CA2177984A1 - Processing lignocellulosic agricultural residue - Google Patents
Processing lignocellulosic agricultural residueInfo
- Publication number
- CA2177984A1 CA2177984A1 CA 2177984 CA2177984A CA2177984A1 CA 2177984 A1 CA2177984 A1 CA 2177984A1 CA 2177984 CA2177984 CA 2177984 CA 2177984 A CA2177984 A CA 2177984A CA 2177984 A1 CA2177984 A1 CA 2177984A1
- Authority
- CA
- Canada
- Prior art keywords
- mat
- water
- fibrous pulp
- pulp
- fibrous
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
- B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F9/00—Complete machines for making continuous webs of paper
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21J—FIBREBOARD; MANUFACTURE OF ARTICLES FROM CELLULOSIC FIBROUS SUSPENSIONS OR FROM PAPIER-MACHE
- D21J3/00—Manufacture of articles by pressing wet fibre pulp, or papier-mâché, between moulds
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21J—FIBREBOARD; MANUFACTURE OF ARTICLES FROM CELLULOSIC FIBROUS SUSPENSIONS OR FROM PAPIER-MACHE
- D21J5/00—Manufacture of hollow articles by transferring sheets, produced from fibres suspensions or papier-mâché by suction on wire-net moulds, to couch-moulds
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mechanical Engineering (AREA)
- Wood Science & Technology (AREA)
- Forests & Forestry (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
A process for forming molded articles from partially delignified non-woody lignocellulosic materials (10) is disclosed that includes forming a mass of fibrous pulp partially delignified lignocellulosic material from a water suspension thereof, and separating (19) the mass into pieces of a size suitable to an airborne tumbling and drying operation. The pulp is subjected to the tumbling and drying operation (32) such that the fibers are sufficiently separated and aligned to be formed into an interconnected mat or web (46).
The mat or web is subjected to sufficient pressure (48) to enable shapes to be molded from a continuous web and articles are molded from the web using a molded press. A water resistant coating (50) may be applied to the mat. A process of delignifying non-wood lignocellulosic material is also disclosed.
The mat or web is subjected to sufficient pressure (48) to enable shapes to be molded from a continuous web and articles are molded from the web using a molded press. A water resistant coating (50) may be applied to the mat. A process of delignifying non-wood lignocellulosic material is also disclosed.
Description
2 217 7 ~ 8 4 PCTNS94/13931 L.~O~ _ LII T-HLOE;TC AGRIC~LTURAL RESIDUE
P~ ~--~~ OF THE INVENTION
I. Field of the Invention The present invention is primarily directed to the digestion or breakdown of agricultural li~n~c~ 1 osic residue material in a manner that allows the lignin to be readily separated from the fibrous or cellulose constituent and particularly wherein the f ibrous material or cellulose constituent is further ~ es~d into useful, self-adhering molded shapes. The process of the invention accomplishe&
the breakdown, i.e., ~ n;fication of rather complex non-woody agricultural materials which are not readily broken down naturally, such as flax straw, for example, without strong alkali materials, using only water and steam and expansion. The lignin is separated from the resulting cellulose f iber pulp of the exploded straw and the f ibrous material processed into a substantially dry self-adhering moldable mat of material which can be formed into desired useful shapes in a subsequent pressing operation.
II. Di ~u~ion o~ the Rel~ted Art Certain agricultural residue materials such as flax straw, because of their chemical makeup, do not readily break down naturally if plowed under the soil after the useful crop is removed and so remain to be disposed of otherwise. Such materials do contain a certain useful fibrous (cellulose) content, lignin, hemicellulose and certain other polysaccharide nutrients if these constituents can be released and separated economically.
The processing of these non-woody materials into useful products and environmentally neutral, readily assimilated residues would result in a profitable use for what is otherwise an expensive cumulative d;cpos~l problem.
Processes and apparatus which enable breakdown and delignif ication of lignocellulosic materials including woody materials and non-woody agricultural residues or other such bio-mass materials are known. One such process WO 95/15252 2 1 7 7 ~ 8 ~ -2- PCT/US94/13931 is described in relatèd patents to Tyson (U. S . Patents 4 842 877 And 5 023 097, in which the non-woody lignocellulosic substrates are treated with an aqueous medium of strong alkali, such as sodium hydroxide, (at pH
10.5-12.5); optionally, the substrate is also treated with 2 chelating agent to chelate metal ions in the material, particularly if it is to be used as an animal feed stock.
The material is fed to an extruder in which heat and pressure applied in an oxygen ~ ,'^re and in the presence of an amount of hydrogen peroxide. The material eYplodes upon emergence from the extruder and the exploded product is suitable for ruminant feed stock, dietary fiber or as absorbent f ibers .
Other processes for delignification include use of steam in combination with lower aliphatic alcohols and/or ketones as disclosed in Sinner et al (U.S. Patents 4 742 814 and 4 520 105). Foody (U.S. Patent 4 461 648 uses steam cooking followed by rapid depressurization (explosion) to process hardwood chips and agricultural residue materials and render the cellulose more accessible to mi~ L~, ~L~.".isms, enzymes and the like, so that it can be used or digested by ruminants . Thompson, in U. 5 . Patent 4 307 121, uses water with C12 as an oxidizing agent to solubilize edible portions of cellulose from agricultural by-products such as soybean hulls.
Attempts have also been made to mold articles using the ~ ni fied fibrous material, however, such prior processes have produced results that have been only partially ~uc-e~_rul. Such processes have not been able to produce usable molded products that are economically competitive with available alternatives.
The present invention contemplates a process for separating useful fibrous pulp constituents from lignocellulosic materials, particularly non-woody agricultural residue which lend themselves to such processing. The invention further contemplates processing Wo 95/15252 217 7 9 ~ ~ PCT/US94113931 the separated fibrous material into useful molded articles of commerce and includes the articles produced.
Accordingly, it is a primary object of the present invention to provide a simplified process for separating 5 useful fibrous pulp material from lignocellulosic feed stock, particularly agricultural residue feed stock.
A further obj ect of the present invention is to produce a fibrous material which is readily formed into a mat and processed into self-adhering molded articles.
A still further object of the present invention includes a method of straightening and aligning fibrous cellulosic materials separated from lignocellulosic materials in a manner which enables them to be readily formed into a mat and molded into self-adhering shapes.
8~RY OF !r~E lh~n _ By means of the present invention, the rl~ nification separation of lignin from f ibrous cellulosic constituents to release useful fibrous pump in such problem agricultural residue materials as flax straw is simplified. The fibrous 20 pulp material is further processed to straighten or align the fibers, which can then be formed into mats and molded into self-adhering shaped articles without the need for additional adhesive or reinforcing agents. Coatings may be used to retard possible degradation from moisture or the 25 like.
In accordance with one embodiment of the invention, flax straw or other lignocellulosic material of interest is shredded to the desired size, normally about 3 inches ( - 8 cm) or less in length, and in~ with an amount of water 30 that is absorbed by the material. The wet or moisturized material is continuously f ed into the receiving end of a pressure cooker in the form of a screw type extruder-~ n~ or the like, where the wet straw is compre6sed in the range of 75 psi to 200 psi (5 to 14 kg/cm2) and an 35 amount of steam added to the _ ezs~-ed straw mixture as it moves toward the exit end of the extruder-expander. The extruder-expander operates at a very high internal pressure 2177~84 in the discharge area (?500 psi to 3000 psi or 35 kg/cm2 to 210 kg/cm2) and as the material di6charges through preferably a central orifice, the material literally explodes out of the barrel.
The exploded material, generally in a f ibrous pulp form, u!ld~:L~ueS a hot water agitation step in which much of the lignin constituent i5 leeched and washed out of the pulp. While complete delignification i5 desired, it has been found that the process produces sufficient separation 10 that a very useful fibrous pulp for making molded articles results and the removed constituents are suitable f or I,luad~DLing back on fields or as animal feed ingredients.
The washed material is then rolled or compressed to extract the bulk of the rr~~inin~ lignin-laden water from 15 the fibrous pulp which becomes a compressed wet cake. The ~ ~ L asDed cake is subj ect to a rotating chopper device which break6 up the cake to what becomes a substantially chunk, pellet or granular form.
The chopped material contains tightly wound and 20 uncooperative fibers. The granules are treated to a pneumatic agitation in which the granules are borne along by air Cul~Vt:yUL devices and caused to tumble and strike obstacles and themselves repeatedly. This treatment extracts moisture from the material and causes the 25 CV~ 1 e~,sed granules or pellets to open and the f ibers to assume a relaxed or straightened and aligned form. The pneumatic agitation includes subj ecting the material to a drying operation which includes feeding it serially through one or more cyclone-type dryers sequentially while 3 0 constantly moving the material using a pneumatic conveying system. Moistened air is constantly removed from the top and the fibrous pulp material from the bottom of each cyclone dryer. A substantially dry fluffy fibrous pulp is produced in which the f ibers themselves are substantially 35 straight or aligned and readily cooperate to be formed into a mat of material of any desired thicknes&. The mat iB
further compressed so that it may readily be conveyed to a WO 95115252 ~ 8 4 PcrluS94/13931 press and molded in a compression molding system to form the desired part.
It should be noted that an amount of material, such as an oil or wax to prevent water damage to the molded part, 5 can be coated on the c e5sed mat prior to molding to protect the surface of the final molded part. The material used for coating preferably should be one such that trimmings from the molded parts can be recycled to the shredder without adding undesirable residues of materials l0 to the process.
One aspect of the invention also includes the recycling of the hot water used to extract the lignin from the pulp. Since no strong alkali or other chemicals need be removed or neutralized, all that needs to be done is to 15 rcmove the solids and the water can be recycled. This is accomplished by continually feeding the hot water effluent and cake _ c~sion residue material into an high-speed centrifuge in which the lignin and other solids contained in the suspension are separated from the water and the 20 water r~l_uLed to extract additional materials from pulp.
The lignin and other solid materials are periodically PYpP1 1 P~l by the centrifuge and can be harmlessly be spread over fields or, if desired, used as a constituent for l ivestock f eed .
The preferred parameters with regard to the operation of the extruder/Pyp~ntlpr include initial compaction in the range of about 75 to 200 psig (5-14 kg/cm2) up until the high-~Les,~uL~= discharge end of the device is reached, the steam is added at a point where the material will be ~r~nt~(~t~cl by steam for a period from about 15 to 90 seconds prior to eYploding, depending on the material being processed and other considerations.
BRIEF DESCRIPTION OF THE DRAWINGS
The single Figure is a schematic flow diagram illustrating a particular mode of operation of the process of the invention.
2~7~
Wo 95/15252 PCr/US94/13931 nT"l'bTT.T!n ~ lCl~--_ As previously fliCrllc~cPd~ the materials processed using the method of the invention comprise cellulosic materials which include ce~ 1 oce and hemicellulose molecules in the 5 form of highly ordered cryst~l1;nP .LLUL~L~S together with an amount of lignin, a phenolic aromatic polymer built up from phenyl propane repeating units which has no systemic structure and is present in the cellulosic material peneLLclting, DuLL~ullding and coating the r~ ose crystalline fibrous ~LU~:LUL~S. This combination is often extremely difficult for the normal 50il or digestive bacteria to break down. Thus, if the material can be broken down quickly and artificially into constituents of which a si~nificant portion can be further processed into commercially 5l1rrPcsful products, what is, in some cases, bP: ;nq an expensive ~iicr-c~1 problem, can turn the use of these wastes into a profitable endeavor. While the process described in accordance with the illustrated ~mhorl i r -nt of the invention involves the processing of flax straw, which is particularly difficult to break down naturally in soil or the like, it will be appreciated that many lignocellulosic materials will lena themselves to similar processing and can be used to produce molded articles in accordance with the actual scope of the present invention.
Figure 1 depicts a schematic flow diagram of one s~lrrpccful process in accordance with the present invention. One size plant using this process has been built to operate at a feed rate of about 2000 lb. (900 kg) per hour. Smaller and larger operations including some with multiple lines are contemplated, of course. The raw materials s~rpl i ed to the process may include large parcels of agricultural residue in the form of non-woody bio-masses. Flax straw, for example, is usually obtained in the form of large round bales weighing upwards of 500 pounds (225 kg). They enter the process at 10, where parcels are initially dumped into a feed hopper as at 12 which allows the tightly, L~:ssed bale of material to Wo 95115252 2 ~ 7 7 ~ 8 ~ PCTIUS94113931 separate and typically drop from a bottom discharge in the feed hopper onto a flat belt conveyor at floor level which conveys the material at a controlled rate upward through a metal ~l~tPntinq system as at 14, which may include magnetic 5 metal removal devices in addition to devices to detect and warn of the E~l asellct: metal obj ects which may be contained in the feed and which might detrimentally affect either a product of the process or any of the devices utilized in the process.
The feed stock is then fed or drops off of the conveyor into the feed hopper of a shredding device at 16 which is typically an heavy-duty, high-torque shredder having a cutter configuration to optimize the desired shredded size and t11L~Iuyil~uL rate desired for the process.
15 Such devices are well known and one shredder that has been successfully used is equipped with rotating blades that rotate at a speed of about 30 rpm. The slow speed contributes to long life and it has been found that, at that speed, the shredder will operate without the normal 20 dust and noise F~YrectPd from other types of size reduction r--^hinP~y In one succi ssful Pn~ho~ L, the shredder was mounted atop a specially fabricated frame that elevated the shredder so that a flat belt discharge conveyor for the ~1~ edded material could be operated below the shredder with 25 the shredded material falling directly onto the flat belt discharge ~U1V~yol.
Typically, a straw feed is chopped so that the stalk lengths are approximately 3 in. or less (~8 cm). The flax straw or other lignnrPllulosic feed material is normally in 30 a partially dried state such that it will readily absorb an amount of available moi5ture. The shredded straw or other bio-mass material is subjected to water spray at 18 in which an amount of water within the limit that will readily be absorbed, held on the surface or otherwise combined with 35 the shredded material is sprayed on the shredded feed as it is conveyed from the shredding step 16 to a pressure cooker, which is pref erably an extruder, at l9 . The Wo 95/1~252 PcrluS94113931 21~79g4 shredded straw is fed into the fééd hopper of the extruder directly from the end of the discharge conveyor leading from the shredder to the extruder or pressure cooker.
At this point in the process, the divided, shredded 5 feed material, in the case of flax straw, is approximately 70-90% straw and approximately 10-30~6 water. This applied water provides lubrication to the straw so that the straw will flow along the flights of the extruder smoothly. This water eventually also turns to steam and aids the pulping 10 process.
The extruder is preferably in the form of a continuous extrusion cooker of a type used for producing textured vegetable proteins, for gelatinizing and ~Yr~n~lin7 cereals or cereal-based foods, dry-pyr~n~l~d pet foods and the like.
15 Such extrusion cookers are well known and generally commercially available. As the material is ul~v~d along through the many flights of the one or more screws of the extrusion cooker, the pressure increases to the range of 75-200 psi (5-14 kg/cm2). The pressurization raises the 20 t~ aLuL~: and additional water and heat are added to the extruder cooker, as the bio-mass is conveyed along, in the form of steam at 20. This occurs when the stream of straw material is about half way through the extruder, and being heated by the friction of the extruder f lights . Steam is 25 applied through a port or ports at any desired pressure at or above that in the exLLud~L~ typically a pressure from 80 to 100 psi (5 . 5-7 . 0 kg/cm2), depending on the extruder :S~-ULe when the steam is infused. The amount of steam can be varied to add enough moisture to raise the moisture 30 content of the straw being processed to as much as 100% of the weight of the straw . The steam is inf used through the flowing mass in a manner such that the steam and straw are in contact with each other for a period from about 15 to 90 seconds, ~ler~n~ i n~ upon the desired results and class of 35 feed stock used. During this time, the straw becomes a mûist hot pulp and the ~r~:.uLe is mechanically increased to a range of from about 500-3000 psi (35-210 kg/cm ).
Wo 95115252 2 1 7 ~ 9 8 ~ PCr/US94/13931 _g_ About one-fourth of the way from the end of the extruder a port may be provided for optionally adding a bleaching material such as hydrogen peroxide (H202) to the straw material being ~I oc~ssed . The addition of hydrogen 5 peroxide is to lighten or remove any dark color from or bleach the straw being processed into pulp. The hydrogen peroxide is typically at a cu~ ll.L-,tion of from 15% to 50%
H2O2. The amount added can vary from 296 of the weight of the straw being ~Lc~_e6~ed to 20% of the weight of the straw 10 being processed A~r~n~ling on the amount needed to achieve the desired color removal. In addition to the lightening of the color of the pulp from the processed straw, the ~-h~mic~1 reactions involving the 11ydLo~:l1 peroxide creates both additional heat and pressure. This added heat and 15 pL~_uLe may be of value in increasing the output of the extruder and ~nhAn~-in~ the completeness of the pulping.
The reacted or digested material is then exploded through one or more die orifices at 22 into a vessel through which a stream of moving hot water f lows 20 continuously. The explosion is occasioned by a sudden release of the pressure to a~ ~ ic from the extruder into a vented chamber at the discharge end of the extrusion cooker. The extrusion cooker may be provided with a f luid-operated valve device to separate or isolate the water 25 containing vessel from the internal portion of the extruder cooker during start-up and until the feed material has est~hl; ~h~Cl the desired positive pressure within the extruder cooker.
The reason for creating the pulp, of course, is to 30 separate the fibers in the straw from the lignin holding the straw together. The more complete the pulping is done, the ea6ier the downstream ef f orts to process the pulp are accomplished. During the explosion, pulp is ripped apart and the fibrous material is released from the tight hold of 35 the lignin bonding the fibers and coating the bonded fibers as it does in the natural state and, after exploding, the digested or cooked material is then suitable for the lignin Wo 95/15252 2 1 7 ~ 9 ~ ~ ` PCr/US94/13931 --10--, ' . . .
or other non-fibrous residue material in the feed stock to be separated from the fibrous material by agitation in a hot water bath as at 24. The stream of recirculating flowing water at 22 is at any desirable rate and a range in flowrate of 15 gallons per minute to 150 gal/min ~55-550 l/min) was used in one successful 6ystem processing about 2000 (900 kg) of flax straw per hour. The water is typically pumped at a ~resDule from 10 psi to 100 psi (0.7 to 7 . 0 kg/cm2) . This water is at a temperature from 130F
to 200F (54C to 94~C).
Agitation from the water flowing through the piping further separates the pulp being conveyed. The pulp is conveyed to a tank at 24 that is filled with water at a temperatur~ from 100F to as much as 200F (37C to 94C).
This tank is agitated by the water circulating in the system through the pump that is providing the f low of water for conveying the pulp from the chamber to the holding tank .
The c~, ^ntS of the pulp are agitated in the tank until the fiber ~nd plant residue reach a concentration of 20% of the water weight to 45% of the water weight. The mixture of hot water and pulp components are pumped from the holding tank to a belt press or other type of machine that squeezes the pulp at 26 and separates the fiber and outer plant residue from the lignin that has been dissolved in the water. The dissolved lignin and water mixture is pumped into a centrifuge 27 that separates the water from the lignin. The lignin is collected in a tank as a thick liquid or a mud or clay type of product that can be ~1isrosF~d of or further processed for other uses at 29. The water which can still contain some dissolved lignin, i5 returned to the holding tank to be used again. It is not ne.:~aD~.y to dispose of this water. The pH of the water is from about 4 to 9 d~r~n~lin~ on feed and whether H2O2 is 3 5 used .
While the water bearing lignin and other dissolved impurities are pumped into the centrifuge for separation, Wo 95/15252 2 ~ 7 7 ~ 8 ~ PCrlU~94113931 the fiber that has been squeezed to remove the moisture is led from the exit end of the belt press or machinery to do this operation as a cake or mat of f iber . At the exit, the cake or mat is broken into small pieces or 5 rL Ls at 28 by being subjected to a chopping step as by a heavy rotary chopper which is attached to the end of the extraction press. The chopper breaks up the cake of fibrous material into a material which is in substantially pellet or granule orm to allow them to be dropped into an l0 orifice of a pneumatic conveying device.
This material is then swept as by a vacuum into a pneumatic ~:UllV~yUL system at 30 which may be operated by means of one or more Venturi-type pump systems which create a suction in an entry du~t into which the material is f ed and carrie6 it 15 U.~L-~aLL~L through a Y or T connection to an adjoining duct using a high-speed air stream. The separate granules or pellet6 of closed or tightly wrapped fibers are subject to a length of pneumatic cul~v~ycl 30 which may include a spiraled internal surface or other roulh~n~ surface such 20 that many collisions occur between the conduit and the material being conveyed and between the pellets or granules themselves .
One successful Venturi-type pneumatic conveying device uses a blower hooked to an eductor which f eeds into a 2 5 length of f lexible conduit or hose having either a rough or smooth interior surface. The exit end of the conduit is hooked to a drying device which is pref erably a cyclone-type separator that allows the conveying air to be exhausted to the atmosphere at 34 and the f iber to be 30 discharged downward into another conveying device 36 which, in turn, feed other serially connected cyclone separators as at 38 and 44. The exhausted air carries moisture from the f iber being conveyed into the ~ , h~e, also at 4 0, etc., and may be vented as desired. In this manner, during 35 this conveying and cyclone drying operation, the pulp is both dried and broken from a small cake, pellet, granule or mat form into individual fibers. The individual fibers are 2177~84 WO 9511525~ PCr/US94/13931 beaten from their rolled up ætate to fiber6 that are dry, substantially straightened and separated from the mass of the cake to f ibers capable of being f ormed into a substantially f lat interwoven web or mat. The conveying 5 and processing can be continued for as many cycles, i.e., through as many cyclone devices or the like, as are QeCpccAry to attain the required state of dryness and straightness .
It is sometimes nP~-PCc~ry or desirable to add heat to lO the conveying air stream to be able to properly dry the f ibers . This can be done in any well-known manner .
Relative humidity of ambient air is one factor that detPr~i nPC whether the addition of heat is nerPSc;~ry .
The last pneumatic ~o1-v~yor leads into the f inal 15 cyclone of the series 44 which is positioned to discharge the fibrous material into a mat-forming chamber which feeds the material onto a moving flat metal conveyor belt which is known as a mat former ;nr ~h as the fibrous material forms a relatively uniform mat or web as it is discharged 20 onto the ~ ~lllV~:yVL at 46. It is this mat of fibrous material that is processed into usable shapes from the pulped and processed fibers. The ~ llVt:yC~L for the mat forming operation may be addressed by one or more parallel cnnnPr tP~ cyclones that discharge or drop portions of f iber 25 delivered to them by the conveying air. The actual mat formation on the CIJ11vt:yur is controlled from the mat f orming chamber which is equipped with internal moving def lectors that distribute the f ibers evenly during their fall to a flat metal belt. The moving mat forming belt 30 positioned below the chamber and cyclone accepts the fibers as a pile or mat that is continuously being formed and removed from below the chamber. The speed of the belt detPrminpc the thickness of the pile of fibers or mat.
The moving mat consisting of an essentially evenly 35 precipitated mass of dried fibers is next ~ ~s~ed to a processible continuous web using a mat forming press that may be attached to the mat f ormer f rame . The mat is Wo 95/15252 2 1 ~ 7 ~ 8 ~ PCr/~S94/13931 transported through the mat forming press at 48 which is tooled with proper tooling for the thickness of the part to be f ormed . The mat f orming press entraps the mat and compresses it to the desired th;rl n~c l3 needed for further processing. Heat can be added during pressing if desired.
The mat forming process is completed once the mat former press has closed about the mat on the co~ y~r from above and below, giving the mat body to allow further handling.
In addition to the ~ssion of the moldable portion of the mat, the trim or flash portion of the mat is simultaneously compressed an additional amount in narrow areas running lengthwise parallel to the direction that the mat is moving. These densely compressed strips or tracks are used ~o support and guide the mat into the press between the open molds. Guide members are provided that run the length of the press from the mat former to the final exit of the press. Those guides are stationary with respect to the frame of the forming press and firmly support the formed mat as it is cycled through the press.
The final part or article forming press is tooled with mold halves that open and close about the horizontally supported mat to form a molded article. The mat is moved forward by the slide r Ivc L of the mat former toward the open molds in he forming press. The slide movement is accomplished by moving the mat former press forward a distance enough to satisfy the mold spacing of the molds in the article forming press. The mat former press presses the mat and, at the same time, is driven or moves forward toward the forming press. When the forward distance is satisfied, the mat former press opens, releases the mat and retracts backward away from the forming press along the mat being precipitated on the mat f ormer conveyor .
Once the mat enters the forming press, the tooling closes on the mat extended between the open molds on guides. This closing applies pressure to the mat and a shape is formed. Heat and ~LcS~ULl= form the molded article for as long as the mold is closed. When the preset time to WO 95/15252 ~ 1 7 ~ ~ 8 4 PCr/US94/13931 form the article i8 complete, the molds are opened and the article is left sl`cp~n-l~fl ai~ong with trim on the guides.
The ~;equence i3 then set for the mat former press to clo3e and again ~_ ~ss the mat and drive the newly compressed mat and the formed article sl~r~n~9 in trim along the guides in the f orming press . The newly ~ ~ essed shape i8 pushed forward by the i- in~ mat being pushed along tracks by the moving mat former press. The second set of tooling in the article forming press can be identical to the first set or be pLoyL~ssively different to further shape the article to its intended shape. This shape can be accomplished in as many steps as are n~r~cc~ry. The last station in the press is a die-cutting station at 54 where the finished article is die cut from the web of connected parts and trim or waste material. The molded die cut part is moved downward out of the press and the trim conveyed upward to a shredder that returns the train or f lash to the pumping extruder for repulping. In this manner, a continuous web is f ashioned into molded articles .
Between the mat former and the press a wax or other waterproofing is optionally applied to the surface of the mat at 50 to malce the final shape resistant to moisture and oil. This wax is preferably biodegradable and repulpable and so does not interf ere with the reprocessing of the flash. Such materials are commercially available and competitive in price for this use. In this manner, the waste or trim from the molding operation can be safely recycled without concern for introducing contaminants.
The process of the invention has been used to make such items as flower pots to replace peat pots, trays and other types of containers primarily for uses in which biodegradability after short-term use is desired. It has been found that the compressed fibrous material self-adheres during the molding to ~n extent such that no additional adhesive material, plasticizer or other constituent is needed. The molded articles will eYentually ~ Wo9S11~2S2 217798~ PCrlUS94/13931 ~iodegrade and the sensitivity to soil, water, etc., can be adjusted as desired with coatings.
~ his invention has been described herein in considerable detail in order to comply with the Patent 5 Statutes and to provide tho5e skilled in the art with the information needed to apply the novel principles and to construct and use ~ i r ~s of the example as required .
However, it is to be understood that the invention can be carried out by specifically different devices and that 10 various modifications can be accomplished without departing from the scope of the invention itself.
P~ ~--~~ OF THE INVENTION
I. Field of the Invention The present invention is primarily directed to the digestion or breakdown of agricultural li~n~c~ 1 osic residue material in a manner that allows the lignin to be readily separated from the fibrous or cellulose constituent and particularly wherein the f ibrous material or cellulose constituent is further ~ es~d into useful, self-adhering molded shapes. The process of the invention accomplishe&
the breakdown, i.e., ~ n;fication of rather complex non-woody agricultural materials which are not readily broken down naturally, such as flax straw, for example, without strong alkali materials, using only water and steam and expansion. The lignin is separated from the resulting cellulose f iber pulp of the exploded straw and the f ibrous material processed into a substantially dry self-adhering moldable mat of material which can be formed into desired useful shapes in a subsequent pressing operation.
II. Di ~u~ion o~ the Rel~ted Art Certain agricultural residue materials such as flax straw, because of their chemical makeup, do not readily break down naturally if plowed under the soil after the useful crop is removed and so remain to be disposed of otherwise. Such materials do contain a certain useful fibrous (cellulose) content, lignin, hemicellulose and certain other polysaccharide nutrients if these constituents can be released and separated economically.
The processing of these non-woody materials into useful products and environmentally neutral, readily assimilated residues would result in a profitable use for what is otherwise an expensive cumulative d;cpos~l problem.
Processes and apparatus which enable breakdown and delignif ication of lignocellulosic materials including woody materials and non-woody agricultural residues or other such bio-mass materials are known. One such process WO 95/15252 2 1 7 7 ~ 8 ~ -2- PCT/US94/13931 is described in relatèd patents to Tyson (U. S . Patents 4 842 877 And 5 023 097, in which the non-woody lignocellulosic substrates are treated with an aqueous medium of strong alkali, such as sodium hydroxide, (at pH
10.5-12.5); optionally, the substrate is also treated with 2 chelating agent to chelate metal ions in the material, particularly if it is to be used as an animal feed stock.
The material is fed to an extruder in which heat and pressure applied in an oxygen ~ ,'^re and in the presence of an amount of hydrogen peroxide. The material eYplodes upon emergence from the extruder and the exploded product is suitable for ruminant feed stock, dietary fiber or as absorbent f ibers .
Other processes for delignification include use of steam in combination with lower aliphatic alcohols and/or ketones as disclosed in Sinner et al (U.S. Patents 4 742 814 and 4 520 105). Foody (U.S. Patent 4 461 648 uses steam cooking followed by rapid depressurization (explosion) to process hardwood chips and agricultural residue materials and render the cellulose more accessible to mi~ L~, ~L~.".isms, enzymes and the like, so that it can be used or digested by ruminants . Thompson, in U. 5 . Patent 4 307 121, uses water with C12 as an oxidizing agent to solubilize edible portions of cellulose from agricultural by-products such as soybean hulls.
Attempts have also been made to mold articles using the ~ ni fied fibrous material, however, such prior processes have produced results that have been only partially ~uc-e~_rul. Such processes have not been able to produce usable molded products that are economically competitive with available alternatives.
The present invention contemplates a process for separating useful fibrous pulp constituents from lignocellulosic materials, particularly non-woody agricultural residue which lend themselves to such processing. The invention further contemplates processing Wo 95/15252 217 7 9 ~ ~ PCT/US94113931 the separated fibrous material into useful molded articles of commerce and includes the articles produced.
Accordingly, it is a primary object of the present invention to provide a simplified process for separating 5 useful fibrous pulp material from lignocellulosic feed stock, particularly agricultural residue feed stock.
A further obj ect of the present invention is to produce a fibrous material which is readily formed into a mat and processed into self-adhering molded articles.
A still further object of the present invention includes a method of straightening and aligning fibrous cellulosic materials separated from lignocellulosic materials in a manner which enables them to be readily formed into a mat and molded into self-adhering shapes.
8~RY OF !r~E lh~n _ By means of the present invention, the rl~ nification separation of lignin from f ibrous cellulosic constituents to release useful fibrous pump in such problem agricultural residue materials as flax straw is simplified. The fibrous 20 pulp material is further processed to straighten or align the fibers, which can then be formed into mats and molded into self-adhering shaped articles without the need for additional adhesive or reinforcing agents. Coatings may be used to retard possible degradation from moisture or the 25 like.
In accordance with one embodiment of the invention, flax straw or other lignocellulosic material of interest is shredded to the desired size, normally about 3 inches ( - 8 cm) or less in length, and in~ with an amount of water 30 that is absorbed by the material. The wet or moisturized material is continuously f ed into the receiving end of a pressure cooker in the form of a screw type extruder-~ n~ or the like, where the wet straw is compre6sed in the range of 75 psi to 200 psi (5 to 14 kg/cm2) and an 35 amount of steam added to the _ ezs~-ed straw mixture as it moves toward the exit end of the extruder-expander. The extruder-expander operates at a very high internal pressure 2177~84 in the discharge area (?500 psi to 3000 psi or 35 kg/cm2 to 210 kg/cm2) and as the material di6charges through preferably a central orifice, the material literally explodes out of the barrel.
The exploded material, generally in a f ibrous pulp form, u!ld~:L~ueS a hot water agitation step in which much of the lignin constituent i5 leeched and washed out of the pulp. While complete delignification i5 desired, it has been found that the process produces sufficient separation 10 that a very useful fibrous pulp for making molded articles results and the removed constituents are suitable f or I,luad~DLing back on fields or as animal feed ingredients.
The washed material is then rolled or compressed to extract the bulk of the rr~~inin~ lignin-laden water from 15 the fibrous pulp which becomes a compressed wet cake. The ~ ~ L asDed cake is subj ect to a rotating chopper device which break6 up the cake to what becomes a substantially chunk, pellet or granular form.
The chopped material contains tightly wound and 20 uncooperative fibers. The granules are treated to a pneumatic agitation in which the granules are borne along by air Cul~Vt:yUL devices and caused to tumble and strike obstacles and themselves repeatedly. This treatment extracts moisture from the material and causes the 25 CV~ 1 e~,sed granules or pellets to open and the f ibers to assume a relaxed or straightened and aligned form. The pneumatic agitation includes subj ecting the material to a drying operation which includes feeding it serially through one or more cyclone-type dryers sequentially while 3 0 constantly moving the material using a pneumatic conveying system. Moistened air is constantly removed from the top and the fibrous pulp material from the bottom of each cyclone dryer. A substantially dry fluffy fibrous pulp is produced in which the f ibers themselves are substantially 35 straight or aligned and readily cooperate to be formed into a mat of material of any desired thicknes&. The mat iB
further compressed so that it may readily be conveyed to a WO 95115252 ~ 8 4 PcrluS94/13931 press and molded in a compression molding system to form the desired part.
It should be noted that an amount of material, such as an oil or wax to prevent water damage to the molded part, 5 can be coated on the c e5sed mat prior to molding to protect the surface of the final molded part. The material used for coating preferably should be one such that trimmings from the molded parts can be recycled to the shredder without adding undesirable residues of materials l0 to the process.
One aspect of the invention also includes the recycling of the hot water used to extract the lignin from the pulp. Since no strong alkali or other chemicals need be removed or neutralized, all that needs to be done is to 15 rcmove the solids and the water can be recycled. This is accomplished by continually feeding the hot water effluent and cake _ c~sion residue material into an high-speed centrifuge in which the lignin and other solids contained in the suspension are separated from the water and the 20 water r~l_uLed to extract additional materials from pulp.
The lignin and other solid materials are periodically PYpP1 1 P~l by the centrifuge and can be harmlessly be spread over fields or, if desired, used as a constituent for l ivestock f eed .
The preferred parameters with regard to the operation of the extruder/Pyp~ntlpr include initial compaction in the range of about 75 to 200 psig (5-14 kg/cm2) up until the high-~Les,~uL~= discharge end of the device is reached, the steam is added at a point where the material will be ~r~nt~(~t~cl by steam for a period from about 15 to 90 seconds prior to eYploding, depending on the material being processed and other considerations.
BRIEF DESCRIPTION OF THE DRAWINGS
The single Figure is a schematic flow diagram illustrating a particular mode of operation of the process of the invention.
2~7~
Wo 95/15252 PCr/US94/13931 nT"l'bTT.T!n ~ lCl~--_ As previously fliCrllc~cPd~ the materials processed using the method of the invention comprise cellulosic materials which include ce~ 1 oce and hemicellulose molecules in the 5 form of highly ordered cryst~l1;nP .LLUL~L~S together with an amount of lignin, a phenolic aromatic polymer built up from phenyl propane repeating units which has no systemic structure and is present in the cellulosic material peneLLclting, DuLL~ullding and coating the r~ ose crystalline fibrous ~LU~:LUL~S. This combination is often extremely difficult for the normal 50il or digestive bacteria to break down. Thus, if the material can be broken down quickly and artificially into constituents of which a si~nificant portion can be further processed into commercially 5l1rrPcsful products, what is, in some cases, bP: ;nq an expensive ~iicr-c~1 problem, can turn the use of these wastes into a profitable endeavor. While the process described in accordance with the illustrated ~mhorl i r -nt of the invention involves the processing of flax straw, which is particularly difficult to break down naturally in soil or the like, it will be appreciated that many lignocellulosic materials will lena themselves to similar processing and can be used to produce molded articles in accordance with the actual scope of the present invention.
Figure 1 depicts a schematic flow diagram of one s~lrrpccful process in accordance with the present invention. One size plant using this process has been built to operate at a feed rate of about 2000 lb. (900 kg) per hour. Smaller and larger operations including some with multiple lines are contemplated, of course. The raw materials s~rpl i ed to the process may include large parcels of agricultural residue in the form of non-woody bio-masses. Flax straw, for example, is usually obtained in the form of large round bales weighing upwards of 500 pounds (225 kg). They enter the process at 10, where parcels are initially dumped into a feed hopper as at 12 which allows the tightly, L~:ssed bale of material to Wo 95115252 2 ~ 7 7 ~ 8 ~ PCTIUS94113931 separate and typically drop from a bottom discharge in the feed hopper onto a flat belt conveyor at floor level which conveys the material at a controlled rate upward through a metal ~l~tPntinq system as at 14, which may include magnetic 5 metal removal devices in addition to devices to detect and warn of the E~l asellct: metal obj ects which may be contained in the feed and which might detrimentally affect either a product of the process or any of the devices utilized in the process.
The feed stock is then fed or drops off of the conveyor into the feed hopper of a shredding device at 16 which is typically an heavy-duty, high-torque shredder having a cutter configuration to optimize the desired shredded size and t11L~Iuyil~uL rate desired for the process.
15 Such devices are well known and one shredder that has been successfully used is equipped with rotating blades that rotate at a speed of about 30 rpm. The slow speed contributes to long life and it has been found that, at that speed, the shredder will operate without the normal 20 dust and noise F~YrectPd from other types of size reduction r--^hinP~y In one succi ssful Pn~ho~ L, the shredder was mounted atop a specially fabricated frame that elevated the shredder so that a flat belt discharge conveyor for the ~1~ edded material could be operated below the shredder with 25 the shredded material falling directly onto the flat belt discharge ~U1V~yol.
Typically, a straw feed is chopped so that the stalk lengths are approximately 3 in. or less (~8 cm). The flax straw or other lignnrPllulosic feed material is normally in 30 a partially dried state such that it will readily absorb an amount of available moi5ture. The shredded straw or other bio-mass material is subjected to water spray at 18 in which an amount of water within the limit that will readily be absorbed, held on the surface or otherwise combined with 35 the shredded material is sprayed on the shredded feed as it is conveyed from the shredding step 16 to a pressure cooker, which is pref erably an extruder, at l9 . The Wo 95/1~252 PcrluS94113931 21~79g4 shredded straw is fed into the fééd hopper of the extruder directly from the end of the discharge conveyor leading from the shredder to the extruder or pressure cooker.
At this point in the process, the divided, shredded 5 feed material, in the case of flax straw, is approximately 70-90% straw and approximately 10-30~6 water. This applied water provides lubrication to the straw so that the straw will flow along the flights of the extruder smoothly. This water eventually also turns to steam and aids the pulping 10 process.
The extruder is preferably in the form of a continuous extrusion cooker of a type used for producing textured vegetable proteins, for gelatinizing and ~Yr~n~lin7 cereals or cereal-based foods, dry-pyr~n~l~d pet foods and the like.
15 Such extrusion cookers are well known and generally commercially available. As the material is ul~v~d along through the many flights of the one or more screws of the extrusion cooker, the pressure increases to the range of 75-200 psi (5-14 kg/cm2). The pressurization raises the 20 t~ aLuL~: and additional water and heat are added to the extruder cooker, as the bio-mass is conveyed along, in the form of steam at 20. This occurs when the stream of straw material is about half way through the extruder, and being heated by the friction of the extruder f lights . Steam is 25 applied through a port or ports at any desired pressure at or above that in the exLLud~L~ typically a pressure from 80 to 100 psi (5 . 5-7 . 0 kg/cm2), depending on the extruder :S~-ULe when the steam is infused. The amount of steam can be varied to add enough moisture to raise the moisture 30 content of the straw being processed to as much as 100% of the weight of the straw . The steam is inf used through the flowing mass in a manner such that the steam and straw are in contact with each other for a period from about 15 to 90 seconds, ~ler~n~ i n~ upon the desired results and class of 35 feed stock used. During this time, the straw becomes a mûist hot pulp and the ~r~:.uLe is mechanically increased to a range of from about 500-3000 psi (35-210 kg/cm ).
Wo 95115252 2 1 7 ~ 9 8 ~ PCr/US94/13931 _g_ About one-fourth of the way from the end of the extruder a port may be provided for optionally adding a bleaching material such as hydrogen peroxide (H202) to the straw material being ~I oc~ssed . The addition of hydrogen 5 peroxide is to lighten or remove any dark color from or bleach the straw being processed into pulp. The hydrogen peroxide is typically at a cu~ ll.L-,tion of from 15% to 50%
H2O2. The amount added can vary from 296 of the weight of the straw being ~Lc~_e6~ed to 20% of the weight of the straw 10 being processed A~r~n~ling on the amount needed to achieve the desired color removal. In addition to the lightening of the color of the pulp from the processed straw, the ~-h~mic~1 reactions involving the 11ydLo~:l1 peroxide creates both additional heat and pressure. This added heat and 15 pL~_uLe may be of value in increasing the output of the extruder and ~nhAn~-in~ the completeness of the pulping.
The reacted or digested material is then exploded through one or more die orifices at 22 into a vessel through which a stream of moving hot water f lows 20 continuously. The explosion is occasioned by a sudden release of the pressure to a~ ~ ic from the extruder into a vented chamber at the discharge end of the extrusion cooker. The extrusion cooker may be provided with a f luid-operated valve device to separate or isolate the water 25 containing vessel from the internal portion of the extruder cooker during start-up and until the feed material has est~hl; ~h~Cl the desired positive pressure within the extruder cooker.
The reason for creating the pulp, of course, is to 30 separate the fibers in the straw from the lignin holding the straw together. The more complete the pulping is done, the ea6ier the downstream ef f orts to process the pulp are accomplished. During the explosion, pulp is ripped apart and the fibrous material is released from the tight hold of 35 the lignin bonding the fibers and coating the bonded fibers as it does in the natural state and, after exploding, the digested or cooked material is then suitable for the lignin Wo 95/15252 2 1 7 ~ 9 ~ ~ ` PCr/US94/13931 --10--, ' . . .
or other non-fibrous residue material in the feed stock to be separated from the fibrous material by agitation in a hot water bath as at 24. The stream of recirculating flowing water at 22 is at any desirable rate and a range in flowrate of 15 gallons per minute to 150 gal/min ~55-550 l/min) was used in one successful 6ystem processing about 2000 (900 kg) of flax straw per hour. The water is typically pumped at a ~resDule from 10 psi to 100 psi (0.7 to 7 . 0 kg/cm2) . This water is at a temperature from 130F
to 200F (54C to 94~C).
Agitation from the water flowing through the piping further separates the pulp being conveyed. The pulp is conveyed to a tank at 24 that is filled with water at a temperatur~ from 100F to as much as 200F (37C to 94C).
This tank is agitated by the water circulating in the system through the pump that is providing the f low of water for conveying the pulp from the chamber to the holding tank .
The c~, ^ntS of the pulp are agitated in the tank until the fiber ~nd plant residue reach a concentration of 20% of the water weight to 45% of the water weight. The mixture of hot water and pulp components are pumped from the holding tank to a belt press or other type of machine that squeezes the pulp at 26 and separates the fiber and outer plant residue from the lignin that has been dissolved in the water. The dissolved lignin and water mixture is pumped into a centrifuge 27 that separates the water from the lignin. The lignin is collected in a tank as a thick liquid or a mud or clay type of product that can be ~1isrosF~d of or further processed for other uses at 29. The water which can still contain some dissolved lignin, i5 returned to the holding tank to be used again. It is not ne.:~aD~.y to dispose of this water. The pH of the water is from about 4 to 9 d~r~n~lin~ on feed and whether H2O2 is 3 5 used .
While the water bearing lignin and other dissolved impurities are pumped into the centrifuge for separation, Wo 95/15252 2 ~ 7 7 ~ 8 ~ PCrlU~94113931 the fiber that has been squeezed to remove the moisture is led from the exit end of the belt press or machinery to do this operation as a cake or mat of f iber . At the exit, the cake or mat is broken into small pieces or 5 rL Ls at 28 by being subjected to a chopping step as by a heavy rotary chopper which is attached to the end of the extraction press. The chopper breaks up the cake of fibrous material into a material which is in substantially pellet or granule orm to allow them to be dropped into an l0 orifice of a pneumatic conveying device.
This material is then swept as by a vacuum into a pneumatic ~:UllV~yUL system at 30 which may be operated by means of one or more Venturi-type pump systems which create a suction in an entry du~t into which the material is f ed and carrie6 it 15 U.~L-~aLL~L through a Y or T connection to an adjoining duct using a high-speed air stream. The separate granules or pellet6 of closed or tightly wrapped fibers are subject to a length of pneumatic cul~v~ycl 30 which may include a spiraled internal surface or other roulh~n~ surface such 20 that many collisions occur between the conduit and the material being conveyed and between the pellets or granules themselves .
One successful Venturi-type pneumatic conveying device uses a blower hooked to an eductor which f eeds into a 2 5 length of f lexible conduit or hose having either a rough or smooth interior surface. The exit end of the conduit is hooked to a drying device which is pref erably a cyclone-type separator that allows the conveying air to be exhausted to the atmosphere at 34 and the f iber to be 30 discharged downward into another conveying device 36 which, in turn, feed other serially connected cyclone separators as at 38 and 44. The exhausted air carries moisture from the f iber being conveyed into the ~ , h~e, also at 4 0, etc., and may be vented as desired. In this manner, during 35 this conveying and cyclone drying operation, the pulp is both dried and broken from a small cake, pellet, granule or mat form into individual fibers. The individual fibers are 2177~84 WO 9511525~ PCr/US94/13931 beaten from their rolled up ætate to fiber6 that are dry, substantially straightened and separated from the mass of the cake to f ibers capable of being f ormed into a substantially f lat interwoven web or mat. The conveying 5 and processing can be continued for as many cycles, i.e., through as many cyclone devices or the like, as are QeCpccAry to attain the required state of dryness and straightness .
It is sometimes nP~-PCc~ry or desirable to add heat to lO the conveying air stream to be able to properly dry the f ibers . This can be done in any well-known manner .
Relative humidity of ambient air is one factor that detPr~i nPC whether the addition of heat is nerPSc;~ry .
The last pneumatic ~o1-v~yor leads into the f inal 15 cyclone of the series 44 which is positioned to discharge the fibrous material into a mat-forming chamber which feeds the material onto a moving flat metal conveyor belt which is known as a mat former ;nr ~h as the fibrous material forms a relatively uniform mat or web as it is discharged 20 onto the ~ ~lllV~:yVL at 46. It is this mat of fibrous material that is processed into usable shapes from the pulped and processed fibers. The ~ llVt:yC~L for the mat forming operation may be addressed by one or more parallel cnnnPr tP~ cyclones that discharge or drop portions of f iber 25 delivered to them by the conveying air. The actual mat formation on the CIJ11vt:yur is controlled from the mat f orming chamber which is equipped with internal moving def lectors that distribute the f ibers evenly during their fall to a flat metal belt. The moving mat forming belt 30 positioned below the chamber and cyclone accepts the fibers as a pile or mat that is continuously being formed and removed from below the chamber. The speed of the belt detPrminpc the thickness of the pile of fibers or mat.
The moving mat consisting of an essentially evenly 35 precipitated mass of dried fibers is next ~ ~s~ed to a processible continuous web using a mat forming press that may be attached to the mat f ormer f rame . The mat is Wo 95/15252 2 1 ~ 7 ~ 8 ~ PCr/~S94/13931 transported through the mat forming press at 48 which is tooled with proper tooling for the thickness of the part to be f ormed . The mat f orming press entraps the mat and compresses it to the desired th;rl n~c l3 needed for further processing. Heat can be added during pressing if desired.
The mat forming process is completed once the mat former press has closed about the mat on the co~ y~r from above and below, giving the mat body to allow further handling.
In addition to the ~ssion of the moldable portion of the mat, the trim or flash portion of the mat is simultaneously compressed an additional amount in narrow areas running lengthwise parallel to the direction that the mat is moving. These densely compressed strips or tracks are used ~o support and guide the mat into the press between the open molds. Guide members are provided that run the length of the press from the mat former to the final exit of the press. Those guides are stationary with respect to the frame of the forming press and firmly support the formed mat as it is cycled through the press.
The final part or article forming press is tooled with mold halves that open and close about the horizontally supported mat to form a molded article. The mat is moved forward by the slide r Ivc L of the mat former toward the open molds in he forming press. The slide movement is accomplished by moving the mat former press forward a distance enough to satisfy the mold spacing of the molds in the article forming press. The mat former press presses the mat and, at the same time, is driven or moves forward toward the forming press. When the forward distance is satisfied, the mat former press opens, releases the mat and retracts backward away from the forming press along the mat being precipitated on the mat f ormer conveyor .
Once the mat enters the forming press, the tooling closes on the mat extended between the open molds on guides. This closing applies pressure to the mat and a shape is formed. Heat and ~LcS~ULl= form the molded article for as long as the mold is closed. When the preset time to WO 95/15252 ~ 1 7 ~ ~ 8 4 PCr/US94/13931 form the article i8 complete, the molds are opened and the article is left sl`cp~n-l~fl ai~ong with trim on the guides.
The ~;equence i3 then set for the mat former press to clo3e and again ~_ ~ss the mat and drive the newly compressed mat and the formed article sl~r~n~9 in trim along the guides in the f orming press . The newly ~ ~ essed shape i8 pushed forward by the i- in~ mat being pushed along tracks by the moving mat former press. The second set of tooling in the article forming press can be identical to the first set or be pLoyL~ssively different to further shape the article to its intended shape. This shape can be accomplished in as many steps as are n~r~cc~ry. The last station in the press is a die-cutting station at 54 where the finished article is die cut from the web of connected parts and trim or waste material. The molded die cut part is moved downward out of the press and the trim conveyed upward to a shredder that returns the train or f lash to the pumping extruder for repulping. In this manner, a continuous web is f ashioned into molded articles .
Between the mat former and the press a wax or other waterproofing is optionally applied to the surface of the mat at 50 to malce the final shape resistant to moisture and oil. This wax is preferably biodegradable and repulpable and so does not interf ere with the reprocessing of the flash. Such materials are commercially available and competitive in price for this use. In this manner, the waste or trim from the molding operation can be safely recycled without concern for introducing contaminants.
The process of the invention has been used to make such items as flower pots to replace peat pots, trays and other types of containers primarily for uses in which biodegradability after short-term use is desired. It has been found that the compressed fibrous material self-adheres during the molding to ~n extent such that no additional adhesive material, plasticizer or other constituent is needed. The molded articles will eYentually ~ Wo9S11~2S2 217798~ PCrlUS94/13931 ~iodegrade and the sensitivity to soil, water, etc., can be adjusted as desired with coatings.
~ his invention has been described herein in considerable detail in order to comply with the Patent 5 Statutes and to provide tho5e skilled in the art with the information needed to apply the novel principles and to construct and use ~ i r ~s of the example as required .
However, it is to be understood that the invention can be carried out by specifically different devices and that 10 various modifications can be accomplished without departing from the scope of the invention itself.
Claims (28)
1. A process for treating non-woody, partially delignified lignocellulosic fibrous material into a moldable self-adhering mat comprising the steps of:
(a) forming a mass of fibrous pulp comprising partially delignified lignocellulosic material;
(b) subjecting the fibrous pulp to a tumbling/drying operation to separate the fibers and render them suitable for forming an interconnected mat;
(c) forming a mat using randomly oriented fibers from step (b); and (d) pressing the formed mat to form a cohesive structure.
(a) forming a mass of fibrous pulp comprising partially delignified lignocellulosic material;
(b) subjecting the fibrous pulp to a tumbling/drying operation to separate the fibers and render them suitable for forming an interconnected mat;
(c) forming a mat using randomly oriented fibers from step (b); and (d) pressing the formed mat to form a cohesive structure.
2. The process of claim 1 wherein the fibrous pulp is squeezed from a water suspension containing fibrous pulp to form a cake thereof.
3. The process of claim 2 further comprising the step of breaking up the cake of fibrous pulp into a form suitable for airborne conveying.
4. The process of claim 2 wherein the water suspension further contains suspended lignin and including the further step of removing the majority of the suspended lignin by centrifuging the effluent resulting when the pulp is squeezed.
5. The process of claim 1 wherein the tumbling/drying operation further comprises subjecting the fibrous pulp to a length of an air conveyance and one or more airborne solid/gas separator drying devices.
6. The process of claim 3 wherein the tumbling/drying operation further comprises subjecting the fibrous pulp to a length of an air conveyance and one or more airborne solid/gas separator drying devices.
7. The process of claim 1 wherein the tumbling/drying operation separates the fibers.
8. The process of claim 5 including the step of adding heat during step (b).
9. The process of claim 1 further comprising the step of compression molding the mat to form desired self-adhering shapes.
10. The process of claim 1 further comprising the step of applying a water-resistant coating material to the mat after pressing.
11. The process of claim 10 wherein the water-resistant coating material is recyclable with trim waste.
12. The process of claim 10 wherein the water-resistant coating material comprises a wax.
13. The process of claim 1 wherein the lignocellulosic material comprises flax straw.
14. The process of claim 11 further comprising the step of re-using the water of the water suspension after lignin removal by centrifuging.
15. The process of claim 9 further comprising the step of applying a water-resistant coating to the mat prior to compression molding.
16. A process for forming a molded article from partially delignified non-woody lignocellulosic materials comprising the steps of:
(a) forming a mass of fibrous pulp comprising a concentrated amount of partially delignified lignocellulosic material from a water suspension thereof;
(b) separating the mass of fibrous pulp into pieces of a size suitable for airborne tumbling/drying;
(c) subjecting the pieces of fibrous pulp to a tumbling/drying operation including the equivalence of a length of airborne conveyance and one or more solid/gas-type separator/drying devices, such that the fibers are sufficiently separated and aligned as to be suitable for being formed into an interconnected web;
(d) precipitating the fibers to form a web of a desired thickness;
(e) subjecting the mat to sufficient forming pressure to enable shapes to be molded from a continuous web of the mat; and (f) molding articles from the web using a molding press.
(a) forming a mass of fibrous pulp comprising a concentrated amount of partially delignified lignocellulosic material from a water suspension thereof;
(b) separating the mass of fibrous pulp into pieces of a size suitable for airborne tumbling/drying;
(c) subjecting the pieces of fibrous pulp to a tumbling/drying operation including the equivalence of a length of airborne conveyance and one or more solid/gas-type separator/drying devices, such that the fibers are sufficiently separated and aligned as to be suitable for being formed into an interconnected web;
(d) precipitating the fibers to form a web of a desired thickness;
(e) subjecting the mat to sufficient forming pressure to enable shapes to be molded from a continuous web of the mat; and (f) molding articles from the web using a molding press.
17. The process of claim 16 including the step of applying a water resistant coating to the web of step (e).
18. The process of claim 15 wherein the water-resistant coating material comprises a wax.
19. The process of claim 16 wherein the lignocellulosic material comprises flax straw.
20. A process of delignifying non-woody lignocellulosic material comprising the steps of:
(a) subjecting a moist biomass of non-woody lignocellulosic material of desired size pieces to heat and pressure in a continuously fed extruder cooker;
(b) contacting the biomass with an amount of steam in the extruder cooker such that the steam contacts the feed for a known time span during which the pressure rises rapidly to the range of 500 to 3000 psi (35-210 kg/cm2);
(c) releasing the pressure suddenly as the biomass leaves the extruder to explode the biomass to include a fibrous pulp;
(d) agitating the exploded biomass including the fibrous pulp in relatively hot water to separate the majority of the lignin and fibrous pulp and form a water suspension thereof; and (e) separating the fibrous pulp from the water agitation of step (d) into a mass of wet fibrous pulp.
(a) subjecting a moist biomass of non-woody lignocellulosic material of desired size pieces to heat and pressure in a continuously fed extruder cooker;
(b) contacting the biomass with an amount of steam in the extruder cooker such that the steam contacts the feed for a known time span during which the pressure rises rapidly to the range of 500 to 3000 psi (35-210 kg/cm2);
(c) releasing the pressure suddenly as the biomass leaves the extruder to explode the biomass to include a fibrous pulp;
(d) agitating the exploded biomass including the fibrous pulp in relatively hot water to separate the majority of the lignin and fibrous pulp and form a water suspension thereof; and (e) separating the fibrous pulp from the water agitation of step (d) into a mass of wet fibrous pulp.
21. The process of claim 20 wherein step (b) further comprises infusing the biomass with steam at a pressure at or above the pressure in the extruder cooker at the point of infusion and wherein the steam contacts the feed for from about 15 to about 90 seconds prior to explosion.
22. The process of claim 20 wherein the water suspension further contains suspended lignin and including the further step of removing the majority of the suspended lignin by centrifuging the effluent resulting when the pulp is squeezed.
23. The process of claim 22 wherein the waste water is recirculated to separate more lignin and fibrous pulp.
24. The process of claim 20 further comprising the step of adding an amount of H2O2 to the biomass in the extruder prior to the addition of the steam.
25. An article made by the process of claim 9.
26. An article made by the process of claim 16.
27. The article of claim 25 further comprising an amount of water-resistant coating.
28. The article of claim 26 further comprising an amount of water-resistant coating.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US16040893A | 1993-12-02 | 1993-12-02 | |
| US08/160,408 | 1993-12-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2177984A1 true CA2177984A1 (en) | 1995-06-08 |
Family
ID=22576787
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2177984 Abandoned CA2177984A1 (en) | 1993-12-02 | 1994-12-01 | Processing lignocellulosic agricultural residue |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2177984A1 (en) |
| WO (1) | WO1995015252A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8492128B2 (en) | 2006-10-26 | 2013-07-23 | Xyleco, Inc. | Processing biomass |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2783740B1 (en) * | 1998-09-24 | 2000-12-15 | Cooperative Agricole Vivadour | MATERIAL BASED ON PLANT MATERIAL FROM CEREAL PLANTS AND PROCESS FOR OBTAINING SAME |
| WO2002002886A1 (en) * | 2000-07-05 | 2002-01-10 | Phenix Biocomposites, Llc | Structural biocomposite materials, systems, and methods |
| PL2862815T3 (en) * | 2013-10-15 | 2017-09-29 | Huhtamaki Molded Fiber Technology B.V. | Method for manufacturing a moulded fibre packaging and moulded fibre food packaging |
| CN215163322U (en) * | 2021-07-02 | 2021-12-14 | 苏州市怡太坊新材料科技有限公司 | Preparation facilities of farming discarded object cotton stalk skin fibre |
| DE102022121490A1 (en) * | 2022-08-25 | 2024-03-07 | Krones Aktiengesellschaft | Fiber material for making a container, method for making a container using the fiber material and container comprising the fiber material |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2757115A (en) * | 1953-01-30 | 1956-07-31 | Weyerhaeuser Timber Co | Felted, lignocellulose products and method of making the same |
| US3903229A (en) * | 1968-12-23 | 1975-09-02 | Andre Mark | Method for producing a compressed band of wood fibers for the production of wood fiber boards |
| US3939532A (en) * | 1972-05-15 | 1976-02-24 | Conwed Corporation | Manufacture of fibrous web structures |
| US4461648A (en) * | 1980-07-11 | 1984-07-24 | Patrick Foody | Method for increasing the accessibility of cellulose in lignocellulosic materials, particularly hardwoods agricultural residues and the like |
| US4676871A (en) * | 1985-08-29 | 1987-06-30 | Johnson & Johnson | Air laid peat moss board |
-
1994
- 1994-12-01 CA CA 2177984 patent/CA2177984A1/en not_active Abandoned
- 1994-12-01 WO PCT/US1994/013931 patent/WO1995015252A1/en active Application Filing
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8492128B2 (en) | 2006-10-26 | 2013-07-23 | Xyleco, Inc. | Processing biomass |
| US8597921B2 (en) | 2006-10-26 | 2013-12-03 | Xyleco, Inc. | Processing biomass |
| US8603787B2 (en) | 2006-10-26 | 2013-12-10 | Xyleco, Inc. | Processing biomass |
| US8609384B2 (en) | 2006-10-26 | 2013-12-17 | Xyleco, Inc. | Processing biomass |
| US8709768B2 (en) | 2006-10-26 | 2014-04-29 | Xyleco, Inc. | Processing biomass |
| US8846356B2 (en) | 2006-10-26 | 2014-09-30 | Xyleco, Inc. | Processing biomass |
| US8852905B2 (en) | 2006-10-26 | 2014-10-07 | Xyleco, Inc. | Processing biomass |
| US8900839B2 (en) | 2006-10-26 | 2014-12-02 | Xyleco, Inc. | Processing biomass |
| US9023628B2 (en) | 2006-10-26 | 2015-05-05 | Xyleco, Inc. | Processing biomass |
| US9347661B2 (en) | 2006-10-26 | 2016-05-24 | Xyleco, Inc. | Processing biomass |
| US10287730B2 (en) | 2006-10-26 | 2019-05-14 | Xyleco, Inc. | Processing biomass |
| US10704196B2 (en) | 2006-10-26 | 2020-07-07 | Xyleco, Inc. | Processing biomass |
Also Published As
| Publication number | Publication date |
|---|---|
| WO1995015252A1 (en) | 1995-06-08 |
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