US1073622A - Method of trapping solid particles in suspension in gas-currents. - Google Patents

Description

. GRADY.

` L E. MURRAY 6b C.

METHOD 0F TRAPPING Som) mwmLES 1N susmimm 1N Gm CURRBNTS.

APPLICATIONYILEDMAYHB,1913.

Patented Sept. 23, 1913.

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entran srarnsrafrnnr printen.

THOMAS E. MURRAY AND CHARLES B. GRADY, 0F NEW YORK, Y.

METHOD OF TRAPPING SOLID PARTICLES IN SUSPENSION'IN GAS-CURRENTS,

Specification f Letters Patent.

Patented Sept. 23, 191,3.

Original application led January 9, 1913, Serial No. 740,946. Divided and this application tlled May 28,

Serial No. 770,305.

To all whom 'it may concern lle it known that we, lnonasll Minnen' and CHARLES B. Grimm', `citizens ot the United States, residing at New York, in the county of New York and State of New York, have invented a certain new and useful Improvement in Methods ot 'lrapping Solid Particles in Suspension in (liras-Currents, of `which the following is a specification.

'he problem which we have solved is to entrap the maximum percentage oi' solid particles entrained with and suspended in a gas'current. This problem presents itselt' in the arts under many and ditl'erent conditions. Those under which we have en countered 'it and which are therefore dealt with herein as typicahiarise trom the need which eists especially in cities and densely populated areas, ot' preventing the discharge of cinders and other solid matter in comminuted forni from chimneys connected to boiler fines-especial ly when :t'orced draft is used and when changes vin the load demand` the driving ot' thei boilers to varying limits often much heyondtheir ratings. This is especially the case when the boilers furnish the power for electric lighting installations, the demands upoii them then varying at different periods ot' the day, and sometimes suddenly increasing. The gas currents in the lines then vary greatly in velocity, with corresponding variations in the quantity of solid mattei' entrained.

lVe provide a body ot' liquid, preferably water, which receives and retains the particles projected upon it. .lVe project the stream of particles vertically downward upon the snrfacA of said liquid. vVhen 'the gas current varies in velocity, we vary the cross sectional area of the delivery outlet proportionately to saidvelocity, so that as this velocity decreases, the area will decrease, and as the veloeitv increases, the

area will increase, thus n'laintaining,i a coustunt-or substantially constant-;velocity ot' the projected jet ot particles, and thus neutralizing the ctt'ect of the velocity changes in the current in the tine. It', therefore, at the outset, and 't'or some selected velocity ot' flue current, the interval between the delivery outlet and the liquid level be chosen which will be, on the one hand,` sutliciently large not. to impose a con stru-tion in the path ogt' the escaping gases, and. onthe other, not too great inateriallv tp diminish the inertia ot' the projected par; ticles' before they strike the liquid, then lit is obvious that no matter what conditions arise in the boilers capable oi changing that;

velocity: by keeping the velocity ot the projected jet'v constant, we can maintain theV advantageous status previously decided upon, or, in other words, eliminate the c ti'ects of the varyingconditions.

ln addition to varying the escape outlet to maintain constant velocity, we may also vari' the interval between the level of the liquid and said outlet or point of projection ot thc particles proportionately to the change in area ol' said outlet. For, obviously,'it'the area din'iinish to keep the discharge velocity 'eonstant, 'then the quantity ot' discharge per given time will bc reduced. Because ot'4 this, we can reduce the interval between outlet and liquid level to an extent sntlicic'fntto accoinnnulate this diminished quantity ot' outflow. 'lhen because the` liquid level has been brought nearer the discharge outlet, the iet of projected particles will strike the liquid with greater energy than before, will, therefore, more deeply penetrate it, and so will become more ctliciently trapped.

Our present invention is the method of trapping solid particles by in'ojecting said particles in a direction normal to and upon the, surface of the body of liquid, and maintaining the velocit)v of said particles' at their point of projection substantially constant. ln another application for Letters Patent, Serial No. 740,946, tiled January 9, 1913, we have set toi-th another niethoihwherein the velocity of the particles at their point ofprojection is varied, and in application for Letters Patent Serial No. 740.947, filed Junuary 9, 1913, we have set l'orth an apparatus in which either ot said methods may be wrriod into practical effect. (lur prcsent apptication is a division ot' the aforesaid application Serial No. 740,946.

In the accompanying drawings-Figure 1 is a section of ou :mparatus on vthe line ai, ai ot' Fig. 2. Fie. 2 isa section 0n the line y,

7/ of Fig. l. Fig. 8 shows the relations of the discharge orifice and the water level as in Fig 1, but on a larger scale;

Similar letters of reference indicate like parts.

A is a flue, leading from any source of gas current, which entrains in suspension the solid particles which are to be trapped. Such particles, for example, may be cinders, flue dust, ash, unconsumed carbon, or any other comminuted material present in the gas current in the flue of a steam boiler. The Hue A communicates with an enlarged flue B, through the top wall C thereof. One end of flue B is closed by wall D. The other end, shown broken oit, in practice communicates with a chimney or other escape conduit. At the bottom of the flue B is a ltank E for holding water. Said 'tank is preferably made of cement, or other material, which will resist the attack of such acids as may be formed by the gas combining with said water. 1IWithin the flue B and terminating at its lower edge, below the horizontal plane coinciding with the water level in the ,i tank E, is a narrow vertical partition F.

G is a swinging plate extending between the partition F and end wall D. Said plate is hinged to the upper wall of flue B in any suitable way. As here shown, it has a hooked upper edge H which is received upon the water supply pipe l., which pipe is supported on the under side of the top wall C. The swinging plate G, the longitudinal wall J of flue B, the end wall D, and the iixed 4partition F, form a substantially funnelshaped'continuation of the flue A, which terminates above the liquid level in tank E, so that the solid particles escaping at the outlet a, 'Fig 3, of said continuation are projected upon the liquid in a direction normal to the'liquid surface. It will be obvious that by swinging the plate G nearer to the wall d', the area of said outlet a will be diminished, and by swinging the plate G farther from the wall J, the area of said outlet L will be increased. ln order to swing the plate G for the purpose of adjusting said outlet area, we here show a drum K mounted in brackets L on the exterior of wall-lt, ahd'connected to plate G by a chain passing through said wall. Said drum is turned by the crank handle M, and is provided ywith a pawl and ratchet N, whereby the plate G is Iheld in adjusted position.

The water supply to tank E is preferably admitted in a constant and regulated flow from the pipe 0, communicating with any suitable source, which pipe connects by pipe P with the pipe I. The pipe I is perforated and is located at the top of plate G, so that a sheet of water Q flows down the inner side of plate G and into the tank E. This stream maybe regulatedby the valve R, in pipe P.

Water iiows from the tank lE by the pipe S located near the bottom thereof and provided outside the tank with a hinged section T. Said section is' connected by .a chain to the drum K. The function of the pipe section T is to adjust the water level in tank E, said level being raised when the pipe section is raised and lowered when said section is lowered. The chains from the swinging plate G and the pipe'section T are connected to the drum K, so that when the drum is rotated, the plate and the pipe section will be moved or be permitted to move simultaneously. Hence, for example, when the area of the outlet a is reduced, the water level in tank E is correspondingly raised from the line to the line c, Fig. 3.

The operation is as follows: The gas current holding the solid particles in suspension enters the top of flue B between the swinging plate G and wall J, and passes downn Wardly, meeting the descending water stream Q. The current then escaping through the outlet a, the solid particles are projected downward upon the surface (indicated by line o, Fig. 3) of the water in tank E. The gas passes through the interval d between the lower end of the swinging plate G and the liquid surface c, and then travels through the flue B to the chimney or other outlet. The downward projection of the particles is assisted by the water cles after striking the water in tank E, enter the same and so become trapped.

Attention is now called to the fact that the passage of which plate Gforms a swinging wall has an inlet e, Fig. l, of substantially the area of the lue A; while, when the plate G is in the position shown in dotted lines, Figs. 1 and 3, the area of the then eX- isting escape outlet a is less than that of inlet e. As the cross sectional area of the passage from inlet e to the escape outlet a decreases, the velocity of the gas current is increased. Hence the inertia of the project` ed solid particles is increased. As this increase varies as the square of the velocity, and as the resistance of t-he projected particles to any force tending to change their direction of travel varies as the inertia, the

result is a very effective trapping of the particles by the water.

Tests made-by us upon an actual apparatus constructed substantially in accordance with our present disclosure show that it is possible to make the velocity of the gases at the escape outlet a or'point of projection of the particles from two to eight times greater than the ordinary velocity of travel of gases in boiler flues, and still not seriously ait'ect the draft.

It will be observed that the cross sectional area of the funnel-shaped passage bounded by plate G is gradually reduced so that the velocity of the particles before projection will be gradually increased. In actual practice, we find that the lengt-li of said passage may be from two toten feet, but it is better to make it as long as possible so that the particles may be carried radually to a velocity at the outlet a, r atively much higher than that which they have influe A.

lln many steam power plants, the Vquantity of steam required from the boilers varies considerably and quite rapidly throughout the day. .For instance, a boiler may be running at a certain rating and the demand may be suchthat double this rating may be required in a comparatively short space of time. When the boiler is running at double rating, approximately twice as much gas will be delivered from flue A. Inusing our apparatus in such circumstances', the swinging plate Gr is normally set in a selected position which gives an outlet area a to produce a certain escape velocity of the particles suitable to a certain rating-say the position shown in full lines in Fig. 1. If the rating is augmented-say doubledthen the pawl and ratchet mechanism N is released and the plate G is permitted to swing to another position whereby the escape area a is increased to a sufficiently to reduce the velocity to that previously chosenusay the position shown in dotted lines in Figs. 1 a'nd 3; or in other words,

byLsuitablyi adjusting the escape area at a, 'as the rating of the boiler is exceeded, We

may keep the velocity of the particles constant'at their point of `projection or escape orifice, n

' In cases Where the velocity of the current in thetlue varies, especially .when forced draft is used, it is desirable not only to vary the area of the outlet a so as to maintain the velocity there constant, but also to vary the interval cl or length of the projected jet of particles between said outlet and the liquid level. Said interval should not be less in area than thearea. of outlet a. On the other hand, it is desirable to make it as small as possible. Let it now bc assumed, for purposes of present explanation, that the plate G and the pipe section T are in the position shown in dotted lines. The corresponding Water level is' then at b. When ther velocita of the flue current falls ofi', the handle operated to'bring the plate Gr into the position shown in full lines, thus reducing the area of outlet from a to a, and increasing the velocity to normal rate. The velocity being kept constant, it follows that the amount of particles projected will be less as the area ofdischarge is conslricted. Hence the interval at Z from partition G to level b may be diminished by raising the water to level c. This is effected as already explained, with an increase iii the trapping` eiliciency.

Tests made by us with this apparat-us applied to four 650 H. P. boilers have shown that ninety-two per cent. of the cinders or flue dust delivered to the;4 apparatus was trapped i'ii the water, and prevented from passing to the chimney.

In order'toremove the accumulated cinders or like'material from thetank E, we provide a branch pipe U from the water supply pipe O which has several inlets V into said tank. Simi-lar outlets are iovided on the opposite side of the tank w ich communicate withv a settling vessel W. lVlien it iS desired to clean outy the tank, the gas current from the flue A` ls shut ott, the valve R'in pipe I is closed to cut oli" the water supply, and the valvie 'X in pipe U is opened. The water entering,r the several inlets V sweeps' the 'solid material to the outlets, and said materialisicollected and drained in thesettling vessel IWL lVc claim: I

1. The method of trapping solid particles iii suspension vin a gas cureiit of varying velocity which consistsiii projecting said particles in a direction normal to'and upon the surface of a body of liquid, and maintaining the velocity of said particles at their point of projection substantially constant.

2. The method of trapping solid particles in suspension in a as current of varying velocity which consists in projectin said particles in a direction normal to an( uponv in the cross-sectional area of discharge at said point and simultaneously varyinff the interval between the surface of said liquid body and said point of projection proportionately to said arca variation.

ln testimony whereof we have affixed our signatures in presence of two witnesses.

THOMAS E. MURRAY. CHARLES B. GRADY.

lVitnesses:

Gnn'riuinn T. PORTER, MAY T. MCGAnnv

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