US1774309A

US1774309A - Method and apparatus for shredding and drying pulp

Info

Publication number: US1774309A
Application number: US348096A
Authority: US
Inventors: Anderson Ossian
Original assignee: Puget Sound Pulp and Timber Co
Current assignee: Puget Sound Pulp and Timber Co
Priority date: 1929-03-18
Filing date: 1929-03-18
Publication date: 1930-08-26
Anticipated expiration: 1947-08-26

Description

Aug. 26, 1930. o. ANDERSON METHOD AND APPARATUS FOR SHREDDING AND DRYING PULP Filed March 18, 1929 4 Sheets-Sheet Aug. 26, 1930. o. ANDERSON METHOD AND APPARATUS FOR SHREDDING AND DRYING PULP Filed Marc h 18, 1929 4 Sheets-Sheet III] ///I III e o a o o 0 0 9 9 2 gwoenlm wa/A/m/ oz ao/y WWW Aug. 26, 1930. o. ANDERSON METHOD AND APPARATUS FOR SHREDDING AND DRYING PULP 4 Sheets-Sheet 3 Filed March 18, 13229 Aug. 26, 1930. o. ANDERSON METHOD AND APPARATUS FOR SHREDDING AND DRYING PULP Filed March 18, 1929 4 Sheets-Sheet oeeeaoaooo ooeacaeoo gnmnto'o USS/AN ANDE/fSO/Y tended by difficulties. Wood pulp chars at Patented Aug. 26, 1930 UNITED/STATES PATENT OFFICE OSSIAN ANDERSON, OF TUMWATER, WASHINGTON, ASSIGNOR, BY MESN'E ASSIGN HENTS, TO PUGET SOUND PULP AND TIMBER 00., OF EVERETT, WASHINGTON, A CORPORATION OF DELAWARE I METHOD AND APPARATUS FOR SHREDDING AND DRYING PULP Application filed March 18, 1929. Serial No. 348,088.

This invention relates to method and apsuch separated pieces are subjected to the paratus for shredding and drying pulp, action of heated air to be dried. and more particularly wood pulp. The process disclosed in my prior patent Heretofore, in the manufacture of wood pulp, it has been customary to leave the pulp in a wet condition for shipment, but such a course involves numerous disadvantages. When the pulp contains a relatively hi h percenta e of moisture, it obviously is Iieavy, and reight rates for the shipment of the pulp are high. It also has been found that the presence of moisture in the pulp sometimes causes the latter to mold and become discolored, thus affecting its market value. Furthermore, it has been found that when wet pulp is shipped during the winter months, the water content freezes, and when the pulp is used it necessarily must be chipped and the fibers of the pulp are thus broken and the tensile strength of the resultant paper stock is seriously affected.

cially practicable to a high degree, but it posses several disadvantages. In the first place, the initial rolling or pressing action was resorted to in order to removeas great a percentage of the water content as pos sible prior to the subjection of the pulp to the action of heated air in order to facilitate the drying action. The pressure of the presser rolls of the wet machine have provided the resultant sheet of wet pulp with a substantial density which, while not in itself a serious disadvantage, causes the subsequent beating of the pulp to be carried out with somewhat greater difliculty than was the case with ordinary wet pulp.

The action of the presser rolls had the effect of somewhat mashing and thus slightreferred to has been found to be commer- The desirability b Shipping pulp in a ly weakening the strength of the pulp fibers,

dr d' h b 1 d t d b /but the pressing action was believed to be y 1 1 n as een (mg ml ers O0 u necessary in order to facilitate the removal the drymg of the pulp has always been at of the remaining moisture in the drier. In other words, it is essential in order that the process be commercially practicable, that the drying action be carried out within a limited period of time, and in order that such time might be reduced to the desired minimum it was thought to be essential that the greatest possible percentage of moisture be removed in the wet machine.

I have discovered however that the disadvantage possessed by the rather dense pulp product of the process disclosed in my prior patent may be eliminated and the process carried out in an even more efiicient manner so far as economy of operation is concerned. I Accordingly, itis an important object of the present invention to provide a method of drying pulp to provide a substantially dry finished product which readily may be baled, and which product will be substantially light and fluffy to permit the beating thereof readily to take place.

' A further object is to provide a method of the character referred to which is of a relatively lower temperature and in applying heat which is necessary for the drying operation, it has been found that the fibers of the pulp char quite readily, thus destroying or at least materially affecting their strength. The diiiiculty of drying the pulp has been due largely to the fact that the pulp passes from the standard wet machines in saturated sheet form, and ithas been found diflicult to shred or separate such sheets to facilitate the drying action because of the fact that the wet fibers of wood pulp are extremely weak and easily broken.

In my prior patent for process of shredding and drying pulp, No. 1,668,446, granted May 1st, 1928, I have disclosed a process fo r shredding and drying wood pulp wherein the wet sheet is, pressed to remove as large a percentage of the water content as possible, whereupon the sheet is gently pulled into relatively small pieces without injury to the fibers of the pulp, whereupon further object is to rovide a method of drying wood pulp wierein the tensile strength of the fibers of the resultant product is preserved.

A further bbject is to provide an improved pulp treatin apparatus adapted for the production 0 a high grade dried pulp ready or baling.

A further object is to rovide a novel form of drying apparatus or the shredded 1 O ther objects and advantages of the invention will become ap arent during the course of the following escription.

As previously stated, it was thought to be essential to the commercial practicability of the process disclosed in my prior patent that the wet pulp be initially subjected to the action of pressure to remove the greater portion of the wet content therefrom. In accordance with the present invention however, I have discovered that only a relatively small proportion of the water need be pressed from the pulp, and that the slightly dried pulp thus provided may be subjected to the action of drying means and the drying action completed in at least as short a space of time as formerly was required, even though the pulp initially subjected to the drying action contains considerably more water than was the case with the pulp dried in accordance with my prior process. It has been found that the relatively light pressure to which the pulp is subjected for removing such substantially slight proportions of water leaves the pulp in a rather loose condition instead of densifying it in accordance with the practice of my prior process.

In the further practice of the method it has been found that after the sheet of wet pulp has been pulled into relatively small pieces, it may be dried in a substantially shprt time, even though the water content of the pulp is relatively large, and this result is obtained because of the fact that the pulp is not densified. Thus the relatively wet pulp pieces may be subjected to substantially the same drying action as the drier pulp used in accordance with my prior method, and the resultant product is a light fluify dried pulp which readily may be baled. The baling of the pulp does not materially densify it, and when the pulp reaches the consumer, the beating action to which it is subjected in the manufacture of paper stock may be readily carried out because of the loose fiuffy condition of the pulp.

More specifically, the present method comprises pressing from the pulp not over 40 per cent. of the water, and preferably the amount of water pressed from the pulp should not exceed 35 per cent. of thetotal water content of the pulp before it is subjected to ressure. The pressin action preferably taizes place in a stander wet machine including a plurality of presser rolls which are so positioned with respect to each other that relatively slight pressure is brought to bear on the sheet of pulp. After having the excess water pressed therefrom in the manner stated, the pulp is subjected to the action of a se arator which operates to pull the sheet 0 pulp gently into relatively small pieces whlch, in practice, fpreferably do not exceed one and one-hal inches in size. After being thus separated into pieces, the

ulp is fed through a drier wherein it is subected to the action of heated air to remove substantially all of the remaining moisture.

The drier employed in connection with the present method includes heating coils which directly radiate heat to the pulp being treated, and over which air is passed to be heated and brought into contact with the pulp to assist in the drying action. The drier also is provided at spaced points with means for agitating or turning the pulp pieces to insure the subjection of the pulp to the action of heat whereby the drying action is facilitated.

In the drawings I have shown one form of F igure 5 is an enlarged plan view of the separator and associated elements,

Figure 6 is a section on line 66 of Figure 5,

Figure 7 is an enlarged fragmentary plan View of the outlet end of the drying apparatus, and,

Figure 8 is a side elevation of the same.

Referring to Figures 1 and 2, the numeral 10 designates a suitable wet machine for use in the initial treatment of the pulp. The

pulp stock is fed through a chute or the like 11 into a vat 12 from which it is fed outwardly in the form of a sheet around a Decker roll 13. The roll 13 picks up the pulp in the form of a sheet as will be apparent and feeds it through pairs of rolls 14, from whence the pulp passes through a further series of pressure rol-ls 15.

The specific type of rolls employed is unimportant, but it should be understood that these rolls, or other means employed, should be of such character that not in excess of 40 per cent. of the water is pressed from the stock. After passing from the rolls 15, the sheet of pulp with the water partially removed therefrom moves downwardly alon an inclined apron 16 at the lower end 0 which the separating action takes place.

The separating means is shown in detail in Figures 5 and 6 of the drawings. At the lower end of the apron 16, a transverse shaft 17 is arranged, and this shaft is sup ported in bearings 18. A plurality of relatively stationary fingers 19 is carried by the shaft 17, these fingers passing througi one wall of a channel iron 20 which is bolted as at 21 or otherwise secured to the shaft 17. The fingers 19 are smooth and are provided with rounded ends so as to avoid damaging the pulp. In Figure 6 of thedrawings a sheet of pulp 22' is shown passing downwardly along the apron 16 to the separator. 7

At each side of the apron 16, theshaft is provided with a rearwardly extending arm 22 which is normally horizontal, and the rear end of each arm is adapted to be supported upon a bracket 23. A counterweight 24 is carried by each arm 22 and is provided with a set screw 25 for securing it in desired adjusted positions.- Obviously, the counter-weights may be placed in desired positions along their respective arms 22.

The coacting separating means includes a transverseshaft 26 arranged parallel to the shaft 17, and the shaft 26 is journaled in bearings 27. Hubs .28 are secured to the shaft 26, at spaced points therealong, by set screws 29. Each hub is provided with a plurality of outstanding arms 30, as clearly shown in Figure 6.

Channel irons 31 are secured to the arms 30 by bolts 32, and each channel iron carries a plurality of puller fingers 33 corresponding generally in shape and size to the fingers 19. The fingers 33 also are smooth and provided with rounded ends to avoid injury to the fibers. The shaft 26 and associated elements are adapted to be rotated in a manner to be described, and during such rotation, the fingers 33 pass between the fingers 19, as shown in Figure 5.

Referring to Figures 1, 2 and 3, the numeral 34 designates a drier casing as a whole including a top wall 35 and

side walls

36 and 37 respectively. The casing is cut away adjacent the inlet end thereof as at 38, and the bearings 27 of the shaft 26 are mounted on the cut away portion of the casing. A motor 39 is mounted on the top wall of the casing and the armature shaft of the motor is provided with a sprocket about which passes a chain 40. The shaft 26 is provided at one end with a sprocket 41, and the chain 40 passes around this sprocket to provide drive means forthe shaft 26. The motor 39 and shaft 26 are driven at relativelylow speeds, for a purpose tobe described. v.

The casing 34 is divided substantially throughout its length by a wall or plate 42 arranged parallel to and spaced from the wall .37 to divide the drier easing into main and auxiliary chambers 43 and 44 respectively. The wall 42 is spaced at its upper end from the top wall 35 of the casing to provide for the circulation of air in a manner to be described. Steam coils or pipes 45 are arranged within the casing 34, the coils being spaced from and arranged arallel to the top wall 35, as shown in igure A screen conveyor 46 is arranged in the drier casing and passes around pulleys 47 and 48 adjacent the inlet and outlet ends of the casing respectively. The upper and lower runs of the conveyor 46 are supported for longitudinal movement within the easing by an le iron guides 49 and 50 respectively. The casing is provided throughout its length with a division plate 51 arranged between the upper and lower runs of the conveyor as shown in Figure 3. The conveyor 46 is preferably of the standard sectional woven wire type, and the screen material employed is preferably of one-fourth inch mesh.

' Air circulating and pulp turning units are arranged at spaced intervals along the drier casing, and since such units are substantially identical, only one need be referred to in detail. Referring to Figures 1 to 4 inclusive, it will be noted that the drier casing is provided at spaced points with transverse shafts 52, and each air circulating unit, as illustrated, is provided with three of these shafts, as shown in Figure 4. One of the shafts is provided outwardly of the casing with a sprocket 53 about whichpasses a,

chain 54 driven by a motor 55 mounted on the top wall 35 of the drier casing. The

'armature shaft of the motor is provided with a small sprocket 56 about which 'the chain 54 passes. Each adjacent pair of shafts 52 is connected by a chain 57 passing around sprockets 58 carried by the shafts 52, and thus it will be apparent that the driving of the sprocket 53 causes all of the shafts 52 to be driven in unison and preferably at the same speed.

Each shaft 52 extends completely through the drier casing and is supported for rotation by bearings 59 carried by the

side walls

36 and 37.

Within the auxiliary chamber 44, each shaft 52 is provided with a centrifugal blower 60 which is arranged adjacent a circular opening 61 formed in the wall 42. Thus it will be apparent that operation of each'blower is adapted to draw air from the main chamber 43 through the upper run of the conveyor 46, and to pump such air upwardly and over into the top of the main chamber 43, and thence downwardly through;

the steam coils 45. Accordingly a continuous circulation of heatedair is provided.

Certain of the air circulating units thus described may be mechanically connected to turning means for agitating or turning the pulp on the upper run of the conveyor 46.

n the drawings, the first two of the air circulating units are shown as being provided with the pulp turning means, but it will be apparent that any number of such means may be employed.

Referring to Figures 1, 2 and 4, the numeral 62 designates a transverse shaft extending through the casing adajacent one of the shafts 52. A plurality of turning fingers 63 is carried by each shaft 62 and the successive fingers passing beneath the shaft 62 are adapted to turn or agitate the pulp pieces on the upper run of the conveyor 46. Each shaft 62 is provided with a sprocket 63 about which passes a chain 64, and this chain, in turn, is driven from the adjacent shaft 52 by means of a sprocket mounted thereon.

The conveyor 46 extends slightly be 0nd the outlet end of the drier casing, an the pulp moving out of the drier casing is adapted to be removed from the screen conveyor by a suitable dofler 65 having a plurality of fin ers 66 therein adapted to en age the pulp. %he pulp thus discharged rom the conve or falls upon a transverse conveyor 67 or transmission to suitable baling apparatus indicated as a whole by the numeral 68. The baling apparatus forms no part of the present application and need not be referred to in detail, it being understood that any suitable type of baling may be employed.

The dofi'er 65 is mounted upon a shaft 69 connected by a suitable sprocket to a chain 70 driven by a transverse shaft 71 mounted upon the top of the drier casing and rotatably supported in bearings 72. Suitable transmission mechanism, shown in the present instance as

comprisin drive chains

73 and 74 connect the shaft 71 to a motor 75, and accordingly it will be apparent that this motor is adapted to drive the doifcr 65.

The pulley 48 over which the screen conveyor 46 passes adjacentthe outlet end of the drier casing, is provided with a gear 76 meshing with a gear 77 mounted upon a vertical shaft 7 8 supported in suitable bearings 79. The upper end of the shaft 78 is provided with a bevel gear 80 meshing with a similar gear 81 mounted upon the outer end of the shaft 71. Thus it will be apparent that the motor also serves to drive the conveyor belt 46. v

The operation of the apparatus is as follows:

The wet pulp from the vat 12 is picked up by the roll 13 and fed between the rollers 14 and 15 which, as previously stated, are so spaced as to not press from the pul over 40 per cent. of t e water content tiiereof, and preferably not in excess of 35 1' cent. of the water. The pulp is thus left in a substantially loose condition with the excess water removed therefrom.

The pulp sheet passes downwardly alon the apron 16 as indicated in Figure 6, and thus is acted upon by the separatin means. The advancing edge of the pulp s set will be supported upon the fingers 19, while the rotating lingers 33 serve to gently pull the pulp to pieces by passing between the fingers 19. The shaft 26 rotates at a relatively slow speed so as to gently pull the pulp into pieces, as previously stated, and the separating action is facilitated because of the substantially loose condition of the pulp. The shaft 17 is mounted to swing so as to provide a certain degree of resiliency where relatively hard spots are encountered in the ulp, to insure separation thereof without injury to the fibers. The counter-weights 24 serve to oppose the turnin movement of the shaft 17 and to retain t is shaft and the fingers 19 associated therewith in normal position.

The ieces of the pulp thus separated fall upon t e screen conveyor 46 and thus are moved slowly through the drier casing. According to the length of the casing, temperature conditions, etc., the linear speed of the screen conveyor may be from ten to twenty feet per minute.

Each of the air circulating units acts in an identical manner, but the temperatures to which the pulp is subjected will vary according to the temperature of the steam within the coils 45. Each blower 60 serves to withdraw air from the main chamber 43 through the upper run of the screen conveyor, and to pum such withdrawn air upwardly through t e auxiliary chamber 44 and thus over and downwardly between the coils 45. Thus the pul) is subjected to a constant'circulation of heated air, and the arrangement of the coils 45 is such that heat will be rotated directly therefrom to the pulp being dried, thus effecting economy in operation. Fresh air will enter the drier casingand quantities of the used air will leave the casing through the open ends thereof, and it will be apparent that the air within the casing will not become saturated with moisture to any appreciable extent.

As previously stated, wood ulp is readily charred, and this is particularly true when the pulp is in a substantially dry condition. Wet pulp may be subjected to somewhat higher temperatures without injury, and accordingly the drying temperature at the inlet end of the casing 34 is preferably higher than at the outlet end thereof. These temperatures may be governed by the admission of steam into the coils 45. If de- I So sired, steam at the proper temperature may be introduced into the coils 45 adjacent the inlet end of the casing, and the steam per- .mitted' to flow throughout the coils 45 toward the outlet end of the casing to be gradually reduced in temperature by radiation. In actual practice. it has been found that the drying action may be carried out comparatively rapidly and without injury to the fibers of the pulp at temperatures rang ng from 160 to 200 F., at the inlet nd of the casing and at from 100 to 120 F.,'adjacent the outlet end of the casing. Obviously, the temperature will be progressively reduced from the inlet end toward the outlet end of the casing.

At spaced intervals within the drier casing, the fingers 63 will act to agitate or turn the pulp pieces so that all sides thereof will be subjected to the drying action. It will be apparent that the present process and apparatus contemplate the introduction into the inlet'end of the casing of pulp containing a higher percentage of water than the pulp employed in connection with the process disclosed in my prior patent. Under such circumstances it would appear that a considerably greater length of time would be required for the drying of the pulp, but I have discovered that by exerting only slight pressure against the pulp to remove only a small percentage of the moisture therefrom, the density of the 'pulp is such as to permit the drying action to take place more rapidly than would be expected, and as a matter of fact, the drying action is ac.- complished in at least as short a period of time as can be accomplished with the process disclosed in my prior patent. As a matter of fact, the time required for the drying is reduced materially \in actual practice, and the resultant product passes from the drying casing in a loose flufly condition. Owing to the lack of density in the finished product it is particularly adapted for the beating action in making the paper stock, and such action readily may be acomplished without injury to the fibers of the pulp.

While I have described in detail the preferred practice of my method, it is to be understood that thedetails of procedure may be widely varied without departing from the spirit of the invention or the scope of the subj oined claims.

I claim:

1. The method of treating pulp which consists in mechanically removing a relatively small percentage of water therefrom, whereby the pulp is in a substantially loose slightly dried condition, and then subjecting the pulp to the action of heat to substantially completely dry it.

2. The method of treating wood pulp to dry it which consists in mechanically removing less than 40 per cent of the water dry it which consists in mechanically removing less than 40 per cent of the water therefrom, separating the pulp into relatively small pieces without injury to the fibers thereof, and then subjecting the pulp to the action of heat to substantially, completely dry it.

5. The method of treating wood pulp to dry it which consists in subjecting a sheet of pulp to mechanical pressure to remove a relatively small percentage of the water therefrom, whereby the pulp is in a substantially loose slightly dried condition, and subjecting the pulp to the action of heat to substantially completely dry it.

6. The'method of treating wood pulp to dry it which consists in subjecting a sheet of pulp to mechanical pressure to remove less than 40 per cent of the water therefrom, and subjecting the pulp to the action of heat to substantially completely dry it.

7. The method of treating wood pulp to dry it which consists in subjecting a sheet of pulp to mechanical pressure to remove a relatively small percentage of the water therefrom, whereby the pulp is in a substantially loose slightly dried condition, separating the pulp into relatively small pieces without injury to the fibers thereof, and subjecting the-pulp to the action of heat to substantially completely dry it.

8. The method of treating wood pulp to dry it which consists in subjecting a sheet of pulp to mechanical pressure to remove less than 40per cent of the water therefrom, separating the pulp into relatively small pieces without injury to the fibers thereof, and subjecting the pulp to the action of heat to substantially completely dry it. v

9. The method of treating wood pulp to dry it which consists in mechanically removing a relatively small percentage of water therefrom, whereby the pulp is in a substantially loose slightly dried condition, separating the pulp into relatively small pieces without injury to the fibers thereof, and then subjecting such pieces to the action of a current of heated air to substantially completely dry them. a p

10. The method of treating wood pulp to dry it which consists in mechanically removing less than 40 per cent of the water therefrom, separating the pulp into relatially less than per cent of tively small gneces without injury to the fibers thereo and then subjecting such pieces to the action of a current of heated air to substantially completely dry them.

11. The method of treating wood pul to dry it which consists in subjecting a s eet of pulp to mechanical pressure to remove a relatively small percenta e of the water therefrom, whereby the pn p is in a substanloose slightly dried condition, separating the pulp into relatively small pieces without injury to the fibers thereof, and then subjecting such pieces to the action of a current of heated air to substantially completely dry them.

12. The method of treating wood pulp to dry it which consists in subjecting a sheet of pulp to mechanical ressure to remove tlie water therefrom, separating the pulp into relatively small pieces without injury to the fibers thereof, and then subjecting such pieces to the action of a current of heated air to substantially completely dry them.

13. The method of treating wood pulp to dry it which consists in rolling a sheet of pulp to remove a relatively small'percenta e of the water therefrom, whereby the pulp is in a substantially loose slightly dried condition, separating;1 the pulp into relatively small ieces wit out injury to the fibers thereo and then subjecting such pieces to the action of a current of heated air to substantially completely dry them.

14. The method of treating wood pulp to dry it which consists in rolling a sheet oi pulp under relatively slight pressure to remove less than 40 per cent of the water therefrom, separating the pulp into relatively small pieces without injury to the fibers thereof, and then subjecting such pieces to the action of a current of heated air to substantially completely dry them.

In testimony whereof I affix my signature.

OSSIAN ANDERSON.