US2425335A - Fiber processing apparatus - Google Patents

Description

g 1947- H. s. MESSING ET AL 1' ,425,335

FIBER PROCESSING APPARATUS Filed Oct. 11, 1943 s Sheets-Sheet 1 4*. f2 ATTORNEY File d out. 11, 1943 ets-Sheet 2 3 She V a," r INVENTORS %?2m.

ATTORQAI? Aug. 12, 1947.

H. S. MESSING ET AL FIBER PRQCESSING APPARATUS Aug. 1947- H. s. MESSING El AL 2,425,335

FIBER PROCESSING APPARATU;

Filed Oct. 11, 1943 3 Sheets-Sheet 3 a? um 155M035 J- ATTORNEY Patented Aug. 12, 1947 FIBER PROCESSING APPARATUS Hjalmar S. Messing, New York, N. Y., and Clarence L. Durkee, Wausau, Wis.

Application October 11, 1943; Serial No. 505,884

4 Claims.

This invention relates to an apparatus for sub jectlng solids in fragmentary form, such as wood or fibre chips, flakes and shreds or small aggregates of vegetable, animal or other origin, to the treating action of a fluid reagent either gaseous or liquid, while under controlled pressures, the same being carried forward in a regulated manner by introduction of untreated material and removal of treated material without loss of the maintained pressure, all while movement into, through and out of the treating fluid is being induced under conditions subject to positive control, and at the same time without drastic mechanical or hydrodynamic disturbance.

, While the apparatus of this invention in its general aspects is adapted for -the processing of a wide variety of substances, edible as well as non-edible, where a thorough contacting of a reagent with the substance being processed with a minimum disruption of structure is desirable, it is contemplated that a major field of its application is and will remain the reduction of wood and other fiber to cellulosic pulp suitable for fiber board paper, textile and chemical uses. This invention is therefore herein described by reference to this specific field of utilization for illustrative purposes and not for any purpose of limitation.

In the processing of wood chips for the production of pulp it is common to subject the wood chipsto the action of treating liquors at temperatures in excess of the boiling point of the liquor at atmospheric pressure, and this requires the maintenance of considerable pressure. Large digesters or cookers provided for this purpose suffer the limitation that their contents are not uniformly treated except with great difiiculty, and then only with a degree of hydrodynamic disturbance which results in much disruption of structure and formation of fine pulp, which must be removed to prevent overtreatment. Furthermore, such batch treatment of bulky material requires large and uneconomical equipment and a comparatively high amount of labor. per unit of material treated. Numerous attempts to carry on pulp digesting processes continuously have been made, but the complexity of the equipment required and the unsatisfactory nature of the results obtained therefrom, largely because of premature mechanically induced disintegration, have limited the adoption of such methods.

It is an-object of this invention to provide an apparatus capable of operating at pressures other than atmospheric pressure and adapted for continuous digesting or processing under conditions permitting preservation of structure and precise control of conditions.

an apparatus for treatment of fibrous materials in which material to be treated may be introduced without substantial escape of reagent or loss of treating pressure and from which treated material may be removed likewise without substantial loss of treating pressure.

Another object of this invention is to provide apparatus for treating fibrous material by submerging in a liquid treating medium atpressures other than atmospheric pressure with a minimum of disruption of the fibrous aggregates undergoing treatment.

The above and other objects of this invention will become apparent from the description which follows. In describing this invention reference is made to the accompanying drawings which form a part hereof, and in which there is set forth by way of illustration and not of limitation one specific form in which an apparatus constructed in accordance with this invention may be assembled.

Inthe drawings:

Fig. 1 is a side view in elevation and partly in section showing one form of the apparatus of this invention;

Fig. 2 is a detail view in section and in elevation viewed through the plane 2-2 indicated in Fig. 1;

Fig. 3 is a detail view partly in section and in elevation of the discharging and disintegrating part of the apparatus shown in Fig. 1, viewed through the plane 33 indicated in Fig. 1;

Fig. 4 is a detail view in elevation and in section of the escape mechanism at the outlet of v the disintegrating mechanism shown in Fig. 3;

cated in Fig. 1, showing the feeding portion of the apparatus;

Fig. 7 is a detail view in section viewed through the plane 11 indicated in Fig. 1, showing the manner in which the flexible conveying element is guided.

The form of the apparatus of this invention iilustrated in the drawings, comprises as a principal element a continuous closed loop of conduit disposed in a vertical plane and designated generally by the numeral I. As appears more clearly in Fig. 1, the loop I is mounted upon supporting struts 2 extending upwardly from beams 8 in a floor 4 of an appropriate structure. Additional support for the loop i is furnished by adjusting bolts 8, which engage the rim of apertures in the floor 4 at the points where the loop passes downwardly therethrough. The adjusting bolts 8 may be set to accommodate for changes in dimension resulting from thermal expansion and the like, thus providing a secure mounting for the loop I at all times.

The loop i is made up of a plurality of segments, each specialized for the particular purpose for which it is to serve. At the extreme top of the apparatus there is provided the driving and discharging segment 8, additional details of which appear also in Fig. 3. Mounted within the segment 8 is a driving sprocket 1 carried upon a shaft 8. The shaft 8 is mounted to turn in bearings provided therefor in the sides of the segment 8 and is surrounded by a packing gland 8 at the point where it emerges from the segment 8. The opposite end of the shaft 8 is covered by a fluid tight cap It, thus permitting the sprocket 1 to be turned by means outside of the segment 8 without escape of fluid contained under pressure therein. The shaft 8 may be turned by any suitable means, such as a pawl II and a ratchet wheel II, as shown in Fig. 3. Extending downwardly from. the segment 8 is a releasing hopper 13 into which material carried into the segment 8 may fall and from which it may pass downwardly into a material discharging and disintegrating apparatus, designated generally by the numeral l4, to be described in greater detail hereafter.

The part of the segment 8 standing to the left in Fig. 1 joins with an inlet segment l comprising an inclined portion and a vertically standing branch portion 18 into which solid aggregates may be introduced by means to be described more fully hereinafter.

Joining with the lower, end of the segment I! is a corner segment l1, which in turn joins with the upper end of a vertical submerging segment I8. The submerging segment 18 comprises a straight vertical section of conduit surrounded by a temperature regulating jacket is and provided at its extreme lower end with a fluid inlet connection 20.

The lower end of the segment l8 joins with a corner segment 2|, which in turn connects with a horizontal inspection segment 22. The inspection which is provided with a temperature regulating jacket 28. The upper end of the emerging segment 21 is provided with a flange 28 in which adjustable mounting bolts 8 are carried. Secured to the flange 28 is a fluid withdrawal segment comprising a flanged outer jacket 38 and an internal perforated sleeve 3| having a bore corresponding with that of theremainder of the loop I.

Joining with the fluid withdrawal segment II is a corner segment 32, which in turns joins with the inclined wash-back and drain segment 88. The wash-back segment 88 at its opposite end joins by means of a packed expansion joint 84 with the driving and discharging segment 8 to complete the closed loop I. A substantial portion of the lower surface of the segment 88 is perforatedto permit withdrawal of fluid and the entire perforated area is embraced by a fluid-tight Jacket 38 for control of withdrawn fluid.

To assist in the discharge of material from the loop I and to enhance the economy of the apparatus by recovery of treating fluid, a wash-back jet 88 mounted as shown in segment 8 is provided. The jet 38 is so mounted and directed that a major part of the washings therefrom may drain through the perforated portion of segment 88 without substantially diluting treating fluid carried elsewhere in the loop I.

Material released for discharge in the segment 8 drops into the discharging mechanism I4 shown in greater detail in Fig. 3. The discharging mechanism l4 comprises a drain casing 81 to which there is attached a conical discharge nose 88 within which a tapering plug-forming screw "is mounted to turn. Solid material to be discharged, falling into engagement with the screw 39, is advanced toward the right as observed in Fig. 3, and in so doing is compacted and part of the liquid content removed by a squeezing action. Liquid thus expressed is allowed to escape through the perforated wall of the drain casing 81 and is caught, collected and carried away by the jacket 40and outlet channel 4|. An appropriate driving means for the screw 38 is provided in the form of a motor and reduction gear 42, sprockets 48 and 44 and a chain 45.

Since the apparatus of this invention is especially suited for the advantageous carrying out of so-called semi-chemical methods of digesting or pulping, the discharge from the nose 38 may be directly fed into an attrition mill of the bur type as indicated generally by the numeral 48 in Fig. 3. or into any suitable mechanical or hydraulic disintegration device such as a rod mill or a high pressure impact target under the impulse of a strong hydraulic jet. Washing, refining, screening, filtering, or any of the usual treatments may be applied to the discharged material as desired, depending upon the degree of digestion attained in the treating loop and the nature of product required.

In the discharge of thematerial through the nose l8 and its compaction a plug is formed, permitting the maintenance of the desired pressures within the system without substantial escape of the atmosphere therein contained. If, for any reason, the pressure retaining properties of this plug are insuflicient an alternately operating pressure gate 41, as shown in Fig. 4, may be applied to the outlet of the mill 48 or directly to the nose 88 if the mill 46 is to be dispensed with.

For introduction of solids to be treated without loss of pressure from the loop I, the arrangement shown in Fig. 6 is provided. This feeding arrangement comprises a plunger 48 arranged to be reciprocated by a crank 58, a rod 58, and a crosshead 54, in a barrel 49, the upper portion of which opens into a hopper 50 through which incoming material is fed. The plunger 48 successively advances-dense, pressure-sustaining increments of the material being fed into an internally ribbed throat SI. The internal ribbed surface of the throat 5| has a configuration such that retrograde movement of the pressure-sustaining lncoming material is inhibited and thus a plug is formed through which the internal atmosphere of the loop I cannot escape. To facilitate starting up and shutting down and to ensure against loss of pressure, if for any reason the plug in throat 5| should become dislodged, a swing check 52 is provided. If the apparatus is intended to operate at pressure below atmospheric pressure, the ribbed surface of the throat 5| may be appropriately modified. Incoming material is advanced through a fore chamber 53 and thence into the vertical receiving portion I6 oi the segment I5 and thus into the loop I. If desired, a packing or carding device, not shown, may be situated in the fore chamber 53 to open up the plug as it enters this chamber when the material does not have sufficient natural resilience to open of its own accord.

Material received in the loop I in the manner above described immediately becomes engaged by a conveying mechanism comprising, as shown in Fig. 1, a continuous flexible member or chain 51 carrying spaced transverse flights 58. This conveying mechanism is advanced in the direction shown by the arrow under the influence of the sprocket I driven as shown by the arrow in the manner previously described. In this way incoming material is immediately engaged and compelled to move in a. positive manner subject to complete regulation. During such movement the material is first subjected for a predetermined interval to the action of the gaseous or vaporous environment above the liquid level 19. The material is then submerged as it reaches the level of the treating liquid contained within the loop i and then is carried in a positive manner through such treating liquid likewise for a predetermined period until it emerges therefrom. The liquid levels designed in Fig. l are illustrative only since it is obvious that they may be varied as desired and in any case the dlifierence between the two liquid levels will depend to a considerable extent upon the rate at which the conveying mechanism is operated and other factors. After emergence, the material undergoing treatment is allowed to drain, is subjected to washing and to the gaseous environment, all for a predetermined interval, and then is released in segment 6 for delivery into the discharging mechanism I4. If desired the entire loop or substantially all of it may be operated full of liquid with direct introduction of material to be treated into liquid instead of vapor, or if desired the entire treating environment may be gaseous with substantially no liquid contained in the loop.

To aid in guiding the conveying mechanism particularly in those portions of the loop I which are not rectilinear, a guiding rail 59 formed integrally with the several loop segments is provided. The guiding rail 53 appears in the upper part of Fig. 1, extending downwardly to the left from sprocket I, and thence throughout the loop I until it terminates at the upper end of segment 32. The transverse flights 58 are cut away as appears clearly in Fig. '7 to permit engagement of the chain 51 with the'guiding rail 59 and in this way the chain 51 is kept centered as it passes the bends in the loop I.

It will thus be apparent that an apparatus is provided in which the type of processing herein described may be carried on at any pressure desired either above or below atmospheric pressure.

This configuration of the flights 58 also permits engagement-of the driving sprocket I with the chain 51 as appears in Fig. i. The vertical disposition of the loop is advantageous from a structural standpoint, but it is obvious that the descending and ascending action may be achieved even though the plane of the loop or the ascending or descending legs of the loop be inclined from the vertical.

In Fig. 5 is diagrammatically shown the apparatus of this invention applied, as an illustrative instance, to the continuous conduct of the caustic process of pulping. In this instance wood chips for example may be fed into segment I5 where they immediately encounter an atmosphere, at say about 100 pounds per square inch gage pressure. This atmosphere is in substantial equilibrium with hot treating liquor, say initially a 10 percent sodium hydroxide solution, in the lower parts of the loop I and consequently is largely composed of steam, but it also will contain considerable non-condensible gases and other vapors, and therefore will be at a temperature of let us say about 320 F.

The chips are fed at such a rate with reference to the speed of the conveyor mechanism that the spaces between the flights 58 are substantially filled with chips, and the chips thus introduced rapidly acquire thetemperature of the surrounding atmosphere. During this preliminary vapor treatment substantial amounts. of volatile substances within the chips, dependfurther evolution of volatile constituents takes place and these have an opportunity to escape upwardly through a relatively shallow hydrostatic layer, which for each increment of chips is of uniform extent or depth. This is in contrast to other methods of treatment where considerable variation in the hydrostatic head, against which volatile matter must be released from different parts of the charge, cannot be avoided. The jacket I9 surrounding the segment I8 may be provided with a heating medium in sufiicient quantity to meet the heat requirement and to maintain the temperature in this portion of the apparatus at an appropriate level, say

"320 F., for the preliminary stages of the process.

Fresh caustic solution, in quantity in keeping with the quantity of material being fed, may be introduced in small part through the conduit 62 7 sired. The heating medium furnished to the jacket 28 may be in such quantity and at such temperature as to cause the final liquor treatment to be at a temperature higher than that maintained during earlier parts of the treatment. If this is the case some water may be vaporized on the right hand side of the loop and may pass over and condense on the left hand side of the loop with the result that the spent li'quor prevailing for withdrawal through the segment 30 is at its highest concentration. Spent liquor withdrawn through the segment 30 and the conduit 61 may be passed through conduit 88 under the influence of pump 89 and thence in part into the conduit 63 to dilute incoming fresh solution, which enters the loop I through conduit 20 or may be passed through conduit 10 into the reserve tank 64 where it may be employed as a diluting medium. The bulk of it, however, may be allowed to discharge through the conduit II and through appropriate screens not shown, to recovery apparatus of conventional form not shown, or to waste. Spent solution returned for dilution and introduction through, inlet 20 is first screened through one of the alternate screens II or 14 for recovery of fine pulp which would otherwise be overtreated if permitted to be recirculated within the loop I. 7

While the apparatus is thus functioning, vapor may be continuously or intermittently vented through the outlet I! or with the solids through outlet 38 and treated for recovery of its values as desired. a

If washing-back through the use of Jet 36 is resorted to, either water or other fluid may be employed for the purpose, and if it is desired to recover the same it may be passed through filter I8 and conduit 11 to the reserve tank 64, as shown, or may be passed through conduit 18 to waste.

If the process thus described is carried forward with a sufilcient time interval, complete pulping may be caused to take place, but because of the gentle and positive manner in which the chips are conveyed through the apparatus they will still retain to a substantial extent their original configuration and structure, under which circumstances the amount of fine pulp which must be screened and filtered to avoid its over- .treatment or loss in th liquor recovery system is reduced to a minimum. This is in decided contrast with the conditions encountered in the usual recirculating type of digester or apparatus in which motion of solids is impelled by violent fluid jets or conveyors of the screw type. The pulp discharged from the segment 6 by means of the discharging apparatus is may thus be thoroughly reduced for immediate treatment in washers or beaters without passing through any mechanical disintegrating device, such as the mill 46. On the other hand, if it is desired to employ .the apparatus of this invention for conducting a semi-chemical pulping treatment, the rate of passage of the chips through the apparatus may be greatly increased or a treatingyliqnor of a different character, or both, may be resorted to, thus delivering to the discharging device is very materially softened and partially digested chips, which upon passage through the mill 46 are reduced to a satisfactory pulp.

Any of the known pulping methods of the chemical type maybe carried forward by appropriate regulation of the apparatus of this invention, as for example, the soda process as well as the sulflte-and sulfate processes may be advantageously carried out, as well as such processes as employ other liquid pulping reagents. It is also possible to carry forward the process by employing a non-liquid reagent including processes which employ steam as the sole treating medium. The apparatus may also be advantageously employed for carrying forward such process as bleaching and the like. In any of these processes it is feasible by regulation of the feeding and discharging mechanisms to cause any degree of recycling of solid material which may be desired. For example, if the discharging mechanism It is stopped until the entire loop is filled with solid material and then operated intermittently together with regulated intermittent introduction of raw material, only part of the solids brought to the segment 8 will be removed and part will pass over and into the segment ii for mixture with the incoming feed and retreatment, Although such method of operating is not preferred in the usual instance, special occasions may arise during which it may be availed of eifectively.

The utilization of ascending and descending pressure resisting conduits successively joined through which a conveyor passes with purely longitudinal motion is a feature of great importance in the apparatus of this invention in that it makes possible to a large extent the improvement in process control, which characterizes this invention. The exact configuration of the loop employed for the purpose and its vertical or inclined disposition may of course be subject to variation in keeping with the particular conditions to be fulfilled. For example, the loop may be made very tall or narrow to accentuate the difference in hydrostatic head under which the several stages of treatment take place, or it may be inclined or may be made very low and wide ii the opposite effect is desired. In one specific form having particular advantages, the loop may be made tall and narrow to such an extent that the submerging and emerging channels are side by side with a common partition wall. It is,

-therefore, contemplated in referring herein to the main conveying channel as a loop that all such modifications are within the purview of the term.

We claim:

1. In an apparatus for the treating of lignocellulose material in fragmentary form by subjecting the same to the action of a pulping fluid while under pressure a closed loop of conduit forming a descending and ascending portion joined at the top and bottom, a continuous flexible chain within said loop. spaced flights secured to said flexible chain transversely disposed with respect to the run of said conduit, means within said conduit for engaging said flexible chain to cause it to move with respect to said conduit, said conduit being provided with guiding surfaces on its inner side as the sole means for guiding said flexible chain and flights, means adapted to introduce said materials into said conduit forming a pressure barrier, said introducing means being disposed on the leaving side of said driving means, and means for releasing said materials without substantial escape of fiuid pressure prevailing in said conduit, said releasing means being disposed to release treated material prior to return contact of the same with said driving means whereby no substantial quan- .tity of material is caused to pass over and interfere with the operation of said driving means.

2. In an apparatu for subjecting ligno-cellulose material in fragmentary form to the action of a pulping fluid a closed loop of conduit forming a descending and ascending portion joined at top and bottom, a continuous flexible chain within and longitudinally disposed with respect to run of said conduit, spaced flights secured to said flexible chain transversely disposed with respect to the run of said conduit, means adapted to introduce material to be treated, into said conduit, means spaced from said introducing means adapted to withdraw treated material from said conduit, driving means adapted to engage and means to said driving means to interfere with the operation thereof or to become re-treated by passing again through aid conduit, and stationary guiding surfaces on the inner portions of said loop adapted to engage and guide said chain in its longitudinal motion constituting the sole guiding means forv said chain other than said driving means.

3. In an apparatus for subjectingv ligno-cellulose material in fragmentary form to the action of a pulping fluid while under pressure, a closed loop of pressure sustaining conduit forming a descending and ascending portion joined at the top and bottom, a continuous flexible chain within and longitudinally disposed with respect to the run of said conduit, spaced flights secured to said flexible chain transversely disposed with respect to the run of said conduit, means adapted to introduce material to be treated into said conduit while maintaining a pressure sustaining barrier against escape of fluid pressure therefrom,

means spaced from said introducing means adapted to remove treated material from said conduit without substantial escape oi. fluid pressure prevailing within said conduit, driving means adapted to engage and propel said chain in that direction which is away from said material removing means and toward said material introducing means, said driving means being so disposed with respect to said material introducing and removing means that no substantial part of the material which has been subjected to treatment is carried beyond said material removing means to said driving means to interfere with the operation thereof or to become re-treated by passing again through said loop, stationary guiding surfaces on the inner portions oi. said loop adapted to engageland guide said chain in its longitudinal motion within said loop constituting the sole guiding means for said chain other than of a pulping fluid while under pressure, a closed loop of conduit forming a descending and ascending portion joined at the top and bottom, a continuous flexible chain within and longitudinally disposed with respect to the run of said conduit, spaced flights secured to said flexible chain transversely disposed with respect to the run of said conduit, driving means within said conduit adapted to engage said chain and to cause it to move longitudinally with respect to the run of said conduit, said conduit being provided with stationary guiding surfaces on its inner side adapted to engage said chain and guide the same in its motion as the sole means within said conduit for guiding said chain, means adapted to introduce material to be treated into said conduit while forming a pressure sustaining barrier, said introducing means being disposed close to said driving means on the side thereof on which said chain moves away from said driving means, means adapted to release material which has been subjected to treatment without substantial escape of fluid pressure prevailing within said conduit, said releasing means being disposed close to said driving means and having access to said chain on the side of said driving means from which said chain approaches said driving means whereby no substantial part of the materials being subjected to treatment passes over said driving means to interfere with the operation of the same and no substantial part of said material is caused to make more than a single passage through said conduit.

. HJALMAR S. MESSING. CLARENCE L. DURKEE.

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

UNITED STATES PATENTS

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