US1077883A - Apparatus for bleaching paper-pulp. - Google Patents

Description

E. D. JEFFERSON.

APPARATUS FOR. BLEAGHING PAPER PULP.

APPLICATION FILED JAN. 12, 1912.

1 ,O77,883 Patented Nov. 4. 1913;

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E. D. JEFFERSON. APPARATUS FOR BLEAGHING PAPER PULP. APPLIOATION FILED JAN. 12, 1912 1,077,883., Patented Nov. 4. 1913.

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E. D. JEFFERSON.

APPARATUS FOR BLEAGHING PAPER PULP.

APPLIUATION FILED JAN. 12, 1912. 1,(')'7"'?,883,- Patented N014, 1913.

4 SHEETSSHEET 3.

B. D. JEFFERSON. APPARATUS FOR BLEAGHING PAPER PULP.

APPLICATION FILED JAN. 12, 1912.

1,077,883. Patented Nov. 4, 1913.

4 SHEETS-$113111 4.

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UNITED STATES PATENT OFFTQ.

EUGENE D. JEFFERSON, OF BOSTON, MASSACHUSETTS.

APPARATUS FOR BLEACHING- PAPER-PULP.

To all wiiom it may, concern:

Be it known that I, EUGENE D. JEFFERSON, a citizen of the United States, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Apparatus for Bleaching Paper-Pulp; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to paper pulp bleaching apparatus.

l-Ieretofore it has been the practice, in bleaching paper pulp, to put the sheets of pulp in a hollander where they were beaten up with a bleach liquor for several hours. A considerable part of the bleach is lost by evaporation from the open hollander, and the process of bleaching is slow, and these two things make the process expensive.

The object of the present invention is to produce an improved apparatus for bleaching paper pulp operating with expedition and economy, and to this end the invention consists in the apparatus hereinafter clescribed and particularly pointed out in the claims.

In the accompanying drawings illustrating the preferred form of the invention; Figure 1 is a side elevation of the apparatus; Fig. 2 is an end elevation, partly in section, on the line 2-2 of Fig. 1; Fig. 3 is a section on the line 33 of Fig. 1; Fig. ft: is a sectional view of one of the diaphragms; and Fig. 5 is a sectional view of the pilot valve.

The illustrated embodiment is described as follows In general, the apparatus consists of two receptacles, one of which is adapted to contain the pulp to be bleached, and the other to contain the bleaching liquor. Suitable connections are provided for forcing the bleaching liquor into the bleaching vessel and through the pulp back into the storage vessel. The bleaching vessel will be called the keir and the storage vessel will be called the tank. Compressed air is used as the motive fluid to drive the bleaching liquor from tank to keir, and keir to tank.

The keir 1 is a cylindrical vessel with crowned ends, one of which is provided with a removable cover 2 secured in place by hinge bolts 3. This keir is lined with cement, for the purpose of providing a space Specification of Letters Patent.

Application filed January 12, 1912.

Patented Nov. 4, 1913.

Serial No. 670,789.

pulp sheets on edge in the pulpreceiving space, the plane of the sheets being at right angles to the axis of the keir. The work of filling is begun, of course, at the rear end of the keir, and the sheets of paper pulp are stood up on the grate bars, filling the en tire pulp-receiving space with pulp standing on dge in the pulp-receiving space. At the open end of the keir, the end of the body of pulp sheets is secured by chains or other suitable means. Then the cover is swung in place and secured. This arrangement of the pulp sheets in the keir contributes to the successful use of the apparatus, whereas in the methods of bleaching paper pulp heretofore practised, it was re quired that the pulp should be beaten up in order to be thoroughly admixed with the bleaching liquor.

In the arrangement described, the pulp sheets, being arranged in the pulp-receiving space with the plane of the sheets parallel to the direction of flow of the bleaching liquor, the liquor will find its way through the pile and bleach the entire body of pulp without necessitating the beating up of the pulp. It is to be observed in this connection that it is immaterial whether the pulp sheets be arranged with their planes normal to the axis of the keir or vertical and parallel with the axis of the keir, the important requisite being that the sheets shall be so arranged as to have their planes parallel with the direction of flow of the bleaching liquor.

The tank 8 for the bleaching liquor is shown arranged parallel to and alongside of the bleaching keir. It is a cylindrical vessel with dome ends of the usual boiler-plate construction. The bleaching liquor is a weak solution of chlo-rid of lime. It is to be observed that both the keir and the tank are closed and that the bleachin liquor is never exposed to the air. This effects a very material saving over the hollander process above described, because it prevents the loss by evaporation incident to such process. Provision is made for forcing the entire quantity of bleaching liquor in the tank into the top of the keir, and in then forcing such bleaching liquor through the pulp in the keir and back into the tank. Compressed air is used for this purpose, and suitable piping connections are provided, together with an automatically-operating controller for causing the proper successive sequence of connections to be made for performing these operations automatically. The piping arrangements are as follows :The bottom of the tank 8 is connected with the bottom of the keir 1 by the pipes 9 and 10, together comprising the bottom pipe. From the middle of this pipe a keir-filling pipe 11, hereinafter called a top-pipe, extends to the top of the keir, where it is connected to a double T 12, two branches 13 of which extend toward the ends of the keir and the fourth branch 1 1 of which extends beyond the keir and is connected with a water supply for purposes hereinafter described. The toppipe 11 is provided with a check valve 111 arranged to permit upward and prevent downward flow through the top pipe 11. The branch pipes 13 enter the keir 1 and are provided inside with perforated nozzles through which the bleaching liquor is projected into the keir on top of the pulp sheets. The water pipe 1% is provided with a cock 15. The bottom pipe 10 is provided with a check valve 16 which prevents flow from the tank to the keir but permits the flow in the opposite direction. The pipe 9 is provided with a cock 17 for purposes hereinafter described. The bottom pipe 10 is provided with an extension 18, having a cock 19 therein for the purpose hereinafter described. Assume the condition of the cocks in the pipes described to be that in which the cock 17 is open and the cocks 15 and 19 are closed, then when pressure is applied to the bleaching liquor in the tank 8, the liquor is driven down into the bottom pipe and being pre vented from flowing into the bottom of the keir by the check valve 16, it rises through the top-pipe 11, being permitted to flow upward by reason of the fact that the check valve 111 opens upwardly, and is discharged through branch pipes 13 into the upper part of the keir. lVhen pressure is exerted upon the bleaching liquor in the top of the keir, the liquor is forced down through the paper pulp sheets out into the bottom pipe 10 and thence through the check valve 16, the pipe 9 and into the bottom of the tank 8. Inasmuch as this pressure exerted upon the liquor in the top of the keir is exerted also in the pipe 11, it closes the check valve 111 and since the tank 8 is at this time vented (see infra), the pressure in the pipe 9 will always be less than the pressure in the pipe 10 so that the liquor flowing out of the keir will flow into the tank and not up through the top-pipe 10.

The air pipe connections consist of a main air supply pipe 20 having a cock 21 for admitting pressure to the apparatus. The air pipe 20 is provided with a branch 2 leading to the tank and a branch 23 leading to the keir. A vent pipe 24 rises from the tank and a similar vent pipe rises from the keir. A valve 24:0 is provided in the vent 2% so the escape of air therethrough may be restricted for a purpose hereinafter set forth. The pipes 22, 23, 2st and 25 are each provided with pneumatic diaphragm valves, of which the valve 26 in the pipe 22 and valve 27 in pipe 25 are opened by the exertion of pressure upon the diaphragm. The valve 26 is illustrated in Fig. 1. The valve 27 is exactly like it. These diaphragm valves are operated by pneumatic pressure on the diaphragms in a manner which is well known to those skilled in the art. The diaphragm valve 28 in the pipe 24: and the diaphragm valve 29 in the pipe are in all respects similar to the diaphragm valves 26 and 27 except that they operate to close when air pressure is exerted upon the diaphragm. The valves 28 and 29 differ therefore from the valves 26 and 27 illustrated in Fig. at by the fact that the valve disk is located upon the opposite side of the valve seat from that in which it is shown in such figure. (Of course this entails a slightly different construction of valve body in order to per mit the valve to be inserted from above instead of from below.)

In the pipe 22 is located a pilot valve 30. This pilot valve controls the admission of air to the four diaphragm valves above referred to. The pilot valve is illustrated in Fig. 5 and has a plunger 81 which when it is moved against the seat 32 closes the pilot valve and when it is moved away from the seat opens the valve and permits the air pressure from the pipe 22 to how into the controlling pipe which leads to four diaphragm valves.

Assuming the tank 8 to be filled with bleaching liquor and the keir 1 to be filled with paper pulp sheets, the cooks 15, 17 and 19 being in the condition above described, viz: 17 being open and 15 and 19 being closed, the opening of the air cock 21 will admit air to the pilot valve and the pilot valve at this time will be open, thereby permitting air pressure to fiow into the pipe 83. Air pressure in the pipe 83 will operate dia phragm valves 26 and 27 to open them and it will operate valves 28 and 29 to close them. The closing of the valve 28 closes the vent to the tank and the opening of the valve 26 permits the compressed air to flow into the tank 8; the opening of the valve 27 opens the vent to the keir and the closing of the valve 29 prevents the air pressure in the top of the keir, so, therefore, air pressure will be exerted only through the pipe 22 upon the top of the bleaching liquor in the tank 8 and that liquor will be forced into the top of the keir, the air displaced in the keir being allowed to escape through the vent pipe 25. The pilot valve 30 will be held open by means presently to be described until all of the bleaching liquor has been forced out of the tank into the top of the keir, then the pilot valve will be closed and the pipe 33 will be vented through the space around the plunger 31, whereupon valves 26 and 27 will be closed, closing automatically by reason of the springs on the valve stems, and the valves 28 and 29 being opened by the springs on their valve stems. Then the air pressure will be prevented from extending to the tank by the valve 26, and the tank will be vented by the opening of the valve 28. The keir will be closed to the atmosphere by the closing of the vent valve 27 and air will flow through the open valve 29 into the top of the keir and force the bleaching liquor down through the pulp sheets and out through the bottom pipe 9 up into the tank.

The mechanism for operating the pilot valve remains to be described. It consists of a ball lever illustrated in Fig. 3. This ball lever, indicated in a general way by the reference character 34, is a lever having a hollow ball 35 at one end and a weight 36 at the other pivo-tally supported upon a stud 37 mounted upon a stationary support conveniently the end of the tank 8. The lower member 38 of the lever 34 is a pipe which connects the bottom of the ball through the pipe 39 with the bottom of the tank and the upper member 40 of the ball lever 34 is a pipe which leads from the top of the ball to the hollow casting 41 of the lever, the pipe 40 connecting the ball with the hollow in the casting 41 which in turn is connected with the pipe 42 leading to and opening into the tank at a point somewhat above the bottom of the tank. Projecting upward from the casting 41 is a boss 43 to which the stem 44 of the pilot valve 30 is attached. The upper end of the hollow in the casting 41 is vented through the pipe 45 to the top of the tank 8. This vent pipe 45 has a ball check valve 46 in it which opens toward the tank, thereby permitting air to flow out of the ball when bleaching liquor is flowing into it.

It will be noted that the pipes 39 and 42 connected with the ball lever 34 are attached near the center of oscillation of the lever. The distortion of the pipes 39 and 42 by the movements of the ball lever are therefore very slight. The vent pipe 45 is attached to the ball lever at a point somewhat more distant from the pivot of the lever but inasmuch as the pipe is slender and flexible this is a matter of no particular consequence as the movement of this portion of the ball lever does not exceed a sixteenth of an inch. This ball lever taken in connection with the rest of the apparatus secures the continuous automatic operation of the complete apparatus.

It is perhaps apparent from what has been stated exactly how it operates, but for the sake of convenience such operation is here specifically set forth.

WVhen the air is turned on to the apparatus and it begins to force the liquor out of the tank 8 and into the top of the keir the ball 35 is full of bleaching liquor or at any rate contains a suflicient quantity of bleaching liquor so that it over balances the weight 36 and pulls upon the stem 34 so that it holds the pilot valve 30 open, thereby causing the diaphragm valves to stand in the condition above described wherein 26 and 27 are open and 28 and 29 are closed. The air pressure on the top of the liquor in the tank maintains a pressure on the liquor in the ball 35 through the pipes 39 and 42, but owing to the fact that there is pressure in the top of the tank, the check valve 46 prevents air from entering the top of the ball of the ball lever, so that the liquor in the ball 35 cannot escape until the level of the liquor in the tank 8 falls below the mouth of the pipe 42, whereupon air enters through that pipe and through the hollow in the casting 41 and the pipe 40 to the top of the ball 35 and permits the bleaching liquor in the ball to run out through the outflow pipes 38 and 39. Thus the ball 35 underbalances the weight 36 and the latter falls, causing the lever to be moved about its pivot in a direction to close the pilot valve 30. hen this valve is closed, the plunger engages the seat and the pipe 33 is vented through the space between the plunger and the valve housing. Thus the pressure in the pipe 33 falls and causes the operation of the four diaphragm valves, so that 26 is closed, thereby cutting 05 the flow of compressed air through the branch pipe 22 to the top of the tank 8; so that 27 is closed, thereby closing the vent from the top of the keir; so that 28 is opened. thereby venting the tank; and so that 29 is opened, thereby permitting the air to flow through the pipe 23 into the top of the keir and forcing the bleaching liquor down between the sheets of the pulp and subjecting the pulp to the bleaching action of the liquor. The valve 240 is maintained so nearly closed that the air can escape but slowly from the tank and in consequence the pressure in the tank 8 and keir 1 will rise as the liquor is forced from the keir into the tank. The sheets of pulp are therefore not only subjected to a forced circulation of bleaching liquor about and through them but are simultaneously subjected to pressure which acts to compress the air bubbles retained in the pulp, thus allowing the bleaching liquor to more thoroughly penetrate and impregnate the fibrous mass of pulp. As the liquor level is forced down through the pulp, the bleaching liquor is replaced by the compressed air which aerates the pulp and so assists in the chemical reactions involved in the bleaching. The compressed air because of its greater density has a greater effect chemically in assisting the bleaching by aerating the pulp than air at atmospheric pressure. The air continues to force the bleaching liquor outof the keir and into the tank until the liquor flows into the ball 35 in sufficient quantity to cause it to overbalance the weight 36, there being no impediment to the flowing of the liquor into the ball at this time, because the pipe 2% is vented at this time and the check valve 46 will therefore permit the air in the ball 35 to flow out through the check into the vent pipe 24. These operations automatically repeat themselves and are allowed to continue for a sutlicient length of time to secure the proper bleaching of the pulp, whereas in the old hollander method of bleaching pulp, it required, with certain kinds of pulp, a much greater length of time to secure the pro-per bleaching of the pulp. A similar material is bleach-ed bv the present apparatus in about one third of the time, and with a further saving due to the absence of the losses due to evaporation of the ehlorin from the open hollander. After the bleaching is completed. and the bleaching liquor is entirely blown back into the tank 8, the cock 17 in the bottom pipe is closed. the air valve 21 is closed, and the cock 15 and the water pipe are opened, and water under pressure is permitted to flow into the keir, and the check valve in the top pipe 11. closes under this pressure. At the same time, the cock 19 and the blower or waste pipe are opened, and the water is run through the pulp and water under pressure of 40 to 60 pounds per square inch is sufiicient to force the water through the pulp and to wash out the bleaching li uor from it. After the washing is completed, the water is shut off, the keir is opened, and the bleached pulp removed.

The present invention is not limited to the construction illustrated in the accompanying drawings described above, as it may be embodied in other forms within the scope of the following claims.

I claim 1. An apparatus for bleaching paper pulp having, in combination, a keir, a tank, a bottom pipe connecting the bottom of the keir with the bottom of the tank, a top pipe leading from the bottom pipe to the top of the keir, a vent pipe for the tank, an air supply pipe, a keir branch and a tank branch therefrom, pressure-operated valves in the vent and air pipes the valves in the tank air pipe and keir vent pipe operating by pressure to open the valves, and the valves in the keir air pipe and tank vent pipe operating by pressure to close such valves, and automatic mechanism operated by the rise and fall of liquor in the tank to operate such pressure valves to cause the opening of the keir vent pipe, the closing of the tank vent pipe, the opening of the tank air valve and the closing of the keir air valve for forcing liquor from the tank into the top of the keir and upon the fall of the level of the liquor in the tank to a predetermined level, to close the keir vent valve, open the tank vent valve, close the tank air valve and open the keir air valve, thereby forcing the liquor through the pulp back into the tank, substantially as described.

2. An apparatus for bleaching paper pulp having, in combination, a bleaching liquor tank, a bleaching keir, pipe connections between the tank and the top and bottom of the keir, air pressure supply means for blowing the contents of the tank into the top of the keir and forcing it through the material in the keir back into the tank having provision for automatically opening and closing vents in the tank and keir and closing and opening the air inlets to the tank and keir, substantially as described.

3. An apparatus for bleaching paper pulp having, in combination, a tank, a keir, pipe connections from the bottom of the tank to the top of the keir and from the bottom of the keir to the bottom of the tank, an air supply, a liquor level control, automaticallyoperated mechanism causing the liquor in the tank to be blown into the top of the keir and for thereafter blowing the liquor from the top of the keir through the material to be bleached back into the tank, substantially as described.

l. An apparatus for bleaching paper pulp having, in combination, a bleaching keir, a bleaching liquor tank, pipe connections from the bottom of the tank to the top of the keir and from the bottom of the keir to the tank, a compressed air supply, and means for admitting compressed air to the tank to blow the liquor from the tank into the top of the keir and for admitting compressed air into the top of the keir to force the liquor through the material in the keir back into the tank having provision for maintaining pressure in the keir while the liquor is being forced through the material in the keir, substantially as described.

5. An apparatus for bleaching paper pulp having, in combination, a bleaching keir, a bleaching liquor tank, pipe connections between the top of the keir and the bottom of the tank and the bottom of the keir and tank, a compressed air supply, means acting automeans acting automatically for intermittently blowing the contents of the tank into the top of the heir, through the material in the keir and back into the liquor tank comprising valves for admitting compressed air to the tank and the keir and valves for venting' the tank and keir, substantially as described.

EUGENE D. JEFFERSON.

Vitnesses:

HORACE VAN EVEREN, GEORGE E. STEBBINs.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C.

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