US 3150038 A
Description (OCR text may contain errors)
p 22, 1954 J. P. RICH CONTINUOUS PULPING APPARATUS Filed Sept. 21, 1962 United States Patent 3,150,038 CGNTINUQUS PULPlNlG APhARATUS John P. Rich, Nashua, NH, assignor, by mesue assignments, to Improved Machinery End, a corporation of Delaware Filed Sept. 21, 1962, Ser. No. 225,264 Claims. (Cl. 162-237) This invention relates to the continuous pulping of fibrous material; more particularly, to apparatus of the type shown in Patent Nos. 2,878,116 and 2,878,117.
In those patents is described and claimed continuous pulping apparatus including an upright vessel having reciprocable foraminous solid particle lifting means, in the form of a perforated helical or fiat piston end surface, for compacting and advancing upwardly through the vessel in columnar form, wood chips or other particles fed onto the piston face, with the liquid in the vessel passing freely through the perforations of the piston face as it reciprocates.
Although the structure shown in said patents has proved to be highly satisfactory and commercially successful when fed with wood chips selected as to their size, clifficulties have arisen in cases wherein the material fed onto the piston face encompasses an extreme range of sizes, particularly when there is a considerable portion of large chips having flat surfaces in combination with material which may best be characterized as relatively small slivers of wood. With such a wood chip mixture, there may arise a relatively high degree of sealing of the perforations of the piston face during upward advance thereof, so that the piston may tend to stall in the direction of its upward movement. This, in turn, reduces the efficiency of the apparatus, or makes necessary the application of higher power to the piston, or both.
It is the object of tie present invention to provide a solution to the above mentioned problem, by providing a wood chip particle advancing member having a novel surface configuration, with projections making possible a greater liquid flow rate through the perforations thereof.
For the purpose of fully explaining further features and objects of the present invention, reference is now made to the following detailed description of preferred embodiments thereof, together with the accompanying drawings, wherein:
FIG. 1 is a cross-sectional elevation showing the particle compacting and advancing structure of Patent No. 2,878,116 with novel surface configuration according to the present invention;
FIG. 2 is an isometric view of the piston portion of FIG. 1;
FIG. 3 is an enlarged isometric view of a portion of the prior art piston surface showing typical wood chips jammed against it;
FIG. 4 is an enlarged isometric view of a portion of the piston surface of the present invention, showing typi cal wood chips supported thereon without jamming;
FIGS. 5 and 6 are, respectively, isometric and sectional views of a modification of the piston surface of FIGS. 1, 2 and 4;
FIGS. 7 and 8 are, respectively, plan and sectional views of another modification of the piston surface of FIGS. 1, 2 and 4; and
FIGS. 9 and 10 are, respectively, plan and sectional views of still another modification of the piston surface of FIGS. 1, 2 and 4.
As best shown in FIGS. 1 through 3, the novel advancing means of Patent No. 2,878,116 includes a foraminous screw means mounted for rotational and reciprocatory movement through a limited distance relatively to the length of the vessel within the reaction vessel 22 3,153,933 Patented Sept. 22, l94
near the lower end thereof by means of a shaft 36 extending vertically through the bottom of said vessel generally axially thereof. More specifically, said foraminous screw means comprises a single turn helical piston plate 32 having therein a plurality of perforations 34 sufficient in number to allow substantially free passage of the liq id therethrough but of small enough size to prevent passage of the chips or other fibrous material. Furthermore, the step of such helical surface is closed by a flat plate 36 extending vertically between its upper and lower edges 38 and 4t and the peripheral edge thereof is positioned closely adjacent the inner Walls of the reaction vessel 22 so that passage of chips into the bottom portion of said reaction vessel 22; may be prevented.
For feeding the pressurized mixture of chips and liquid to the upper surface of said plate, a tubular member 42 having its inner wall concentric with and spaced from shaft 3% is mounted on the lower surface of said helical plate 32 extending downwardly therefrom, thus providing a central aperture 44 between the upper and lower radial edges 38 and 40 respectively of said helical plate and extending radially from said shaft to said member in the lower portion of the helical surface near said lower edge 4d. Said movable member 42 is positioned closely within a fixed tubular member 43 mounted in the lower end of reaction vessel 22 and extending both upwardly therefrom to overlap the downwardly extending edge of movable tubular member 42 and downwardly therefrom to provide a connection to inlet valve 24 through pipe 46, the lower end of said fixed member being provided with a suitable seal 48.
The lower end of shaft 3%) extends into a hydraulic cylinder 50 mounted beneath the lower end of reaction vessel 22 and forms the piston thereof, said cylinder 50 being provided with an inlet pipe 52 connected to a suitable source of fluid pressure to raise said shaft with the helical plate 32 to reciprocate said plate, the force of the vessel pressure against the area of the upper end of said shaft being great enough to rapidly lower the plate when the pressure in cylinder Stl is exhausted, the pressure vessel 22 in such circumstances acting as an accumulator to provide the necessary force at a rapid rate. Suitable means (not shown) for alternately connecting pipe 52 to its source of pressure and to exhaust may be provided to reciprocate helical plate 32 at any desired rate. For rotating shaft 39 to rotate plate 32 in such direction as shown by the arrow in FIG. 1, a gear 54 is mounted on shaft 3%) for reciprocatory movement relatively thereto as by a heyway, and is driven through a pinion 56 by a hydraulic motor 58 operated from a suitable source of pressure (not shown).
In operation, the solid particle-liquid mixture or slurry is fed into the reaction vessel 22 by a centrifugal pump (not shown) so that it will be pressurized before entering said vessel. The mixture thus passes through the passageway formed between shaft 36 and tubular members 42 and 43, and finally outwardly through aperture 44 into the lower end of the reaction vessel 22 above the perforated helical plate 32. During a run, the reaction vessel is kept full of chips to maintain a compacted elongated mass or zone thereof, the individual chips moving slowly upwardly as they are reduced to pulp and discharged through mechanism 26 at the top of the reaction vessel.
During the feeding of the slurry into reaction vessel 22, the helical plate 32 is both rotated at a rate of say 6 revolutions per minute as shown by the arrow in FIG. 1 and reciprocated for a short distance axially thereof at a rate of say 12 strokes per minute as shown by the reference numeral Elia in FlG. l to provide an axial component of movement of the chips fed through aperture t") 44 to move them upwardly to the bottom of the mass of chips in the reaction vessel and compact them thereon and advance them therethrough by exerting force only against the chips at the bottom end of said mass or zone.
Since the mass of chips fills the reaction vessel and its bottom extends downwardly toward the helical plate, such rotational and reciprocatory movement acts on the bottom of said mass of chips to advance it upwardly at a desired uniform average rate as well as to compact it, and makes it possible for the helical plate 32 to move the mass of chips upwardly without exerting extraordinarily high pressures on the chips, as too high pressures seriously damage the chips and cause a substantial reduction in the quality of the resulting pulp. The digested chips are discharged as pulp through mechanism at the top of the vessel while at the same time the mixture of chips and liquid is continuously fed into the bottom of the reaction vessel beneath the mass of chips through aperture 44. Preferably, the limited reciprocatory movement is arranged to function normally to successively advance the mass of chips, the rotational movement acting normally to feed the chips outward through aperture 44- below the mass of chips. This may be accomplished by arranging the hydraulic pressure on motor 58 so that it stalls when the rotating helical plate comes into firm contact with the mass of chips. Since, with uniform chips, the liquid component of the mixture passes freely through the perforations in helical plate 32 during such reciprocation or rotation, neither the reciprocatory nor rotational movement will affect the movement of the liquid so that the chips may be advanced independently thereof.
The upward movement of plate 32 due to the pressure in hydraulic cylinder St? is relatively slow, occupying say 90% of the total cycle, while the downward movement due to the pressure of the vessel acting on the end of shaft 30 is much more rapid, occupying but about of the cycle. This is made possible by using the vessel in effect as a hydraulic accumulator. Such rapid down ward movement forces the liquid under plate 32 to move rapidly through the perforations 34, thus flushing away any solid particles that may have become lodged in or over the perforations 34.
As is shown in FIG. 3 however, a wood chip mixture having a considerable proportion of large fiat chips, particularly in combination with small slivers and the like, sealing of the perforations 34 tends to occur on upward movement of the piston face 32, such that liquid flow through said piston is restricted to a substantial degree. This restriction in flow is caused by the fiat surfaces of the large chips lying with the flat faces over the perforations 34, and with the areas between the large chips being filled with slivers and other debris of small pieces of wood chips. According to the present invention, a novel surface configuration is provided on the surface of piston 32 which will decrease the effect of chip sealing upon upward movement of the piston to the extent it is no longer a problem. The invention may accomplish such result by means of one or more of a variety of surface configurations, two of which are shown in FIGS. 1, 2 and 4.
Referring to those figures, the two projection means shown, either of which may be used independently of the other, comprise a multiplicity of discrete protuberances 60 distributed between perforations 34 generally uniformly throughout the surface of the piston plate 32, and a plurality of generally radially extending eddy bars 72, 74, 76, 78 each extending from the center of the plate 32 to its outer rim.
The protuberances. 60, as best shown in FIG. 4 are tapered in form, so that their tnansverse cross sectional area increases progressively from its top downward for at least a portion thereof so that jamming of a wood chip between adjacent protuberances cannot occur. With such protuberances, a multiplicity of channels are in (l effect provided between the protuberances along the surface of plate 32 for liquid flow therealong beneath the bottom of particles such as large wood clips supported on the tips of the protuberances. The protuberances shown in FIGS. 1, 2 and 4 may be constructed by utilizing drops of weld metal welded to the surface of plate 32, but other structures may be used as well, such as tapered studs 64 welded to plate 32 (FIGS. 9 and 10), circular grooves 66 cut in plate 32 providing channels connecting a plurality of perforations 34 (FIGS. 7 and 8), or a plurality of grooves 68 extending radially of a plurality of perforations 34 to provide liquid channels along the surface of plate 32 beneath Wood chips or other particles supported thereon (FIGS. 5 and 6). With such protuberances, when the piston surface 32 is moved upward to advance the column of Wood chips, the flow of liquid downwardly through perforations 34 caused thereby will tend to cause the wood chips to be sucked against the surface of the piston. However, the protuberances with channels therebetween will prevent the chips from sealing the perforations 34, because liquid will be able to flow along the channels provided and into and through perforations 34.
The eddy bars 72, 74, 76, 78 operate on a somewhat different principal by reason of the circular flow of the liquid on plate 32 caused by either the inflow velocity of liquid from aperture 44 or by the rotation of the plate 32 or both. This causes an eddy on the downwstream side of a bar such as is shown by the circular arrow in FIG. 4. Such an eddy will cause the large chips which are first drawn down onto the plate 32 to be arranged in a random manner with many of the chips edgewise to the plate. Thus fewer of the holes 34 are covered by large fiat chips and there is less opportunity for small slivers and the like to seal up the remaining perforated area. Thus liquid flow will be increased by reason of the change in average alignment of chips to a position less parallel with plate 32 than would otherwise be the case.
Thus the invention provides novel means effective to improve continuous pulping apparatus of the reciprocating piston type such as is shown in Patent Nos. 2,878,116 and 2,878,117. Various modifications of the invention, not shown herein, within the spirit of the invention and the scope of the appended claims, will occur to those skilled in the art.
1. In apparatus for the continuous treatment of the solid particle component of a solid particle-liquid mixture in an upright elongated vessel, means for feeding said mixture into the lower entrance end of said vessel and advancing the solid particle component thereof upwardly through said vessel substantially independently of the movement of said liquid in said vessel including a piston having a vertical central axis and a circular surface extending generally in a horizontal plane across substantially the entire cross section of said vessel, said piston having a multiplicity of perforations distributed throughout its surface and a plurality of generally radially extending eddy bars projecting from its surface in a direction parallel to said axis and means for rotating said piston about its central axis to move said eddy bars in a direction generally perpendicular thereto to reduce solid particle inteference with at least some of said perforations for free movement of said liquid therethrough.
2. Ln apparatus for the continuous treatment of the wood chip component of a wood chipdiquid mixture in an upright elongated vessel, means for feeding said mixture into the lower entrance end of said vessel and advancing the wood chip component thereof upwardly through said vessel substantially independently of the movement of said liquid in said vessel, said means including a piston having a wall extending generally in a horizontal plane across said vessel with a multiplicity of through perforations for flow of the liquid,
through said wall, and with an imperforate wood chip contacting operating surface extending continuously between and around said through perforations, said imperforate surface having a multiplicity of protuberances thereon providing channels between said protuberances for liquid flow along said channels and beneath the bottom of wood chips in contact with and supported directly by said imperforate surface including said protuberances, and means for reciprocating said piston, said wood chips being in contact with and supported directly on said imperforate surface including its protuberances upon upward movement of said piston for free flow of said liquid through said perforations.
3. In apparatus as claimed in claim 2, wherein a multiplicity of discrete protuberances are provided between said through perforations, providing a multiplicity of channels between said protuberances.
4. In apparatus as claimed in claim 2, wherein said piston has a circular operating surface with a central axis, and wherein said piston surface has a plurality of eddy bars projecting therefrom in a direction parallel to said axis, said eddy bars extending generally radially along said surface for a major portion of the radius thereof and further including means for rotating said piston.
5. In apparatus as claimed in claim 3, wherein the transverse cross sectional area of each of said protuberances increases progressively from its top downward for at least a portion of said protuberance.
References Cited in the file of this patent UNITED STATES PATENTS 1,259,048 Roberts Mar. 12, 1918 1,860,836 Gustin May 31, 1932 2,878,116 C-arlsmith Mar. 17, 1959