US1942622A

US1942622A - Paper manufacture

Info

Publication number: US1942622A
Authority: US
Inventors: Traquair John; Francis G Rawling
Original assignee: Mead Corp
Current assignee: Mead Corp
Priority date: 1928-04-27
Filing date: 1928-04-27
Publication date: 1934-01-09
Anticipated expiration: 1951-01-09
Also published as: GB339333A; US1821237A; DE560421C; FR681219A

Description

Jan. 9, 1934- J. TRAQUAIR ET AL PAPER MANUFACTURE Filed April 27, 1928 2 Sheets-Sheet l INVENTORS i A BY AT ORNEYS.

Jan. 9, 1934. J TRAQUAIR ET AL 1,942,622

PAPER MANUFACTURE Filed April 27 1928 2 Sheets-Sheet 2 INVENTQRS 2 5 A TTORNEYS. I

v Patented Jan. 9, 1934 v PATENT OFFICE PAPER MANUFACTURE John Traquair and Francis G. Rawling, Chillicothe, Ohio, assignor, by mesne assignments, to The Mead Corporation, Dayton, Ohio, a corporation of Ohio Application April 27, 1928. Serial No. 273,242

25 Claims.

This invention relates to the manufacture of paper and the like from cellulose-containing materials, and particularly to the treatment of fibrous material in the production of pulp.

One of the principal objects of the invention is to provide a method for continuously treating fibrous material or stock of high consistency with a gaseous treating agent.

Another object of the invention is to provide a 3;: method of chlorinating fibrous material or stock of high consistency with a gaseous chlorinating agent, which permits of continuous, controlled,

' uniform and effective treatment, with high economy in the use of the chlorinating agent.

Still another object of the invention is to provide apparatus for carrying out the above method, which apparatus is simple in construction, highly effective and automatic in operation, providing accurate control with a minimum of attention.

Other objects and advantages of the invention will be apparent from the following description when taken in connection with the accompanying drawings and appended claims.

In the drawings in which like characters of reference designate like parts throughout, the several views thereof- Fig. 1 is an elevational view, partially diagrammatic, with certain parts in vertical section, of. apparatus constructed in accordance with the present invention;

Fig. 2 is a horizontal sectional view on the line 2-2 of Fig. 1; and

Fig. 3 is a diagrammatic view of pressure-regulating and control mechanism for the control valves of the apparatus of Figs. 1 and 2.

The present invention provides a method of treating fibrous materials, which have been given a preliminary defibering treatment so as to more or less completely separate the fibers thereof, 43 with a gaseous treating agent whereby a high.

concentration of gaseous treating agent is secured in the fibrous material to secure a rapid.

and highly effective treatment. The method and apparatus of this invention are particularly adapted for the treatment of pulp of high consistency with a gaseous chlorinating agent, such as gaseous chlorine or bromine; this treatment being hereinafter termed chlorination; and they are particularly designed for carrying out the second stage of the chlorination treatment described in the application of John Traquair, Serial No.'2'l3,241, filed of even date herewith.

In accordance with this method, fibrous stock of high consistency such that it is readily permeable to' a gas and a continuously replenished gaseous chlorinating agent are moved relatively to each other in intimate reacting contact. Very satisfactory results are obtained with stock of a consistency above which is readily permeable to a gas, such stock for the purposes of descrip- 0 tion being hereinafter termed dewatered stock. Such dewatered stock can be continuously passed by gravity through an upright treating chamber. A continuous and controlled rate of travel of the fibrous material through the chamber may be v secured by continuously feeding the material into the treating chamber adjacent the upper end thereof, and continuously slushing out or diluting with liquid and washing the material out of the treating chamber adjacent the lower discharge end.

In accordance with this invention, very satisfactory results are obtained with marked economy in the consumption of the chlorinating agent by passing dewatered stock through a column of a gaseous chlorinating agent continuously maintaind within the treating chamber. The extent of the treatment is readily controlled by controlling the rate of passage of the material through the chamber, and by controlling the depth of the chlorinating column maintained within the cham. ber. The depth of the column of the gaseous chlorinating agent continuously maintained within the treating chamber is controlled. by choking the escape of gases adjacent the base of the treating chamber. The treated material is subjected to a dechlorinating action before being discharged from the treating chamber, by passing a fiuid inert with respect to the material and the chlorinating agent through the material to wash out the excess of the chlorinating. agent retained therein. I

Referring to the drawings, in which a preferred embodiment of the invention is illustrated, a chlorinating chamber or tower is indicated generally at 10. This tower comprises a shell 11 constructed of acid-proof material such as tile, the size of the shell depending upon the desired capacity of the .particular plant. In a plant for the production of about 20 tons of pulp a day, a shell substantially 25 to 30 feet high having an interior diameter of 3 to 4 feet, is a typical example for commercial installations. Dewatered stock is continuously fed into the tower at a. rate coordinated with the travel of stock through the tower and the discharge therefrom. As shown, dewatered stock or comminuted fibrous material of high consistency is fed by a chute 14 to an elevator 15, which in turn feeds the stock into a hopper 16. From the hopper 16, the material 110 passes into a screw conveyor 18 passing over an open upper end 12 of the tower. The screw conveyor 18 has an opening 19 on its lower side opposite the open upper end of the tower, and the material drops into the tower through this opening 19 as needed to maintain the tower filled, the surplus material handled by the screw conveyor 18 being discharged at the end 20 and returned to the source of supply.

The lower end of the shell 11, which is slightly constricted at its extreme bottom, as indicated at 25, is surrounded by a concentric shell 26 attached at its upper end in gas-tight relation to the shell 11 and forming an annular chamber 2'7 therebetween. The lower end 26' of the shell 26 is spaced from a suitable tile or concrete base 28 which is constructed to form with the shell 26 a water-sealed discharge for the tower. The base 28 beneath the tower shell is somewhat concaved as indicated at 29, and the outer peripheral lip 30 of this concaved portion surrounds and extends to a vertical height above the lower end of the shell 26, thus providing an annular trough for the water seal, and a peripheral discharge opening for the treated material.

For uniformly slushing out the treated material through this peripheral discharge, a rotary water distributor is provided, having a hollow shaft 33 passing through a stuffing box 34 within a centrally arranged opening 35 at the base of the tower. Shaft 33 has at its lower end a bearing gland 3'7 rotatably connecting it to a stationary water-supply pipe 38, and at its upper end has branched water-distributing and agitating arms 39, shown to be two in number, which are adapted to discharge jets of water toward the peripheral discharge. A worm-gear keyed to shaft 33 is driven by a worm 41 on a drive shaft 42 operated from any suitable source of power.

The stock slushed out through the water-sealed discharge overflows the lip 30 into an annular trough 43 formed in the base 28. Trough 43 has a lower discharge side 44 connected to a pipe 45 discharging the treated stock into a storage tank 46 containing stock of regulated consistency as is hereinafter described. Within the storage tank is a float 47 which serves to control through suitable linkage connections 48 a valve 49 within the water-supply pipe 38, whereby the fiow of water to the rotary water-distributing arms 39 is controlled in accordance with the level of treated stock inthe storage tank 46. The construction is such that the amount of water fed to the rotary distributors is controlled in accordance with the demand for treated stock, and consequently the rate of travel of the pulp through the treating tower is coordinated with the demand for treated stock. As the float 4'7 in the storage tank 46 falls with a drop in the level of stock therein, the valve 49 in the pipe 38 is moved by means of the linkage connections 48 toward open position to admit a larger quantity of water to the water-distributing arms 39 to increase the rate at which the material is slushed out from the treating tower, thereby increasing the rate at which the stock passes by gravity from the feeding end to the discharge end of the treating tower. Conversely, when the float 47 rises clue to a rise in stock level in the storage tank 46 such as results from a decrease in the demand for treated stock, the valve 4'7 is moved toward closed position to reduce the quantity of water supplied to the distributing arms.

The construction of the chlorinating tower 10 is such that three distinct treating zones are formed therein, an upper feeding zone A, a central chlorinating zone B and a lower dechlorinating zone C. An inlet pipe 50 provides for the introduction of a gaseous chlorinating agent into the chlorinating zone B of the tower. Preferably, liquid chlorine confined under high pressure in tanks is used, and this liquid chlorine is fed at a controlled rate through suitable pressure-reducing valves and a heater to provide a regulated feed of chlorine gas under slight pressure to the chlorinating tower. As shown, a tank 52 containing liquid chlorine discharges into a pipe 53 through a control valve 54 and a pressurereducing valve 55 into a heater 56 comprising a steam or other fluid-heating chamber 57 having heating-fluid inlet and outlet connections 58 and 59. Within the heater is a coil 60 connected at one end to pipe 53 and at the other end to inlet pipe 50. Within the pipe 50 is a pressure-controlled valve 61 constructed to control the introduction of chlorine gas in accordance with pressure conditions within the tower.

Chlorine gas, being of higher specific gravity than air, tends to travel downwardly within the shell 11 of the chlorinating tower. An outlet 65 from .the chamber 27 provides for the escape of gases from the base of the tower. In order to maintain a column of chlorine gas of controlled depth within the tower, the outflow of gas through the outlet 65 is controlled by means of a valve 66 actuated in accordance with the pressure existent at the base of the tower. A pressure pipe or passage 67 leads off from the upper end of the chamber 27 to a suitable sensitive pressureregulating device shown diagrammatically as comprising an inverted bell '70 dipping within a suitable liquid within a container '71, the pressure space within the inverted bell '70 being in communication with the open end of the pressure pipe 67. The bell 70 is in turn connected through suitable mechanism indicated diagrammatically at 73 which serves to magnify slight movements of the bell, and this mechanism is in turn operatively connected to the operating stem of the valve 66, whereby movements of the bell '70 serve to actuate the valve. The pressure-regulating device may also be connected as indicated at '74 to the operating stem of the valve 61, or a separate pressure-regulating mechanism may be provided for this valve.

In Fig. 3 is disclosed a satisfactory form of sensitive pressure-regulating mechanism which is responsive to very slight pressure fluctuations, and in which electrical means are used to magnify slight movements of the pressure bell to thereby actuate the valve or valves to which it is connected. As shown, the pressure bell 70, which preferably is of relatively large area to give increased buoyancy, is suspended from a support by an adjustable screw 81, and a fine coil spring 82 connected at one end to the screw 81 and at the other end to a supporting wire or rod 83 for the bell. Carried by the rod 83 and movable therewith upon movement of the bell is a mercury cup 84 electrically connected to the rod, and a contact 85 also electrically connected thereto. Cooperating with the movable mercury cup 84 is a fixed contact 86 connected by wire 87 to one side of a battery 88. The other side of the battery 88 is connected by wire 89 to one primary terminal of a relay 90, the other primary terminal of the relay 90 being connected by wire 91 to the coil spring 82 to complete the electrical circuit through the spring 82 and rod 83. Cooperating with the movable contact 85 is a stationary mercury cup 94 connected by wire 95 to one side of a battery 96, the other side of battery 96 being connected by wire 97 to one primary terminal of a second relay 98. The other primary terminal of relay 98 is connected by wire 99 to wire 91 to thereby complete the primary electrical circuit for relay 98.

The secondary terminals of relay 90 are connected by wires 103 and 104 with the opposite ends of a solenoid coil 105 having a movable core 106. The secondary terminals of relay 98 are connected by

wires

107 and 108 with the opposite ends of a second solenoid coil 109 having a movable core 110. The

solenoids

105 and 109 are arranged in spaced relation and in alignment on opposite sides of a stirrup 111 to which the solenoid cores 106 and 110 are pivotally'connected by respective links 112 and 113. The stirrup 111 is suspended by rod 114 connected to a strap 115 rotatably mounted on a crank-pin 116 projecting from a driven disk 117. The disk 117 is continuously driven in the same direction in any suitable manner, such 'as by electric motor 118 through a reduction gearing 119. The branched

arms

121 and 122 of the stirrup 111 carry

pawls

123 and 124 respectively adapted to engage in certain operative positions of the stirrup with a double ratchet wheel 125 having oppositely disposed teeth on opposite sides thereof, as indicated at 126 and 127. The ratchet wheel is keyed to a shaft 128, which in turn may be operatively connected directly through

gears

129 and 130 or through intermediate connections to the valve shaft 131 carrying the valve to be controlled. One side of the shaft 128 may be connected to actuate the valve 66, and the other side of the shaft 128 may be connected through similar gears 129' and 130' and shaft 131' to actuate the valve '61, although it may be preferable to provide a separate mechanism for each valve.

Adjustment of the pressure bell having been made through the screw 81 for a predetermined pressure within the tower, then when thepressure therein rises above this predetermined normal upward movement of the bell 70 and rod 33 brings movable mercury cup 84 into electrical contact with fixed contact 86 to close the primary circuit of relay 90. This energizes the solenoid coil 105, therebymoving the connected cores 106 and 110 and the stirrup 111 to the left, as shown in Fig. 3, to bring pawl 124 into engagement with the teeth 127 on the righthand side of ratchet wheel 125. Continuous rotation of disk 117 by motor 118 imparts through the crank 116 and intermediate connections an oscillatory movement to the stirrup 111, which thereby imparts through the pawl 124 a stepby-step rotation of ratchet wheel 125 and

shafts

128 and 131 to effect opening movement of valve 66 to permit a more rapid outflow of gases from the base of the tower to bring the pressure back to the predetermined normal. At the same time the valve 61 is movedthrough the gearing and shaft 131 toward closing position to reduce the supply of chlorinating agent to the tower.

Conversely when the pressure at the base of the tower falls below the predetermined normal, falling movement of bell 70

breaks contacts

84 and 86, and closes contacts 85 and 94 to close the primary circuit of relay 98. This energizes the solenoid coil 109 and effects shifting move- I ment of the cores 110 and 106 and stirrup 111 to the right to thereby move pawl '124 out of engagement with the ratchet wheel and bring pawl 123 into operative engagement with the teeth 126 on the left-hand side of ratchet wheel 125. The teeth 126 being oppositely faced to the teeth 125, the ratchet wheel and connected shafts now are rotated in the opposite direction to move valve 66 toward closing position to further choke the escape of gases from the base of the tower, and to move valve 61 toward opening position to increase the supply of chlorinating agent to the tower. The described construction provides extremely sensitive adjustment and actuation for the control valves, and tends to maintain a predetermined pressure within the chamber 27 at the base of the tower. At the same time the introduction of chlorine gas is controlled in accordance with the consumption through reaction with the fibrous material or escape through the gas outlet.

The predetermined pressure within the chamber 27 and at the bottom of the shell 11 is so selected as to maintain a column of gaseous chlorinating agent of the desired depth within the tower. When chlorine gas which is heavier than air is used, a pressure the base of the column which is equal to the excess weight of the chlorine gas column over a like column of air. A column of chlorine gas of the desired depth is maintained within the tower by so controlling the pressure at the base of the tower as to just balance this excess weight of the chlorine gas column. Such pressures are quite small, and with an apparatus of the size heretofore mentioned, are of the order of .005 to .0005 pounds per square inch above atmospheric. By slightly increasing the predetermined pressure effective at the base of the tower, the depth of the column of chlorine gas within the chlorinating zone of the tower is increased. Conversely, by decreasing the predetermined pressure existent at the base of the tower, the depth of the maintainedcolumn of chlorine gas is decreased. Any desired depth of column of chlorine gas within the capacity of the tower is thus readily obtained and controlled within narrow limits.

Adjacent the lower end of the upper feeding zone A of the tower is a gas offtake pipe 138, which forms in effect an upper limit for the chlorinating column. The pipe 138 is preferably placed under slight subatmospheric pressure. Air which is trapped in the fibrous stock introduced into the upper feeding end A of the tower and which is displaced by the chlorine as the stock passes into the chlorinating atmosphere of the chlorinating zone B passes off by this pipe 138. Some slight diffusion of chlorine gas upwardly through the tower may take place, and this gas is also removed by the offtake pipe 138 so prevented from escaping through the open upper end of the tower into the atmosphere. Should the depth of the chlorinating column be increased to such an extent that the upper level of the chlorine column'reaches the offtake pipe 138, then this excess chlorine gas is removed by thispipe and prevented is formed at from passing up through the feeding zone A into the atmosphere.

Fibrous stock passing. downwardly from chlorinating zone B toward the water-sealed discharge, carries with it some trapped chlorine gas, and this is removed before the material is discharged to the exterior by the introduction of a dechlorinat- 1 are positioned adjacent the base of the tower beneath the water-distributing arms 39. Jets of air discharged at a controlled rate into the treated stock displace and wash out the excess chlorine, and the air and removed chlorine pass off through the offtake by virtue of the pressure slightly in excess of atmospheric at the base of the tower. The action of the water-distributing arms 39 in agitating and diluting the stock combined with the action of the air jets effects a substantially complete dechlorination of the stock before it is discharged from the tower. The construction, including the shell 26 surrounding the lower constricted end 25 of the shell 11 and forming a separate chamber 27 and dechlorinating zone C to which the offtake 65 is connected, is such that air introduced for dechlorination is removed without objectionable diffusion of air into the chlorinating zone B of the tower. This may be due in part to the fact that the shell 11 is maintained filled with stock, thereby preventing the setting up of convection currents within the tower, and further may be due to the fact that the path of least resistance to gas flow is directly to the offtake 65. In any event, the air is effectively removed from the dechlorinating zone C by means of the offtake pipe 65 without passing up through the tower.

Base 28 of the tower has a peripheral flange 145 which forms the outer side of annular trough 43, and also has a plurality of upwardly extending arms or spiders 146 to which the shell 26 is fastened, thus forming a supporting structure for the shells 11 and 26 of the tower. The hollow shaft 33 is provided with a port 148 adapted to introduce water within the opening 35 immediately above the packing gland 34 for the purpose of keeping the upper part of the gland 34 free from corrosive solutions as well as to provide a flow of water from the center of the base outwardly to the annular seal to assist in the slushing action.

For assisting in the removal of treated stock overflowing the lip 30 of the Water seal, a pipe 150 is provided for introducing suitable liquid into the trough 43. To prevent undue dilution of stock, slush pulp of controlled consistency from the storage tank 46 is preferably supplied to the pipe 150, the construction being also adapted to control the consistency of the stock within the storage tank 46. As shown, a pump 151, of any suitable character such as a centrifugal pump, withdraws stock from the storage tank 46 through a pipe 152 and feeds it through a pipe 153 to a branched pipe, one branch 154 of which is connected to the pipe 150 for introducing the slush pulp into the trough 43 of the tower, the other branch 155 leading to a consistency regulator 156which may be of any suitable conventional character and so is not illustrated in detail. The consistency regulator 156 serves in a well-known manner to introduce dilution water through a pipe 157 into the suction side of the pump 151 in accordance with the consistency of the pulp fed to the consistency regulator 156 through the pipe 155. The pulp discharged from the regulator 156 passes back to the storage tank 46 through a pipe 158.

In operation, dewatered stock is fed into the tower by means of the elevator and screw conveyor construction so as to maintain the tower continuously full of stock. Treated stock is slushed out at the base of the tower by the controlled water distributor in accordance with the demand for treated stock. Stock within the 'ower' passes downwardly therethrough by gravity from the feeding end to the discharge end as the stock is slushed out at thedischarge end. A controlled column of definite depth of a gaseous chlorinating agent is maintained within the tower at all times, and the dewatered stock passing through this column at a controlled rate is continuously and uniformly chlorinated. The treating time is usually fifteen minutes to half an hour, but may be longer. The treated stock is subjected to a dechlorinating action of air to remove the excess chlorine before being discharged from the tower. Gases passing off through the offtakes are preferably passed to suitable chlorine absorption apparatus (not shown) where I the chlorine gas is recovered. Slush pulp made down to a controlled consistency. is used to assist in removing the stock discharged from the tower to a storage tank, where it is accumulated for further treatment or use.

While the method herein described, and the fo:m of apparatus for carrying this method into effect, constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to this precise method and form of-apparatus, and that changes may be made in either without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. The method in the manufacture of pulp,

which comprises continuously moving dewatered fibrous material and a continuously maintained gaseous chlorinating agent relatively to each other through a treating chamber, and continuously washing out the excess of the gaseous chlorinating agent from the treated material prior to the discharge of the treated material from the treating chamber.

2. The method in the manufacture of pulp, which comprises moving fibrous stock by gravity through a controlled gaseous chlorinating atmosphere within a treating chamber, and removing the treated pulp from the chamber by slushing the pulp out of the chamber with a liquid through a liquid sealing bath.

3. The method in the manufacture of pulp, which comprises introducing a gaseous chlorinating agent into a treating chamber, controlling the escape of gas from adjacent the base of the chamber in accordance with pressure existent within the chamber, and subjecting fibrous stock to the action of the gaseous chlorinating agent so maintained.

4. Apparatus of the character described, comprising a chlorinating chamber, means for continuously moving dewatered fibrous material therethrough, and pressure responsive means for maintaining a controlled atmosphere of a gaseous chlorinating agent within said chamber.

5. Apparatus of the character described, com

prising a chlorinating tower having a feeding end and a discharge end, means for feedingdewatered fibrous stockinto the feeding end of said tower, means for introducing liquid into the interior of said tower adjacent the discharge end thereof to slush the treated stock out of said tower, a container receiving the treated stock discharged from said tower, and means responsive to the level of treated stock in said container for automatically controlling the rate of introduction of said liquid to thereby control the rate of passage of saidfibrous stock through the tower.

6. Apparatus of the character described, comprising a chlorinating tower open to atmosphere adjacent its upper end, means for controlling the supplying of chlorine gas to said tower, means for controlling the discharge of gas from said tower, and pressure-regulated means responsive to pressure of gas within said tower to regulate at least one of said controlling means to maintain a column of chlorine gas within said tower controlled as to height so that the top of the column is below the open upper end of said tower.

7. Apparatus of the character described, comprising a chlorinating tower through which dewatered fibrous stock passes by gravity, said tower having a lower discharge end having an annular discharge channel, and a rotary jet within said tower for supplying a stream of liquid of constantly changing direction toward said annular discharge channel.

8. In fibrous-stock chlorinating apparatus of the character described, a shell, a base spaced from the lower end of said shell and having an upwardly flared lip surrounding the lower end of said shell forming a water seal with said shell and providing also an annular treated stock discharge, an annular slush trough associated with said base on the exterior of the water seal, and means for introducing liquid into said slush trough to slush out the stock overflowing sai annular stock discharge.

9. The method in the manufacture of pulp, which comprises introducing a gaseous treating agent of greater specific gravity than air into a reating chamber, controlling the escape of the gaseous treating agent adjacent the base of the column to create a pressure sufficient to balance the excess weight of the column of gaseous treating agent over the weight of a like column of air, and subjecting fibrous material to the action of the gaseous column so maintained.

10. Apparatus of the character described comprising a chlorinating chamber, means for continuously moving dewatered fibrous material therethrough in a substantially continuous fibrous mass, and pressure responsive means for maintaining a quiescent column of chlorine gas of controlled depth therein.

11. Apparatus of the character described, comprising a chlorinating tower, means for supplying chlorine gas to said tower, a gas offtake from said tower, a valve within said gas oiftake, and pressure responsive means for controlling the positioning of said valve to automatically regulate the flow of gas through said offtake in accordance with the pressure within said tower.

12. Apparatus of the character described, comprising a chlorinating tower having an open upper feeding end and a lower discharge end, means providing a water seal for the lower disa charge end of said tower, means for introducing chlorine gas into said tower, a gas offtake adjacent the lower discharge end of said tower, and controlmeans for controlling the flow of gas through said offtake to thereby maintain a predetermined pressure within the base of said tower, said pressure being such as to balance the weight of a maintained column of chlorine gas within said tower.

13. Apparatus of the character described comprising a shell having an open lower end, a second shell surrounding said lower end of the first shell providing a chamber in communication with the space within said first shell adjacent the lower end thereof, a gas offtake from said chamber, means for introducing a gaseous chlorinating agent and fibrous material into said first shell,

and means for supplying a dechlorinating fluid to said chamber.

14. Apparatus of the character described, comprising a chlorinating tower having a peripheral discharge opening adjacent the lower end thereof, means for introducing fibrous stock into said tower, and a rotary liquid distributor for supplying liquid adjacent said discharge end to slush out treated stock through said peripheral discharge opening. 4

15. Apparatus of the character described, comprising a chlorinating tower, a base spaced from the lower end of said tower forming a Water sealed peripheral discharge opening for said tower, means for introducing fibrous stock into said tower, a hollow rotary shaft, means for supplying water to said hollow shaft, said shaft having water distributing and agitating arms adjacent said discharge, and means for rotating said shaft to agitate and uniformly slush out treated stock through saidperipheral discharge opening. A

16. In apparatus of the character described, a shell, a base spaced from the lower end of said shell and surrounding the lower end of the shell to form therewith a combined water seal and annular discharge passage, means for introducing fibrous stock into said shell to be treated therein, means for introducing water adjacent said base to slush out treated stock through said water seal and annular discharge passage, and means for introducing air adjacent said base and within said water seal to dechlorinate the stock previous to the slushing out of the stock.

17. In apparatus of the character described, a shell, means for introducing fibrous stock into said shell to be treated therein, a water sealed discharge opening for said shell, a base spaced from the lower end of said shell forming a slush trough on the exterior of said water seal for receiving treated stock overflowing the water seal, a slush pulp tank, means for feeding stock slushed out of said tower to said slush pulp tank, means for regulating the consistency of the stock within said tank, and means for introducing said stock of regulated consistency from said tank into said slush trough for slushing out the stock overflowing the water seal of said tower.

18. In apparatus of the character described, a shell, a base forming therewith a water seal, said base having an opening therethrough, a hollow shaft passing through said opening, a stufling box for said shaft within said opening, means for introducing water into said hollow shaft, said shaft having a port therein located within said shell adjacent said stufiing box for discharging water onto said stufling box and base.

19. The method in the manufacture of pulp, which comprises passing fibrous material of a consistency controlled so as to be permeable to a gaseous chlorinating agent through a continuously maintained and replenished atmosphere of a gaseous chlorinating agent within a treating chamber, introducing a gaseous washing fluid such as air into the chlorinated ma- '5 agent, and removing the treated and dechlorinated fibrous material from the treating chamber.

20. In apparatus of the character described, a chamber, means for introducing fibrous material into said chamber, means for maintaining a gaseous treating atmosphere within said chamber including a gas pipe, a valve therein, electrical control means for regulating the position of said valve, and pressure responsive means cooperating with said electrical control means to control the operation thereof in accordance with the pressure existent within said chamber.

21. In apparatus of the character described, a tower, means for introducing fibrous material into said tower, means for maintaining a column of gaseous chlorinating agent of controlled depth within said tower, including a gas inlet pipe for said tower, a gas ofitake pipe for said tower opening therein adjacent the base of the gaseous column, a valve within said offtake pipe for regulating the escape of gas from said tower, and automatic means for regulating the position of said valve including an electrical control means, and pressure means responsive to pressure within said tower adjacent the base of the gaseous column therein for controlling the action of said electrical control means.

22. The improved process of treating pulp which consists in feeding the same while in a moist but non-liquid form downwardly through a gaseous heavier-than-air chemical treating medium, then immersing the treated pulp in a liquid diluting bath and then progressively removing the diluted pulp while utilizing said liquid as a carrier in effecting said removal and adding liquid to said bath to replace that removed with the pulp.

23. The method in the manufacture of pulp, which comprises moving fibrous stock in a continuous fibrous column through a continuously maintained and quiescent column of a gaseous chlorinating agent, controlling the depth of the column of chlorinating agent effective upon the pulp and the rate of passage of the stock through the gaseous column to provide a predetermined chlorinating action.

24. The method in the manufacture of pulp, which comprises passing fibrous stock through a maintained column of a gaseous chlorinating agent of predetermined but variable depth, and controlling the depth of the chlorinating column and the rate of feed of the pulp therethrough, to efiect predetermined chlorinating action on said pulp.

25. The method in the manufacture of pulp, which comprises moving fibrous stock of a consistency of substantially 15% or higher in a fibrous column through a continuously maintained column of a gaseous chlorinating agent, and controlling the depth of the column of chlorinating agent effective upon the pulp and the rate of travel of the pulp through said maintained column of chlorinating agent to provide a predetermined chlorinating action.

JOHN TRAQUAIR. FRANCIS G. RAWLING.

CERTIFICATE ot CORRECTION.

Patent No. i, 942, 622.

January 9, 1934.

JOHN TRAQUAIR, ET AL.

it is hereby certiiieti that error appears in the printed specification of the above numbered patent requiring correction as ioliows: Page 3, line 132, after iii" insert the word and; page 5, aise 5., iin ineiad line 24, claim 8, strike out the word and insert the same before "providing" in same line and claim; page e iii, ciaini 1.7, beginning with the word "means" strike out all to and ing the word "iorming" in line 114-, and insert instead a base spaced irort the iower end oi said shell forming a water sealed discharge opening icr said shell, treated therein;

means for introducing fibrous stock into said shell to be and that. the said Letters Patent should be read with these correction therein that the same may conform to the record of the case in the l atent iiiiiee.

(Seal) i Hopkins Acting Commissioner of Patents.