US2616802A

US2616802A - Fiberizing lignocellulose steamed under pressure and apparatus

Info

Publication number: US2616802A
Application number: US106904A
Authority: US
Inventors: Richard D Kehoe; Surino Alphonse; Ronald G Goodwin
Original assignee: Pandia Inc
Current assignee: Pandia Inc
Priority date: 1949-07-26
Filing date: 1949-07-26
Publication date: 1952-11-04
Anticipated expiration: 1969-11-04
Also published as: FR1022903A; GB678761A; NL84387C; DE847685C; BE496868A

Description

.u 'O m m 1 m 8 a 2 9. v 6 e 092.35 .wKS O E h 055:? f G N 00 s //(/l/ Alli/l m D M D m 2 w .HW A 4 Mme. A h a W H w. N S *2 v N m L O 3 2.3509. IRAR Y 0523 B R. D. KEHOE ET AL FIBERIZING LIGNOCEILLULOSE STEAMED UNDER PRESSURE AND APPARATUS Filed July 26, 1949 Nov. 4, 19 5 2- Nov. 4, 1952 KEHQE rr 1, 2,616,802

FIBERIZING LIGNOCELLULOSE STEAMED UNDER PRESSURE AND APPARATUS Filed July 26. 1949 3 Sheets-Sheet 2 INVENTORSI RICHARD D. KEHOE, ALPHONSE SURINO & RONALD G. Gooowm,

-Nov. 4, 1952 KEHQE 5 AL 2,616,802

FIBERIZING LIGNOCELLULOSE STEAMED UNDER PRESSURE AND APPARATUS 3 Sheets-Sheet 3 Filed July 26. 1949 INVENTORSI RICHARD D. KEHOE, ALPHONSE SURINO & RONALD G. GOODWIN,

BY WW ATTORNEY Patented Nov. 4, 1952 PATENT NG .LifiOCELLULOSE STEAMED "tiND'ER PRESSURE AND APPARATUS *RliehhfdDxKahoe, nialyme, Conii., and Alphonse fis lii'inogcwhite Plains, and Ronald ,G; Goodwin, Mgnnt yegnongl assignors to Pandia, Inc., a corporation of New .York

"iiiiiiiicfitioh ifiiiy', 1949, "sari-aim. 106,904

8 claims.

screening *andxi-efining offbfhshing o'utjto mike o the 'iiulp' suitable. for phiiei'making; Thus, in normal-practice thereii'siisedhisequenc ofmichinesi-ncliidinga, digster "a-'""dfibrtd1fi,' '5,- screen,

anderefiner. n v n V I .n

The. digester 2nd .defibratbr hais' Been made into a station that oilefate'bi :in "a continuous manner as compared with batch ofierat-icfi "and intead of digesting the wood-chips While inubmergehce in the digestahtliciudr,.digetithe wood-chins in Kehosj 1N0. 2323,19 1 eta-l c ens; 1943. In this fib ate unsie h i eager; I I

The wood 'chifis While ex ing sfgsmewhat due to the saturated 'refem tend to retaint-heir general chip hape or form durin the di t'd m'fizitfi"? in .thefciiiibf pulp that is bfo down an the chipiorm existing in the digester. ch61; thi inv nt on is to devie a; atisfac Solution that problem.

and yet di'chirging waiws and means for 'fragnientihfi'g mhet functions 1) of U f t pandeq ate al- 6f thedi '"tiichifisl mtd a bili'z'ed suspeni u the gasfecusgatmesgheecr the digester; (2)] attaxsmenenea :chiijfs 0 than rmgmnts against been where a "gains-t 5djaceht parts of the ai eetefiwracni teflifther rmgmentiz ing 61f 'ljriking cam for we am forms; and (3) bfaddi'n a fiioj'etiile'ifiihiils'e to the indbiliied hot r're fiw to" facilitatet eir passage t d "out from ai'chafg outlet in diminiited when: And Still ffiftfier object ofthis invention i's'td devi a discharge outlet or I'iort which when ii'sld m a ss citi'on with such means 11*; emiefip antigen-steamy in'calrriing but thefoi'ego g objects' fi'aihefi' in the form of at 'l'a'St' one sm l -ori ce having: "certain characteristics" here'm rter set' forth.

The continuoigs' vapli'f digesiii-of said patent and-flue t 'pncetidfi is characte ized-by a chip feeding-m2 "eye conduit or wide halving Iioii 'zoiita'il or lea ehip suppoftmg extent; and a combine 6r; "Z0 ing vertical extentddwn vtihicfi'the not'ma'te 1 e1 fans" and from which the material go to discharge with meris iIi-Lat least the horiioiiitfl zrie, to? controlling the rate bf progression of thechip's being"dige'std.-.

suc ariasrsembw, it a, featiireof'this' ire'htiofi to'prqvia a remame bIadedimpeHer so that digesting chip'ss6 ifalling ownwardly en counter theiinpliei'l 'fli ihifiller'has design and a speed of reset in summat the chips 21% rendered i made tip of siich chibe 25nd fra'gm'ent's thereof. 'Ifh ciearafie Between the impe-uer-maaesand the rici'sinlgi peripheral wallxsurrounding it is critical for fc'fcing by centrifugal action such mobilized suspended particles through one or more discharge ports or oiifices (also of critical size) that extend through the encasing wall. Such orifice tends to dirr'iinute still-further the fragmentized chips into shiv'es and fiber-mun-v d1es' even to' the extent offi'aying ends "of the latter. The impeller ha's'to have its blade formstion so designed and its Speed, of rotation sufficient to hindle filictuating'loads of chips fall-c' 'ing into it evh though these loads are somewhat 'ciihioried "by the high concentration of heat softened chip-fragments maintained in mobilized suspension around and in the general environment of the speeding impeller. Moreover, so that the impeller may impart to particles of the suspension sufiicient centrifugal impulses, and so that the fragments do not roil upwardly too far away therefrom, the diameter of the impeller is larger than the effective diameter of the down-pipe leading thereto whereby just above the free ends of the impeller blades, there is provided a limiting annular shoulder against which particles are forced by the blades. The particles are then reflected back by the shoulder either to be hit again by the blades or to engage the bottom of the impeller casing to be re-refiected. This continual batting about of the chip-forms sets up a high concentration of mobilized fragments in an annular zone within the casing surrounding the blades and from which discharge of particles takes place by centrifugal action through the discharge orifice in the impeller casing. j

In other words, the speed of the impeller is such that it is surrounded by and has justabove it, an atmosphere in intense swirling vortical motion or turbulence that is highly concentrated with suspended particles fragmented from the chip-forms. This turbulent mobilized suspension of substantially annular shape then flows away from the impeller through the adjacent discharge orifice under the combined forces (1) of the cen trifugal impulses given thereto by the impeller, (2) by the flowing stream of steam passing to escape to the atmosphere through the orifice as a result of the super-atmospheric steam pres- I sure within the digester, and (3) by the ends of the impeller blades wiping across the entrance to the orifice to prevent clogging thereof. There must be no tendency of the cellulosic fibers discharging through the orifice to explode 'when they reach the atmosphere because they would thus be degraded from a paper-making standpoint. Therefore, the steam pressurein the vapor digester must be controlled to be low enough to avoid that happening.

Another feature of this invention is the size of the orifice since it seems to have a screening or size-controlling effect on the chip-fragments that are permitted to passthrough it. Asconditions vary, it may be desirable to have means for controlling the size of the orifice used, bu cause shives are to be minimized in the pulp that is so emitted. Such fragments apparently are tumbled and batted about by the impeller blades as well as reflected or deflected between them and the walls encasing them so that they are still further fragmentized or diminuted until they are of a size small enough to pass through the screening or size-controlling orifice.

. The gradually increasing size of the emission conduit through which discharged pulp is blown from the orifice guards against degradation of such pulp by assuring their encountering gradually rather than suddenly or disruptingly release of pressure thereon and the residual momentum of the particles is great enough to keep them in turbulent non-segregating and nonplugging motion while protecting them from significant loss of temperature until they are delivered to a further treatment station. This is important because in the digester, the treatment temperature is such that the binding incrustants of the fibers are softened and it is often desirable that they be maintained above the congealing temperature of the softened incrustants after 4 discharge from the orifice and up to the time of the further treatment which includes refining or brushing out of the fibers.

The Beveridge and Kehoe Patent 2,323,194, shows the use of a defibrator acting on the cellulosic material of the heat-and-press'ure zone or chamber just prior to its discharge therefrom to the atmosphere. That defibrator has two coacting abrasive discs of which at least one is ro tatable. The purpose of the defibrator is to reduce the softened heat-treated material to a mas whose fibers are more or less individualized but are capable, without further treatment, of being used directly in making up hard board, insulating board, dry (saturative) roofing felt, and as a substitute for rags. The abrasive discs of the defibrator cut the softened Wood chips across the grain as well as parallel to the grain. Unlike that defibrator, it is a feature of this invention that its impeller has no abrasive functions, and one of its principal novel features is that the wood chips are notcut across the grain. Thus the impeller of this invention functions in such a way that nodefinite shear of the material is effected; it breaks the chips along the line of least resistance, that. is, with the grain or natural lie of the fibers. The clearance'between the impeller blades and their surrounding vertical enclosing walls is such that the softened wood chips are not subjectedto'shear ing. If the chips are raw and unsoftened, there might be shearing action but the size of the dis charged pulp shows that the. treated material has not been subjected to shearing. Thus, the wood-chips are broken down parallel to. the grain only, that is along their line of cleavage, so that the discharged pulp has its fibers in bundles or filaments or slivers that are not noticeably shortened but which have their ends significantly frayed out so that the filamented fragments are readily shredded or fiberized. Nevertheless, the discharged pulp is not suitable for direct use but must be further refined or brushed out before it is ready for making into sheets.

The pulp so producedv falls into two classes, namely, heat-treated pulp in one class, and in the other chemically-treated pulp. In both classes, the pulp discharged from the orifice and cooled, is a springy fibrous mass of woody par ticles, ranging in diameter from inch down to fine dust and ranging in length from fine dust up to one inch. Pulp that has been heat-treated only is a rather light brown, while alkaline chemically treated pulp is decidedly dark brown. However, neutral sulphite semi-chemical pulp is light brown. In the steam treated pulp, there is a greater proportion of larger bundles of fibers or slivers than in the chemically treated pulp. A noticeable characteristic of all of the particles and especially the larger ones is that their ends are fairly well frayed. The bundles or clumps or slivers of fibers are not at all brittle but they cohere so lightly that they are readily pulled apart with very little effort.

The best embodiment of this invention now known is illustrated in the accompanying drawings, in which Figure l is a somewhat diagrammatic view with parts broken away while Figure 1 is an entirely diagrammatic view showing the motions of material being treated. Figure 2, is a side elevation, also with parts broken away showing a practical embodiment of the invention with its associated apparatus. Figure 3 is an enlarged sectional viewof the suspension-inducingr i-mpellenthe discharge"orificegiits operah mg controls, andthe pulp omission' pipe. Fig ure is an enlarged, fragmentary, el'ewational view showing partswhich will "be -hereinafter fully described. Figure: 5 18 8 similar view but showing a different position or a movable p'art. Flgureois a drawnapartisometric view of the: parts shown in Figures 4- and 5 with control members as"--will"be hereinafter-described and explained. Figure 7 is anisometric view of the parts-shown inl'l igure t in assembled condition. Figure 8 is a fragmentary detail, sectional view takenat one end-oi "the views shown in Figuresv Sand '7.

Referring to Figures 1 and 2 the appara'hi's has a 'feeding in zone A, I and. I intermediatenzone B -'from which dependsa discharge-zone Cincluding an orifice-bearing closed-end terminal: zone D of a mobilized-suspension ol' tragmentized chips'slivers an'dfiber bundles, discharged therefeeder I2 forms the chips into a compacted plug formation [4 sufi'ciently dense to preventheat and pressure lossfrompipeor conduit l5 'of'the intermediate zone B. Conduit l5 has the'plu'g formation fed thereto eccentrically through feed opening I6" and the conduit ishori'zontally placed or'atfleast 'suificiently horizontal to support-the material beingtreated therein. Saturatedsteam is supplied to the conduit -l-5"through valved inj-ector pipe ""for maintaining super 'atmospheric pressure" and a temperature above 212"F-.. in both the intermediate zone 'Band'the discharge zone C for softening the middle llamella ror lig'neous incrustants of 'the fibers; Intothose'zones may also be supplied a chemical through'valved injection pipe I8 for'use in the event thatchemical or semi-chemical pulp rather thanmerely heattrea'tedpulp is desired. The chemical usedis such as to be reactive with the lig'neous: incrustants-on the cellulosic fibers of the chips-to render the normally water-insoluble incrustants while in situ'to-be water-soluble. The. conduit 1:5 'is much larger in diameterthanithe plug t4 in the neek-like casing 13 so that as the chips expand under th influence of the moist'heat in the conduit |'5;theyistil1 do'not fill thatrconduit substantially'over its axial line. Aiscrew conveyor-13, suitably rotated, is provided in the conduit'l iafor the: purpose of controlling carefully the rate of progress 'ofrchips 520 throughand-along the con rli as well'as the-total time-rot their transit therethrough under conditions that there 1 is no localized over treatmentt or degradation of the cellulosic fibers. Connectedttoward one "611C170! the conduit 15 depends: a down pipe 22 down whichv chips 120 from the "conduit 15 freely fall through opening 23. The down pipemerges into an impellenrcompartment that is clnsedofi at its bottom by closure wall or: bottom 24 through which extends a shaft '25 driven "byanotor 26. On. the upper end of the shaft2.5 is I an impeller '21. having blades 28. In'the horizontal plane of the impeller 21, there is at least one discharge outlet orifice or port 2 9 opening. into a discharge conduit that leads the pulp to=urther treatment. The efiective size of thedischarge orifice 29 .is controlled, such as by apparatusshown-in Figure 3, :and th clearance between the blades :28 of the impeller 2! and the encasin'g walls is 6 ens-earths "is the' diameter of :the discharge Gfl'fi. I -Rife'lrm'g now td 'athe impeller 21 is heldin lace on' sha ftili by nut'or hub 32..and each blade 28 isprferably set non-radial to the hub 32 provide pumpi'ng'action and "also is preferably shaped so that the outer 'iree end thereof is-somewhat taller than the inner "end thereof. The lower outer edge 34 is curved'to correspond with the 'cl'o'su're bottom 2! beneath the mpeller, because it is important that the clearance 'betweenlthis and the blades be nfinimized while the clearance between the blade ends- 33 and their encasmg wall 22' must be e critical distance. Just above the top of'the'blades 28, the effective diameter of the down-pipe 22 is smaller than the diameter of the wall 22' encircling the impeller z'l. One manner or: accompli'shing this relative relationship of smaller erfec'tive diameter of feed delivery pipe to larger diameter-of impel-lens by the interpositi'onaki aIIycf -thesIeeVe 35 in'the down-pipe 22, so that thelower terminus of the sleeve forms'an annular baflle' or shoulder '36 above the outer extremities or the blades za; I'he annular shoulder 30 and tend to cause -the fragments to rise, swirl'or r'o'il upwardly against the shoulder 36 which results in the strong defiective action downwardlybeing' imposed on'them. Meanwhile, the high rate. oi

rotation or the blades rotates or whirls the'mo bil'i'z'ed suspension so rapidly that c'entrifugalimpulsesare imposed on the iragmentssuffici'ent in addition to the flow velocity of the stream of steam in which they'are to impel them through the size-controlling discharge orifice 29.

The "speed of rotation of the impeller seems tobe most satisfactory at about 900 R. PJM. Clearanceb'etween the tops 33 of impeller-blades 2-8 and the annular shoulder 36 and clearance 1 between the'bottom of the impeller"bladesand the-bottom closure-24 should beaslittle'a's po's's'i ble so 'asto have no binding. The clearance-be tween the ends of :the impeller blades and the adjacent vertical wall -22" of its casing, which should be less than /8 inch or at least such that the ends of the impeller blades act as'wipe'rs' rmwiping the mobilizedfragments'past theorific'e and also reventing an clogging ofthe orifice by such fragments.

The discharge orifice 29 discharges" treated pulp into an emission conduit 30 of progressively increasing cross secti'on which conducts the pulp toa cyclone 38 having a gas-escape stack 39 and a water spray 40 as Well as a usual 'rniiier 4| for thoroughly mixing the treated-pulp'in a water bath 4| in a usual stock-chest. This bath may be heated by steam or otherwise, to control its temperature, as desired. A water suspension of the pulp overflows a usual weir 42 to pass through pipe 43' for further treatment, such as arefin'e'r or other combing-out machine 44-, such as a Sprout-Waldron refiner, the characteristic or.

which is thatthe pulp passes betweentwo abrasive'elements of which at least one rotates. The cyclone and refiner are. referred to collectively as further treatment station or refining station E.

Since the, effective size of the discharge orifice 29 is critical, one example of means forvarying its size is as follows: Referring to Figures 4 and 5, it will be noted that the discharge orifice 29 is practically oblong or elliptical in shape and is formed in a dished member 50 which is located in the side wall 22 encasing the impeller. The dished member 50 (Figures 6 and '7), is formed with a base portion 5| having annular walls 52, a portion of which is cut away at 53. A bore 54 is formed in the base 5| through which a shaft 55 engages. The dished member 59 has held in place thereon a threaded bolt 55 which engages through a bore 51 in the base portion 5| for securing an arcuate stop block 58 to the dished member 58.

An annular plate or disk 59, formed with a peripheral cut-out portion 59 is mountedwithin the dished member 50 and is adapted to oscillate therein. The shaft 55 engages through a bore 6 in the annular plate 59. One end of the shaft 55 is formed with a squared head .62 which engageswithin a corresponding recess 63 upon the annular plate 59 to lock the annular plate and shaft together. The outer or opposite end of the shaft 55 is mounted in a bearing 64 (Figure 8), formed in an upright supporting lug 65 formed upon the casing forming the pulp emission conduit 39.

That portion of the shaft 55 which extends outwardly beyond the bearing 54 is slightly contracted in diameter and is threaded as at 66. Upon the shaft 55, to the inner side of the supporting lug 65, there is attached a handle or lever 67 having a collar 68 which engages over the shaft 55 and is secured thereon by means of a set-screw B9. A similar handle or lever 19, slightly shorter than lever 61 is fixed upon a collar having a threaded bore which engages over the threaded portion 65 of the said shaft 55. Upon the extreme end of the threaded portion 66 of the shaft 55, there is provided a pair of lock-nuts T2 to limit the outward movement of the collar H.

The shaft 55 is locked against oscillatory movement, when the collar II is turned and jammed against the said supporting lug 95. When however the collar H is turned in the opposite direction it moves away from the supporting lug 65 and allows the shaft to be oscillated by the lever 61 and impart a corresponding oscillatory movement to the said plate 59 to fully open or close the said discharge orifice 29. The orifice size controlling means fit into a tapered coupling 13 having flanges l4 and '15 with a neck 16 adapted to enter a complementary opening in the wall 22' of the impeller casing. Flange l5 aids in attachment of the coupling in position while flange 15 aids in holding in position the handle assembly 5?, l and so on.

In Figure 4 the position of the plate 59 shows the discharge orifice 29 fully open while in Figure the plate 59 is positioned to partially close the orifice 29.

Operation The wood-chips are supplied to the feeding-in zone A of the digester or pulper, wherein the screw-feeder l2 forces the chips into the intermediate zone B of the digester under'conditions that prevent any substantial loss of steam therefrom. Saturated steam is supplied through steam-injection pipe ll while chemicals may (or may not be) added through chemical injection pipe I8. The digester is maintained at a temperature above; 212 F. and at super-atmospheric pressure by the supplied steam. The screw conveyor IS in the intermediate zone B that finds embodiment'in the horizontal or at least material-supporting pipe l5, and has as its purpose the determination of the rate of progression of the chips therealong whereby the time of transit of the chip-forms through the digester is under the control of the operator. The quantity of chips fed is correlated to crosssectional area of the horizontal pipe l5 (or vice versa) so that the chips never fill that area but space is left for the chips to expand due-to the heat, pressure and moisture conditions in that pipe. Although only one horizontal pipe I5 is illustrated as comprising the intermediate section, more than one pipe can be used.- Indeed, such digesters have been designed that make use of as many as eight superposed horizontal pipes connected by suitable vertical pipes therebetween.

The discharge zone C of the digester finds embodiment in a vertical pipe 22 that functions as'a down-comer or down-pipe down which chipforms freely fall from the screw conveyor l9. In so falling, the chip-forms encounter in the closed-end terminal zone D what may be termed a cushion of a mobilized, fluidized, whirling suspension of chips, chip-fragments, shives and fiber-bundles. This suspension that is generally annular in shape is produced by intense agitation and turbulence generated in the zone by means such as the impeller 27 with its blades 28. High speed rotation thereof causes the chipforms to be broken into fragments, or shives, and those fragments in turn are further broken down into fiber-bundles or slivers but all without cutting. This is accomplished by the speed of the blades which bat the chips around and especially against the walls encasing the impeller and the annular shoulder.

The suspension then is impelled out through orifices 29 partly due to the stream of steam flowing therethrough but more particularly by the impulses imparted thereto by the impeller. The diameter of this orifice is important because it seems to limit or control the maximum size of the fragment or fiber-bundles thereof that can be emitted threadingly through that orifice. To aid in the control of the maximum particlesize in the emitted suspension'the diameter of the orifice desired is under the control of the operator, by means of the handle or lever 67 for turning shaft 55.

From the orifice, the discharged suspension is conducted through the emission conduit 30 of increasing cross-sectional area to be emitted to the atmosphere. This gradually expanding emission conduit brings about a gradually decreasing pressure on the suspension so that when the fibrous material thereof does reach the atmosphere, no force is exerted on them that tends to' explode or otherwise degrade those fibers.

This turbulence minimizes segregation of the suspended particle during their transit through the conduit to the cyclone 38 and pressure energy of the steam in which they are entrained is transformed into kinetic energy, while the steam pressure is dropping approximately to a pressure equal to atmospheric plus the pressure head required'for conveying the particles to the cyclone. Due to the phenomenon of supersaturation which accompanies the expansion of steam in the conical conduit 39 from the so-called critical pressure to a little above atmospheric, the separating TI'Yhus all the available: heat willb imposed on the; fibrous ma-terial itself; while it is flowing through the conduit to the cyclone, instead of being spread Ollli'ilil, the cyclone or in escaping steam; Which would happen if the steam were not expanded "enough in the conduit. The high velocity of the flow in the conduit between the orifice and the. cyclone inducesheavy turbulence,

which greatly reduces the danger of plugging; A

v certain rubbing of the suspended fibrous: particles between themselves and on th wali of the conduit, further-g contributes to the ,fragmentizing of those particles.

This fibrous suspension or. pulp retains its. temperatureabove the congealing. point of the ligneous' fiber incrustan'ts (that bind the fibers. together. in wood) which havebeen significantly softened'within the 'digester,geither as a result (1) .of-steamtreatment alone'there-in, or (2) of steam and a lign'in-reactive chemical; If the-.fibrous suspension or pulp has been subjected solely to steam treatment in the digester, the pulpv (sometimescalled heat-treated pulp). can be conducted while .h'ot. directly to the secondary treatment station Eembodying a refiner. 44- or otherfiberbrushingout device. However, if the fibrous suspensioner pulp has been subjected in'the digesters tocombined action of steam and aligninrea'ctive chemical" '(such as caustic soda). that chemical reacts in the 'digester. With the? fiberincrustants to convert them while in situ on the fibers, from being water-insoluble into being water-soluble, then it is, usuallydesirable-to-conrequisite; temperature, and, pressure. Thus. there is :a constantly, flowing stream "of steam through the machine substantially from inlet to outlet, whose velocity is dependent upon the amount of steam pressure used. This flow'of steam from the discharge orifice will tend to entrain and carry with it some of the fibrous suspension but it has been found that there is a stronger tendency for the relatively tiny discharge orifice to clog or plug up. So one of the functions of the impeller is to have its blades sufficiently close to the orifice so that its inlet side or face is continually wiped to counteract any such clogging.

But a major function of the impeller is to fragmentize generally the heat-softened wood chips and render the fragments into a mobilized suspension plus imposing on each a centrifugal projection impulse which in addition to any entrainment capability of the stream of steam, impels the suspended particles through the orifice with significant force. While an important function of the discharge orifice is for controlling specifically the size of the discharge fibrous particles, its effective opening must be correlated to the steam pressure and the load on the impeller. The greater the steam pressure, the less is the load on the impeller and the smaller the discharge orificecan be. Also, the greater the steam .pressure-,..the less is the consumption of steam pressure per ton of pulp produced Therefore, as the steam pressure falls, the size of theori fice is increased to equalize the load on theimpeller so that it remains; substantially constant. But even so, the-variation in effective size of the orifioe is only permissible between narrow limits,

for" it hasbeen found possibleywhen using poundsof steampressure, only to vary the orifice openingto lie a range of from .1'96 to 1.Q4 square: inches; with the latter appearing to be themaximum, 4 1 V More than onedischarge orifice can be used, if desired, but each should be provided with the generally conical discharge conduit; If two orificesare used, they should be substantially apart,- and if four are used; they should be approximately 90 or less apart, but too much discharge areainvolves an uneconomic steam pressure.

The normal expectation isthat (1) the impeller will consume an uneconomic amount of;power, and..(2) that an uneconomic loss of steam will takeplace through the discharge orifice, but unexpectedly, neither takes place. Indeed, the imex-pected advantage of this invention is thatthe impeller takessubstantially less power to drive i-tfthana defibrator so it is cheaper to install as well as to operateryet at the same time itincreases substantially the output of the machine. While a refinerisrequired for secondary treatment, it too takessless power than otherwise and its output in turn is higher, so on the whole significant savings. result from-the use ofv this-invention. Theinvention is usable in connection with lignocellulosic material of many kinds of bothannual as well as perennial growths, besides wood-chips.

We claim: 1-. The continuous process oftrea-ting cellu 1051c fi-ber bearing material such as wood chips fonfiberizing them into pulp, which comprises maintaining atsuper-pressure anclsuper-temperature above 212 F; an enclosed conduithaving at least one material-supporting sectionleading to I a free-fallsection followed by a-closedend'terminal section having an orifice-in its peripheral wall for determining the diameter-of fragments passing therethrough, supplying a stream of pressured steam flowing through the conduit to exit from the orifice, feeding such chips into the conduit while minimizing loss of steam pressure therefrom, conveying such chips along the material-supporting section while softened by the steam, dropping the softened chips down the free-fall section, and ejecting chipfragments of predetermined size range from the orifice minimized as to shearing and degradation thereof as a result of treating them by the following steps: speeding the chips in the closedend terminal section in the plane of the orifice by projective and centrifugal force to form them into a whirling turbulent mass of mobilized gassuspended particles wherein the chips are generally diminuted along their lines of cleavage, maintaining the orifice in unobstructed condition by rotation of the whirling mass concentrated to wipe it clean, and forcing fragments from the whirling mass through the orifice with the stream of steam exiting therethrough while reducing specifically their diameter further along their lines of cleavage by threading them through that orifice.

2. The process according to claim 1, with the 11 addition of conducting the discharged suspension to the atmosphere through a passage of increasing cross-sectional area for minimizing explosive disruption of the fragments.

3. Apparatus for treating cellulosic fiber-bearing material such as wood chips for fiberizing it into pulp, which comprises an enclosed conduit having a feed section and means for feeding chips therethrough while minimizing escape of heat and pressure therefrom, a steam-containing material-supporting section larger than the feed section, a conveyor in the material-supporting section for conveying such material therealong while such material becomes softened by the steam, a free-fall section connected with the materialsupporting section into which the conveyor delivers the softened chips to fall therethrough, a closed-end terminal section to which the freefall section leads and which has an orifice through its peripheral wall, a motivated bladed impeller in the terminal section the outer edges of which lie in the plane of the orifice for keeping the latter wiped in non-clogged condition by having minimized clearance therefrom, means for supplying to the conduit a stream of steam under pressure to maintain the conduit at super-atmospheric pressure and super-temperature above 212 F. as well as to flow therealong to escape through the orifice, and means for controlling the maximum diameter of chip-fragments projected threadingly through the orifice by the impeller while surrounded by steam for specifically fragmentizing. them along their lines of natural cleavage.

4. Apparatus according to claim 3, with the addition of a conduit for conducting the suspension discharged from the orifice to emission to the atmosphere, with the conduit having increas ing cross-sectional area in the direction leading to the atmosphere.

5. Apparatus according to claim 3, wherein the effective internal diameter of the free-fall section is smaller than the diameter of the impeller.

6. Apparatus according to claim 3, wherein there is a generally horizontal annular shoulder opposite but adjacent to the impeller.

7. Apparatus according to claim 3, with means .for varying the efiective size of the discharge orifice.

8. Apparatusaccording to claim 3, with means for varying the effective size of the discharge orifice comprising a disc provided with a maximum size orifice therethrough, and pivoted gate means alignable with the orifice for reducing its effective size.

RICHARD D. KEHOE. ALPHONSE SURINO. RONALD G. GOODWIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 44,989 Whelpley Nov. 8, 1864 88,710 Hodges Apr. 6, 1869 369,836 Blackman Sept. 13, 1887 548,727 Spieldiener Oct. 29, 1895 848,484 Newnham Mar. 26, 1907 1,123,033 Stobie Dec. 29, 1914 1,127,615 Gilligan Feb. 9, 1915 1,293,654 Adams Feb. 11, 1919 1,383,881 Thomas July 5, 1921 1,450,600 Lendle Apr. 3, 1923 1,655,618 Mason Jan. 10, 1928 1,850,832 Ellis Mar. 22, 1932 1,922,313 Mason Apr. 15, 1933 1,991,244 De la Roza Feb. 12, 1935 2,063,367 De la Roza Dec. 8, 1936 2,129,789 Seaborne Sept. 13, 1938 2,184,248 Bonotto Dec. 19, 1939 2,289,934 Rapisarda July 14, 1942 2,342,225 Schnyder Feb. 22, 1944 2,359,543 Branzall et al Oct. 3, 1944 2,388,592 Asplund et a1 Nov. 6, 1945 2,394,182 Inglis Feb. 5, 1946 2,396,587 Lowgren et a1 Mar. 12, 1946 2,400,544 Kline et a1 May 21, 1946 2,422,522 Beveridge et al June 17, 1947 2,435,335 Messing et al Aug. 12, 1947 FOREIGN PATENTS Number Country Date 112,850 Austria Apr. 10, 1929 56,985 Denmark Nov. 2'7, 1939 a 551,013 France Mar. 26-, 1923 591,921 Great Britain Sept. 2. 1947 332,337 Italy Nov. 27, 1935 63,480 Norway Apr. 28, 1941

Claims

1. THE CONTINUOUS PROCESS OF TREATING CELLULOSIC FIBER-BEARING MATERAL SUCH AS WOOD CHIPS FOR FIBERIZING THEM INTO PULP, WHICH COMPRISES MAINTAINING AT SUPER-PRESSURE AND SUPER-TEMPERATURE ABOVE 212* F. AND ENCLOSED CONDUIT HAVING AT LEAST ONE MATERIAL-SUPPORTING SECTION LEADING TO FREE-FALL SECTION FOLLOWED BY A CLOSEDEND TERMINAL SECTION HAVING AN ORIFICE IN ITS PERIPHERAL WALL FOR DETERMINING THE DIAMETER OF FRAGENTS PASSING THERETHROUGH, SUPPLYING A STREAM OF PRESSURED STREAM FLOWIG THROUGH THE CONDUIT TO EXIT FROM THE ORIFICE, FEEDING SUCH CHIPS INTO THE CONDUIT WHILE MIMNIMIZING LOSS OF STEAM PRESSURE THEREFROM, CONVEYING SUCH CHIPS ALONG THE MATERIAL-SUPPORTING SECTION WHILE SOFENED BY THE STEAM, DROPPING THE SOFTENED CHIP DOWN THE FREE-FALL SECTION, AND EJECTING CHIP FRAGMENTS OF PREDETERMINED SIZE RANGE FROM THE ORIFICE MINIMIZED AS TO SHEARING AND DEGRADATION THEREOF AS A RESULT OF TREATING THEM BY THE FOLLWING STEPS: SPEEDING THE CHIPS IN THE CLOSED END TERMINAL SECTION IN THE PLANE OF THE ORIFICE BY PROJECTIVE AND CENRIFUGAL FORCE TO FORM THEM INTO A WHIRLING TURULENT MASS OF MOBOLIZED GASSUSPEDED PARTICLES WHEREIN THE CHIPS ARE GENERALLY DIMINUTED ALONG THEIR LINES OF CLEAVAGE, MAINTAINING THE ORIFICE IN UNOBSTRUCTED CONDITION BY ROTATION OF THE WHIRLING MASS CONCENTRATED TO WIPE IT CLEAN, AND FORCING FRAGMENTS FROM THE WHIRLING MASS THROUGH THE ORIFICE WITH THE STREAM OF STEAM EXITING THERETHROUGH WHILE REDUCING SPECIFICALLY THEIR DIAMETER FURTHER ALONG THEIR LINES OF CLEVAGE BY THREADING THEM THROUGH THE ORIFICE.