US2405213A - Process and apparatus for production of fiber from vegetable matter - Google Patents

Description

Aug. 6, 1946. c. c. HERITAGE v 2,405,213

PROCESS AND APPARATUS FOR PRODUCTION OF VFIBER FROM VEGETABLE MATTER Filed Aug. s, '1940 space by the expansion of v content of the original Patente ug. 6, ld

PBOGESS AND APP l,

TON F MTTER 'ros non Pnonuc- .'le snor/r vnoa'rnnnn Clark C. Heritage, Cloduet, Minn., asslor to Wood Conversion Coni corporation oi Belawar pany, Cloquet, e

Application August 3, 1940, Serial No. 351,066

(ci. az-o) Cla.

The present invention relates generally to the production of pulp, and in particular to apparatus therefor. p Reference is made to the Asplund U. S. Patent No. 2,008,892, describing a machine for the production of pulp. The raw material in the form of wood chips, grasses, straw, bagasse, cane, and the like is fed into a. magazine ahead of a steam pressure chamber in which is housed a rotary device for reducing the material to pulp in a steam environment and particularly in the absence of suspending water. Beyond the defibering chamber there is an outlet device having in series alternately operating valved orice's. By this device, one oriiice discharges from the machine while the other oriiice is closed. The :fiber trapped be-` tween the valves is discharged from the intervalve the high temperature steam also trapped in said space. As originally taught and disclosed the said device discharges the ber into water.

In applying the Asplund machine to other uses. wherein it became desirable to dry the ber directly, the discharged fiber was carried by a belttype conveyer. to a suitable drier device which happened to be located at some distance from the machine and at a. considerable height above it.

One object of the present invention is to provide means to carry the discharged fiber from the machine for considerable distances away from and even to a higher level, without the use .of mechanical means and power to convey the fiber.

In particular, it is an object of the invention to utilize the pressure of the discharged steam to convey the ber for long distances with or without elevation.

n is sun a further object of the invention to provide a cyclone system at the end of said conduit for separating :dber and any steam or gases attendant the discharged material.

A further object of the invention is to provide to said cyclone system a supply of drying gas or air for the removal of water from, or for drying, the ber in the cyclone system.

It is also an object oi the invention continuously to reduce lignocellulose raw material, especially wood, to a mass of ilbers, and especially dry fibers, with retention of substantially all the solid material, and with change in the content of the original material so that it presents less resistance to certain treatments by ,water. chemical solutions` and other reagents, where it is desired to use the ber as a starting point to produce bers lacking in some of the solid content of the original wood other than its alpha cellulose content.

Various other and ancillary objects and advantages of-the invention will become apparent from the following description and explanation of the invention, as illustrated by the accompanying drawing in which:

2 that a back I many factors involved Fig. 1 represents a plan view of a machine according to the Asplund U. S. Patents No. 2,008,892 and No. 2,145,851.

Fig. 2 represents a. conduit and a cyclone system attachedy to the machine and used to separate steam and gas from the rlber as formed, and used also to dry the ilber.

The apparatus not only provides economy in power and convenience in handling, but may give desirable processing to the ber. It is a stated objective of the Asplund patent and its process Patent No. 2,008,892, to minimize the time of exposure of the material to the elevated temperatures used in forming the liber. yIn connection with other developments employing forming conditions as they emst in the said Asplund machine, I have found that it may be desirable to expose the material, and especially the formed ilber, to elevated temperatures, and particularly to steam, ior a much longer time than is permitted by normal operation of said machine. l

By employing a long conduit, I have discovered pressure may exist continuously in the conduit at the discharging orifice of the machine. This is reduced as the body of ber carriecl in the conduit moves on toward the discharge end into the atmosphere or other receiving space -of pressure lower than that in the debering machine. Of course, the length of this pressure zone in the conduit is dependent in part upon radiation from the conduit, which may be controlled by insulation or its heat surroundings, or both. ere the gas pressure ceases to exist in the conduit the fiber is moved along as a column :by mechanical pressure from that portion of the ber which is moved bythe gas pressure.

It is vof course to be understood that there are which anyone skilled in the art will naturally be obliged to consider in in,- stalling or operating the apparatus.- Friction of fiber with the conduit, weight of the' column of iiber tobe lifted, and the existing moisture of added condensate, are all forces opposing the pressure. With these opposition forces also must be considered the loss or pressure in the gas or steam as a result of its expansion or its cooling.

However, in spite of all these oppositions, I have found that a conduit in diameter the same as the machine oriiice, say 6 inches, may extend ior 150 to 200 feet and at the same time elevate the :ber

. by as much as 50 feet, the conduit discharging may be operated to into air from a deiibering pressure of lbs. per sq. in. steam pressure. Such distances readily accommodate various pieces of equipment in a plant, at different levels, and at remote locations, to simple connection by a conduit to a iixedly located debering machine, whereby a plant is made flexible, and whereby a defiberingmachine produce and discharge fiber for various processes of utilization.

The exposure of raw material to thesteam'in the machine continues for such a short time, that the chemical reaction-in the machine is limited. I have found for example, that by extracting bers ofraw aspen not at al1 preheated, using 2% ber consistency in water for two hours, the water soluble extract is about 4% to 5% of the dry wood used. Using liber debered in the Asplund machine at 135 lbs. pressure of steam;and imme-4 diately exposed to the atmosphere, the watersoluble content is about I have also determined that prolonged exposures to steam will bring thelike water extract to about 2'1 as a practical limit. By use of the conduit as a steam chamber I may control water solubles to various degrees, in the case of aspen, between substantially 10% and 27%. I have also found that high temperatures and short times can produce as much water-extract as a certain combination of lower temperature and longer time, there being less darkening of the ber at the latter condition. Hence, for prolonging the steam eilect it is desirable to use a lowertemperature than exists in I the Asplund machine. The discharging valve structure of the Asplund machine-is an excellent pressure reducing device for such purpose, and the lengthy conduit is an excellent means for prolonging the time of exposure.

esdry m Fig. 1, an spinne machine is illustrated in' part, showing the essential parts.

A tubular chamber i 0 is used to introduce wood as chips, or other lignocellulose material into a high pressure environment within the machine. The inlet i0 has a serrated or notched interior wall which acts to prevent steam pressure Vpushing back a plug in the inlet iormed'of the raw material by the action of a ram or plunger I I, acting on raw material fed into the path of the plunger through a hopper opening i2 (Fig. l) under a hopper i3 (Fig. 2). The inlet l0 opens into a magazine il capable of holding high pressure steam therein. The bottom of the magazine connects by a passageway i5 having a screw conveyer I6 therein, operated on the axis i1, by power.

connection i8. The conveyor feeds the raw material to the center of opposed grinding disks 2d and 2|. Disk 20 is stationary and receives the raw material near its center. Disk 2| rotates at high speed on connection 23. Means (not shown) permits adjusting the spacing between the disks. A housing 24 for the grinding disks opens .to an outlet connection 25. Steam is fed from a supply 26 to a distributing system 21 for introducing the steam into various inlets to the spaces within the machine.

The outlet is connected to an oflset extenthus led into a fan housing axle 22, driven by a powerful belt Y sion xture 28 with valves 30 and 3l at its ends.

The valves are arranged to have parallel operat 33. and mechanism (not shown) so operates them that when one is closed or substantially so the otheris open or substantially so, as indicated by stressed arrows 34 and 24". These reciprocate rapidly andin operation, rst admit steam andberintothexture ,thenatleast ingstemsSZand partially closethe Aiixture at the machine end other end to discharge the opening of the valves and control the the ilber while opening at the ber. The degree of the vtiming is adjustable, in order to amount or steam pressure accompanying to move it along as described below.

The discharge end or nx'ture 2l is connected by elbow 35 to an extending conduit 3i, shown in Fig. 2 only in cross-section, indicating its vertical extent, better shown in Fig.

longV distances' horizontally and vertically, and

2. IThis may run for' be branched and valve-controlled. To avoid plugging bythe body of ber moving therein, sharp angles are avoided, as represented by sweeping bends and Il. A Y fixture l2 and valves 43 and Il are shown, as oi the gate type. These may be opened readily, but for closing, the supply of fiber may be stopped until the valve is cleared by the end of the moving liber. Branch I5 leading from valve 43 represents a supply to any use. Branch IB leading from valve 44 represents connection to a cyclone or cyclone system.

In the machine, some slight amount oi' gas ls generated from reactions in the wood at the temperature of the steam, and it is desirable to discharge these. This is permitted by any 'simple cyclone to separate the fiber from the gas and also any residual steam, the discharged ber being moist. Where moist liber is useful, it may be taken from such a simple cyclone. However, for the purpose of producing dry fiber, the first cyclone is made a part of a cyclone drying system as now described.

A plurality of cyclones is used, the number being dependent upon design to effect ultimately a fiber. Four are illustrated and designated 50, 5l, 52 and 53. Conduit 46 enters the top of cyclone 50 which discharges gas and steam to the atmosphere at 54. The bottom of cyclone 50 has alternative outlets, merely for the purpose .of illustration. Outlet 55 represents the path for removing moist fiber, and a valve 56 is shown to cut on such outlet. The other outlet is associated with the cyclone system as follows:

Cyclone 50 drops the iiber into a housing 51 in which a vaned rotor 58 operated by motor 59, drops the fiber into a conduit S0 supplied by hot gas from a supply main 6l Fiber and hot air are 63 which blows it through conduit 54 into cyclone 5 i The cyclones 5I and 52 continue the series in the same way by like equipment, with some lows: hot gas conduits 55 and 66, fans S1 and 68. ian-outlet conduits 69 and T0. Conduit 10 leads into cyclone 53, which drops dry ilber into e, receiver 1i.

Where the fiber is useful dry, a high yield is obtained from Wood or the like with substantially all the solid substance preserved, as described in my copending application U. S. Serial No. 227,338, now abandoned, filed August 29, 1938, of which the present invention is a continuation in part.

Where the ber is to be used as a raw material for a solvent extraction, the moist or the dry fiber may be used for extraction by an aqueous solvent.

The extent to which the liber is subjected to steam (see my copending application U. S. Serial Nos. 351,041 to 351,065, filed August 3, 1940, and related cases), inuences the content of extractable-matter and the character of the liber.

composition.y By design and operation as above described, the extent of time and exposure to parts indicated as folv debering means in to feed lignocellu-` -movement of the said nbermg by said centering means, said feeding means being arranged and constructed to prevent the exit of steam from said chamber, pressurereducing means operated to open intermittently in rapid succession for providing an outlet from said chamber for steam and ber, whereby small .batches of loose ber are discharged in rapid whereby said pressure-reducing means freely discharges ber in to saidconduit and into an atmosphere of steam under a pressure which eects small batches of ber along the conduit to said discharge end While exposing all the bers thereof to the steam in said conduit for a period of time during traverse of the conduit, the length of said conduit further being such that the time of exposure of bers inA said conduit to steam is longer than the time of exposure of lignocellulose to steam in said chamber.

2. Apparatus for continuously producing ber comprising in combination a high pressure chamber for containing steam under pressure, means to feed high pressure steam into said chamber at a temperature to effect softening of lignocellulose said chamber, whereby thermal action in the and at which the lignocellulose becomes softened continuously discharging steam and ber froml said chamber into an elongated laterally conned space and reducing the pressure of the steam at said discharge, while continuously moving said ber alongsaid space and discharging said ber from said space by the reduced pressure o1' said steam into a region of pressure still lower than said reduced pressure, and while employing the length of said space to create a pressure of steam increasing in the direction from said region to presence of steam is'eiected on all the ber in said space to alter its composition as it moves alongsaid elongated space..

4. The method of continuously producing ber which comprises continuously introducing lignoceilulose material t be defibered into a pressure debering said lignocelluchamber an'd in the absence of a suspending quantity of water at a temperature above 212 F.

to permit ready debration, while substantially continuously discharging steam and ber from said chamber into an elongated laterally' conned space and reducing the pressure of the steam at said discharge while continuously moving said length of said space .to create in said chamber, feeding means to feed lignocellu- 1,

lose vegetable matter into said chamber to be debered, said feeding means being arranged andv constructed to prevent the exit of steam from said' chamber, rotary debering means in said charnber, means within said chamber to feed said lignocellulose to said debering means, pressure-reducing means operated to open intermittently in rapid succession for providing an outlet from said chamber for steam and ber, whereby small batches of loose ber are discharged in rapid succession, and an open-ended conduit connected to and extending from said pressure-reducing mean for containing ber and steam under pressure-and for conveying the ber, said conduit l having a length and cross-section which together are such as to permit said pressure-reducing means to eiect a reduction in pressure and t0 `cause a back pressure of steam in said conduit increasing from the open and discharge, end of said conduit to said outlet of said chamber,

whereby said pressure-reducing means freely discharges ber into said conduit and into an atmosphere of steam under a pressure which effects movement of the said small batches of ber along the conduit to said discharge endwhile exposing all the bers thereof to the steam in said conduit for a period of time during traverse of the conduit, the length of said conduit further being such that the time of exposure of bers in said conduit to steam is longer than the time of exposure of lignocellulose to steam in said chamber.

. 3. The method of continuously producingber which comprises continuously introducing lignocellulose material to be debered into a pressure chamber, continuously debering said lignocellulose mechanically in the presence of steam in said chamber and in the absence of a suspending quantity of water at a temperature above 212 F. and at which the lignocellulose becomes softened to permit ready debration. while substantially ber along said space and discharging said ber from said space by the reduced pressure of said steam into a rgion of pressure sti1l.lower than said reduced pressure, and vvhile employing the `a pressure of steam increasing in the direction from said region to said chamber, whereby thermal action in the presence of steam is effected on all the ber in said space to alter its composition as it moves along said elongated space, the time of exposure of the ber to steam at the reduced pressure in said space being longer than the time of exposure of the lignocellulose to steam at the higher pressure in said chamber.

5. The method of continuously producing ber which comprises continuously introducing lignocellulose material to be deflbered into a pressure chamber, continuously debering said lignocellulose mechanically in the presence of steam in said chamber and in the absence of a suspending quantity of water at a temperature above 212 F. and at which the lignocellulose becomes softened to permit ready debration, while substantially continuously discharging said chamber into an elongated laterally conned space and reducing the pressure of the steam at said discharge, while continuously moving said ber along said space and discharging said-ber from said space by the reduced pressure of said steam into a region of pressure still lower than said` reduced pressure, and while employing the length of said space to create a pressure of steam increasing inthe direction frdm said region to said chamber, whereby thermal action in the sure in said chamber.

,CLARK C. HERITAGE steam and ber from

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