US1560286A - Method and apparatus for handling foaming and frothing liquids - Google Patents

Description

Nov.3 1925- 1,560,286

W. D. MOUNT METHOD AND APPARATUS FOR HANDLING FOAMING AND FROTHING LIQUIDS Filed March 1, 1924 avibentoz William 17. Mount v m8 61mm Patented Nov. 3; 1925.

UNITED STATES um n. noUmg-or nyucnnune, VIRGINIA,

IETHOD AND APPARATUS FOR HANDI-ING IOAMING AND FROTHING LIQ' UIDS.

Application filed March '1, 1924. Serial No. 696,407.

To all whom it may concern:

Be it known that I, WILLIAM D. MOUNT, a-citizen of the United States, residing at Lynchburg, in the county of Campbell and State of Virginia, have invented certain new and useful Improvements in Methods and Apparatus for Handling Foaming and Frothing Liquids, of which the following is a full, clear, and exact description.

This invention .relates to the handling of foaming and frothing liquids, and particularly to the handling of the hot digestor liquor in a pulp mill. The hot digestor liquor, after its separation from the pulp, has a tendency to foam and froth to such an extent that it cannot be handled satisfactorily by pumps, because the froth and foam spoils the vacuum created by the pump. It is practically impossible toarrange the various apparatus of a mill in such a manner that pumps for the handling of the digestor liquor may be eliminated. Accordingly, an

object of the invention is to provide an 1mproved method and apparatus for the ban-- dling of foaming and frothing liquids, and the destruction of the foam and froth. A further object to provide an improved system for the washing of paper pulp and the handling of the filter liquor therefrom. A still further object is to provide improved apparatus for accomplishing the above objects which will be exceptionally simple, effective, relatively inexpensive, and readily applicable to existing apparatus and systems used in pulpmills. Other objects and advantages will be apparent from the following description of an embodiment of the invention, andthe novel features will be particularly pointed out hereinafter in claims. I

o In the accompanying drawing a pulp separating and washing system embodying the invention is illustrated.

In the illustrated apparatus, the pulp from the digestor is blown into pans or tanks in which it is diluted to the desired consistency. The dilution is usually accomplished by the addition thereto of hot digestor liquor from which other pulp has been separated. This diluted pulp is then conveyed to the stock or supply chest 1 from which it is withdrawn by a'pump 2 and circulated through a pipe 3 to the pan'4 of a filter or separator, the overflow or surplus returning to the stock chest by a return pipe 5. The filter or separator may be of any suitable construction but is preferably subject matter of my copending application for patent Serial No. 636,365, filed May 3,

In this filter and Washer, the diluted pulp is circulated through the pan of the filter continuously to avoid the necessity of agitation in order to keep the pulp fibres in suspension, the overflow returning through pipe 5 to the stock chest.

The rotary filter drum 6 is mounted for rotation so as'to dip partially into the diluted pulp in the pan 4. As is well known, the drum is divided into a plurality .of compartments which are connected in succession to suitable suction devices for effecting the filtering operation. In this type of filter or washer, a suction pipe 7 is connected to the rotary drum 6 in such a manner that the suspending or filter liquor passes therethrough as the cake is formed upon the periphery of the drum, and this suction is continued through the portion of the drum periphery immersed in the. diluted pulp in the pan 4. The liquid is drawn through the pipe 7 by suction from a source to be presently explained.

A vacuum trap Sis provided with a lower or inlet chamber 9, an intermediate chamber 10, a steam belt 11, and an upper chamber 12. The upper chamber 12 communicates with the intermediate chamber 10 by passages 13 which pass through the steam belt 11. The steam belt comprises a casing separated by end walls from the intermediate chamber 10 and the upperchamber 12, to which steam is admitted by a pipe 14 and from which the condensation or drip is removed through a pipe 15. The passages 13 may conveniently be provided by tubes which are expanded into the end Walls of the steam belt casing.

The-upper chamber 12 is connected by a pipe 16 to the upper end of a condenser'17, and the condenser, at its upper end but spaced from' the inlet from the pipe/16,

' circumference of the chamber 9. During the swirling of the digestor liquor, the foam or froth will be separated from the liquor by centrifugal action, collecting in the central part of the chamber around the axis of swirling, then will rise upwardly from the chamber 9 into the intermediate chamber 10, and thence pass upwardly into the passages 13.

As the foam or froth moves along the passages 13 the heat of the walls of the passage will change the vapor tension of 7 the froth or foam so that the bubbles will break and the froth and foam will be killed, all ormost of it draining back down the tubes or passages and into the lower chamber 9, and any of it which goes over the top of the tubes or passages 13 will collect in an annular trough 20 in the upper chamber 12, located below the upper ends of the tubes or passages 13. A mushroom battle 21 is mounted in the upper chamber 12 over the upper ends of the tubes or passages 13, so asto deflect-into the annular trough any of the liquid that may pass upwardly through the'tubes. The

baflie 21preferably has a small vent passage 22 therethrongh from its center, so as toprevent the formation of an air look under the baffle.

A pipe 23 opens into the lower chamber 9 centrally through thei' 'bottom wall. 24 thereof, and is connected to the inlet side of a strong liquor pump 25. A pipe 26 connected to the discharge side of thepump is connected through valves 27 and 28 to pipes 29 and 30 which convey the strong liquor to to a recovery plant or to the dilution tanks,

the disposition of the strong liquor depending upon whichplpf the valves 27or 28 is open. A small c aiin pipe 31 connects the annular trough 20 with the pipe 23 leading.

to the Suction side of the pump 25 so that any liquor collecting in the annular trough will be removed by the action of the pump.

A mushroom bafile 32 is disposed in the lower chamber 9'over the outlet into the pipe 23 and, in spaced relation to both the bottom and the side walls of the chamber, so that only the liquid from the periphery of the chamber may enter the pipe 23 running to the pump;

The liquor swirlingaround the periphery of the lower chamber will not have any ma terial quantity .of froth or foam, and this liquid will pass beneath the bafile 32 and small vent 33 extending from its central portion to approximately the lower end of the intermediate chamber 10 so as to prevent the formation of an air lock beneath the baflie.

In the washer 0r filter illustrated, the pulp cake or layer on the drum is subjected to two washings successively through spray devices 34: and 35,-which are arranged above the drum so as to spray the filter cake successively. The fresh water or washing fluid for the final wash is conducted through the pipe 36 to the second wash spray 35, from which it is sprayed upon the filter cake. This'sprayed liquid is drawn through the filte cake and drum and passes through the suction outlet 37 into a wash trap 38. A pipe 39 connects the upper end of the wash trap 38 with the pipe 16, so that the vacuum created in the pipe 16 by the exhauster 19 u will be transmitted to the wash trap, and create a suction in the pipe 37 which draws the second spray water through the filter cake and through the drum. The wash water collecting in the trap 38 will pass through the pipe 40 to the wash pump 11,- from which it is forced through the pipe 42 into and through the first. wash spray device 34. This wash liquid is sprayed upon the newly formed filter cake and subjects it to the first washing. v

The first wash liquid is drawn through the filter cake and through the drum into the outlet pipe 43 leading to a second wash trap 44. The upper end of the wash trap 44 is connected by a pipe 45 to the pipe 39 which runs to the pipe 16, so that. the vacuum created by the exhauster 19 will be transmitted through the pipes 18, 16, 39 and 45 to the wash trap44, in whichit produces a suction in the pipe 43 and draws the first wash liquid through the filter cake anddrum. This first wash liquid is conducted from the bottom of the trap through a pipe 46 to the pump 4", from which it is fo ced through a pipe 48 to the recovery plant.

In the operation'of this-apparatus the exhauster 19 creates a vacuum in the pipe 18 which is transmitted to the condenser '17 and to the upper chamber 12 of the vacuum trap 8,-and the vacuum thus created in the trap 8 produces a suction n-the pipe 7. At

be transmitted to the wash traps 3S and 44 the same time the vacuum in the pipe 16 will so asto producea suction in the pipes 37 .and 43. The stufli'jpump 2 is operated to circulate the diluted pu from the stock chest or dilution tank through the pan 4 of the filter. and washer, and back through the pipe 5. I v

The suction inthe' pipe;7 will draw the liquid carrying the pulp in suspension through the sieve-like periphery of the drum 6, which causes the formation of the filter cake upon the portion ofthe periphcry of the filter drum which is immersed -in the liquid in the .pan 4. The digestor or filter liquor will be conducted through the pipe 7 into the lower chamber 9 of th e trap dlscharging it in a direction approxiuid withoutthe foam, will be drawn through mately tangential to the chamber, and in entering the chamber in he," manner the liquor .will swirl around the lateral wall of the chamber with the result that the liquid will by centrifugal action, remain around the lateral wall .of the chambenand the froth or 'foam carried thereby will collectin into the. annular trough and drained through the pipe 31- into the inlet pipe 23 leading to the strong liquor pump. The liqpipe 23 to the pump 25 and then forced to the diluting tanks, or-to the recovery plants where the chemicals carried thereby ,are re moved or recovered. I

The drum 6 isrotated by any suitable source of power, the cake or layer ofpulp formed thereon passing successively under the spray from the devices 34 arid 35, and after being washed the cake of pulp will .beremoved in any suitable manner such as by the sdraper or doctor blade 49. The washed pulp removed in this manner, drops, or is conveyed into/a stock chest where clean water is added, and the water and pulp mixture is then'delivered to the screens, or to the Jordan mills for treatment, preliminary to bleaching or delivery 'to the'paper machines.

The layer of pulp upon the drum is sprayed by fresh water :or washing liquid from the spray device 35, and the spray is drawn through the drum and the pipe 37. into the trap 38, from which it is Withdrawn and forced by the. pump 41 through c the spray device 34 to give the pulp its initial washing. The first wash liquid from the device 34 is drawn through the cake or layer of pulp, and through the pipe 43 into the trap 44 from which it is withdrawn and forced by the pump 47 through the pipe .48 to the recoyery plant. Any moisture or vapor'in the traps 38 or 44 and the upper chamber 12 of the vacuum trap 8', which is carried over into the condenser 17, will be condensed therein and drain through a pipe 50 into a hot well 51 and thence into a sewer d1 disposal device 52.

- Itwill be observed that with this apparatus, the strong liquor from the filter and washer is handled efi'ectively, and the foam and froth is killed so as not to interfere with the action of the strong liquor pump or pass over to the exhauster which provides the suction for the strong liquor pipe 7.

connecting the various parts of the apparatus in the mannerdisclosed, the only additional apparatus necessary will be the vacuum trap 8v for killing the froth and foam in the strong digestor liquor coming from the filter and washer, and such a trap is readily applicable to existing pulp handling appa- Ihtus and systems.

It will be understood that by the use of the term vacuum throughout the specification and claims, Lmean in effect a partial vacuum, since it is impossible in practice to produce a'perfect vacuum. It will also be un-' derstood that. while I have described a method and apparatus for killing the froth and foam as applied to the strong filter liquid in the pulp washing industry, in which application it has great value, it will be understood that it maybe used equally well for killing the froth and foam of other liquids. The vacuum trap 8 may also be connected in common to any number of filters and washers.

The washer or filter is referably located 30 feet or over above t e lower or inlet chamber 9 of,the trap 8:50 that when the filtering action is ones started by thevacuum in the chamber 9, that-falling head of liquor in the pipe 7 will produce a'si honing aceon which'will continue to pul the liquor through the filter drum 6 from the pan 4- of the washer. Consequently there will be less tendency for the strong sulphateliquor to foam or froth, than would be the case where the vacuum was depended upon continuously. The washer is constructed to cut off communication of the various filter sections with the pipe 7 as soon as the sections emerge from the liquid in the pan 4, so as to prevent as far as possible the entrance of air into, the pipe 7 because air. in ,the liquortends to induce foaming and frothing. Since the suction from pipe43 may be communicated to the sections of the filterimmediately after they are. disconnected from pipe 7 there can be no cake or pulp layer uponthe falling ofi prematurely.

It will be-obvious that various changes in the details andarrangeme'nts of parts,

drum periphery danger of the filter herein described and illustrated for the purpose of explaining the nature of the'invention, may be made by those skilled in the.

art within'the principle and scope of the invention as expressed in the appended claims.

I claim:

1. A vacuum trap comprising a casing having upper and lower chambers connected by a heated passage, means for introducing the liquid to be treated into the lowerchamber approximately tangentially thereof to cause a swirling of the introduced liquid, a pump connected at its suction side to the bottom of the lower chamber for removing the body of the liquid, any foam and froth created and rising through the heated passage being brokenmp by theheat.

2. A vacuum trap comprising a casing having an inlet'cham'ber and a heated section communicating with the upper part of the inlet: chamber, means for admitting the liquid to be treated to the inlet chamber in a. direction approximately tangentially of,

the chamber whereby the entering liquid will swirl around the chamber and the froth and foam created will collect in the center and rise into the heated section where the bubbles tion communicating with the upper part of the inlet chamber, means for admitting the l quid to be treated to the inlet chamber in a direction approximately tangentially of the chamber whereby the entering liquid will swirl around the chamber and the froth and foam created will collect in the centertion to the chamber and spaced from the lateral wall whereby only the liquid from the outerand lower part of the chamber may pass to the pump.

4 4. A vacuum trap comprising a casing having an inlet chamber and a heated section communicating with the upper part of the inlet chamber, means for admitting the hquid'to be treated to the inlet chamber in a direction approximately tangentially of the chamber whereby the entering liquid.

will swirl around the chamber and the froth and foam created will collect in the center and rise into the heated section where the bubbles will bebroken up by the heat, the

liquid running back into the chamber, a

pump connected at its suction side to the ottom of the chamber centrally thereof, and a baflle wall disposed in spaced relation to the bottom wall over the pump connec-' tion to. the chamber and spaced from the lateral wall whereby only the liquid from and rise into the heated section where the bubbles will be broken up b the heat, the liquid running back into t e, chamber, a pump connected at its suction side to the bottom of the chamber centrally thereof,

and a mushroom baflie wall disposed in spaced relation to the bottom wall over the pump connection to the chamber and spaced from the lateral wall whereby only the liquid from the outer and lower part of the chamber may pass to the pump, said bafile wall having a small vent pipe leading from substantially the highest part of the .batlle wall to-prevent the formation of an air lock under the bafile wall.

6. A vacuum trap comprising a casing havin an inlet chamber in the lower part and a heati'ng chamber above the. inlet chamber, said heating chamber having a passage therethrough and communicatin at one end with the inlet chamber, means for creating a vacuum connected to the other end of the passage, means for introducing the liquid to be treated into the inlet. chamber in a direction approximately tangentially thereof to cause a circumferential swirling of the introduced 11 uid, and suction means for withdrawing t e liquid from the inlet cham- -ber at a point 'ecc'entrically, of the axis of swirling, whereby the non-frothin and nonfoaming liquid will be drawn 0 and the foam and froth dollecting in and rising from the center of the swirling liquid will enter the passage and be brolten up by the action of the heat.

7. A vacuum trap comprising a casing having an inlet chamber in thelower part and ra heating-chamber .above the inlet chamber, said heating chamber having a passage therethrou hand. cdmmunicating at one end with the inlet chamber, means for creating a vacuum connected to the other end of the passage, means" for introducing the-liquid. t be treated into the inlet chamber in a direction approxim ly tangentially thereof to cause a cir inferential swirling of the introduced liquid, suction means for withdrawing the liquid from the inlet chamber centrally at the bottom thereof, and a bafiie wall in the inlet chamher, over the outlet to the suction meansin spaced relation; to the bottomand lateral walls whereby the non-frothing and nonfoaming liquid will be drawn ofi'v from the outer edge of the bottom of the inletchamher, and vthe foam and froth collecting in and rising from the center of the swirling liquid. will enter the passage and be broken up by the action of the heat.

8. A vacuum trap comprising a casing having an inlet chamber in the lower part and a heatingchamber above the inlet chamber, said heating chamber having a passage therethrough and communicating at one end withthe inlet chamber, means for creating a vacuum connected to the other end of the passage, means for introducing the liquid to be treated into the inlet chamber in a direction approximately tangentially there r of to cause a circumferential swirling of the introduced li uid, suction means for withdrawing the iquid from the inlet chamber centrally at the bottom thereof, and a mush- I room bafile wall in the i let chamber over the outlet to the 'suctio means in spaced relation to the bottom and lateral wallswhereby the non-frothin and non-foaming liquid will be drawn ofl' rom the outer edge of the bottom of the inlet chamber, and the foam and froth collecting in and risin from the center of'theswirlingliquid wil enter the passage and be broken up by the action of the heat, said bafiie wall having a vent therein to prevent theformation of an air lock thereunder.- A

'9. A vacuum trap com rising a casing having upper and lower 0 ambers connected by a passage, means by which the assage may be heated, a baflle over the en of the passage entering the upper-chamber, a drip conduit for removing any s it-over from the passage into said upper c amber, means by whichawa'cuum may be created in the upper chamber, a liquid inlet confor connection to the inlet side of a hereby the frothand foam in the 11am;

duit opening into the lower' chamber in a direction approximately tangentially of the chamber to cause a swirling of the liquid entering the lower chamber, and an outlet from the bottom wall of the lower chamber pump,

uced liquid, will, by reason of the swirl ing movement, collect in the center and rise having upper and lower "chambers connectfrom the swirling liquid, and entering said passage will be broken up by the. heat.

10. A vac trap comprising a casing ed by a passage, means by which the assage may be heated, abafiie over the en of the ,passa e entering the upper chamber, a drip con uitfor removing any splt over from the passage into said upper chamber, means by which a vacuum may be created in the uper chamber, a liquid inlet conduit opening into the lower chamber in a direction approximately tangentially of the chamber to cause a swirling of the liquid entering the lower chamber, an outlet from the bottom wall of the lower chamber for connection tothe inlet side of apump, whereby the froth and foam in the introduced liquid will, by reason of the swirling movement, collect in the center and rise from the swirling liquid, and entering said passage will be broken up by the heat, and a second bafile in the lower chamber over the outlet whereby the liquid withdrawn will'be taken. from the swirling part which is without foam.

11. A vacuum trap comprising a casing having upper and lower'chambers connected by a passage, means by which the passage may be heated, a baflle over the end of the passa e entering the upper chamber, a 'drip con uit for removing any s it-over .from the passage into said upper c amber, means by which a vacuum may becreated v in the upper chamber, a liquid inlet conduit opening into the lower chamber in adirection approximately tangentially of the chamberto cause a swirling of the liquid entering the lower chamber, an outlet from the bottom wall of the lower chamber. for connection to the inlet side of a pump, whereby the froth and,foam in the -intro-' duced liquid will, by reason of the swirling movement, collect in the center and rise from the swirling liquid, and entering said passage will be broken up by the heat, and

without foam,'said' baflies both having vents '-therethrou h to revent the formation of air lockstereun er. a

12. A vacuum trap comprising a casing having upper and lower chambers connected vby a passage, means by which the passage may be heated, a baflie over the end of the passage entering the upper chamber, a drip conduit for removing any s it-over from the passa e into said upperc amber, means by whicfi' a vacuum may be created in the upper chamber, a liquid mlet conduit opening intothe lower chamber in a direc t1on approximately tangentially of the chamber .to cause raswirling of the liquid entering the lower chamber, an

outlet from the bottom ,wall of the lower chamber "for connection. to the inlet sideof a pump, whereby the froth and foam in the introduced liquid will, by reason of the swirling movement, .collect in the center and'rise fromthe swirling liquid, and

entering said passage willbe broken up by chamber over the outletwhereby the liquid withdrawn will be taken from. the swirling )art which is without foam, said bafiles 0th having vents therethrough to prevent 5 the formation of air locks thereunder, the

Vent from ing liquid.

13. The

the battle in the lower chamber method of handling strong digestor liquor which comprises causing a swirling of the liquor to centrifugally separate the foam and froth from the liquid, and heating the froth and foam rising from the swirling liquor to break the bubblesfby a change in their vapor tension. 7

In Witness whereof I hereunto subscribe my signature.

- WILLIAM D. MOUNT.

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