US2614651A - Method and apparatus for recovering gas suspended liquid-soluble material - Google Patents

Description

1952 H. A. WINTERMUTE METHOD AND APPARATUS FOR RECOVERING GAS SUSPENDED LIQUID-SOLUBLE MATERIAL 3 Sheets-Sheet 1 Filed Feb. 7, 1951 Y M9805 19.35651 x0203 1258 5 2 55m ED; \L

INVENTOR HARRY A. WlNTERMUTE ATTORNEYS 1952 H. A. WINTERMUTE METHOD AND APPARATUS FOR RECOVERING GAS SUSPENDED LIQUID-SOLUBLE MATERIAL 3 Sheets-Sheet 2 Filed Feb. 7, 1951 1N VENTOR m. M R E T W W A Y R R A H BY 1M 8 ATTORNEYS H- A. WINTERMUTE METHOD AND APPARATUS FOR RECOVERING GAS Oct. 21, 1952 SUSPENDED LIQUID-SOLUBLE MATERIAL Filed Feb. 7, 1951 3 Sheets-Sheet 3 INVENTOR HARRY A. WINTERMUTE BY Jada/$422M ATTORNEYS Patented Oct. 21, 19 52 ING GAS SUSPENDEDv LIQUID-SOLUBLE MATERIAL Harry A. Wintermuta Plainfield, N. J assignor to Research Corporation, New York, N. Y., a corporation of New York Application February 7, 1951, Serial No. 209,825

. lv This invention relates to a method and apparatus forrecovering gas-suspended liquid-soluble material and more'particularly to a method and apparatus for ,recovefrin'gsulfate, ash from thesump meansgas inlet 'andgas outl'et means Y 5 Claims. (01. lac-"1) in the casing directing a streamof gasto'be cleaned between the complementary. electrodes, means for maintaining in the'sump means 'a pool of liquid-solventfor thematerial of sub stantially constant depth, means f'orint'roducing the exhaust gases of a furnace used to recover 5 values from black'liquor in the sulfate kraft a stream of liquid solvent for. the materialintopaper industry." g I the sump means at one side thereof, means for I An object of the invention fis to provide a withdrawing from the sump meansat the'oppo' method and apparatus for-efliciently ,and 'ecosite, side thereof a stream of liquid solvent at nomically collecting liquid-soluble material, eslo substantiall'y'the same rate asthe rate of intropecially finely divided material, from a stream duction thereof, means for reintroducing ,the of gasesbearing' the same. Withdrawn solventintothe sump means at, said Another object is to provide an iinproved elecopposite side thereof'a't a point adjace'nt to "the trical precipitator that will remove. such mapoint at which the stream of solvent .iswithterial from a stream of gases and dissolve it in a drawn, means for withdrawing a stream of-'solliquid solvent without the necessity of employing v'entfrom the sump means at said one side there any internal agitating device. v of at a point adjacent to thefpoint' at which .Another object is to -provide'anelectrical preliquidis first introduced into the sump means, cipitator that is relatively simple ,tojconstruct, whereby to establish in the sump means, two and-easy to operate and maintain. adjacent parallel streams of solvent flowing Still another object is to providefapparatus countercurrentlyrto each other, and means for and a method for increasing the efiiciency and dislodging precipitated material from the collecteconomy ofoperation ofthe'sulfate paper procing electrodes.

v i i s ess. I I The objects set forth hereinbefor,e,-. and other r In accordancewith theinvention, a process is objects and advantages as may appear herein, provided for recovering liquid-soluble material are realiz'edin an exemplaryform of,the invenfrom a stream of gas in whichsuch material is .tion as shown in the drawings and described in suspended which includes electrically precipitatthe following-text. In :the drawingsi ing the material from the stream of gas'upon an Fig. 1 is a diagrammatic, view of a system for extended surface in a precipitating zone. Apool recovering valuable materials from black} liquor of liquid solvent for the material is established obtained in the. sulfate paper making process, in a dissolving zone subjacent to and in .comwhich system includes an electrical precipitator munication with the precipitating zone. At one in accordance with the invention; 1 side of the pool a stream of liquid solvent is in- V Fig. 2 is an enlarged elevational view of an troduced into the poolandastream of solvent is electrical p p or as employ d in the s m withdrawn from the pool at an-oppositeside of Fig.1,partsbeingbroken away; thereof, preferably ataratelsubstantially equal Fig. 3 is a sectional view taken along'the line to the rate of introduction of the solvent, to 33 of Fig.2; and. i I establish a stream of solvent flowing acrossthe Fig. 4 is a vertical sectionalyiew. of a liquid pool. The withdrawn solvent is reintroduced 0 level control device for the p'recipitator of Figs. into the pool at a point adjacent to the point of 7 2 and 3. i f 1 withdrawal and caused to flow back across the Referring to. the drawings, particularly to, Fig. pool in a stream flowing parallel and counter- 1, the'black liquor recovery system shown has a currently to the first stream to a point of withtank ID for storage of weak black, liquor come drawal adjacent to the point" of original intromonly obtained asfiltrate fromdigested pulp in duction of the solvent, The electrodes, especial-" the. sulfate paper process. The weak black'liq- 3 ly the collecting electrodes, are rapped or otheruoris conveyed into the tanli Iii through a pipe, wise operated upon to dislodge precipitated mall. Fromthe tank In, weak blackliquor is con? teri'al therefrom, which material falls into the ducted to a multiple efiect evaporator l2 through pool of solvent and isdissolved in the countercura pipe I3 undercontrol of a valve 14.; rently. flowing streamsthereinu Y The multiple effect evaporator is "conventional Theapparatus of the invention includes a casand, as indicated in the drawing, hasiour efing, means providing a liquid sump in the casing, f ects; it includes a steam supply line 13 and complementary high tension and collecting elecbarometric condenser l4. ."In the evaporator,-the trodes mounted in the casing-anddisposed above 'weak black. liquor is' concentrated to a certain degree by evaporation of,water therefrom and the thus preliminarily concentrated black liquor issues into. the pipe I5 and is impelled by a pump I5 either to a heavy black liquor storage tank l'lthrough a pipe I8 under control of a valve H), or to the sump of an electrical precipitator'2l) through a pipe 2! as controlled by a valve 22. As" will be explained in detail hereinafter, the preliminarily concentrated black I liquor is further fortified in the precipitator by 1 control valve 24.

Through a branch line a regulated portion of the black liquor from the evaporator [2 may be passed through a conventional disc evaporator 26, or other waste heatevaporating device, in which this portion of liquor is concen- I I! has a concentration sufficiently high to provide a combustible liquor.

This heavy black liquor is forced from the storage tank i! .by a pump 29 through a pipe 3'0 to a furnace charging tank 3| from which it is fed to a furnace charger 32 that injects the liquor into the recovery furnace 33. I

The liquor is burned in the furnace, the lignin an'd'other organic components of the liquor furnishing the necessary combustible material. The sodium sulfate fraction of the liquor is reduced to sodium sulfide and such sulfide, together with the sodium. carbonate content of the liquor, is converted to a dry ash. This ash is discharged from the furnace into a dissolving tank 34 in which it is dissolved in water to provide a solution that is impelled by a pump 35 to a point at which the liquor isrefined for reuse in the digestionof more wood chips.

The exhaust gases from the recovery furnace are hot jand contain considerable moisture and some sulfate ash in suspension. This ash consists chiefly of sodiumsulfate and sodium carbonate in finely divided form and is known as sulfate ash. I

The exhaust gases are passed through the disc evaporator 26, in which some of the heat of the gases is utilized to concentrate a portion of the black liquor as explained hereinbefore. The gases are next'blown by afan 36 into and through the electrical precipitator 20 in which they are largely relieved of their burden of sulfate ash. Cleaned gases are exhausted from the precipitator through a duct 31.

Turning to Figs. 2 and 3 of the drawings, showing the electrical precipitator 20 in enlarged detail, this precipitator has a. casing including 'a bottom 38, side walls 39,40,41 and '42, and a top 43. As shown by way of illustration, the precipitator is of the vertical gas fiow type. Suspended from the upper part of the precipit-atorare vertically extending paralare suspended parallel curtains of discharge wire electrodes tensioned by weights 45 attached to the bottoms of the wires. It will be understood that in operation a high electrical cipitating conditions potential is appliedf between the discharge and collecting electrodes to provide ionizing and pregas treating sections.

in the precipitating zone occupied by the assembly of electrodes. When gas bearing suspended particulate material is caused to flow between the electrodes, the suspended particles are charged and attracted to and deposited upon the plates 44. I

The precipit-ator is divided into two parallel The lefthand section is included between the partitions 41 and 48 and the right-hand section is included between the partitions 49 and 50. provided between side wall 39 and partition 41, "between partitions 48 and 49, and between partition 5i! and side wall 49. Gas inlet pipes 51,

-52=and '53 communicate with the tops of the inlet passages and gas outlet pipes 54 and 55 communicate respectively with the left-hand and right-hand gas treating sections, as clearly shown in Fig. 2.

Rapper bars 56 operatively engage the collecting plates 44 and the bars are vibrated to shake the plates for the purpose of dislodging precipitated material therefrom.

In the bottom of the precipitator' there is provided a sump 51 in which is maintained a pool '58 of liquid solvent. Solvent is admitted to the pool from the pressure pipe 2| through a level control device designated by the general reference numeral 59. This device has an inlet valve including a valve seat 60 and cooperating valve 5!. The valve has a stem 62 supported by a float B3. The stem is substantially restricted to vertical movement by the ring guides 64. carried by brackets 65 armed to the casing 65 of the device. The casing has a top 6'! that preferably is sealed to the casing sidewalls andthe interior of the casing communicates with the precipitator sump 5! through'a pipe 68 that has an outwardly flaring nozzle 69.

In operation, as the level of the'pool 58 of liquid in the sump falls, the level of liquid in the control device 59 also falls. This action causes the float 63 to descend and opens the valve S l to increase the rate of flow of solvent into the pool and thus to restore the level of the liquid. Conversely, if the'level of the pool rises, the valve 6| closes thus reducing the flow of liquid into the pool and tending to lower the surface of the liquid to its desiredlevel.

Solvent is. discharged from the precipitator sump through another level control device designated by the general reference numeral 10. This device is'indicated in Fig. 3 and shownin detail in Fig. 4. The device has a pipe H receiving solvent from the precipitator sump and a'casing 12 .having an outlet, pipe section 13 at the bottom.

This pipe section discharges into the line v 23 of Fig. 1. The pipe 13 provides. avalve seat 14 and a valve cooperates therewith. The valve has a stem 16 constrained to vertical motion by guide rings 11 and a fioatlG supports the valve stem.

It will be readily seen that a lowering of the liquid level in the sump 5l moves the outlet valve towards closed position'allowing the liquid level to rise to its desired point while a raisin ofthe liquid level opens the valve and permits the liquid level to descend to normal.

The liquid level control devices 59 and 10 may be used conjointly as shown and described orthey may be used independently of. one another to control thelevel of liquid in the 'precipitator sump.

Directly acrossthe sump 51 from the solvent inlet 69 is a'solvent'outlet l9 that communicates through a pipe 89 with the suction side of a pump Gas inlet passages are .the outlet 19.

H A 'imilar recirculating device ispositioned OD- posite the pump 8 I ".It includes an ofitake nozzle 84 alignedflwiththe nozzei83, theforrner com- 'm'unicating through apipe 85 with thesuction side of a pump 86' that discharges through a pipe 581 to areturn nozzle 88. 1

[Further recirculation is provided by another pump"89f having an intake 90- communicating.

with the. sump through a pipev terminating in an inta e nozzle 9| aligned with the opposed nozzle 88. Bur-11115189 returns "liquid to the sump through aj'pi'pe SZ'terminating in a nozzle'93 positioned opposite the final discharge pipe 1 .As bestseen in Fig. 3, solvent is admitted to the fsump through the inlet 69, fiows across the sump a's-indicated by the arrows and is drawn into ;the'..pump 8| through the outlet 19.. A cross- "flowing stream of solvent isthus established in thesump. Liquid withdrawn by the pump .8! is reintroduced into the sump through the'inlet 83 and this reintroduced liquid flows across the sump to the outlet 84 in the form of.-a second stream flowing parallel, adjacent and countercurrently tothe first stream. A third streamjs' established between the inlet 88 and" outlet 9| which stream flows countercurrently to the second stream. Similarly, a ,fourth countercurrent stream is established betweenthe inlet 93 and the'fi'nal outlet pipe 1 l r The pumps 8|, 86 and 89 preferably are oper- 1 6. and falls into the cross-flowing streams {o'f black liquorin the'su mp' 51. 'Thesulfate ash dissolves in'the liquor to fortifythe same, and'th 8 'f0rti-j fied liquor, that is discharged from the sump -is'- conducted to the heavy black liquor"js'torage tank l1. It will be observed that in the particular typ e of precipitator shown the incoming hot gases, sweep overthe surface" of the pool 59' of liquor thereby' effecting some evaporation of water'from the'solution 'and thus further concentrating the solution. From the foregoingdescription, a variety of modifications that does not departfrom' the in vention will readily occur tothose skilled in the art. For example, horizontal gas fiowjprecip'ita tors may be employe'dto advantage with means providing alternate, 'countercurrent streams in a sump beneath the electrodes. Substantially'vertically extending tubular collecting electrodes may alsobe used. 1 I. 'Iclaimz. ILA process for recovering liquid-soluble material suspended in astream of gas'which comprises electrically precipitating said niateri'al from astream of such gas upon an extended pool of liquid solvent for said niaterialin -a dissolving zone subjacent to and in communication Overall recirculation of a part or all of the solvent may be effected through a branch pipe I00 receiving liquid from the outlet pipe H and forcing it by means of a pump Illl through the pipe 102 to the inlet pipe 68. The proportion of solvent that is recirculated is regulated by a valve I03 in the pipe I02. By employing overall recirculation, the velocity of the cross-flowin streams of liquid in the sump may be maintained even though the throughput from the inlet level control device 59 to the outlet/level control device 10 is reduced.

The velocity or" the counter-flowing streams in the sump preferably is maintained high enough described with said precipitating zone, introducing a stream of solvent into-said pool atone side thereof and withdrawing a stream of solvent from said pool-at an opposite side thereof 'to *establishqa cross-flowing first stream of solventi nsaidpool, reintroducing said withdrawn solvent as'a stream into said pool of solvent-at said 'opposite side thereof at a point adjacent to the point'at which said first'stream is withdrawn from said pool, withdrawing a stream of solvent from said pool at said one side thereof at a point adjacent to the point at which said stream of solvent is' first introduced intosaid pool to establish a second stream of solvent in said pool flowing adjacent to, parallel with and countercurrently to said first stream of solvent, and transferring precipitated material from said precipitating zone to said dissolving zone wherein it is dissolved in said counterflowing streams of solvent.

2. A process forv recovering sulfate ash suspended in a stream of exhaust gases from a sulfate pulp process recovery furnace which comprises electrically precipitating said sulfate ash from a stream of such exhaust gases upon an extended surface in a precipitating zone, establishing a pool of black liquor in a dissolving zone subjacent to and in communication with said precipitating zone, introducing a stream of black liquor into said poolv at one side thereof and. withdrawing at substantially the same rate a I stream of black liquor from said pool at an opposite side thereof to establish a cross-flowing first stream in said pool, reintroducing said witha black liquor recovery system such as is shown in Fig. 1. Hot gases from the recovery furnace The 33 are passed through the precipitator. complementary discharge andco'llecting electrodes are energized and sulfate ash'borne by the drawn black liquor as a stream into said pool of black liquor at said opposite side thereof at a point adjacent to the point at which said first stream is withdrawn from said pool, withdrawing a stream of black liquor from said pool at said one side thereof at a point adjacent to the point at which said stream of black liquor is first introduced into said pool to establish a second stream of black liquor in said pool flowing adjacent to, parallel with and countercurrently to said firststream of black liquor, and transferring precipitated sulfate ash from said precipitating zone to said dissolving zone wherein it is dissolved in said counter-flowing streams of black liquor.

- 3; A process as defined in claim 2 wherein said extended surface is vibrated to remove Iprecipitated sulfate ashtherefrom and the ash transferred from said precipitating'zone to said dissolving zone drops into said pool of black liquor by gravity. 7

4. Apparatus for recovering liquid-soluble ma- 1 terial suspended in a stream of gas which comat the opposite side thereof a stream of liquid solvent atsubstantially the same rate as the rate of introduction thereof, means for reintroducing the withdrawn solvent into said sump means'at said opposite side thereof at a point adjacent to the'point at which said stream of solvent is withdrawn, means for withdrawing a stream of solvent from said sump means at said one side thereof at a point adjacent to the point at which liquidis first introduced into said sump means, whereby to establish in said sump means two adjacent parallel streams of solvent flowing countercurrently to each other, and means for dislod p cipitated material from said col- Iecting electrodes.

v5. Apparatus for recovering liquid-soluble material' suspended in a stream of gas which comprises'a casing, means providing a liquid sump in said casing,,complementary high tension and collecting electrode mounted in said casing and disposed above said sump means, gas inlet and gas outlet means in said casing directing a stream of gas to be cleaned between said complementary electrodes, means for maintaining in, saidsump means a pool of liquid solvent for said material of substantially constant depth, means for introducing a stream .of liquid solvent for said material intosaid sump means at one side thereof, a pump having a liquid intake means communieating with said sump means at the opposite sidethereof and liquid output means communi eating with said sump means, at said opposite side thereof and adjacent to the point at which said liquidintake means communicates with said sump means, means for withdrawing a stream of solvent from said sump means at said one side thereof at ,a point adjacent to the point at which liquid is 'firstintroduced into said sump means, whereby to establish in said sump means two adjacent parallel streams of solvent flowing countercurrently to each other, and means for dislodging precipitated material from said collecting electrodes.

' HARRY A. WINTERMUTE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,604,553 Hechenbleikner Oct; 26, 1926 2,100,155 Beran NOV. 23, 1937 2,258,401 Badenhausen Oct. '7, 1941 2,334,621 Go'dell Nov. 1 1943

Claims (1)

1. 2. A PROCESS FOR RECOVERING SULFATE ASH SUSPENDED IN A STREAM OF EXHAUST GASES FROM A SULFATE PULP PROCESS RECOVERY FURNACE WHICH COMPRISES ELECTRICALLY PRECIPITATING SAID SULFATE ASH FROM A STREAM OF SUCH EXHAUST GASES UPON AN EXTENDED SURFACE IN A PRECIPITATING ZONE, ESTABLISHING A POOL OF BLACK LIQUOR IN A DISSOLVING ZONE SUBJACENT TO AND IN COMMUNICATION WITH SAID PRECIPITATING ZONE, INTRODUCING A STREAM OF BLACK LIQUOR INTO SAID POOL AT ONE SIDE THEREOF AND WITHDRAWING AT SUBSTANTIALLY THE SAME RATE A STREAM OF BLACK LIQUOR FROM SAID POOL AT AN OPPOSITE SIDE THEREOF TO ESTABLISH A CROSS-FLOWING FIRST STREAM IN SAID POOL, REINTRODUCING SAID WITHDRAWN BLACK LIQUOR AS A STREAM INTO SAID POOL OF BLACK LIQUOR AT SAID OPPOSITE SIDE THEREOF AT A POINT ADJACENT TO THE POINT AT WHICH SAID FIRST STREAM IS WITHDRAWN FROM SAID POOL,WITHDRAWING A STREAM OF BLACK LIQUOR FROM SAID POOL AT SAID ONE SIDE THEREOF AT A POINT ADJACENT TO THE POINT AT WHICH SAID STREAM OF BLACK LIQUOR IS FIRST INTRODUCED INTO SAID POOL TO ESTABLISH A SECOND STREAM OF BLACK LIQUOR IN SAID POOL FLOWING ADJACENT TO, PARALLEL WITH AND COUNTERCURRENTLY TO SAID FIRST STREAM OF BLACK LIQUOR, AND TRANSFERRING PRECIPITATED SULFATE ASH FROM SAID PRECIPITATING ZONE TO SAID DISSOLVING ZONE WHEREIN IT IS DISSOLVED IN SAID COUNTER-FLOWING STREAMS OF BLACK LIQUOR.

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