US1073620A

US1073620A - Method of trapping particles in suspension in gas-currents.

Info

Publication number: US1073620A
Application number: US74094613A
Authority: US
Inventors: Charles B Grady
Original assignee: Individual
Current assignee: Individual
Priority date: 1913-01-09
Filing date: 1913-01-09
Publication date: 1913-09-23
Anticipated expiration: 1930-09-23

Description

Patented Sept. 23, 1913.

T. E. MURRAY L C. B. GRADY.

APPLICATION FILED JAN.9, 1913.

i IL- iff' l I" l l l l l l I 1 t METHOD 0F TRAPPING PARTICLBS 1N SUSPENSION 1N GAS CURRBNTSA prin THOMAS E. MURRAY AND SATS 'PATE'I METHOD OF TRAPPING PARTICLES IN SUSPENSION IN GAS-CURR-ENIS.

Application filed January 9, 1913.

Specification of Letters Patent.

Patented Sept. 23, 1913. Serial No. 740,946.

To all whom it may concern.' y

Be it known that we, THOMAS E. MURRAY and CHARLES B. GRADY, citizens of the United States, residingy at New York, in the county of New York and State of New York, have invented a certain new and useful Improvement in Methods of Trapping Particles in Suspension in Gas-Currents, of which the following a specification.

The problem which we have solved is to entrap the maximum percentage of solid particles entrained with and suspended in a gas current. This problem presents itself in the arts under many and different conditions. Those under which we have encountered it and which are therefore dealt with herein as typical, arise from the need which exists especially in cities and densely populated areas, of preventing the discharge of cinders and other solid matter in comminuted form from chimneys connected to boiler Haes-especially when forced draft iS used and when changes in the load demand the driving of the boilers to varying' limits often much beyond their ratingsl This is especially the case when the boilers furnish the power for electriclighting installations, the demands upon them then varyingV at different periods of the day, and sometimes suddenly increasing. The gas currents in the flues then vary greatly in velocity, with corresponding variations in the quantity of solid matter entrained.

We provide a body of liquid, preferably Water, which receives and retains the particles project/ed upon it. We project the stream of particles vertically downward f* upon the surface of said liquid.-

When the ,qas current varies in velocity, we vary the cross sectional area of the delivery outlet proportionately to said veloc-` ity, so that as this velocity decreases, the area will decrease, and as the velocity increases, the area will increase, thus neutralizing the effect of the velocity changes in the current in the lue. If, therefore, at the outset, and for some selected velocity of 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 constriction in the path of the escaping gases, and, on the other, not too great materially to diminish the inertia of the projected particles before they strike the liquid, then it is obvious that no matter what conditions arise in the boilers capable of changingthat velocity, by suitably varying' the velocity of the projected jet, we can maintain thc advantageous status previously decided upon, or, in other words, eliminate the etl'ccts of the varying conditions.

In addition to varying the escape outlet, we may also vary the interval between the level of the liquid and said outlet or point of projection of the particles proiuntionately to the change in area of said outlet. lVhen the liquid level is brought nearer the discharge outlet, the jet of projected particles will strike the liquid with ,greater energy than before, will, therefore, more deeply penetrate it, and so will become more etliciently trapped.

Vire have invented a method and an apparatas for carrying said method into practical effect.

Our present invention is the method, more particularly set forth in the claims.

In another application for Letters Patent, Serial No. 740,947 simultaneously tiled herewith, we have setl forth said apparatus and in still another application, Serial No. 770,305, tiled May 28th, 1013, we have claimed the method of trapping solid particles in suspension in a gas current of varylng velocity which consists in 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.

In the accompanyingr drawings-Figure 1 is a section of our apparatus on the line m, w of Fig. 2. Fig. 2 is a section on the line y, jz/ of Fig. 1. Fig. 3 shows the relations of the discharge orifice and the water level as in Fig'. l, but on a larger scale.

Similar letters of reference indicate like parts.

A is a flue, leading from any source of gas current, wliiclrentrains in suspension the solid particles which are to be trapped. Such particles, for example, may he cinders, flue dust, ash, unconsumed carbon, or any other connninuted material present in the gas current in the flue of a steam boiler. The flue A connnunicates with an enlarged flue B, through the top wall C thereof. 011e end of flue B is closed bv wall D. The

-to the drum K,

other end, shown broken 0H, in practice communicates with a chimney or other escape conduit. At the bottom of the Hue B is a tank 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. Within the Hue B and terminating at its lo-wer edge, below the horizontal plane coinciding with the water level in the 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 ofv Hue B in any suitable way. As here shown, it has a hooked upper edge H which is received upon the Water supply pipe I, which pipe is supported on the under side of the top wall C. The swinging plate G, the longitudinal wall J of Hue B, the end wall D, and the fixed partition F, form a substantially funnelshaped continuation of the Hue 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 J, the area of said outlet a will be diminished, and by swinging the plate G farther fromthewall J, the area of said outlet c will be increased. ln order to swing the plate G for the 4purpo-se of adjusting said outlet area, we here show a drum K mounted in brackets L on the exterior of wall J, and connected to plate G by a chain passing through said wall. Said drum is turned by the crank handle M, and is provided with a pawl and ratchet N, whereby the plate G is held in adjusted position.

The water supply to tank E is preferably admitted in a constant and regulated How from the pipe O, 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. Hows down the inner side of plate G and into the tank E. This stream may be regulated by the valve R, in pipe P.

Water Hows from the tank E by the pipe S located near the bottom thereof and provided o-utsi-de the tank with a hinged section T. Said section is connected by a cha-in to the drum K. VThe 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 sai section is lowered. The chains from the swinging plate G and the pipe section T are connected so that when the drum is rotated, t-he plate and the pipe section will be moved or be permitted to move simultaneously. l-lence, for example, when the area. of the outlet a is reduced, the water level in tank E is ,correspondingly raised from the line L to the line c, Fig. 3.

The operation is as follo-ws: The gas current holding the solid particles in suspension enters the top of Hue B between the swinging plate G and wall J and passes downwardly, 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 c, Fig. 3) of the Water in tank E. The gas passes thro-ugh the interval d between the lower end of the swinging plate G and the liquid surface c, and then travels through the Hue B to the chimney or other outlet. The downward projec- Vso tion of the particles is assisted by the water l stream Q, delivered into them. The particles 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 G forms a swinging wall has an inlet e, Fig. l, of substantially the area of the Hue A; while, when the plate G is in the position shown in dotted lines, Figs. l. and 3, the area of the then existing outlet o is less than that of inlet e. As the cross sectional area of the passage from inlet c to the escape outlet a decreases, the velocity o-f the gas current is increased. Hence v the inertia of the projected solid particles is increased. As this increase varies as the square of the velocity, and as the resistance of the projected particles to any force tending to change their direction of travel varies as the inertia, the result is a very eHective 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.Y of the gases at theescape outlet a orpoint of projection of the particles from two to eight times greater than the ordinary velocity of travel of gases in boiler Hues, and still not seriously affect 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. ln actual practice, we find that the length of said passage may be from two to ten feet, but it is better to make it as long as possible so that the particles mty be carried gradually to a velocity at the outlet a, relatively much higher than that which they have in Hue A.

ln many steam power plants, the quantity f escape ltime. When the boiler is running at double rating, approximately twice as much gas will be delivered from 4flue A. In using our apparatus in such circumstances, the swinging plate G is normally set in a selected position which gives an outlet area a to produce a certaln 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 released and the plate G is permitted to swing to another position whereby the escape area a is increased to a suiiiciently to reduce the velocity to that previously chosen-say the positionshown in dotted lines in Figs. l and 3; or in other words, by suitably adjusting the escape area at a, as the rating of the boiler is exceeded, we may vary the velocity of the particles at their point of projection or escape orifice.

In cases where the velocity of the current in the flue varies, especially when forced draft is used, it may be desirable not only to vary the area of the outlet a, but also to vary the interval d or length of the projected jet of particles between said outlet and the liquid level. Said interval should not be less 1n area than the area of outlet a. On the other hand, it is desirable to make it as small as possible. Let it now be assumed, for purposes of present explanation, that the plate G and the pipe section T are Vin the positions shown in dotted lines. The corresponding water level is then at b. When the velocity of the iiue current falls off, the handle M is operated to brin the plate G into the position shown in full ines, thus reducing the area of outlet from a to a, and increasing the velocity. The interval at d from partition G to level Z) may be di,- minished by raising the water to level c. This is effected as already explained, with an increase in the trapping efficiency.

Tests made by us with this apparatus applied to four 650 H. P. boilers have shown that ninety-two per cent. of the cinders or flue dust delivered to the apparatus was trapped in the water, and preventedfrom passing to the chimney.

In order to remove the accumulated cinders or like material from the tank E, we provi-de a branch pipe U from the water supply pipe O which has several inlets V into said tank. Similar outlets are provided on the opposite side of the tank which communicate with a settling vessel W. When it is desired to clean out the tank, the gas current from the flue A is shut ofi", the valve R in pipe P is closed to cut od the water supply, and the valve X in pipe U is opened. The water entering the several inlets V sweeps the solid material to the outlets, and said material is collected and drained in the settling vessel W.

We claim:

l. The method of trapping solid particles in suspension in a gas current which consists in projecting said particles in a directionnormal to and upon the surface of a body of liquid and varying the velocity of said particles at their point of projection.

2. The method of trapping solid particles in suspension in a gas current which consists in projecting said particles in a direction normal to and upon the surface of a body of liquid and varying the velocity of said particles at their oint of projection, and delivering a liquid current into said particles before they reach said liquid surace.

3. The method of trapping solid particles in suspension in a gas current of varyinfr velocity which consists in projecting said particles in a direction normal to and upon the surface of a body of li uid, and varying the velocity of said partie es at their point of projection correspondingly to the variations of said current.

4. The method of trapping solid particles in suspension in a gas current which consists in projecting said suspended particles in a direction normal to and upon the surface of a body of liquid, varying the velocity of discharge of said particles at their point of projection, and simultaneously varying the interval between said point of projection and said liquid surface.

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

THOMAS E. MURRAY. CHARLES B. GRADY.

Witnesses:

GERTRUDE T. PORTER, MAY T. MCGARRY.