US2645378A

US2645378A - Pulp storage tower and method of emptying same

Info

Publication number: US2645378A
Application number: US13214A
Authority: US
Inventors: Richter Johan Christoffer Carl
Original assignee: Kamyr AB
Current assignee: Metso Fiber Karlstad AB
Priority date: 1947-03-20
Filing date: 1948-03-05
Publication date: 1953-07-14
Anticipated expiration: 1970-07-14

Description

July 14, 1953 J. c. F. c. RICHTER 5,378

PULP STORAGE TOWER AND METHOD OF'EMPTYING SAME Filed March 5, 1948 j /orney Patented July 14, 1953 PULP STORAGE TOWER 'ANDMETHOD O EMPTYING, SAME J ohan Christoffer Fredrik CarlfRichter, Karlstad,

1 Sweden, assignor to Aktiebolaget Kamyr, Karlstad,Sweden, a company of Sweden Application March 5, 1948, Serial No. 13,214

v In Sweden March 20, 1947 In the cellulose and paper-making industry it is often necessary to store pulp. Thick pulp, that is to say, pulp having a consistency of to per cent dry matter, is usually stored in so-calIed pulp bins, that is to say, open receptacles which have a comparatively small height but are quite large so that they require a large floor space. Even withsuch shallow receptacles the withdrawal of the thick pulp, which cannot be transported by pumping, involves certain difficulties. Usually, the removal of the pulp is effected by means of so-called pulp diggers over the upper rim of the receptacle, orby means of scrapers from thebottom of the receptacle, or by means of powerful water jets. All these prior art methods involve, however, the use of comparatively complicated, expensive and power consuming apparatuses.

In order to save floor spaceuseis often made of high and narrow receptacles, so-called storage towers. When such towers are used, however, the difliculties connected with the withdrawal of the pulp by the use of themethods above mentioned, are further increased. When high storage towers are used, there is also the risk of the withdrawal of the pulp becoming irregular due to the column of pulp in the tower having a tendency to stick at intervals to the walls of the tower.

It is an object of the present invention to eliminate the said difliculties and to provide a very simple and efficient method of emptying high consistency pulp from a storage tower into which the pulp is charged from the top of the tower. The invention is also concerned with a simple and efiicient improvement in pulp storage towers for carrying out this method. The essential characterizing feature of the invention resides in the emptying ofthe pulp being effected by the introduction of a liquid under pressure into the bottom of the tower below the pulp therein, such liquid serving to progressively displace the column of pulp upward to the top of the tower thereby to effect discharge of the pulp therefrom.

When thick pulp is displaced upward in the tower in this manner by the introduction of water into the bottom of the tower, it has been found that dilution of the pulp occurs only at the contact surface between the pulp and the water if the so-called flotation action is utilized. Such flotation action is due to the fact that thick pulp contains larger or smaller quantities of air which produces flotation, that is to say, the pulp will float on the water introduced into the tower 14 Claims.

2 I with an air cushion between the pulp and the water. If for any reason the thick pulp charged into the tower does not contain the quantity of air required for floating the pulp on the water, the present invention provides for the introduct'ion of a suitable quantity or air simultaneously with the displacement liquid into the bottom ofthe tower.

In the accompanying drawing, Fig. 1 and Fig. 2 illustrate'somewhat diagrammatically and by way of example two constructional forms of apparatuses for carrying out the method according to the invention.

Referring to Fig. 1, which illustrates the simplest form of apparatus according to the invention, I represents a vertical storage tower which is open at it's top so that the thick pulp to be stored may be charged into the tower in a simple manner by the use of any suitable means, such as a belt conveyer. When it is desired to withdraw a quantity of pulp from the tower, a displacement liquid, such as water, is introduced into the bottom 4 of the tower, as from a tank 8 by means of a pump I through a conduit 5 connected to the bottom of the tower and having a control valve 6. The liquid flowing into the bottom 4 of the tower progressively displaces the column of thick pulp 3 upward above the overflow edge 9 at the top of the tower, so that the pulp flows over said edge onto a belt conveyer III by means of which the pulp is conveyed to the desired place of use. When the desired quantity of pulp has been emptied from the tower in this manner, the water is drained from the bottom of the tower by opening the valve II in the conduit l2. The water drained from the tower may be used in the plant, preferably as back water, so as to recover the quantity of fiber that remains in the displacement liquid. If the pulp does not contain the quantity of air required for floating the pulp on the watenair may be introduced into the bottom of the tower through an air conduit 13 having a control valve M. The air is preferably introduced simultaneously with the introduction of displacement liquid through the conduit 5.

Fig. 2 illustrates a second constructional form of apparatus according to the invention, in which means are provided for effecting a fairly accurate n l nd mea ring of the quantity of pulp withdrawn from the storage tower. The same reference numerals as inJFig. 1 are used in Fig. 2 to denote similar parts. In the apparatus illustrated in Fig. 2, the displacement water is supplied by gravity from a tank [5 through the conduit to the bottom of the storage tower l. The tank i5 is provided with a suitable water level indicator, such as a glass gauge 56, which may be graduated to indicate the volume of water contained in the tank, for instance in cubic meters. Also in this case the introduction into the bottom 4 of the tower of a certain quantity of water from the tank I5 results in a corresponding quantity of pulp being displaced upward above and over the overflow edge 9 at the top of the tower to the conveyer band [0. The accuracy of the measuring of the pulp withdrawn from the tower is, of course, dependent upon the upper surface of the column of pulp in the tower being maintained at the same level. For this purpose there is provided suitable means for fixing the upper level of the pulp, such means being illustrated as comprising a rotary scraper I! at the top of the tower, said scraper being driven through suitable gearing 18 by a motor I9. Also .with this constructional form air for effecting flotation may be introduced through the conduit l3. When the desired quantity of pulp has been emptied from the tower, the water is drained from the tower by opening the valve H in the conduit 12, the water drained 01f being used at any suitable place in the plant. Fresh pulp may then be charged into the tower l by means of the conveyer 2.

One of the advantages of the present invention resides in the fact that the pulp is always available for distribution from a comparatively elevated point in the plant, due to the fact that while the pulp is emptied from the tower the pulp is progressively-raised to the top thereof. It is not necessary, therefore, as according to the methods hitherto practised, first to dilute the thick pulp to such consistency that it may be conveyed by pumping to the place of use, and then again to concentrate the pulp at such place. According to the present invention it is possible to convey the thick pulp without changing its consistency, for instance by means of a belt conveyer, and to allow the pulp to move by gravity from the conveyer belt to the place where the pulp is to be further treated. As an example, Fig. 2 shows a scraper or deflector 20 which deflects the pulp from the belt conveyer l0 and causes the pulp to fall through a chute 2| into a beater 22 in which it is usually desired that the pulp being treated shall have a comparatively high consistency. The advantage above stated becomes, of course, still more marked in such cases when it is desired to use thick pulp alone and where, therefore, the dilution incident to CAD withdrawal of the pulp by means of water jets from the bottom of the receptacle has resulted in added difficulties which it is desired to avoid.

From the point of View of simplicity and accuracy of measuring the quantity of pulp withdrawn from the storage tower, the present invention has a particularly important application to such manufacture where it is necessary accurately and in a convenient manner to mix several kinds of pulp stored in different storage towers, for the purpose of balancin the properties of such pulps. This may be the case, for instance, in a cellulose plant where artificial silk pulp is manufactured, and where an equalization of the viscosities is desirable. The same advantage is attained in paper mills where it may be desirable to mix accurately measured quantities of pulps of different qualities.

It will be understood that the constructional forms of apparatus above described and illustrated in the drawing are only given 'as examples and that they may be modified in respect of their details within the scope of the following claims.

I claim:

1. In the cellulose and paper making industry, the method of emptying high consistency fibrous pulp from a substantially vertical storage tower containing a column of pulp charged into said tower from the top thereof, which comprises introducing a liquid under pressure into the bottom of the tower directly below the pulp therein at a rate of flow such that a distinct border surface is maintained between the pulp and the liquid introduced, thereby progressively displacing the column of pulp upward to the top of the tower so as to eifect discharge of the pulp at the top of the tower.

2. The method of emptying high consistency fibrous pulp from a substantially vertical storage tower containing a column of pulp charged into said tower from the top thereof, which comprises introducing a liquid under pressure into the bottom of the tower directly below the pulp therein, thereby progressively displacing the column of pulp upward to the top of the tower so as to effect discharge of the pulp at the top of the tower, and introducing air into the bottom of the tower below the pulp therein simultane ously with the introduction of liquid to effect a flotation action between the pulp and the liquid.

3. In the cellulose and paper making industry, the method of emptying high consistency fibrous pulp from a substantially vertical storage tower containing a column of pulp charged into said tower from'the top thereof, which comprises introducing a liquid under pressure into the bottom of the tower directly below the pulp therein at a rate of flow such that a distinct border surface is maintained between the pulp and the liquid introduced, thereby progressively displacing the column of pulp upward to the top of the tower, and effecting discharge of the pulp by progressively scraping off the upper layer of the column of pulp as the column rises to the top of the tower.

4. In the cellulose and paper making industry, the method of emptying high consistency fibrous pulp from a substantially vertical storage tower as defined in claim 1, further comprising measuring the volume of liquid introduced into the bottom of the tower to provide a measure of the quantity of pulp discharged at the top of the tower.

5. In the cellulose and paper making industry, the method of storing high consistency fibrous pulp in a substantially vertical storage tower and emptying such pulp from said tower, which comprises charging pulp into the tower from the top thereof to form a column of pulp in the tower, and effecting withdrawal of a predetermined quantity of the pulp stored in said tower by introducing a corresponding quantity of a liquid under pressure into the bottom of the tower directly below the pulp therein, and by progres sively displacing the column of pulp upward to the top of the tower by said liquid so as to effect discharge of the pulp at the top of the tower.

6. Apparatus for use in the cellulose and paper making industry storing high consistency fibrous pulp, comprising a substantially vertical pulp storage tower having a uniform cross-sectional area alongits height from its bottom to its top and having at its top an opening of equal crosssectional area for charging pulp into and for per-.-

mitting the discharge of pulp from said tower in a lateral direction, a layer of high consistency fibrous pulp extending across the interior of said storage tower to provide a substantially continu ous border surface underlying the pulp to be stored within said tower, and inlet means of substantially lesser cross sectional area connected to the bottom of said tower and communicating directly with the interior thereof for introducing liquid under'pressure into thebottom of said tower directly below said pulp layer therein thereby to progressively displace the pulp in said tower upward to the opening iatthe top thereof.

area along itsheight from its bottom to its top and having at it's top an opening of equal cross sectional area for charging pulp into and for permitting the discharge ofpulp from said tower, means connected to the bottom of said tower for introducing a liquid under pressure into the bottom of said tower directly below the pulp therein to progressively displace the pulp in said tower upwardly to the opening at the top thereof,

and means connected to the bottom of said tower for effecting a controlled introduction of air into the bottom of said tower below the pulp therein.

9. Apparatus for storing high consistency fibrous pulp as defined in claim 6, comprising means for measuring the quantity of liquid intower directly below the pulp therein thereby to progressively displace the pulp in said tower upward to the opening at the top thereof, said means comprising a liquid-containing tank, a conduit connecting said tank to the bottom of said tower, flow-controlling means in said conduit, and a liquid level indicator connected to said tank to indicate the quantity of liquid distroduced through said liquid introducing means 1 into the bottom of said tower.

10. Apparatus for storing high consistency fibrous pulp as defined in claim 6, comprising means for discharging pulp in a lateral direction from said opening at the top of said tower.

11. Apparatus for storing high consistency fibrous pulp as defined in claim 6, comprising a movable scraper at the top of said tower adapted to progressively scrape off the top surface layer of the pulp at the top opening of said tower.

12. Apparatus for use in the cellulose and paper making industry for storing high consistency fibrous pulp, comprising a substantially vertical pulp storage towerhaving a uniform crosssectional areaalong its height from its bottom to its topand having at its top an opening of equal cross-sectional area for charging pulp into and charged from said tank through said conduit into the bottom of said tower.

13. In the cellulose and paper making industry, the method of emptying material from a substantially vertical pulp storage tower which is open at the top which comprises the steps of providing a layer of high consistency fibrous pulp which forms a contact surface betweensaid material and a liquid which may be disposed beneath said material in said tower, and introducing a liquid under pressure into the bottom of said tower directly below the material contained'therein at a rate of fiow such that the contact surface provided by said pulp layer will be maintained, thereby progressively displacing said material upwardly to the top of said tower so as to permit said material to be discharged from the open top thereof.

14. In the cellulose and paper making industry, the method of emptying high consistency fibrous pulp from a substantially vertical storage tower containing a column of pulp charged into said tower from the top thereof, which comprises introducing a' liquid under pressure into the bottom of the tower directly below the pulptherein,

thereby progressively displacing the column of pulp upward to the top of the tower so as to effect discharge of the pulp at the top of the tower, and introducing air into the bottom of the tower below the pulp therein to effect 'a flotation action between the pulp and the liquid.

J'OHAN CHRISTOFFER FREDRIK CARL RICHTER.

References Cited in the file of this patent UNITED STATES PATENTS