US1329844A - Downdraft wet precipitator - Google Patents

Description

-A. LMESTON; DOWNDRAFT WET PRECIPTATOR.

APPLICATION FILED NOV. 25,1911.

#1,329,844, Patented Feb. 3,1920.

3&2; @fm/uw @mgm UNITED STATES PATENT OFFICE.

.ARCHIBALD F. MESTON, 0F NEW YORK, N. Y., SSIGNOR TO RESEARCH CORPORATION,

OF NEW YORK, N. Y., A CORPORATION OF N EW YORK. I

To all 'whom t may concern:

Be it'known that I, ARCHIBALD F. Mns- ToN, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented cer- Awhich gases or gaseous mixtures are subjected to a preliminary treatment for the purpose of promoting the separation. of the suspended particles from the gaseous bodies.

-The object of the invention is to treat gases or gaseous mixtures preliminary to electric treatment in a precipitator with a iiuid agent to thereby put the gases, gaseous mixtures or particular gaseous constituents into a favorable condition for the electrical treatment.

It is the particular object to bring a fluid agent in a finely divided condition into a near-molecular contact with a gas or gaseous mixture to bei treated tov thereby promote the susceptibility of the gas or gaseo-us mixture to electrical treatment.`

To carry out these objects I'make provisions wherebyT the fluid agent is caused to intercept a gas stream as a whirling or churning body of finely divided particles and the resulting mixture in this condition 'of intimate near-molecular contact is immeparatus shown in Fig. 1; and

Fig. 3 a horizontal section on line 3 3, Figl. The precipitator structurek comprises a skeleton frame constructed in any suitable way as of upright beams 1 interconnected bv guyv wires 2. a collecting electrode system consisting of a plurality of vertical tubes 3 supported by transverse webs 4 on the frame DOWNDRAFT WET PRECIPITTOR.

Specification of Letters Patent.

` Patented Feb.`3,192o.

Application filed November 26, 1917. Serial No. 204,020.

as an illustration of the usual form of discharge chambers. Both the collecting electrodes and discharge electrodes may be constructed in different ways. Above the collecting electrode system is provided a closed chamber 6 extending substantially across the whole frame and communicating with the tubes 3. The only access to this chamber from the outside is through an inlet 74 through which the gases are conducted into the precipitator.

The discharge electrodes are suspended from` a common frame 8 located above the chamber 6 and supported on insulators 9 resting on the frame. Centrally on the frame 8 is supported a rod 10 extending through an insulator 11 into the chamber 6 and carrying at its lower end a transverse frame 12 to which all the discharge electrodes are connected. At their lower ends the discharge electrodes are connected to a spacing frame 13 which is held in fixed position relatively to the general structure and the collecting electrodes in particular by insulators 14. These insulators may be attached to the skeleton frame in any suitable;

way as by insulating blocks 15. Weights 16 are preferably attached to the lower ends of the wires 5 to hold them taut. The portion below the collecting electrodes is inclosed to form a chamber 17 similar to chamber 6 and has an outlet 18 through which the treated gas is passed to a smokestack not shown). At the bottom the chamber 17 is connected to the outside through a liquid seal 19 through which the material collected may be drawn ofi' without allowing the gases to pass out.

In the chamber 6, which I term the mixing chamber, I have placed a system of nozzles 2O connected to a liquid supply as for instance water by a pipe 21 which may be controlled by a valve 22. These nozzles are so constructed and disposed as to produce conjunctively a line lspray uniformly distributed across the chamber 6 to intercept the entire gas stream, thoroughly mix with it and the suspended particles. 'The nozzle 2O may be disposed in various ways tp insure a thorough mixing of the spray with the gases, but I have found'that the arrange- -llt ment shown in lFigs. 2 and 3 gives particularly good results, since the impact of the atomized particles of liquid on the gas tream andthe particles suspended therein. due to the uniformly angular position of the nozzles relatively to each other, sets up a whirling or churning motion at right angle to the tubes 3.

The tubes or pipes `3 have preferably a daring mouth at the upper as well as the lower end. llt has been found thatlan excess of liquid suspended in the gases at the upper end and an agglomerate of precipitated particles at the lower end is likely to cause undesirable disruptive discharges. By expanding the pipes 3 this contingency is practically obviated.

The spray is normally A.so adjusted by means of the valve control 22 that after thorough mixing an excess of the iinely divided liquid particles coalesces to cause a film or thin sheet of liquid to continuously run down the walls of .the collecting electrodes. The heavy charge of atoniized liquid increases considerably the specific gravity of the gaseous mixture and this factor together with the kinetic energy of the gases developed in a downward direction facilitates the precipitation of the suspended particles. The above can be illustrated by describing the use of the apparatus for removing from 'la gaseous mixture the soot or carbon blaclr arising from a bituminous coal burning furnace.

As it is well known, the soot particles given olf when coal is burned, leave the fuel in a finely divided state, probably approaching the molecular in size, but they tend to ag glomerate'as they are carriedthrough the furnace dues. imperfect combustion of bituminous coal also gives ott tarry'particles,

lso

especially at those portions ofthe fuel bed wherethe temperature is comparatively low.

These tarryvparticles combine or agglomerate with the soot particles but the' resulting material is in very une state of subdivision even when leaving a smoke stach as the familiar black smoke.9 lt is an extremely dipicult matter to wet line soot particles. with water when they are mixed with water in the usual waysgespecially is this true when the particles are coated with tarry substances..

-WVhem as before described, the gases are intermixed with the mist produced by the atomized water, all that is needed is some action to bring the suspended particles and the atomized Water together. lf there is a pronounced affinity of the particles for the liquid this will come about rapidly and with` out the introduction of special methods. ln

the case of tarry soot and water mist, however, this does not occur and special means are necessary to bring about the wetting of the particles. This is accomplished in the recente apparatus described by the use of an electric field and preferably by the additional use of a corona discharge accompanying the electric lield. lin the discharge chambers Where this wetting occurs the particles of water and the suspended soot particles are both removed from the gases by action of the electric iield and are thrown against the collecting electrodes, vl. c., the walls of the tubes 3, and are intimately mixed on the surface thereof. .'lhe removed material would normally adhere to the collecting electrodes but in this'apparatus the excessive water present forms a continuously running lmcon the surface of the collecting electrodes and washes the deposited material down into the sump 19. This apparatus also permits the use of the phenomenon of water particles becoming nuclei for ions and thereby becoming more actively attractive to suspended particles, thereby wetting them and removing them from the gases.

lncidentally liquid has the advantages of giving the gases better electric characteristics and adds materially to the success of the process of removing the suspended particles.

'llhe above described manner of treating gases has particular utility in` connection with electrical precipitation for the collection of combustible materials which ordinarily would catch fire from the electric discharge in precipitators as ordinarily operated. By the intimate mixture of such ma- .terials with a spray of a non-inflammable liquid, such as watertfor instance, the dan ger isavoided.

ln' the cla1ins,iin the absence of a better term, lt use the term non-wettable to dene the 'characteristic' of a certain class of substances which do not have an affinity for waterland-therefore are not readily wetted when brought into contact with water vor other suitable liquid.

- ll claimtl.` The metliod Vof removing suspended particlesfroin gases which consists in adding a liquid in the form ofl a inist to the gases andsubjecting the gases and mist to the action of an electric eld.

2. The method of removing suspended particles from gases which consists in adding to the gases liquid in finely divided form and in greater quantity .than will be evaporated at that temperature of the gases which will result from the addition of said liquid and then subjecting the gases to the action of. an electric held.

' 3. rll`he method r of removing suspended particles fro-mgases which consists in passing the gases through a; zone of nely divided liquid, supplying the liquid at a rate which is in excess of that at which the liquid is evaporated under prevailing temperature conditions of the gases and subjecting the mixture of gases and liquid to the action of an electric field.

4. The method of removing suspended solid particles from gases Which consists in spraying the gases Withliquid and passing the mixture of gases and suspended solid and liquid particles into an electric Field.

5. The method of removing. solid parti-A cles from gases Which'consists in introducing liquids into the gases in linely divided form, electrically .precipitating the solid and liquid particles simultaneously to form a sludge.

6. The method of removing solid particles from gases which consists in introducing liquids into the gases in iinely divided form, electrically precipitatingthe solid and liquid particles simultaneously to form a sludge and recovering said sludge by gravity settling.

7., The method of removing non-Wettahle particles from gases, which consists in adding a liquid in the form of a mist to the gases containing the particles in suspension and subjecting the gases and mist to the action of an electric field. H

8. A method of removing suspended particles from smoke, which consists in adding a liquid in the form of a mist to the smoke and subjecting the smoke and mist to the action of an electric field.

9. The method of removing non-Wettable particles from a gas, which consists in adding a liquid in the form of a mist tothe gases containing the particles in suspension in such a Way as to intimately mix the gas and the mist and then subjecting the mixture to the action of an electric field.

10. The method of removing suspended particles from smoke, Which consists in adding a liquid in the form of a mist to the smoke in such a Way as to intimately mix the smoke and the mist and then subjecting the mixture to the action of an electric iield.

11. In an apparatus for treating gaseous bodies, the combination With 4a vertically disposed electrical discharge chamber, of a gas receiving chamber immediately above the discharge chamber, means for discharging a fluid into the receiving chamber in a nely divided condition, and means for mixing the incoming gas and the said fluid.

12. In an apparatus for treating gaseous bodies, the combination with a vertically disposed electrical discharge chamber, of a gas receiving chamber immediately above the discharge chamber, means for discharging a liquid into the receiving chamber in a iine spray, and means for mixing the incoming gas and the said liquid spray.

13. In an apparatus for treating gaseous bodies, the combination With a vertically disposed electrical discharge chamber, of a gas receiving chamber immediatelyabove the discharge chamber, means for discharging a liuid into the receiving chamber in a finely divided condition and in the form or' a Whirl intercepting the flow of gas, said means comprising a system of nozzles disposed in the receiving chamber in symmetrical angular relation to each other.

14. In apparatus for separating suspended particles from smoke, the combination With a vertically disposed discharge chamber, of a smokereceiving chamber immediately above the discharge chamber, means for discharging a liquid into the receiving chamber in a inely divided spray, and means for mixing the incoming smoke and the said liquid.

In testimony whereof I aiiix my signature.

ARCHIBALD F. MESTON.

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