US2608151A - Steeping press - Google Patents

Description

Aug. 26, 1952 J. FLOR! ETAL STEEPING PRESS 4 Sheets-Sheet 1 Filed March 27, 1947 INVENTORS l/OSEPHFLORI whom ATTORNEY Aug. 26, 1952 J. FLORI ET AL 2,608,151

STEEPING PRESS Filed March 27, 1947 4 Sheets-Sheet 2 T f w IN VEN T0125 (/OSEPH F1. OR! AND N 72/0MA5 A TTO/YNEY Aug. 26, 1952 J. FLORI ET AL STEEPING PRESS 4 Sheets-Sheet 3 Filed March 27, 1947 Snventors JZJEPH fzae J. FLOR] ET AL STEEPING PRESS 4 Sheets-Sheet 4 Filed March 27, 1947 3nuentors Patented Aug. 26, 1952 UNIT S 2,608,151 'STEEPING rnEss- Application March 27, 1947, Serial No. 737,694 In France March 8, 1944 Section 1, Public Law 690, August s, 1946 Patent expires March 8, 1964 6 Claims.

This invention relates to the preparation of alkalicellulose to be'us'ed in the preparation of viscose. More particularly, it relates to a new and improved steeping press for the preparation of alkali cellulose. 1

In the preparation of viscose, the first chemical operation is the conversion of the cellulose to alkali cellulose by a process generally called fmercerizingP In such process, the cellulose is steeped in caustic soda or other caustic alkali at an appropriate concentration, such as an aqueous solution containing 230 to 260 grams of caustic soda per liter. This treatment, which can be carried out on the cellulose in the form of sheets, strips or fibers, also leaches out the hemicelluloses which are soluble in the caustic alkali. After the cellulose has been steeped for the required period of time, the excess alkali is removed by pressing or in any other suitable manner.

When the treatment is carried out on sheets, the steeping and pressing operations are generally achieved in a steeping press in which the sheets of cellulose pulp, arranged for example in lots of 10 to 20, are stacked on edge vertically between perforated metal plates suspended from cross-pieces disposed on the edges of the longitudinal walls of an elongated tank. After the arrangement of the sheets, the tank is filled with aqueous caustic soda solution of the desired concentration and the pulp is steeped for a suificient period to insure a complete impregnation of the sheets by the concentrated alkali. Thereafter, the excess steeping alkali is drained. After drainage of the excess alkali, the sheets are pressed by means of a piston moving longitudinally in the tank and driven by hydraulic or mechanical means. During the pressin operation,exce ss alkali is expressed from the sheets which yield at the same time a greater part of the hemicelluloses present therein. Generally, the pressing operation is continued until the weight of the pressed sheets is equal to; about 3 times the weight of thealpha-cellulose employed. Thus, for example, with a 90% alpha-cellulose pulp, the pressed weight, i. e. weight of the sheets after pressing, is about 2.7 times the weight of the dry pulp. v

During the pressing operation, the hemicellulose content of the alkali progressively increases until it reaches a maximum, and then it decreases slightly until the pressing operation is completed. For example, when an aqueous caustic soda solution containing 240 grams per liter and 10 grams of hemicellulose per liter is used, the concentration of the hemicellulose increases gradually until it reaches a maximum of about '25 to 35 grams per liter. This maximum is attained just prior to the completion of the pressin operation, andithereafter the concentrationof the hemicellulose decreases to 20 to 25 grams per liter.

Usually, the drained caustic soda contains about 225 grams of caustic soda and l6'grams of hemicelluloses per liter. Such drained caustic soda is generally treated with appropriate quantitles of fresh caustic soda or purified'expressed caustic soda tobri'ng it up to the desired concen tration whereby it can be reused. The expressed causticsoda must be purified by dialysis or other convenient process before it canbe reused.

For efiicient operation, it was thus necessary to collect separately the drained caustic soda and the expressed caustic soda. With this in view, the steeping presses were provided with two outlets which were controlled by valves manually operated by the worker on .duty. Alternatively, the outlets were controlled by a three-way valve manually operated'by the worker.

In the preparation of alkali cellulose, it is usual to add to the drained caustic soda the first parts of the caustic soda obtained by the pressing operation and, if it is desired to recover the maximum caustic soda'for directreutili'zation, .it is necessary to operate again the valves at the end cf the pressing operation. Hence, it was essential that the workers supervising the steeping and pressing operation be entirely familiar with their work and periodically effect the required operations. Nevertheless, in spite of this, improper handling frequently occurred whereby. the ex-.- pressed caustic soda was mixed with the drained caustic soda, with the result that the hemicellulose contents were increased and themixed caustic soda was less suitable for direct reutilization. Alternatively, the quantity of the expressed caustic soda was increased uselessly.

Proposals for achieving an automatic separation of the drained and expressed caustic soda have been made but, since'the-devices proposed were very complicated and included a great number of moving parts, their practical utilization was difiicult if not impractical.

An object of this'i'nvention is to provide a new and improved steeping press for the preparation of alkali cellulose- 'Another object of this invention is to provide a steeping press having associated therewith simple means to separate automatically the drained caustic soda from the expressed caustic soda.

Other and additional objects will become apparent hereinafter.

The objects of this invention are accomplished, in general, by appropriately associating with a steeping tank a valve-controlled outlet for draining the steeping caustic soda, a valve-controlled outlet for the discharge of the expressed caustic soda, and means actuated by the movement of the piston to open and close at least one of said valves in sequence and, at predetermined times, to discharge successively the steeping caustic soda and the expressed caustic soda.

In one embodiment of the invention, there is rigidly secured to the piston a plate which carries a roller adapted to ride over a cam on a pivoted lever, one end of which is secured to the rod carrying the valve cooperating with the outlet through which the expressed caustic soda is to be discharged. The cam is of such a contour that when the roller rides thereover the lever will be moved and the valve controlling the discharge of the expressed caustic soda will automatically be opened and closed at predetermined time's'so that successful separation between the drained caustic soda and the expressed caustic soda is obtained. In this embodiment, the valve controlling the discharge of the drainingcaustic soda remains open during the entire operation. However, such discharge outlet is at a higher level than the discharge outlet for the expressed caustic soda, with the result that during the pressing operation the caustic soda obtained therein will be discharged through its discharge opening. In the preferred form of this embodiment, the valve mechanisms are provided in a vat secured to the steeping tank. The vat and tank are connected so that liquid will flow from the tank into the vat. An overflow is provided in the vat to maintain the liquid therein and in the tank at the desired level.

In another embodiment of the invention, both outlets are controlled by rotary valves. The rotary valve which controls the discharge for draining the caustic soda is manually opened, and thereafter the necessary sequence of opening and closing the valve controlling the discharge of the expressed caustic soda, as well as the closin of the valv controlling the discharge of the draining caustic soda, is obtained by means carried by the piston and which cooperate with the valveoperating mechanisms.

The present invention will more fully be understood by reference to the following detailed description when taken in connection with the accompanying drawings, in which:

Figur l is an elevation of a steeping press partly broken away and embodying the details of the invention;

Figure 2 is a vertical section of the vat containing the valve mechanisms associated with the steeping press shown in Figure 1; I

Figure 3 is an elevation of the modified form of the invention;

Fig. 4 is a detailed plan view of the actuating rod for the valve mechanism of Fig. 1;

Fig.- is a detail view in plan of th actuating mechanism for the valve assembly of Fig. 3; and

Fig. 6 is an enlarged detail view in elevation showing the mounting of the fingers for operating the valve assembly of Fig. 3.

Referring now to the drawings wherein like reference numerals designat like parts, the elongated steeping tank, generally indicated by the reference numeral I, is mounted on legs 2 and 3 which'are secured to the ground or floor on which the press is disposed. The tank I is provided with a piston P which is movable longitudinally in the tank. A rod4 rigidly secured to the piston carries an idler roller 5 which, during the movement of the piston P, rides on a lever 6 which is pivoted on a pin 1 appropriately carried on the tank. The piston is adapted to move during the pressing operation in the direction indicated by the arrow F under the action of a screw driven by a gear 8. The specific means for operating the piston and the mounting thereof are well known and, since such specific details of construction form no part of this invention, it is deemed unnecessary to describe them in detail.

The lever 6 comprises two members 9 and I0 longitudinally adjustable relative to each other. The member 9 carries two fixed spaced screws II and I2, and the member I 9 is provided with three spaced slots I3, I4 and I5. The screws II and I2 and the slots I3, I4 and I5 are so arranged that the screws II and I2 will cooperate with the slots I3 and I4 or the slots I4 and I5, whereby the member I0 canbe longitudinally adjusted relative to the member 9. Wing nuts (not shown) cooperate with the screws II and I2 to lockthe member I 0 in adjusted position on the member 9.

The element I 0, which is designed to cooperate with'the roller 5, constitutes a cam having inclinations I6 and I1. The roller 5, as it passes up the inclination I6, will cause movement of the lever 6 in the direction of the arrow F and, when the roller passes down the inclination I1, the lever 6 will be moved in the opposite direction. The vertical movement of the lever 6 is limited by a strap I8 which is attached to the tank I in a position to engage the end of the member I0.

On the front wall of the tank I, there is secured a vat I9 which is connected at its lower part to the tank I by means of. a pipe 20, whereby the liquid present in the steeping tank will also be present to the same level in the vat I9. The vat I9 is provided with an overflow which permits the discharge of the excess caustic soda on filling the tank therewith and thereby avoids overflowing of the concentrated caustic from the tank, whereby damage to the ground or floor and endangering of the safety of the personnel and premises is prevented.

Referring now to Figure 2, the vat I9 is composed of two compartments 2| and 22 separated by a partition 23. The compartment 2| constitutes the overflow and is provided with a discharge outlet 24 which is connected to a pipe 25. The compartment 22 is provided with two discharge outlets 26 and 21 which are connected to pipes 28 and 29 respectively. The pipes 28 and 29 lead to appropriate reservoirs (not shown). For reasons which will become apparent hereinafter, the outlet 21 is on a level lower than the outlet 26and the pipe feeds into the pipe 28.

A valve 30 cooperates with the outlet 26 and is appropriately secured at the lower end of a rod 3I, the upper end of the rod being provided with a handle 32 adapted for manual gripping. A valve 33 provided witha tight band 34 cooperates with the outlet 21. The valve 33 is secured to the lower end of a rod 35, the upper end being provided with an ear '36 which is pivotally mounted on a pin 31 carried by the lever}. as shown in Figure 1. Guides 39 and39; appropriately secured to the partition 23 and a wall of the vat I9 respectively; serve to guide the rods 3| and35respectively.

ln operation, with th'episton retracted so that it is at the left in Figure 1, sheets of cellulose pulp are arranged on edge vertically in the tank between depending perforated separator plates in the well-known manner. With both of the valves 30 and 33 closing their respective outlets, a solution of caustic soda of the desired concentration is then introduced into the press in the usual manner. As the caustic soda solution progressively fills up the tank, it enters from the pipe into the compartment 22 of the vat I9 and finally, when the level of the caustic soda solution in the tank reaches the top of the partition 23, overflows into the compartment 2| from which it is discharged through the pipe 25 into the pipe 28. When sufficient quantity of the caustic soda solution has been introduced into the tank so that the sheets will be completely submerged therein, further supply thereof is discontinued and the sheets are permitted to remain in contact with such caustic soda until the'cellulose is converted toalkali cellulose. This may take one hour or more depending on the concentrations, temperatures, etc; At the end of the treatment, the handle 32 is manually gripped and the rod elevated whereby the valve'3t opens the outlet 26, with the In its travel, th piston carries with it the rod 4 whereby the roller 5 rolls along on the lever 5. On reaching the incline It, the lever 5 is moved about its pivot l, with the result that it elevates the rod 35 which, in turn, elevates the valve 33, opening the outlet 21 through which the expressed caustic liquor is discharged. Due to the fact that the discharge 26 is located at a higher level than the discharge 21, all the liquid'at the bottom of the tank I9 will pass, when the valve 33 is raised,

through the outlet 2'! into the line 29, which A,

conducts it to a suitable reservoir. Continued movement of the piston causes the roller 5 to ride on-the member In, whereby the valve 33 will be maintained in open position until the roller begins its movement on the downward incline ll. When the roll 5 rides over the downward incline lLthe lever B is caused to move about its pivot 1 due to the weight of the valve members in such a direction that the valve 33 will be seated and close the outlet 21, The-contour of the cam elemerit i0 is such that the discharge 2! will be closed prior to the completion of the pressing action by the piston so as to discharge the last portions of the expressed caustic soda to be discharged through the outlet 25. A separate pipe (not shown) can be-employed for the complete emptying of the tank I.

Referring now to Figure 3, the tank a is supported on the stands 2a and 341, as in the previous modification. A discharge outlet 40 is appropriately connected to the tank la whereby liquid in said tank can be discharged; As shown in Figure 3, the discharge 40 is divided into two branches 4! and 42, the'branch 4| serving for draining the excess steeping caustic soda from the tank, and the latter for discharging the expressed caustic soda; A rotary valve 43 controls the passage of liquid from the discharge 40 into thebranch 4i and a rotary valve 44 controls the discharge fromthe outlet 40 to the branch 42.

Valves 43 and 44 are of the type .to open or close upon 90" rotation. The rotary valve 43 is mounted at the bottom of-a rod 45, which is rotatably mountedin bearings carried by th wall of the tank. A pinion 41 secured to the rod 45 is incooperative relationship with a gear 49 secured on a shaft 65 appropriately mounted ina.

bearing carried by the wall of the tank la. Similar sets of lateral fingers 5| and 53, for reasons which will become apparent hereinafter, are secured in spaced relationship on the shaft 65. In the form shown, the fingers are carried by collars 55 and 61 respectively, which in turn are secured to th shaft 65. Similarly, the valve 44 is carried at the lower end of a vertical rod 46 rotatably mounted in a bearing on the wall of the tank. A pinion 48 secured to the rod '45 is in cooperative relationship with a gear 50 secured on a shaft 10 rotatably mounted in bearings carried by the wall of the tank. Similar sets of lateral fingers 52 and 54 are secured in spaced relationship on theshaft it. In the form shown, the fingers are carried by collars H and 12 respectively, which in tu'r ar secured to the shaft 10.

In the embodiment shown in Figure 3, the piston 55 which is of the well-known type and controlled in the well-known manner carries a'support 56 in which a supporting bar 51 is rigidly secured. The supporting bar is provided with two adjustable sleeves 58a and 53a carrying members- 58 and 55 which are in spaced relationship and disposed so that, when the support 5515 moved longitudinally of the tank, the fingers 5| and 52 will be successively engaged thereby. The supporting bar 51 is also provided with two additional adjustable sleeves a and 61a carrying members 60 and 6| which'are in spaced relationship and disposed so that, when the support 55 is'moved longitudinally of the tank, the fingers 53 and 54 Will be successively engaged thereby. The sleeves 58a, 59a, 60a and 61a may be adjusted along the bar 51 as desired.

In operation, with the valves 43 and 44 in closed position and after the sheets of pulp have been positioned on edge between the perforated spacer plates (not shown), the steeping alkali is introduced into the tank. An appropriate overfiow mechanism (not shown) is provided to pre vent overflow of the caustic liquor from the steeping tank. After thecellulose sheets have been steeped for the desired period of time, the valve 43 is opened by hand by proper manipulation of the finger-5 i and the caustic soda drains through the branch 4!. The piston is then actuated in its movement (to the left in Figure 3),and'at a predetermined time the member 58 will engage the finger 5i, causing the shaft 65 to rotate, with the result that the gear 49 rotates the gear 4'1, which in turn rotates the rod 45, whereby the valve 43 is rotated into closed position. On continued movement of the piston 55, the member 58 will engage the finger 52 and, through the ele-' ments 55, 48 and 46, the valve 44 will be rotated 90 into open position, whereby the expressed caustic alkali isdischarged through thebranoh 42. Further continued movement of the piston causes the member 59 to engage the fingers 5| and 52 and rotate the valves 43 and 44 a further 90 whereby the valve 43 is opened and the valve 44 closed. By these actions, the excess caustic soda is first drained, then the expressed caustic soda strongly charged with hemi-cellulose is separately discharged, and finally the portions of the expressed caustic soda, obtained during the final stages of the pressing operation and containlng less hemi-cellulose, ar discharged through the valve 43. On the return of the piston 55, the members GI and 60 each respectively engage the fingers 54 and 53 to return the valves to origina1 position. The members 58 and 59 are free to pivot during the, return stroke of the piston, but are rigid during the pressing stroke and the members 60 and SI are free to pivot during the pressing stroke, but are rigid during the return stroke. Hence the members 58 and 59 are effective on the pressing stroke only and the members 60 and BI are efiective on the return stroke only.

The contour of cam I and the movement of the piston are such as to permit the opening and closing of the outlet 21 in the desired sequence and at the desired times. Likewise, the arrangement of the fingers and cooperating members and the movement of the piston are all correlated to effect the desired sequence of operations at the desired times.

Since it is obvious that various changes and modifications can be made in the above description without departing from the nature or spirit thereof, this invention is not restricted thereto except as set forth in the appended claims.

. We claim:

1. A steeping press for the preparation of alkali cellulose by steeping-cellulose in caustic soda. comprising an elongated tank, a piston movable longitudinally in said tank, means to actuate said piston,-said tank having drainage means associated therewith including an outlet for draining the steeping caustic soda in said tank and a second outlet for discharging the expressed caustic soda obtained during movement of said piston, a valve controlling the first outlet, a rod, a second valve controlling the second outlet carried on the lower end of said rod, a pivoted lever having one end thereof connected to the top of said rod and extending along the path of travel of said piston, a cam associated with said lever, and a cam roller carried by said piston and adapted to ride over said lever and cam during movement of said piston, said cam being of a contour to move said lever to open and close the second valve in sequence and at predetermined positions of said piston during its forward stroke.

2. A steeping press for the preparation of alkali cellulose by steeping cellulose in caustic soda,

comprising an elongated tank, a piston movable longitudinally in said tank, means to actuate said piston, said tank having drainage means associated therewith including an outlet for draining the steeping caustic soda in said tank and a second outlet for discharging the expressed caustic soda obtained during movement of said piston, a manually operated valve controlling the first outlet, said first outlet being at a level higher than the second outlet, a rod, a second valve controlling the second outlet carried on the lower end of said rod, a pivoted lever having one end thereof connected to the top of said rod and extending along the path of travel of said piston, a cam associated with said lever, and a cam roller carried by said piston and adapted to ride over said lever and cam during movement of said piston, said cambeing of a contour to move said lever to open and close the second valve in sequence and at predeterminedpositions of said piston during its forward stroke...

3. A steeping press for the preparation of alkali cellulose by steeping cellulose in'fc'austic soda, comprising an elongated tank, a piston movable longitudinally in said tank, means to actuate said piston, a vat secured to said tank, a pipeconnecting said vat and tank whereby steeping caustic soda solution in said tank flows into said vat, said vat having an outlet for draining the steeping, caustic soda and an outlet for discharging the expressed'caustic soda obtained during movement of said piston, the first outlet being at a level higher than the second outlet, a manually operated valvecontrolling the first outlet, 2. rod, a second valve controlling the second outlet carried on the lower end of said rod, a pivoted lever having one end thereof connected to the top of said rod and extending along the path of travel of said piston, a cam associated with said lever. and a cam roller carried by said piston and adapted to ride over said lever and cam during movement of said piston, said cam being of a contour to move said lever to open and close the second valve in sequence and at predetermined positions of said piston during its forward stroke.

4. A steeping press for the preparation of alkali cellulose by steeping cellulose in caustic soda, comprising an elongated tank, a piston movable longitudinally in said tank, means to actuate said piston, a vat secured to said tank, a pipe connecting said vat and tank whereby steeping caustic soda solution in said tank flows into said vat, an overflow in said vat to limit the level of. the caustic soda in said tank, said vat having an outlet for draining the steeping caustic soda and an outlet for discharging the expressed caustic soda obtained. during movement of said piston, the first outlet being at a level higher than the second outlet, a manually operated valve con trolling the first outlet, a rod, a second valve controlling the second outlet carried on the lower end of said rod, a pivoted lever having one end thereof connected to the top of said rod and extending along the path of travel of said piston, a cam associated with said lever, and a cam roller carried by said piston and adapted to ride over said lever and cam during movement of said piston, said cam being of a contour to move said lever to open and close the second valve in sequence and at predetermined positions of said piston during its forward stroke.

5. A steeping press for the preparation of alkali cellulose by steeping cellulose in caustic soda, comprising an elongated tank having a discharge outlet divided into two branches, one of said branches constituting an outlet for draining the excess steeping caustic soda in said tank and the other constituting an outlet for discharging the expressed caustic soda, a piston movable longitudinally in said tank to express caustic soda solution from said cellulose, means to actuate said piston, a rotary valve controlling the outlet for draining the excess steeping liquid, a second rotary valve controlling the discharge of the expressed caustic soda, a pair of spaced fingers operatively connected to rotate the first valve to open and closed position, a pair of spaced fingers operatively connected to rotate the second valve to open and closed position, a support secured to said piston, a pair of members carried by said support and adapted to engage one of each pair of said fingers upon movement of the piston during the expressing operation to open and close said valves in the desired sequence and at the desired times, and a second pair of members carried by said support and adapted to engage the other finger of each pair upon the return stroke of said piston to restore said valves to original position. I

6. A steeping press for the preparation of alkali 9 cellulose by steeping cellulose in caustic soda, comprising an elongated tank, a piston movable longitudinally in said tank, means to actuate said piston, said tank having drainage means associated therewith including a first outlet for draining the steeping caustic soda and a second outlet for discharging the expressed caustic soda obtained during movement of said piston, valve means controlling said first outlet, a second valve means controlling said second outlet, and an actuating member moving with said piston and operative in its forward stroke to open and close said second valve means in sequence and at predetermined points in said stroke so as to discharge through the first outlet at the beginning and end of the stroke and through the second outlet at an intermediate part of the stroke.

JOSEPH FLORI. IVAN THOMAS.

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

UNITED STATES PATENTS Number Name Date 1,690,894 Dutzmann Nov. 6, 1928 1,814,542 Blanco et al July 14, 1931 1,863,399 Dutzmann June 14, 1932 2,174,241 Grotzinger Sept. 26, 1939 2,220,600 Grotzinger Nov. 5, 1940 FOREIGN PATENTS Number Country Date 526,481 Germany June 6, 1931

Images