US2340179A - Rapper mechanism - Google Patents

Description

Jan. 25, 1944. H. c. ENGELMAN RAPPER MECHANISM I Filed Jan. 4, 1943 2 Sheets-Sheet 1 Jan. 25, 1944. H. c. ENGE'LMAN 2,340,179

` RAPPER MECHANISM l Filed Jan. 4. 194s 2 sheets-sheet 2 n g. n

Vm @M25/L Patented Jan. 25, 1944 RAPPER MECHANISM Herman C. Engelman, Staten Island, N. Y., as-

signor to Research Corporation, New York, N. Y., a corporation of New York Application January 4, 1943, Serial No. 471,271

9 Claims.

The present invention relates to means for rapping or vibrating apparatus utilized in removing suspended particles from gases and its general purpose is to free the surfaces of such apparatus of collected particulate material. The invention relates more specifically to a mechanical system and apparatus which will subject the electrodes of an electrical precipitator to the resilient jarring provided by the impact of a freely falling ball.

The electrodes of electrical precipitators used in most installations involving the removal of suspended dusts and the like from gases must be shaken or jarred from time to time to remove the material which has been electrically or mechanically deposited on the surfaces of the electrodes if the deposits are not to build up and interfere with the normal operation of the precipitator. Various devices have been proposed for shaking precipitator electrodes, many of them comprising mechanically operated hammers. Hammers have not been altogether satisfactory. If the head is fastened to the operating mechanism with a strong, stiff handle, the handle restrains the movement of the head at the instant of impact and prevents resilient reaction between the head and the structure being hit. This resiliency, or ability to rebound and vibrate, is a very important factor in setting up movements throughout the electrode structure and loosening deposits on different portions of the electrode surface. Hammers with exible handles produce more effective vibration with a blow of equal magnitude than do hammers with stiff handles but limber handles vibrate and often break of fatigue after rather short periods of operation.

The present invention provides means for moving a ball, say of fracture resisting iron alloy, back and forth along a path above the electrode structure to be rapped and causing thc ball to fall-under the force of gravity (which may be augmented by mechanical forces), at designated locations along the path, upon anvils attached to the structure. The electrode structure may be a single more or less rigid electrode comprising discharge and/or collecting surfaces, or a single structural member giving support or guidance to one or more electrodes, or a frame made up of structural members from which depend a considerable number of electrodes. The invention will be described and illustrated with reference to an electrode structure comprising a built-up frame, suspended in the top header of an electrical precipitator in electrically insulated relation to the precipitator housing, and vertlcally extending discharge electrodes suspended from the frame.

The principal object of the invention is to provide means for subjecting an electrode struc-V ture of an electric precipitator to the impact of a missile of substantial mass, such as a metal ball, which is substantially unrestrained, mechanically, at the time of impact, for the purpose of jarring depositedmaterial from the surfaces of the electrodes.

A further object of the invention is to provide a pair of anvils on an electrode structure and means -for repeatedly raising a rapping ball and causing it to drop alternately on first one and then the other of said anvils, the means provided being characterized by freedom from friction and wear and being capable of continuous and effective-operation with non-varying results for long periods of time.

Another object of the invention is to provide means for dropping a rapping ball on an electrode structure, the means being so constructed that balls. of `different size or weight can be readily substituted one for another without stopping the operating mechanism and beingcapable of changes in operating frequency without making any change except one in prime mover speed.

Another object is to provide a ball elevating mechanism which imparts an accelerating mechanical push to the ball as it leaves the elevating mechanism and begins its downward course pulled by the force of gravity.

Still another object is the provision of a dual purpose structure made up of a frame for supporting the velectrode elements and a frame for supporting the rapping mechanism, characterized by resilient spring'means between the two frames of the structure, thus preventing rapping jars imparted to the electrode support from being transmitted with any severity to the mechanism support. l

Other objects and purposes of the invention will be set forth in the following description wherein reference will be had to the accompanying drawings, in which:

Fig. 1 is a side elevation of apparatus illustrating a simple embodiment of the invention;

Fig. 2 is a partial side elevational View of apparatus illustrating a preferred embodiment of the invention;

Fig. 2a is a detail sectional view on line 2a-2a of Fig. 2;

Fig. 2b is a plan view of a detail comprised in the apparatus shown in Fig. 2;

Fig. 3 is a plan view of the electrode structure which supports the electrodes and operating mechanism shown in Fig. 2;

Fig. 4 is a diagrammatic view, in side elevation, of the ball raising cradle illustrated in Fig. 2, and

Fig. 5 is a fragmentary side elevational view of a different embodiment of the invention.

In the apparatus illustrated in Fig'.V 1, horizontally positioned structural members I. and 2, which are here shown as parallelchannels, support angle members 3 and A1| which are illustrative of the members from which discharge electrodes 5 with weights at the bottom Gare suspended. Channels I and 2 also support, on cross plates I, anvils 8 and they support bearing block 9 which in turn supports horizontally extending 'shaft I on which 'ball raising cradle II is mounted and with which it oscillates. Cradle lI is Amade up of a hub I2 to which are fastened arms I4 and I4 which are shown as made 'up of a continuous piece of flat metal riveted to hub I2. Near the end of arms I4 and I4' are fastened shelf members and I5', respectively, upon which the ball 24 rides as it is elevated as will be moreparticularly described later. Ends I3 and IB' of arms I4 and I4', respectively, are sufficiently narrow adjacent track rods 20 and 2| to permit movement of the arms between the rods but the ends of the arms beyond the rods `spread out and are forked to straddle anvils 8 and to provide a seat for the .ball while it is being lifted. Ball 24 is shown as it is about `to hit the anvil at the left of the figure. p Beams I and 2 are supported by vertical rods 26 (one rod only being shown) which pass through insulating bushings 21 which cover openings in plate 28. Bushings 2'I areV in a compartment which 'houses such Yinsulators as are necessary to me- `chanic'ally support'rods `26 and the structure supported thereby and to electrically insulate the vrods and 'electrode structure from the grounded Yportions of the precipitator.

A rod 30 attached atits upper end to Va crank z (not shown) is connected at its lower end i through spring assembly 4UI to hollow rod 3|, rotatively connected to crank 32 which is rigidly -attached to shaft Il). In spring assembly 4|), a plate 33 is fastened to rod 30, the end of the rod .is drilled or `otherwise fabricated to receive a 'plurality of guide pins 38 (only one ofwhich is shown) and the rod is dimensioned to fit into vhollowv rod 3| with a sliding t. A plurality of slots 39 machined in hollow rod or tube 3| .match the holes in rod 30 for pins 38, with which the slots make a sliding t, a stop plate or washer 31 ts over rod 3l with a sliding fit, and a collar 35 is fitted to the end of rod 3| by screw threads or other suitable means. Dur- 'ing assembly as the end of rod 38 is inserted into the hollow end of rod 3| a helical spring'- 34 is placed over rod 30 between c ollar 35 and stop plate 33,` and another helical spring 35 is placed over hollow rod 3| between washer 37 and collar 35. With collar35 fastened on the endi of rod 3| andy pins 38 inserted in the end Iof rod 3| I-behind washer 31, springs 34 and 36 Tareun'der appreciable, and approximately equal jcomprssion, the dimensions required to'produce such' conditions being easily ascertained by comu putation or by trial.

The manner of operation of the ball moving apparatus shown in Fig. 1 will be described while referring to the figure. Cradle II comprising arms I4 and I4 is oscillated on shaft I0 by a reciprocative movement of rod 30. Cradle II, as shown, has just come to a stop with arm I4 at the left of the vertical position after having delivered ball 24 to the top of the path provided by track rods 20, 2|. Ball 24 is shown about to 'strike anvil 8. It has been rolling down on track rods 20, 2| under the influence of gravity until it has acquired suicient velocity to cause it to leave the guide and drop freely along anew path toward anvil 8. Just above Vthe anvil the ball enters a cage of rods 20, 2|,

22 and 23 as shown more clearly on the right of the ligure.` The ball will bounce and strike the anvil several times unless the cradle in the meanwhile starts to move and the forked end I6 of arm I4 raises above anvil 8, catches the ball, and begins its travel to the top of the ball path. While being raised, ball-24 cannot roll orslide upon rods 20, 2| :because of shelf I5' or I5. Only after it passes the vertical position and begins to move under the force of gravity does itroll off shelf I5,'or I5', as the case may be, and begin its accelerated travel down the path provided by rods 20, 2|. It is lifted with, and pushed by, an arm of the cradle through an arc of somewhat more than (for instance, from about 96 to 110) inorder that the component of the force of gravity-which is tangent to th'e position on the ball path then occupied by the ball is sufficiently great to cause it to roll free of the cradle arm. A ball moving arm must not start the ball too soon, however, else the ball will reach the anvil before the other arm ha moved out of the way below the anvil. Figs. 2 and 3 illustrate apparatus which comprises improvements not found in the apparatus shown in Fig. 1, improvements found valuable in installations subjected to long continued service `and in large precipitators where the electrode structures'are so large that propagation of effective vibrations throughout the structures is difficult to obtain. It is to be understood in the following description of the structures which support the electrodes and rapping mechanism that the structures are symmetrical about center linesand hence only one quadrant is illustrated in Figs. 2 and 3. The electrodes to be shaken, indicated as discharge electrodes 50, say, small twisted rods, depend from horizontally extending structural angles 5I which are attached near their outer ends to structural members 52 (only one of which is shown). An anvil beam 53 is supported by angles 5I to which it is rigidly attached and on each end of beam 53 is an anvil 54. This electrode structure, made up `of electrodes 50, and structural members 5I, 52 and 53, the latter member comprising the anvils, depends by rods 55 (one of four being shown) from two beams 58 each made up of two structural members 59 and 'tie plates 6I, 62, the lower ends of rods 55 being fastened to members 52 and the upper ends to plates B2. Beams 58 support a single transversely positioned beam 63 made up of two parallel members 64, here shown as structural channels, fastened in spaced apart position by plates 65 and other members as may be needed. Beam 53 serves as a rapper mounting bridge and to it are attached two plates 55 which support bearings for shaft 61 to which ball raising cradle 10 is attached and with which it oscillates. It will be noted that in this embodiment of the invention that portion of the apparatus which supports the ball dropping mechanism is relative1y-independent of the electrode] structure being rapped and vibrated. The separation is made more nearly complete when. spring means are incorporated in the suspensions which comprise rods 55. As the spring suspension is not a part of the present invention no detailed description of the same will be given. The rapper Supporting structure comprising members 58 and 63 depends by members, indicated by the rod 60, from any suitable insulated means, usually in a separate compartment (not shown) above the compartment housing the rapper support.

The ball raising cradle is made up of a yoke 1|, which is keyed'to. shaft 61, arms 12 and 13, which are attached rigidly to yoke 1I, and auxiliary arms 14 and 15, which are attached, respectively, to arms 12 and 13 through pivots 15', and which comprise ball supporting shelves 11, and weights 18. Stir-rups 19 attached to the ends of arms 12 and 13 pass around auxiliary arms 14 and and limit the extreme outward positions which can be taken by arms 14 and 15, respectively. Also keyed to shaft 61 is a crank 82. A connecting rod 83 connects crank S2 to a shorter crank B4 and when the latter rotates about its driving shaft 85, crank 82 oscillates through an arc of about 100 degrees.-

Ball 90 which is shown resting o-n anvil 54,

may vary in its composition, size and Weight; in the present example, it is 4.1,@ inches in diameter, is made of manganese steel, and weighs approximately 13 pounds. While moving just above the anvil, ball 90 is guided, tothe extent guidance is necessary, by two bent plates ill, and a bar 92 which are held spacially positioned about the ball,

.as indicated in Fig. 2b, by a small frame made up of angles 93 and cross bar 94, the frame in turn being bolted to members 64 in adjustable manner.

The path taken by the ball in moving from one anvil to the other (one half only of the path is shown in Fig. 2) is provided by track rods $6, guide rods 91, and guide rail 98. The rods and rail are mutually supported near the upper end of rail 98 by partial hoop S9 which nearly encircles the group and is attached to each member by welding. An inverted U-shaped brace mi! is attached at the open end to members 64; the closed end goes over the rods and rail and is attached to these members. Plate 65, fastened across members S4, is cut out for entrance of ball 90 and is attached by welding to rods 95 and 91, and rail 98 and so positions and anchors these members.

The apparatus operates as follows: In Fig. 2, cradle 10 is shown at the extreme position reached after turning counter-clockwise. Ball 90 is at rest on the top of anvil 54, The pronged end of auxiliary arm 15 is straddling elevated top 54 of anvil 54 and is resting on the base vportion of the anvil.. Crank 84, afterpassing dead center, will `turn the cradle clockwise, arm 13 will rise under arm 15 which will then rise and lift ball 9U.- 'lhe ball 90 will ride on the prongs of arm 15 and shelf 11 and be carried to the top of the path. As it goes over the vertical position, weight 18 will pull auxiliary arm 15 forward with accelerated velocity and throw the ball olf shelf 11 and start it rolling down rods 96 of the right-hand side (not shown) of the track where at the bottom it will strike theanvil at that end of member 53. Crank 84 will at approximately the same ,time pass through its other dead center position and arm 14 'of' the cradle will then pick upl the ball and carry it counter-clockwise to the top of the path. From experience with this rapper, satisfactory removal of dust can vbe obtained if the ball hits an anvil about once every minute. If there is reason to speed up the apparatus to where centrifugal forces become,r factors in its operation, counterbalancing ofY the cradle and operating mechanism must receive consideration, as those familiar with the design and operation of such mechanisms will appreciate. At'higher speeds the throw of booster arms 14 and 15 can be lessened; and, as ball 9,0 will tend to move tangentially away from rods 96 near the bottomY ends of the path, the positioning of the guide assembly comprising members 9| and S2v may have to be altered.

The action of auxiliary arms 'I4 and 15 can best be explained by referring to'Fig. 4. Balla!) moves along an arc m with center O. Any force moving the ball must have a component which is tangent to that point of the arc where the ball is at the moment. -The movement of assembly made up of weight 18, shelf -11 and arm 14 can be assumed to be, for dynamical purposes, along an arc n passing through its center of lmass and which has o` as a center; and the magnitude of any force which tends to rotate the assembly is measured by the magnitude of the component which acts tangentially along arc n through the center of mass. (In a'complete analysis of the problem, the movement of the assembly 80 about center O cannot be neglected but this factor is of minor importance in the independent movement of the assembly about center o). The movement of arm 12 while ball 9B is moving through a position directly over center O is very slow because crank 84 is then approaching dead cerr- -ter, and the ball receives no positive push from arm 12 to start it down the path toward the anvil. The ball must be moved into a position where the force of gravity has a tangential component of sufficient magnitude to overcome frictien and start the ball on its general downward path. Now the tangential force `on the ball is g sin A, where g is the gravitational force and A is the angle between two lines passing through the center of the ballone avertical line and the other a line passing through center O. This angle increases in magnitude very slowly while the ball is near the vertical position. The pull of gravity tending to move assembly 80 along arc 'nl equals g sinv a, where ais the angle between the two lines passing through thevmass center of the assembly-one vertical, the other passing Vthrough center o. lNow as arm 12 moves past the vertical position, angle a increases much faster than does angleA and the force tending to rotate assembly 80, comprised of weight 18 and associated members and having an aggregate mass preferably as great or greaterthan the mass of ball 90, quickly becomes great enough to pull arm 14 forward and to-cause it to impart a push of considerable vmagnitude to the ball. It can readily'be seen that the further forward the center of mass ofassembly 89 is positioned with respect to center o the morequickly, with relation to the position of arm 12, will the force of gravity pull the assembly forward and cause arm 14 to accelerate the movement of ball 90. The position ofthe center of mass of assembly 8B can be varied by fastening weight 18 with an adjustable mounting and through the use of this variable mounting the time'of starting ball 90 "rolling down tracks 96 can be chosen to synchroi nize with the position of arm 15. v It is advisable to the extent practical to lower arm 15 (and, alternately, arm 14) gently, without .jar or noise, to anvil 54 and to pick up ball 90 slowly and without jerking the lifting mechanism. This is possible by having the actuating v-crank 84 pass through dead center during this part of the operation. But it presents the drawback of compelling ball 90 to roll off shelf 11 at the: top of the path while cradle 10 is moving very slowly. This drawback would be very real vif arms 12 and 13 extended as stiff members out tothe ball, but hinged and weighted booster -arms 14 and 15, which move relatively inde pendent of the speed of the cradle as they pass through the vertical position, alternately give the ball an eifective push when it is most needed. .f' A further advantage of the construction illustrated' in Figs. 2 and 3 -lies in the ease with which "balls can be removed. At the top of the path comprising tracks 96, there is no cover strap '98.' fHere'the ball can be removed with the hands li'f"'tl'ie apparatus is stopped and temperature and atmospheric conditions inside the precipitator' are favorable. But as it is often important 'l to maintain operation without stopping the ow Aof gas, arrangements can be provided for inserting tongs or a rake through'an opening, norvm'ally'closed, in the side ofthe top header of the Vprecipitator and picking the ball off the track and substituting'a new ball or one of different size as conditions may indicate. The high voltage structure is de-energized before inserting the tongs.v A lateral track, permanently installed,

nor inserted under a rake, can be used to run 'the ball toward the opening in the wall after it has been raked off of the path with the rake. "I'his'track must either be insulated or else terminated at proper distance from the precipitator wall if 'it is to remain in the precipitator while the latter is energized.

Fig. illustrates an embodiment of the invention which permits the ball to drop freely from Iaconsiderable height without adding to the 'height of the apparatus.

One side of the apparatus is shown; the other side is similar. Ball |04 is caused to drop on anvil |05, with restricted `impact portion |05', which is` mounted on a mem- 'bei` similar to beam 53 in Figs. 2 and 3. The ball is alternately raised by booster arms |05 and |01,

which are comprised in a cradle that may be mounted on a bridge, here indicated by member f|'22"and which is similar to cradle 10 in Figs. 2

vand 3, along two parallel rods ||0 comprising a .track. No shelves are shown on arms |06 and |01 for carrying the ball. While useful in minimizing wear of ball and tracks, such shelves are not necessary, at least where the apparatus is --used infrequently. In descending, the ball rolls on track rods I2, which are inclined but slightly from the horizontal and guide the ball to the verwardly along track rods ||0 to raise the free ends of rods ||2 to the by-pass position indicated by dash lines l5. After the ball passes, the free ends of rods ||2 drop back upon rods H0 and provide a path along which the ball travels downwards when again raised from side of the apparatus.

I claim: 1. Apparatus for rapping a material-collecting member comprising an anvil member mounted in vibration-transmitting relation with .said material-collecting member, means providing a trackway for guiding a falling missile upon said anvil, and means movable with respect to said anvil for periodically lifting a missile from said anvil to the upper portion of said trackway.

2. Apparatus for rapping a material-collecting structure comprising a pair of spaced anvils mounted on said structure, means providing a trackway for a missile between said anvils passing through a point of maximum elevation above and substantially midway of said anvils and positioned to guide a missile at each end of said trackway into substantially vertical impact upon the corresponding anvil, and means movable with respect to said anvil for periodically transporting a missile along said trackway from a position of rest upon an anvil to a position beyond said point of maximum elevation with respect to such the opposite v anvil.

3. Apparatus for rapping -a material-collecting structure comprising a pair of spaced anvils mounted on said structure, an arcuate trackway positioned above said anvils to guide a missile at each end of said trackway into substantially vertical impact upon the corresponding anvil, and means movablev with respect to said anvil for periodically transporting a missile along said trackway from a position of rest upon an anvil to a position beyond the point of maximum elevation of the trackway with respect to such anvil.

4. Apparatus for rapping a material-'collecting structure comprising a pair of spaced anvils mounted on said structure, means providing a trackway for a missile between said anvilsv pass.- in-g through a point of maximum elevation above and substantially midway of said anvils and positioned to guide a missile at each end of said trackway into substantially vertical impact upon the corresponding anvil, and a pivotally mounted pair of arms each having a missile-engaging portion positioned for motion along said trackway upon movement of the arms about the pivot, said missible-engaging portionsv being spaced along said trackway a distance slightly less than onehalf the length of the trackway.

5. Apparatus for rapping a material-collecting structure comprising a pair of spaced anvils mounted on said structure, means providing a trackway for a missile between said anvils passing through a point of maximum elevation above and substantially midway of said anvils and positioned to guide a missile at each end of said trackway into substantially vertical impact upon the corresponding anvil, and a pivotally mounted pair of arms each having a missile-engaging portion positioned for motion along said trackway upon movement of the arms about the pivot, the angular relation of said arms being such that when one of the missile-engaging portions is in a position slightly beyond the point of maximum elevation of the trackway toward one o'f said anvils, the other of said missile-engaging portions is positioned sufciently below the surface of such anvil to permit a missile to freely strike the anvil.

6. Apparatus for rapping a material-collecting structure comprising a pair of spaced anvils mounted on said structure, means providing` 'a trackway for a missile between said anvilspassing through a point of maximum elevation above and substantially midway of said anvils and positioned to guide a missile at each end of said trackway into substantially vertical impact upon the corresponding anvil, a pivotally mounted pair of arms each having a missile-engaging portion positioned for motion along said trackway upon movement of the arms about the pivot, said missile-engaging portions being spaced along said trackway a distance slightly less than one-half the length oi the trackway, and means for periodically swinging said arms through approximately a quadrant along said trackway.

'7. Apparatus for rapping a material-collecting structure comprising a pair of spaced anvils mounted on said structure, means providing a trackway for a missile between said anvils passing through a point of maximum elevation above and substantially midway of said anvils and positioned to guide a missile at each end of said trackway into substantially vertical impact upon the corresponding anvil, and a pivotally mounted pair of arms each having a missile-engaging portion positioned for motion along said trackway upon movement oi the arms about the pivot, the angular relation of said arms being such that when one of the missile-engaging portions is in a position slightly beyond the point of maximum elevation of the trackway toward one of said anvils, the lother of said missile-engaging portions is positioned sufficiently below the surface of suoli 8. Apparatus for rapping a material-collecting structure comprising a pair of spaced anvils mounted on said structure, means providing a trackway for a missile between said anvils passing through a point of maximum elevation above and substantially midway of said anvils and posi- -tioncd to guide a missile at each end of said trackway into substantially vertical impact upon the corresponding anvil, and a pivotally mounted pair of arms each having a missile-engaging portion positioned for motion along said trackway upon movement of the arms about thepivot, the angular relation of said arms being such that when one of the missile-engaging portions is in a position slightly beyond the point of maximum elevation of the trackway toward one of said anvils, the cth r of said missile-engaging portions is positioned sufficiently below the surface of such anvil to permit a missile to freely strike the anvil, said missile-engaging portions being mounted for limited pivotal movement on said arms in the plane oi movement of the arms and including an adjustable weight for varying the angular moment oi said missile-engaging portions.

9. Apparatus for rapping a material-collecting structure comprising a pair of spaced anvils mounted on said structure, means providing a trackway for a missile between said anvils passing through a point of maximum elevation above and substantially midway of said anvils and positioned to guide a missile at each end of said trackway into substantially vertical impact upon ie corresponding anvil, means for periodically transporting a missile along said trackway from a position of rest upon an anvil to a position beyond said point of maximum elevation with respect to such anvil, and means resiliently supporting said trackway and missile-transporting means above said anvils.

HERMAN C. ENGELMAN.

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