US2614652A

US2614652A - Electrical precipitator

Info

Publication number: US2614652A
Application number: US241538A
Authority: US
Inventors: Norman W Sultzer
Original assignee: Research Corp
Current assignee: Research Corp
Priority date: 1951-08-13
Filing date: 1951-08-13
Publication date: 1952-10-21
Anticipated expiration: 1969-10-21

Description

Oct. 21, 1952 w, SULTIZER 2,614,652

ELECTRICAL. PREC IP ITATOR Filed Aug. 15, 1951 3 Sheets-Sheet l RECOVERY FURNACE WEAK BLACK LIQUOR |3 STORAGE DISSOLVING TANK HEAVY BLACK LIQUOR i STD RAGE NORMAN W. SULTZER INVENTOR B 3 9- Erma ATTORNEYS Oct. 21, 1952 N. w. SULTZER ELECTRICAL PRECIPITATOR 3 Sheets-Sheet 2 Filed Aug. 15, 1951 INVENTOR' LEM NORMAN W. SULTZER ATTORNEYS Oct. 21, 1952 N, w, SULTZER 2,614,652

ELECTRICAL PRECIPITA'VIOR Filed Aug. 15, 1951 3 Sheets-Sheet 3 IN VENTOR NORMAN W. SU LTZER BY M ATTORNEY S Patented Oct. 21, 1952 4;;

to ResearchCoi-poration, NewYoi-k, N. Y a corporation of New York Application Au usv s, 1951'," Serial No. 241.53

8 Claims.

This invention relates to tors and more particularly to electrical precipitators having a liquid-washed devicein the lower portion thereof for recovering in liquid solution or liquid suspension the precipitated material.

removed from the precipitator electrodes. More especially, the precipitator of this invention is adapted to recover sulfate fly-ashinthe" form of an aqueous 'solution'from' the exhaust gases of a recovery furnace burning black liquor from the digesters in a sulfate paper mill." I I An object of the invention is to provide an electrical precipitator having an improved device for recovering precipitate in liquid form. *==Another object is to provide in such a precipitator a liquid washed recovery device having no moving parts. 7

Another object is to provide an electrical precipitator of the foregoingtype that is simple to build and operate and that requires a minimum of maintenance care.

Another object is to provide in such a precipitator an arrangement for reducing the foam that tends to be produced with certain 'washing liquids such as black liquor. U

These and other objects of the invention are realized in an electrical precipitator having a casing, complementary extended surface and high tension electrodes mounted in'a casing, a panel mounted in an inclined position in the casing and positioned to receive dust falling from the electrodesythe panel having a plurality of riffles projecting upwardly therefrom, means for applying liquid to an elevated "area of the panel,

and sump means below the panelfor' receiving liquid from the n The invention will' be described in greater --detail with'reference to thedrawingsin' which? Fig. l is a diagrammatic viewofa' black liquor recovery systememplo'yint a prec'ipitatorin accordance with the invention; 3?

Fig; 2 is anend elevational view'of' an" electrical precipitator as used in the system-of Fig. 1, parts being broken away; Fig. 3 is a sectional view 3-3- of Fig. 2;-and

Figs. 4 and-5 show details of construction of taken on the line weir pieces at 'the loweredge 'of the flow panels. --Referring to the drawings, particularly tol' ig. -l-=thereof, the black liquor recovery system shown includes a storage tankfor weak black-liquor 'receivedthrough the conduit H from the digesters and pulp filters (not shown) of a su l fate paper mill. The weak black liquor is passed through a pipe -l2un'der control of valve ';l:3 to

electrical iprecipitaat'which the heavy Ihe-heavy black liquor is conducted by a pipe 15' to a-heavy'black liquor storage tank 16.

a conventional multiple efiect evaporator l4 having-the usual barometric condenser l5. In the evaporator I4, the black liquor is concentrated by evaporation of water therefrom to a degree black liquor can be burned.

Heavy black liquor from the storage tank it flows through a pipe I! to a charging tank l8 and from thence through the line I!) to a furnace charging device that introduces a spray of heavy black'liquo'r into the recovery furnace 2|.

Inthe furnace, the heavy black liquor is burned.

' The lignin contained therein, together with other combustible material, oxidized to provide heat that vaporizes the water of the liquor. The furnace action reduces the principal inorganic ingredient/of the liquor, sodium sulfate, to sodium sulfide tha't is' the principal component of the furnace ash 22 thatis discharged into a dissolving-tank 23. In the dissolving tank, the 'ash is dissolved in water to provide a solution that is subsequently; purified" and reused for digesting additional quantitiesof wood chips.

Hot gases from the furnace, containing water vapor and products of combustion of black liquor. also contain a small but significant burden of fly ash in susp'ension.- This fly ash contains a large percentage of sodium sulfate which it is desired to recover from the gases before they are discharged into theatmosphere.

The hot gases are passed from the furnace througha disc evaporator 24 in which some of 29 to be described in greater'detail hereinafter. 'In the precipitator, the gases are substantially relieved of their burden of sulfate ash and the cleaned gases pass by way of a flue 30 to a stack (not shown) for discharge to the atmosphere.

- Fly ash precipitated in the electrical precipitator is dissolved therein black liquor and the solution is ultimately fed to the black liquor storage tank l6 through the pipe 3| under control of the valve 32. The black liquor used for dissolving the sulfate ash may consist of (1) heavyb1ack..1iquor pumped from the storage nated 29, is shown in detail in Figs. 2 and 3. Referring to these figures, the precipitator shown has a shell or casing 36 that may be of concrete construction. Gas inlet andsoutletfiuetsfl and 38 are provided and gas flows through the pre cipitator in the direction of the arrows of Fig. 3.

As is usual in such precipitators, a plurality of complementary extended surface electrodes 39 and high tension electrodes 40 are positioned in the casing. The extended surface electrodes Bdmay take the formjofa plurality :Of' vertically disposed, horizontally-spaced. parallel .plates providing. :parallelgducts. 4 I through which-flows the gas to: be. cleaned. The high tension electrodes. 40 are.- discharge electrodes in the form of ,fi'n wires suspende curtai formatio in the gasducts between adjeoentplates. Each e.wire as has a tensionin wei ht at the bott that keeps the wire t ut.

Those persons skilledin the a t wi l eadily understand that, in operat n. as to e c eaned is pass d thr u h her eein atorrand h h el c potential i applied c oss the m:-

elementa y di ch r e and. extended: surfac Co a d s harseoeeu s at e th Wire l r de a rtielessu ende i th electrodes.

s s re c ge -,and att c ed hr; he nte e eo ode fie r the. xtended sur ace ele trodes. The particles are deposited upon the end ur ac e eetr si i' y ibrati er vrapping the electrodes, or otherwise suitably cleaningthem in the'conventional way the precipitate is dislodged from the -e lec trodes and allowed to fall into the section of the-precipita- -tor beneath the electrodes.

. In accordance with theinvention there-is provided in the casing 36 beneath theelectrodes and ina position to receive. dust falling thereirom a device-for dissolving or suspending the .dust in a liquid medium. Thisdeviceinoludes a zig-zag arrangement of riiiie-bqards over which flows the solvent liquid. and onto at least some 5 of which falls dust from the precipitator electrodes. This arrangement efiects rapid dissolution .of the dustlin the solvent and the dust is -rernoved from the precipitator in the solvent liquid Asseen in Fig. 2 the riille board structure-is symmetrical. about ;a vertical plane running through the center of the .precipitator; therefore, only one half of the structure will be dei i The uppermost rifile board includes an inclinedpanel 43 that slopes downwardly irqm near-thecenter lineof the precipitator towards n f the walls hereot: e an le oislone is not critical and may'range from about to about 35 -Theane s o id d ith a plurality of upstanding riffles 0r cleats 44 that are arrangedin-spaced parrallel relation down the slope of the panel 'tointerrupt the smooth flow of; liquid down the panel and cause turbulence in theliquid.

Solvent, liquid-is ted to thedupper area of -'panel :43 from an ovenficzw trough :45 that "ex- .member '41 'tion of thebolt holes 50, the weir piece 48 may 41 "and a weir piece 4'8 attached thereto. De-

tails of this construction are best seen in Figs. 4 and 5 wherein it is seen that the weir piece -48 is fastened to the member 41 by means of bolts 49 passing through vertically elongated ""bolt holesifl in the weir piece and through cir- "cular "close 'fitting bolt holes 5| in the lateral Owing to the elongated configurabe leveled and thereafter bolted securely to the member 41.

seen in Figs. 4 and 5, the lower edge 52 of the weir piece depends below the bottom of the an 3 and is serrat d t r u out. its le s h- Th s serra ed c nst u ti n pr i es a plurality of drip points along the lower edge o t e we ie and ass u i rm owv o liquid from the weir piece to the immediately sebi ent fle o d Riiiie board 53 slopes from the outer wall of the c si g 36 b a h. the t m board 3 inward y o e -oi iee n t e c te in oi h precipitator. .Riffle board 53 is similar in construction to the board 43 described hereinbe- -fore It is provided with cleats 44' and a dam at its lower edge including the weir piece 48.

Positioned below the .riflie board 53 is another and similar riiiie board 54 that slopes from the center towards the outer wall of the precipitator. The discharge dam including the weirpiece 48]" discharges solution or liquid to a sump. 55. hav- ,ing a lateral trough 56 receiving the solution.

solution is discharged from the trough through the pipe 3|.

Solvent liquid is introduced into the trough 45 thrQliQhlthe inlet pipe 33 having a header 5! extending above and parallel to the-trough, the header being equipped with a plurality of horizontally spaced outlet nipples 5t that distribute the liquid into the trough. Additional liquid, either solvent or plain water, maybe introduced behind. the riiiie board dischar dams through headers 59, 6D and BI having distribution nipples '62,

Inbperationin the recovery system of "Fig. 1,

gases from the recovery furnace are 'blbwn throug'h the precipitat'or 29 that is energizedin the usual manner. Sulfate ash-is precipitated upon the collecting electrodes. Black liquor of the desired concentration;is ied to the ash dissolving-device through the pipe 33 and additional black liquor or water is fed through-headers '59,

60 and GI as may be desirable to increaseliquid flow through the dissolver. Black-liquor flows in a zig-zag path over the riflle-

boards

43, 53 and 4 nd nto esumpii, ts n w down th rifile boards, the liquor-- is continually agitated and any sediment that tends to collect behind the dams is agitated into suspension byiliquiid rodueedhr ue he n les 62- Sulfate ash from-the e ectrodes 39 and Hogans into the black :liquor flowing down the. rifiiezboard 43 and is carried along by the liquorand dissolved therein as the stream flows through the dissolving device. Solution is di$charged through the pipe 'h n8'--. 11..cl0se proximity "to the uppermost, mime 5 boards. A strong electric field is set up between the highly charged weights and the grounded uppermost riffie boards and this field tends to break any foam that may form in the black liquor on the uppermost riffie boards and in the feed trough 45. Also, the concentration of the black liquor is maintained near the point at which it has a minimum foaming tendency.

From the foregoing description it is seen that the present invention provides an electrical precipitator that accomplishes in a simple way the Q objects of the invention.

I claim:

1. An electrical precipitator comprising a casing, complementary extended surface and high tension electrodes mounted in said casing, a panel mounted in an inclined position in said casing and positioned to receive dust falling from said electrodes, said panel having a plurality of rifiles projecting upwardly therefrom, means for applying liquid to an elevated area of said panel and sump means below said panel for receiving liquid from said panel.

2. An electrical precipitator comprising a casing, complementary extended surface and high tension electrodes mounted in said casing, a panel mounted in an inclined position in said casing and positioned to receive dust falling from said electrodes, said panel having a plurality of rifiies projecting upwardly therefrom, means including an overflow trough positioned adjacent the top of said panel for applying liquid to an elevated area of saidpanel, and sump means below said panel for receiving liquid from said panel.

overflow dam positioned adjacent the bottom of said panel, and sump means below said panel for receiving liquid from said panel.

4. An electrical precipitator comprising a cas ing, complementary extended surface and high tension electrodes mounted in said casing, a panel mounted in an inclined position in said casing and positioned to receive dust falling from said electrodes,-said panel having a plurality of rifiles projecting upwardly therefrom, means for applying liquid to an elevated area of said panel, an overflow dam positioned adjacent the bottom of said panel, means for introducing additional liquid behind and adjacent said overflow dam, and sump means below said panel for receiving liquid from said panel.

5. An electrical precipitator comprising a casing, complementary extended surface and high tension electrodes mounted in said casing, a plurality of inclined panels mounted in zig-zag arrangement in said casing, thetopmost of said panels being positioned to receive dust falling from said electrodes, said panels having rifiles projecting upwardly therefrom, means for applying liquid to an elevated area of the topmost of said panels, means directing liquid from a lower area of each said panel to an upper area of the immediately subjacent panel, and sump means below the lowermost of said panels receiving liquid from the latter.

6. An electrical precipitator comprising a casing, complementary extended surface andhigh tension electrodes mounted in said casing, a plurality of inclined panels mounted in zig-zag arrangement in said casing, the topmost of said panels being positioned to receive dust falling from said electrodes, said panels having riilies projecting upwardly therefrom, means for applying liquid to an elevated area of the topmost of said panels, means including an overflow dam directing liquid from a lower area of each said panel to an upper area of the immediately subjacent panel, and sump means below the lowermost of said panels receiving liquid from the latter.

'7. An electrical precipitator comprising a casing, complementary extended surface and high tension electrodes mounted in said casing, a plurality of inclined panels mounted in zig-zag arrangement in said casing, the topmost of said panelsbeing positioned to receive dust falling from said electrodes, said panels having riflles projecting upwardly therefrom, means for applying liquid to an elevated area of the topmost of said panels, means including an overflow dam having a serrated lower drip edge directing liquid from a lower area of each said panel to an upper area of the immediately subjacent panel, and sump means below the lowermost of said panels receiving liquid from the latter.

8. An electrical precipitator as defined in claim 7 wherein the means for applying liquid to the topmost of said panels includes an overflow) trough positioned adjacent the top of said panel.

NORMAN W. SULTZER.

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

UNITED STATES PATENTS Number Name Date 768,450 Hardie Aug. 23, 1904 1,342,651 Squires June'8, 1920