US3076501A

US3076501A - Apparatus for treating fibrous materials in the production of cellulose or semi-cellulose

Info

Publication number: US3076501A
Application number: US847162A
Authority: US
Inventors: Schinn Ernst
Original assignee: Escher Wyss AG
Current assignee: Sulzer Escher Wyss AG
Priority date: 1956-11-08
Filing date: 1959-10-19
Publication date: 1963-02-05
Anticipated expiration: 1980-02-05

Description

She'ets-Shef 1 Feb. 5,\ 1963 E. scHlNN APPARATUS FOR TREATING FIBROUS MATERIALS IN THE PRODUCTION oF cELLuLosE 0R swr-CELLULosE 'Original Filed Nov.. 8, 1956 INVENTOR. Erns; Schirm ccornegs Feb. 5,* 1963 E. scHlNN l ,076,501

APPARATUS FOR TREATING FIBROUS MATERIALS I N THE PRODUCTION OF CELLULOSE OR SEMI-CELLULOSE Original Filed Nov. 8, 1956 2 Sheets-Sheet 2` INV ENTOR. Erns Schnn @Wgww .Att o'rn egs United States Patent Otice 3,076,501 Patented Feb. 5, 1953 APPARATUS FR TREATING FIBROUS MATE- RIALS IN THE PRODUCTION OF CELLULOSE OR SEMI-CELLULOSE Ernst Schinn, Weingartshof, near Ravensburg, Germany, assignor to Escher Wyss Aktiengesellschaft, Zurich, Switzerland, a corporation of Switzerland Original application Nov. 8, 1956, Ser. No. 621,116. Divided and this application Oct. 19, 1959, Ser. No.

sl claims. (cl. 16a- 237) This invention relates to apparatus for carrying out a continuous process for treating fibrous material in the production of cellulose or semi-cellulose, in which the fibrous material is impregnated with a digesting liquid and, after being freed from excess liquor, is heated and digested in an -ambient of steam.

The present application is a division of my application Serial No. 621,116, tiled November 8, 1956, now abandoned, and is offered pursuant to the examiners requirement for restriction.

In a known process of this kind, impregnation of the brous material with digesting liquor takes place at superatmospheric pressure and at a temperature of 100 to 120 C.

The aim of the invention is to simplify the process and the the same time to improve de-aerating of the brous material. To this end, according to the invention, in a process of the kind specified, the vfibrous material is subjected to a vacuum in the course of its being impregnated with the digesting liquor.

The invention also extends to apparatus for continuously carrying out this process, the apparatus comprising a vacuum chamber which is sealed at its inlet and outlet side for the ibrousmaterial to be impregnated, by a column of digesting liquor.

The accompanying drawings depict an example of apparatus for carrying out the process according to the invention, in which drawings:

FIG. 1 is a sectional elevation of the de-aerating and impregnating apparatus.

FIG. 2 is a sectional elevation of the digester.

According to FIG. 1, a vacuum chamber 1 has two downwardly extending pipes 2 and 3. The pipe 2 dips into an open container 4 and the pipe 3 into an open container 5. The Vacuum chamber 1 is in communication with a vacuum pump 6. A pipe 7 carries a feed funnel 8 at its upper end and extends into a downwardly open chamber 9 below the downwardly open pipe 2. Within the pipe 3 there is a screw conveyor 10 which is driven by a motor 101 and the upper end of which extends to a height 11.

A pipe 12 which has a valve 13 built into it and opens into the container 4, supplies digesting liquor. The latter is at a level 14. The container is lower than the container 4 and contains digesting liquor up to a level 15. The liquid surface 15 is thus lower than the surface 14 by an amount h. The valve 13 is controlled by sensers 16 which control the liquid levels in the containers 4 and 5.

By Virtue of the vacuum in the chamber 1, which is produced by the vacuum pump 6, digesting liquor is sucked from the containers 4, 5 through the pipes 2 and 3, respectively, so that

liquid columns

17, 18 are formed to a

level

19, 20 respectively. The level 20 is lower than 19 by the same amount h.

The illustrated apparatus works continuously. The iibrous material to be treated enters the pipe 7 via a conveyor belt 21, driven by means not shown, and the funnel 8. There it forms a floating material column 22. The weight of newly arriving material presses this column downward, thus pushing particles of material from the lower end of the column 22 into the chamber 9. Here they enter the lower end of pipe 2 and rise in the liquid column 17 which seals the inlet side ofv the vacuum chamber 1. In column 17, the particles are moistened and freed from adhering air.

The rising particles form a material column 23, at the top of the liquid column 17, in the upper part of the pipe 2. The material continuously added to the lower end of this. column lifts the column so that particles at the top thereof flow over the edge at the liquid level 19 and slide to the level 20 which is lower by the distance l1. There they form a second material column 24 which floats on the liquid column 18. Column 18 seals the exit path from the vacuum chamber 1 against the entrance of air. As thermaterial column 24 grows, its portion lying below the liquid level 26 reaches the screw conveyor 11i which takes the particles downward.

The submerged depth of the material column 24 is thus kept constant, as is the height of the part of the column lying above the level 20. This last contains the major portionof the iibrous material situated in the vacuum chamber 1'. This, and also the part of the column 23 lying above the level 19, are exposed infthe chamber 1 where air readily separates out under the action of the vacuum. The air is withdrawn by the pump 6. The particles reaching the conveyor 10 are taken downward through the liquid column 18 where the proper impregnation is complated. The particles then reach the container 5 and are removed by a conveyor belt 25 driven by means not shown.

The digesting liquor absorbed by the fibrous material during its passage through the apparatus is continuously replaced'through the pipe 12 which opens into the containerl 4, i.e., into the part of the apparatus lying on the inlet side of the vacuum chamber. rl'he valve 13 opens whenever one of the

liquid levels

14, 15 drops below the respective senser 16. The new liquor supplied to the container 4 rises with the liquid column 17 runs over the edge at level 1.9, through the vacuum chamber 1 into the liquid column 18 and down it into the container S.

The rising new liquor in the column 17 assists the elevation of the fibrous material. However, conveyor means such as a screw may also be arranged in the pipe 2 for that purpose.

The iibrous material may also be moved mechanically from the pipe 2 to the pipe 3 within the Vacuum chamber. In that case, the screw 10` may project beyond the liquid level 20 in the pipe 3. The mechanically moved material would then represent the material content of the vacuum chamber.

Similarly, the material in the pipe 7 may be moved mechanically.

The speed of the various conveyor means is preferably variable.

The digester, according to FIG. 2 comprises a pressure chamber defined by a vertical casing 31. The impregnated fibrous material which is removed from the container 5 by the conveyor belt 25, is continuously introduced at the top of the casing 31 by a rotary feeder 32 from a funnel 33. The feeder 32 is driven by a motor 34. The feeder 32 seals the interior of the casing 31 from the atmosphere.

The fibrous material introduced into the digester contains only the quantity of digesting liquor which replaces the air which has been extracted in the vacuum chamber, and no liquid bath is provided within the casing 31. The fibrous `material is raised quickly to the digestion temperature by injecting steam under pressure through a conduit 35 with built in valve 36, and digestion thus is effected in an ambient of steam.

To discharge the cooked product from the casing 31, a delivery worm 37 driven by a motor 38 is provided at its lower end. The cooked product leaves the pressure chamber through an opening 39, in advance of which is a delivery stirrer 40 driven by a motor 41.

For operating the apparatus in a continuous process, the introduction of the material and the output of the delivery worm are to be controlled in relation to each other in such a manner that the pressure chamber is always filled with the impregnated fibrous material up to a certain level in order to obtain sufficient time for the throughput of the material. Furthermore, sufficient concentration of chemicals in the impregnating liquor contained in the container 5 is required in order to afford complete digestion within the casing 31.

What is claimed is:

1. Apparatus for continuously impregnating and deaerating fibrous material in the production of cellulose or semi-cellulose comprising in combination a casing enclosing a vacuum chamber; two tubular members extending downward from said chamber, one serving for the supply of the fibrous material to the vacuum chamber and the other serving for the discharge of the material from the vacuum chamber, the supply member having its upper end connected with the vacuum chamber at a point at least as high as the connection between the upper end of the discharge member and the vacuum chamber; two containers open to atmosphere; means supplying digesting liquor to said containers, the supply member having its lower end communicating with the interior of one of said containers below the liquid level therein, the discharge member having its lower end communicating with the interior of the other container below the liquid level therein; means responsive to the level of liquid in said containers controlling the level of liquor in said members whereby each is substantially filled with liquor; means opening into said one container below the liquid level maintained therein for introducing fibrous material into the lower end of said one member whereby said material rises within said one member to the vacuum chamber and air there separates from the material under the action of the vacuum; means for removing the separated air from the vacuum chamber; mechanical means for conveying the deaerated material downward through the column of digesting liquor in said other member in which impregnation of the de-aerated material with digesting liquor takes place, the upper end of the mechanical means being beneath the liquid level maintained in said other tubular member; means for collecting the impregnated material in the other container below the liquid level therein; and means for separating excess liquor from the collected material.

2,. The apparatus defined in claim 1 in which the means serving to introduce the fibrous material includes a pipe extending into said one container, with its outlet below the lower opening of the tubular member serving to supply material to the vacuum chamber.

3. In combination the apparatus defined in claim l and a digester comprising a vessel enclosing a pressure chamber; means for continuously introducing the said collected impregnated material, from which the excess liquor is separated, into said vessel at the top of the vessel; means for supplying steam under pressure to said pressure chamber, so that the impregnated material is brought to cooking temperature; and means for continuously discharging the material from the bottom of the vessel after digestion is completed.

4. The apparatus defined in claim 1 in which the said means for conveying the de-aerated material downward from the vacuum chamber comprise a screw conveyor arranged near the top of said other tubular member below the liquid level so as to continuously discharge de-aerated material from the vacuum chamber.

5. The apparatus defined in claim l in which said one tubular member opens into the vacuum chamber at level higher than the level at which said other tubular member opens into said vacuum chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,938,060 Wood Dec. 5, 1933 2,359,543 Branzell Oct. 3, 1944 2,709,652 Plunguian May 3l, 1955 FOREIGN PATENTS 135,529 Sweden Apr. 29, 1952 1,096,833 France Feb. 9, 1955

Claims

1. APPARATUS FOR CONTINUOUSLY IMPREGNATING AND DEAERATING FIBROUS MATERIAL IN THE PRODUCTION OF CELLULOSE OR SEMI-CELLULOSE COMPRISING IN COMBINATION A CASING ENCLOSING A VACUUM CHAMBER; TWO TUBULAR MEMBERS EXTENDING DOWNWARD FROM SAID CHAMBER, ONE SERVING FOR THE SUPPLY OF THE FIBROUS MATERIAL TO THE VACUUM CHAMBER AND THE OTHER SERVING FOR THE DISCHARGE OF THE MATERIAL FROM THE VACUUM CHAMBER, THE SUPPLY MEMBER HAVING ITS UPPER END CONNECTED WITH THE VACUUM CHAMBER AT A POINT AT LEAST AS HIGH AS THE CONNECTION BETWEEN THE UPPER END OF THE DISCHARGE MEMBER AND THE VACUUM CHAMBER; TWO CONTAINERS OPEN TO ATMOSPHERE; MEANS SUPPLYING DIGESTING LIQUOR TO SAID CONTAINERS, THE SUPPLY MEMBER HAVING ITS LOWER END COMMUNICATING WITH THE INTERIOR OF ONE OF SAID CONTAINERS BELOW THE LIQUID LEVEL THEREIN, THE DISCHARGE MEMBER HAVING ITS LOWER END COMMUNICATING WITH THE INTERIOR OF THE OTHER CONTAINER BELOW THE LIQUID LEVEL THEREIN; MEANS RESPONSIVE TO THE LEVEL OF LIQUID IN SAID CONTAINERS CONTROLLING THELEVEL OF LIQUOR IN SAID MEMBERS WHEREBY EACH IS SUBSTANTIALLY FILLED WITH LIQUOR; MEANS OPENING INTO SAID ONE CONTAINER BELOW THE LIQUID LEVEL MAINTAINED THEREIN FOR INTRODUCING FIBROUS MATERIAL INTO THE LOWER END