation, or carbon filter). The blower 448 may provide a desired volume of air to the reactor 400, such as to provide variable aeration rates through variable speed drives.

[0060] The reactor 400 or silo 402 may be unloaded through the bottom into either transport equipment or onto the material return conveyor for recirculation. For instance, screw or spiral conveyors may be used for each of unloading the silo 402 to transport (direct unloading) and unloading to recirculation (via pneumatic conveyor). The unloading ports may be opened when the screws or spirals are turned to remove material. Unloading the reactor 400 may cause all of the material in the reactor 400 to move downwards, which may disrupt preferential air pathways. Thus, it may be preferential to unload the reactor 400 at least daily if not more frequently. The reactor 400 may be loaded at the same frequency or at a different frequency.

[0061] In examples, the reactor 400 may be configured for continuous drying of the biomass material in the silo 402. For example, a continuous or near-continuous fill and emptying of the silo 402 may occur during the process. The continuous process (e.g., continuous fill and emptying of the silo 402) may be facilitated by downward flow of the biomass material in the silo 402. The biomass material may be the wettest at the top of the silo 402 and the driest at the bottom of the silo 402. In such examples, the dryness of the biomass material may increase with downward flow of the biomass material in the silo 402.

[0062] Material may be unloaded directly from the reactor 400 or silo 402 into transport equipment. In other examples, the unloading process may include one or more postprocessing steps, including crushing, shredding, or another grading process. For material returning for recirculation, an intermediate hopper may be positioned between the reactor 400 and the mixer 426.

[0063] FIG. 8 is a flow diagram of a method 800 for biologically drying anaerobically digested municipal waste and / or wastewater solids, according to some embodiments. The method 200 may utilize use any of the assemblies, systems, subsystems, or components disclosed herein. At step 810, method 800 may include forming biomass cake, such as via conventional or known processes.

[0064] At step 820, method 800 may include blending biomass cake with biodried biomass to form a mixed biomaterial. Blending the biomass cake with biodried biomass may include mixing a portion of previously biodried biomass with fresh cake. The biomass cake may be mixed with biodried biomass in substantially any ratio (e.g., 1:1 ratio by volume, greater biomass cake to biodried biomass by volume, greater biodried biomass to biomass cake by volume). Blending may be performed via front loader 176, material stacker 178, window turners, rototillers, pug mill mixers, mix boxes, or another suitable process or assembly. Depending on the application, step 820 may be performed in bays 130 or silo 402. For example, front loader 176 and / or material stacker 178 may be used to add fresh cake on top of left over biodried material in bays 130. In other examples, mixer 426 may mix fresh cake with biodried material prior to being fed to silo 402.

[0065] At step 830, method 800 may include aerating the biomass by forced air ventilation throughout the mixed biomaterial to form a biodried material. In some embodiments, step 830 may include continuous or intermittent forced ventilation of pile 142 through air sparge system 146, as described with reference to FIGS. 1-3. In other embodiments, step 830 may include continuous or intermittent forced ventilation of silo 402 through air sparge system 446, as described with reference to FIGS. 4-7. Step 830 may include an aeration rate configured to maintain an average temperature of the mixed biomaterial between about 30°C and about 65°C for the duration of the process. Step 830 may be configured to reduce the moisture concentration of the mixed biomaterial to between about 35 percent and about 45 percent water (e.g., about 40 percent water). In other words, the biodried material may include between about 55 percent and about 65 percent solids (e.g., about 60 percent solids), thereby substantially decreases the mass of the biodried material compared to the dewatered biomass cake and the mixed biomaterial.

[0066] At step 840, method 800 may recycle biodried material back into the biodrying process. In some embodiments, the recycled biomass may form at least a portion of the previously biodried biomass discussed above in step 820. The recycle biomass may be recycled directly (e.g., left over in bays 130, fed directly into silo 402, etc.), in some embodiments, or they may be stored and / or processed for later use at the same or a different facility.

[0067] Steps 810, 820, 830, 840 of method 800 are for illustrative purposes. For example, any of the steps 810, 820, 830, or 840 may be performed in different orders, split into multiple acts, modified, supplemented, or combined. In an example, one or more of the steps 810, 820, 830, 840 may be omitted from method 800. Any of the acts 810 to 840 may include using any of the assemblies or systems disclosed herein.

[0068] While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting.

[0069] Terms of degree (e.g., “about,” “substantially,” “generally,” etc.) indicate structurally or functionally insignificant variations. In an example, when the term of degree is included with a term indicating quantity, the term of degree is interpreted to mean + 10%, ±5%, or +2% of the term indicating quantity. In an example, when the term of degree is used to modify a shape, the term of degree indicates that the shape being modified by the term of degree has the appearance of the disclosed shape. For instance, the term of degree may be used to indicate that the shape may have rounded corners instead of sharp comers, curved edges instead of straight edges, one or more protrusions extending therefrom, is oblong, is the same as the disclosed shape, etc.

[0070] The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments of the invention as defined in the claims. Although various embodiments of the claimed invention have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, it is appreciated that numerous alterations to the disclosed embodiments without departing from the spirit or scope of the claimed invention may be possible. Other embodiments are therefore contemplated. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative only of particular embodiments and not limiting. Changes in detail or structure may be made without departing from the basic elements of the invention as defined in the following claims.

Claims

We claim:

1. A system for biodrying biomass material, comprising: a slab defining multiple bays to receive biomass material; and an air sparge system associated with the slab and configured to supply air to the bays, the air sparge system comprising one or more sparge pipes,wherein the one or more sparge pipes are movable to accommodate emptying and subsequent refilling of the bays of the biomass material.

2. The system of claim 1, wherein the one or more sparge pipes are withdrawable from the slab to accommodate emptying the bays of the biomass material.

3. The system of claim 1 or 2, wherein the air sparge system comprises separate air sparge subsystems associated with each bay, each air sparge subsystem comprising a blower and a piping system.

4. The system of any of claims 1-3, further comprising channels defined in or above the slab, wherein the sparge pipes extend within the channels.

5. The system of any of claims 1-4, wherein the sparge pipes include removable ends configured to selectively allow air to blow loose biomass material out of the sparge pipes.

6. The system of any of claims 1-5, wherein the sparge pipes include downward facing holes to supply air to the biomass material.

7. The system of any of claims 1-6, wherein the air sparge system comprises a manifold, and wherein the one or more sparge pipes are releasably coupled to the manifold.

8. The system of any of claims 1-7, wherein the bays comprise a first set of bays adjacent one another and a second set of bays adjacent one another, and wherein a gap is defined between the first set of bays and the second set of bays to allow vehicular access.

9. The system of claim 8, wherein the system is embodied in a building comprising an entry and an exit, and wherein the gap aligns with the entry and the exit to define a straight passthrough.

10. The system of any of claims 1-9, wherein the multiple bays are separated by retaining walls.

11. The system of any of claims 1-10, wherein the slab comprises a heated floor configured to assist drying of the biomass material.

12. The system of any of claims 1-11, wherein the air sparge system is configured to preheat the air supplied to the bays.13 The system of any of claims 1-12, wherein the biomass material comprises treated or untreated dewatered sewage sludge.

14. A system for biodrying biomass material, comprising:an enclosure defining a volume to receive biomass material; andan air sparge system comprising one or more sparge pipes located in the volume and configured to supply air to a bottom of the enclosure,wherein the one or more sparge pipes are configured to limit an intrusion of the biomass material.

15. The system of claim 14, wherein the enclosure comprises a silo and a cover, and wherein the cover comprises one or more filling or extraction ports.

16. The system of claim 15, wherein the silo is positioned above ground to define an equipment access beneath the silo.

17. The system of claim 15 or 16, wherein the system is configured for continuous drying of the biomass material in the silo through continuous fill and emptying of the silo.

18. The system of any of claims 15-17, wherein the system is configured to create a downward flow of the biomass material in the silo.1519. The system of any of claims 15-18, wherein the silo comprises a live bottom, and wherein the live bottom comprises a first port and a second port, the first port configured for unloading dried biomass material into transport equipment, the second port configured for unloading dried biomass material onto a material return conveyor.

20. The system of claim 19, further comprising a mixer configured to blend the dried biomass material with fresh biomass material to produce blended biomass material.

21. The system of claim 20, wherein the blended biomass material is fed into the top of the silo.

22. The system of any of claims 14-21, wherein the one or more sparge pipes have an aerofoil shaped cross-section.

23. The system of any of claims 14-22, wherein the one or more sparge pipes comprise an underside and holes on the underside.

24. The system of any of claims 14-23, wherein the one or more sparge pipes are movable to limit a bridging of the biomass material across the one or more sparge pipes.

25. The system of any of claims 14-24, wherein the air sparge system comprises a blower coupled to the one or more sparge pipes.s

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