Size reduction of cohesively fibrous crop straw feedstock into homogenously sized pellet feedstock particles

Abstract

A method and system for size reduction of cohesively fibrous crop straw into homogenously sized straw particles are disclosed. A two-stage processing system comprises a debaling apparatus that removes bale-retaining means and breaks down feedstock into manageable sizes. The material is then transferred to a coarse stage reduction unit where a shearing rotor cuts the straw to a desired first stage size, facilitated by an arcuate discharge filter. The sheared straw is conveyed to a fine stage reduction unit where it is ground to a finished particle size appropriate for pelletization. The system ensures continuous, efficient processing of various fibrous straws such as flax, wheat, barley, and corn stover into fine particles, enhancing the feasibility of biomass pellet production, reducing the energy requirement and mitigating equipment clogging risks.

Description

[0001] SIZE REDUCTION OF COHESIVELY FIBROUS CROP STRAW FEEDSTOCK INTO HOMOGENOUSLY SIZED PELLET FEEDSTOCK PARTICLES

[0002] FIELD OF THE INVENTION :

[0003] The present invention relates to agricultural machinery and processes , speci fically to a two-stage system for the si ze reduction of cohesively fibrous crop straw into uni formly si zed particles suitable for biomass pellet production .

[0004] BACKGROUND OF THE INVENTION :

[0005] The increasing global demand for sustainable and renewable energy sources has spurred interest in biomass as a viable alternative to fossil fuels . Biomass pellets , made from compressed organic matter or bio-waste such as agricultural residues , wood, and other plant materials , are increasingly recogni zed for their potential to replace coal in power generation . Notably, the utili zation of agricultural residues for biomass pellet production not only provides a renewable energy source but also contributes to waste management solutions for agricultural industries . Agricultural residues such as straw from crops like wheat , barley, corn, and flax are abundantly available by-products that have traditionally been underutili zed or treated as waste . These residues can pose signi ficant environmental issues when left to decompose in fields or burned openly, contributing to air pollution and greenhouse gas emissions . Consequently, the conversion of these residues into biomass pellets is a promising strategy for energy production and environmental protection .

[0006] The process of converting agricultural residues into high- quality biomass pellets is technically challenging . The fibrous and cohesive nature of crop straws , characteri zed by long, tough fibers , signi ficantly complicates their processing . These materials are di f ficult to grind, and their fibrous nature can lead to operational issues in conventional pellet production machinery, primarily due to clogging and inconsistent feedstock flow .

[0007] Traditional biomass processing technologies have been predominantly designed for woody biomass , which is fundamentally di f ferent in composition and physical properties compared to agricultural residues . Woody biomass is generally more homogeneous and less fibrous than straw, allowing for easier size reduction and processing. In contrast, the long and flexible strands of crop straw can intertwine and create blockages in the machinery, disrupting the production process and posing a fire hazard.

[0008] The typical process for converting straw into biomass pellets involves several stages: collection, drying, grinding, and pelletizing. Each stage must be carefully managed to ensure the final product's quality and the process's efficiency. One of the most critical and problematic stages is grinding, where the straw must be reduced to small, uniform particles that can be easily pelletized.

[0009] Currently, most systems employ a single-stage grinding process using hammer mills or similar equipment. While effective for woody biomass, these systems are less suitable for straw due to the aforementioned reasons. The single-stage approach often results in significant downtime for maintenance and clearing blockages, reducing the overall efficiency of the biomass production process.

[0010] Furthermore, the energy consumption associated with grinding fibrous materials like straw is considerably higher than for woody biomass . This increases operational costs and impacts the sustainability of the biomass pellet production process .

[0011] Recogni zing the limitations of existing technologies , there is a pressing need for a speciali zed system capable of ef ficiently processing fibrous agricultural residues like straw . The ideal solution would address the challenges of fiber length, toughness , and the material ' s propensity to clog machinery . It would also optimi ze energy consumption and minimi ze operational disruptions .

[0012] SUMMARY OF THE INVENTION :

[0013] The present invention relates to a method and system for reducing cohesively fibrous crop straw into homogeneously si zed straw particles suitable for subsequent pelleti zation . This innovative approach is particularly advantageous for processing fibrous agricultural residues such as flax straw, wheat straw, barley straw, and corn stover, which are notoriously challenging to process using conventional systems due to their tendency to clog machinery and their high energy processing requirements . Central to this invention is a two-stage processing system that begins with a debaling apparatus equipped with a discharge that operatively engages an intake conveyor . This debaling apparatus is adept at mechanically removing bale-retaining means from feedstock bales and breaking down the unbound feedstock bale material onto the intake conveyor to facilitate further processing . The debaling apparatus ' s ability to handle bales of various shapes , whether rectangular or cylindrical , showcases its versatility and adaptability to di f ferent agricultural practices .

[0014] Following debaling, the feedstock enters a coarse stage reduction unit which comprises a shear housing . This housing is equipped with a straw intake for receiving unbound feedstock bale material from the intake conveyor and features a first- stage discharge that allows the passage of sheared crop straw of a desired first stage si ze . Within this unit , an arcuate discharge filter, characteri zed by a circular inner concave surface with multiple filter openings , collaborates with a powered shearing rotor . This rotor, adorned with multiple identical shearing blades arrayed along its outer surface and aligned approximately parallel to the discharge of the feed conveyor, facilitates a shearing action that si zes the straw to the desired first stage particle si ze , which is no more than 15 cm. The design of the rotor and the filter ensures that only appropriately sized straw pieces exit through the first-stage discharge .

[0015] The sheared crop straw is then conveyed by a stage conveyor, optionally equipped with a surge hopper to normalize feeding rates, to a fine stage reduction unit. This unit is tasked with refining the straw to a finished particle size no greater than 6 mm, suitable for pelletization. It comprises at least one powered mill, which could be either a hammer mill or a knife mill, reflecting the system's flexibility in adapting to different processing requirements. The powered mill is efficiently driven by an electromotor, optimized for energy use within the range of 30 to 40 horsepower / tonne / hour, highlighting the invention's commitment to energy efficiency.

[0016] The fine stage reduction unit culminates in a fine stage discharge, where the finished crop straw particles are either ready for direct use or further processing, such as through a pelleting mill to produce biomass pellets. This integration exemplifies the invention's utility in creating a seamless and efficient workflow from raw agricultural waste to a finished product suitable for industrial applications. The invention ' s modular design allows for the inclusion of variants that would fall within the scope of the claims . For instance , modi fications to the debaling apparatus to enhance its ef ficiency or adaptations to the shearing rotor to accommodate di f ferent types of crop straw are envisaged . Furthermore , alternative configurations of the powered mills and adj ustments to the operational parameters of the stage conveyor to handle di f ferent throughput requirements could also be implemented without departing from the essence of the invention .

[0017] In summary, this invention provides a comprehensive and adaptable solution to the longstanding problem of processing cohesively fibrous crop straw, thereby enabling more ef ficient production of biomass pellets and contributing to the sustainable use of agricultural residues . The detailed description of each component and their interplay not only supports the invention ' s utility but also ensures that a person skilled in the art can replicate the system with ease , ful filling the requirements of enablement .

[0018] This two-stage processing system not only mitigates the technical challenges associated with processing fibrous crop straws but also enhances the overall ef ficiency and sustainability of biomass pellet production . By reducing equipment downtime and minimi zing energy consumption, the system significantly improves over traditional single-stage grinding technologies .

[0019] BRIEF DESCRIPTION OF THE DRAWINGS:

[0020] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced. The drawings enclosed are:

[0021] Figure 1 is a schematic view of one embodiment of the system of the invention, showing the flow of materials from the debaling apparatus (100) to the fine stage reduction unit (400) ;

[0022] Figure 2 is a detailed view of the debaling apparatus (100) of Figure 1;

[0023] Figure 3 is a cross-sectional view of the coarse stage reduction unit (200) of Figure 1, illustrating the arrangement of the shearing rotor (220) and the arcuate discharge filter (230) ; Figure 4 is a schematic of the stage conveyor (300) of Figure 1 with an optional surge hopper (310) ;

[0024] Figure 5 is a detail view of the fine stage reduction unit (400) of Figure 1; and

[0025] Figure 6 is a flowchart depicting one embodiment of the method including operational steps from debaling to the discharge of finished particles.

[0026] DETAILED DESCRIPTION:

[0027] The present invention pertains to a novel system and method designed for the efficient size reduction of cohesively fibrous crop straw into homogeneously sized straw particles, specifically tailored for biomass pellet production. The system incorporates a two-stage processing approach that significantly mitigates issues such as equipment clogging and excessive energy consumption commonly encountered with traditional processing methods . The system fundamentally comprises several key components structured to operate in a sequential and integrated manner. These components include a debaling apparatus (100) , a coarse stage reduction unit (200) , a staging conveyor (300) , and a fine stage reduction unit (400) . Each component is designed to perform specific functions that contribute to the efficient transformation of baled crop straw into finely processed particles suitable for pelletization.

[0028] The debaling apparatus (100) is equipped with a discharge (110) that is operatively connected to an intake conveyor (120) . This apparatus is capable of handling both rectangular and cylindrical bales of crop straw feedstock. Its primary function is to remove bale-retaining means, such as wires or twines mechanically, and to break down the unbound feedstock bale material onto the intake conveyor (120) in a format suitable for further processing. The apparatus (100) can accommodate different bale shapes, enhancing its utility across various agricultural settings. Configuration of the cutter removal apparatus to remove the bale retaining means will be understood to those skilled in the art and any type of the cutting apparatus that will achieve this purpose will be understood to be within the scope of the invention. As shown in this Figure it is contemplated that the D Bailey apparatus might comprise some type of ranking configuration or some other type of a mechanical separating device which would separate the material and loosen the bale once it was released from its retaining means , to allow for the discharge of loosen to crop straw to the intake conveyor 120 on route to the course stage conditioning apparatus 200 .

[0029] Figure 2 shows a detailed schematic view of an example of the debaling apparatus 100 . A large rectangular bale . I s shown having been loaded into the top of the device . As shown in the apparatus would exert disintegrating were loosening motion on the bale using an internal belt conveyor in its floor, and a raking apparatus or some other type of a disruption tool to loosen the feedstock for feed out from the discharge 110 as shown .

[0030] Positioned to receive material from the intake conveyor ( 120 ) , the coarse stage reduction unit ( 200 ) includes a shear housing ( 210 ) that houses a powered shearing rotor ( 220 ) equipped with multiple shearing blades ( 222 ) . A feed roller 215 is also shown . The feed roller 215 is responsible for the aggressive and continuous feeding of unbaled feedstock from the intake conveyor 120 into the shearing rotor 220 . The rotor ( 220 ) is aligned parallel to the conveyor discharge and works in conj unction with an arcuate discharge filter ( 230 ) positioned around the rotor . The filter ( 230 ) has multiple filter openings 231 si zed to allow only the correctly sheared crop straw to pass through . The rotor ( 220 ) shears the straw to a first-stage si ze (not more than 15 cm) , which then exits through a first-stage discharge ( 240 ) .

[0031] The stage conveyor ( 300 ) is tasked with transporting the sheared crop straw from the coarse stage reduction unit ( 200 ) to the fine stage reduction unit ( 400 ) . The stage conveyor 300 might be a pneumatic conveyor, or in other cases might comprise a belt conveyor similar to the intake conveyor as shown . Any type of conveyancing means for the movement of first stage si zed sheared straw feedstock to the fine stage reduction unit 400 will be understood to be within the scope of the present invention . Optionally, a surge hopper may be incorporated within the conveyor system to normali ze the flow and feeding of straw into the fine stage reduction unit , thus ensuring continuous and ef ficient operation .

[0032] Figure 4 shows one embodiment of a stage conveyor 300 in accordance with the present invention which is a pneumatic conveyance system by which material would be received into the top of the surge bin 301 and then pneumatically fed therefrom out to the fine stage processing unit 400 . The design and manufacture of a pneumatic surge system such as this , including necessary pumps, compression systems and the like, will be understood to those skilled in the art. Similarly asserted to be in her storage could also be manufactured using gravity conveyors, augers or the like and again would be understood to be within the scope of the invention.

[0033] The fine stage reduction unit (400) receives the pre-sheared straw from the stage conveyor (300) and subjects it to further size reduction. This unit includes one or more powered mills (410) , which could be hammer mills or knife mills, configured to grind the straw to a finished particle size of no more than 6 mm. The ground straw is then discharged from the system through a fine stage discharge (420) , ready for pelletization or other uses. The design of different types of hammer mills or knife mills which could be grind the straw to the finished desired particle size will be understood to those skilled in the art. Shown in Figures 1 and 5 is a very basic schematic example of a hammer mill with a rotary hammer flail 401 and ground straw discharge 420 therefrom. Any type of a powered grinder or mill configuration capable of achieving the grinding of the first stage straw output into the desired particle size will be understood to be within the scope of the present invention. The operation of the system follows a sequential process, beginning with the loading of baled crop straw into the debaling apparatus (100) . Upon activation, the apparatus (100) debales the straw and discharges it onto the intake conveyor (120) , which moves the material to the coarse stage reduction unit

[0034] (200) . Here, the straw undergoes initial size reduction. The resulting sheared straw is then transferred via the stage conveyor (300) to the fine stage reduction unit (400) for final grinding .

[0035] Referring to Figure 6 there is shown a flowchart demonstrating the steps in one embodiment of the method of the present invention. Shown in the first step at 6-1, one or more bales of feedstock would be loaded in the debaling apparatus, the apparatus then being used to remove the retaining means such as wine, wire etc. and generally speaking prepare the feedstock for further processing. This is shown at step 6-2.

[0036] The debaled feedstock would be moved from the debaling apparatus to the coarse stage reduction unit by the intake conveyor and fed to the rotary feed roller. Transition of the debaled feedstock to the rotary feed roller is shown at step 6-3. The rotary feed roller will then force-feed feedstock into the shearing rotor, shown at step 6-4, where it will be sheared into the desired first stage si ze . The sheared crop straw of that desired first stage course si ze , having exited the filter openings will be discharged from the coarse stage unit shown at 6-5 .

[0037] The sheared crop straw will be transitioned via the stage conveyor, with or without a surge bin, to the fine stage reduction unit where it will be milled . Loading of the sheared straw to the fine stage reduction unit is shown at 6- 6 . The fine stage reduction unit would then mail the sheared crop straw to the desired finished particle si ze , shown at stage 6-7 , from which it would ultimately be discharged as finished crop straw particles capable of beneficial use in a crop straw pelleti zation process ( 6- 8 ) . It will be understood to those skilled in the art that many changes could be made to the method flowchart shown without departing from the intended scope and intention of the present invention and all such changes are contemplated within the scope of the present invention .

[0038] By addressing the challenges associated with existing biomass processing methods , the invention not only improves operational ef ficiency but also contributes to the sustainability of biomass pellet production . It will be apparent to those of skill in the art that by routine modi fication the present invention can be optimi zed for use in a wide range of conditions and application . It will also be obvious to those of skill in the art that there are various ways and designs with which to produce the apparatus and methods of the present invention . The illustrated embodiments are therefore not intended to limit the scope of the invention, but to provide examples of the apparatus and method to enable those of skill in the art to appreciate the inventive concept .

[0039] Those skilled in the art will recogni ze that many more modi fications besides those already described are possible without departing from the inventive concepts herein . The inventive subj ect matter, therefore , is not to be restricted except in the scope of the appended claims . Moreover, in interpreting both the speci fication and the claims , all terms should be interpreted in the broadest possible manner consistent with the context . The terms " comprises" and " comprising" should be interpreted as referring to elements , components , or steps in a non-exclusive manner, indicating that the referenced elements , components , or steps may be present , or utili zed, or combined with other elements , components , or steps not expressly referenced .

Claims

CLAIMS :1 . A method of si ze reduction of cohesively fibrous crop straw feedstock into homogenously si zed straw particles using a two-stage processing system comprising : a . a debaling apparatus with a discharge operatively engaging an intake conveyor, the debaling apparatus capable of debaling bales of crop straw feedstock by mechanically removing bale-retaining means from feedstock bales and breaking down the unbound feedstock bale material onto the intake conveyor in si ze and format capable of further processing by the remainder of the system; b . a coarse stage reduction unit comprising, within a shear housing having a straw intake for receiving unbound feedstock bale material from the intake conveyor and a first-stage discharge to permit the passage of sheared crop straw of a desired first stage si ze therethrough :i . an arcuate discharge filter having a circular inner concave surface and a plurality of filter openings therein whereby sheared crop straw passing through the filter openings will exit the housing via the first-stage discharge ; ii . a powered shearing rotor having a plurality of identical shearing blades arrayed on the outer surface thereof each terminating at a distal tip, the shearing rotor being mounted approximately parallel to a discharge of the feed conveyor and in axial alignment and proximate cooperation between the outer circular shearing circumference of the shearing rotor defined by the distal tips and the inner concave surface of the discharge filter whereby sheared crop straw of the desired first stage si ze can pass through said filter openings as it is raked across the inner concave surface by the operating shear rotor and exit the first stage discharge ; and iii . a rotary feed roller operative to force feed crop straw feedstock from the straw intake into the shearing rotor ;c. a fine stage reduction unit comprising: i. a fine stage input for intake of sheared crop straw from the coarse stage reduction unit; and ii. at least one powered mill for grinding the sheared crop straw to a desired finished particle size; and iii. a fine stage discharge for the discharge of finished crop straw particles therefrom; and d. a stage conveyor connecting the first stage discharge and the fine stage input; said method comprising: a. loading baled feedstock into the debaling apparatus; b. debaling baled crop feedstock using the debaling apparatus, and discharging unbound feedstock bale material onto the intake conveyor;c. operating the coarse stage reduction unit: i. receiving unbound feedstock bale material to the rotary feed roller from the intake conveyor via the straw intake of the shear housing; ii. via the rotary feed roller, feeding unbound feedstock bale material to the shearing rotor; iii. using the shearing rotor, shearing the unbound feedstock bale material to sheared crop straw of the desired first stage size; and iv. discharging sheared crop straw to the stage conveyor; d. operating the fine stage reduction unit: i. receiving sheared crop straw to the fine stage input from the stage conveyor; ii. using the at least one powered mill, grinding the sheared crop straw to a desired finished particle size; andiii . discharging finished crop straw particles from the fine stage discharge .2 . The method of Claim 1 wherein the stage conveyor further comprises a surge hopper for storing sheared crop straw to normali ze the feeding thereof to the fine stage reduction unit .3 . The method of Claim 1 wherein the baled crop straw feedstock is in bales of rectangular or cylindrical volume .4 . The method of Claim 3 wherein the debaling apparatus is capable of convertibly breaking down feedstock bales of both rectangular or cylindrical volume .5 . The method of Claim 1 wherein the at least one powered mill is powered by an electromotor power in the range of 30 to40 horsepower / tonne / hour .

6. The method of Claim l_wherein the desired first stage particle size is no more than 15 cm.

7. The method of Claim 1 wherein the desired finished particle size is no more than 6 mm.

8. The method of Claim 1 wherein the cohesively fibrous crop straw is selected from the group of flax straw, wheat straw, barley straw, and corn stover.

9. The method of Claim 1 further comprising feeding the finished crop straw particles through a pelleting mill to yield agricultural biomass pellets.

10. A system for use in the two stage size reduction of low-density, cohesively fibrous crop straw feedstock into homogenously sized straw particles, said system comprising: a. a debaling apparatus with a discharge operatively engaging an intake conveyor, the debaling apparatuscapable of debaling bales of crop straw feedstock by mechanically removing bale-retaining means from feedstock bales and breaking down the unbound feedstock bale material onto the intake conveyor in si ze and format capable of further processing by the remainder of the system; b . a coarse stage reduction unit comprising, within a shear housing having a straw intake for receiving unbound feedstock bale material from the intake conveyor and a first-stage discharge to permit the passage of sheared crop straw of a desired first stage si ze therethrough : i . an arcuate discharge filter having a circular inner concave surface and a plurality of filter openings therein whereby sheared crop straw passing through the filter openings will exit the housing via the first-stage discharge ; ii . a powered shearing rotor having a plurality of identical shearing blades arrayed on the outer surface thereof each terminating at a distal tip, the shearing rotor being mounted approximatelyparallel to a discharge of the feed conveyor and in axial alignment and proximate cooperation between the outer circular shearing circumference of the shearing rotor defined by the distal tips and the inner concave surface of the discharge filter whereby sheared crop straw of the desired first stage si ze can pass through said filter openings as it is raked across the inner concave surface by the operating shear rotor and exit the first stage discharge ; and iii . a rotary feed roller operative to force feed crop straw feedstock from the straw intake into the shearing rotor ; c . a fine stage reduction unit comprising : i . a fine stage input for intake of sheared crop straw from the coarse stage reduction unit ; and ii . at least one powered mill for grinding the sheared crop straw to a desired finished particle si ze ; andiii . a fine stage discharge for the discharge of finished crop straw particles therefrom; and d . a stage conveyor connecting the first stage discharge and the fine stage input ; wherein operation of the system comprises : a . debaling baled crop feedstock using the debaling apparatus , and discharging unbound feedstock bale material onto the intake conveyor ; b . operating the coarse stage reduction unit : i . receiving unbound feedstock bale material to the rotary feed roller from the intake conveyor via the straw intake of the shear housing; ii . via the rotary feed roller, feeding unbound feedstock bale material to the shearing rotor ; iii . using the shearing rotor, shearing the unbound feedstock bale material to sheared crop straw of the desired first stage si ze ; andiv. discharging sheared crop straw to the stage conveyor; c. operating the fine stage reduction unit: i. receiving sheared crop straw to the fine stage input from the stage conveyor; ii. using the at least one powered mill, grinding the sheared crop straw to a desired finished particle size; and iii. discharging finished crop straw particles from the fine stage discharge.

11. The system of Claim 10 wherein the powered mill of the fine stage reduction unit is either a hammer mill or a knife mill.

12. The system of Claim 10 wherein the stage conveyor further comprises a surge hopper for storing sheared crop straw to normalize the feeding thereof to the fine stage reduction unit.13 . The system of Claim 10 wherein the debaling apparatus is capable of convertibly breaking down feedstock bales of both rectangular or cylindrical volume .14 . The system of Claim 10 wherein the at least one powered mill is powered by an electromotor power in the range of 30 to 40 horsepower / tonne / hour .15 . The system of Claim 10 wherein the desired first stage particle si ze is no more than 15 cm .16 . The system of Claim 10 wherein the desired finished particle si ze is no more than 6 mm .17 . The system of Claim 10 wherein the cohesively fibrous crop straw is selected from the group of flax straw, wheat straw, barley straw, and corn stover .

18. The system of Claim 10 wherein the fine stage discharge is connected to a pelleting mill.

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