US2123473A - Electrode rapping - Google Patents

Description

July 12, 1938.

A. F. MESTON ELECTRODE RAP-PING Filed Aug. 28, 1936 2 Sheets-Sheet 2 Swag 144M Patented July 12, 1938 UNITED STATES PATENT OFFICE 2,123,473 Emerson]; RAPPING Archibald F. Meston, Middlesex, N. J.,'assignor-to Research Corporation, New York, N. Y., a corporation of New York Application August 28, 1936, Serial No. 98,418

12 Claims.

This invention relates to electrodes for apparatus commonly referred to as electrical precipitators and utilized for removing suspended particles from fluids. It is particularly directed at improvements in the suspending and jarring of electrodes to bring about the dislodgement of the material that is electrically deposited on the surfaces of the electrodes.

It is common practice at the present time, where it is desirable to remove the deposits in dry condition, to pass scraping means across the surfaces upon which material has been deposited,

or to rap the electrodes by striking them with hammers or similar jarring means with manually or mechanically operated mechanisms, or to lift them a short distance and then let them drop upon suitable anvils.

Scrapers that operate satisfactorily are complicated and expensive and usually necessitate shutting 011" the power before they can be operated. Where rappers have been used it has been customary to have them directed at one or two points on the frame of the electrode where it is structurally able to sustain repeated shocks. But the vibrations imparted at these local positions are seldom severe enough to produce movement over the entire surface of the stiffened electrode. Most electrodes are made up of several members ofdifierent weight and shape and nodes of little movement with relation tovibrations set up at distant points commonly exist. At such nodes the removal of the deposit is not satisfactory. Y

It is an object of the present invention to provide means for imparting vibrations toan electrode or electrode assembly in such manner that several trains of effective vibrations will proceed over the surface of the electrode from several points thus eliminating the possibility of a node existing at any point on the electrode throughout the rapping cycle.

Another object of the invention is to provide a movably pivoted support for an electrode so that the electrode can be readily moved, rapped and vibrated in a manner conducive to the re- .moval of material clinging thereto.

Still another object of the invention is to provide an improved mechanism for imparting movement to an electrode so that especially effective jarring is furnished for removal of deposits from the surface of the electrode.

The manner of realizing the above mentioned and further objects of the invention is set forth in the description that follows. relerence being had to the appended drawings in which:

, suspension for the assembly shown in Fig. 1;

Figs. 4 and 5 are diagrammatical views of the assembly shown in Fig. 2 to illustrate the utilization of the forces that jar the assembly;

Figs. 6 and 7 are fragmentary views in side elevation and plan respectively of a further suspension for the assembly shown in Fig. 1; and

Fig. 8 is a side elevational' view of a further modification of the means for supporting and 16 jarring the electrodes in accordance with the invention.

The discharge electrode assembly identified by numeral in Fig. 1 comprises a frame 8| with horizontal top member 8|, a bearing retaining member 82 attached to member 8| and carrying a bearing with pin 93, and anvil pads 85 and 88. Assembly 80 depends from a structure 84, electrically insulated from. grounded parts by means not shown, by link 83, with ro- 25 tatable means, such as pins, at 93 and 94 allow ing movement of link 83. In the operation of electrical preoipitators, the discharge electrodes are usually maintained at high potential above ground. All members in contact with assembly 30 88 must, therefore, be insulated from the grounded shell and the collecting electrodes comprising theprecipitator of which assembly 80 is a part. To fulfill this requirement, the bearings supporting the cam shaft which revolves'35 cam 87 are mounted on insulators 89 and restraining member 88 is mounted on insulators 9|], a fragmentary portion'of one of each of these insulators being shown in Fig. 6.

Where it is desired to save head room, supporting structure 84 can be lowered by using the construction shown in Figs. 2 and 3. 'In this construction, member 8| of fr'ame 8| is made up of two pieces 8|a and 8 lb joined by a structurally strong sleeve 92 with a hole in the bottom to let dust fall through. Bearings held in the sides of pocket 92 near the bottom thereof support pin 93 to which link 83 is fastened and about which it may rotate.

In the form of suspension shown in.-Figs. 6 and 50 In this construction the topmember 8| of the 55 electrode assembly 80 moves to one side.

electrode frame has fastened thereto a member 05, bent at right angles at its upper end to form a bearing for roller 06 which runs in curved track 31 supported directly upon the roof 30 of the precipitator. The electrode is displaced from its normal position by means of double cam 38.

The manner in which the invention as embodied in Figs. 1, 2 and 3 functions will now be explained with reference to Figs. 4 and 5. As cam 81 is rotated to bring the high" surface of the cam in contact with pad 85 on frame 8|, the

force now acting in link 83, represented in diagram A by 0 may be considered the resultant of the force of gravity pulling directly downwards as represented by a and a horizontal component, due to the action of the cam, as represented by b. The electrode frame proper hangs vertically and the forceacting upon it below pin 93 is that of gravity represented by arrow B. Now when the high point of cam 81 slips off pad 85, the forces are no longer in equilibrium and the unbalanced horizontal pull on pin 93 represented by 12 causes the top end of the frame to move quickly towards cam 81 and hit strongly the bottom surface of the cam. The bottom end of the frame, because of inertia, does not move over simultaneously with the top end with the result that the center of gravity of the mass making up the electrode assembly is now off center with regard to a perpendicular line passing through point of suspension 93 and integrated forces with a horizontal component represented by e in diagram C pull the bottom of the frame over and cause it to strike stop 88. In fact, a set of jerky, oscillatory, movements are set up which cause the frame to strike first at 81 and then at 88.

The support shown in Figs. 6 and 7 operates in the same manner as that described for Figs.

1, 2 and 3, except that the pivot point of the .electrode suspension moves along curved track 31 when the electrode is moved to one side by the cam 99 or other means. The resulting forces may be represented by diagram similar to Figs. 7 and 8 and a. similar series of jerky, oscillatory motions will be set up. By the use of the unsymmetrical double cam as shown, the electrode is alternately given a relatively strong rap at the top and a weak rap at the bottom, and then a relatively weak rap at the top and a strong rap at the bottom.

Fig. 8 shows a modification of the invention as applied to an electrical precipitator unit of the type disclosed in U. S. Patent No. 2,040,378, of Hedberg et al.

In the figure each collecting electrode plate IOI is depended from a structural element I04 by a rigid member I03 fastened to the plate by a rotatable pin member I02 and to member I04 by another rotatable pin I05. Displacing member I03 extends upwards beyond pin I05 and the end of this extension I03 contacts a cam I06 rotated by a cam shaft I01. This operating mechanism is supported above the precipitator roof H0 in a small compartment I08 here shown as a lean-to on the end of the high voltage insulator compartment II3. A small slot (which can be closed by a flexible boot, say, of leather or asbestos cloth) provides the only open- I ing between compartments I08 and H2 thus permitting the operating mechanism to be kept in a clean atmosphere where it is readily accessible throughcover plate III for inspection, lubrication and repairs. An oil cup II4 mounted on The member I03 receives oil forthe bearing of pin I02.

An anvil I20 is provided to receive blows from hammer head I24 mounted on collecting plate IOI. Anvil I20 is shown of wedge shape and is arranged to slide over tapered plate I2I fastened to structural members I22. By raising anvil I20, the distance between the anvil and hammer I24 is increased. This change is brought about by rotation of cam member I26, mounted on shaft I21, in slot I28 in anvil head I29.

Hammer head I25 fastened to the bottom corner of plate I M is positioned to strike against anvil I3I mounted against tapered member I32 on structural member I33. Anvil I3I is fastened in position with one or more tap bolts I34 projecting through a slot in members I32 and I33. After loosening bolt I34, tapered anvil I3I can be raised or lowered to change the distance between members I25 and I3I. When a suitable position for the anvil is found, bolt I34 can be tightened and locked by well known methods.

The operation of the mechanism is as follows. Shaft I01 is revolved causing cam I06 to push end I03 of displacement bar I03 to one side, and moving plate IOI in the opposite direction a distance, ordinarily, of less than two inches, depending upon length of plate and intensity of rapping desired, until end I03 slips off the high point of cam I06 and permits the plate to return towards and.overswing its free hanging position. The top of the plate moves over first due to the horizontal component of the forces acting upon pin I02. Hammer I24 strikes anvil I20 a strong blow, then rebounds, and hammer I25 comes over and hits anvil I3I. The plate soon comes to rest usually leaning against one or both of the anvils, depending upon their position, but will be moved horizontally again and prepared for another series of blows as cam I06 turns against bar end I03. The frequency of rapping may be from 2 to 60 or more times per minute but 6 to 10 times per minute may be expected to give good results, in most dust collecting prob:

ems.

It has been found that when the top of the plate raps strongly the bottom does not swing over and receive an equally strong rap but if the top anvil, member I20 in Fig. 12, is positioned well away from hammer I24 and these members come together gently or not at all there is a vigorous return of the top of the plate and a vigorous swing of the bottom plate towards anvil I3 I. To realize to the utmost this discovery shaft I26 is revolved at one half the speed of shaft I01 which causes the withdrawal of anvil I 20 every other swing of the plate and causes a vigorous rap to be imparted alternately to the top and to the bottom of the plate.

In the figureattenuated members I39 are discharge electrodes supported by cantilever members I40 which in turn are supported by frame I. Frame I which may serve as a support for other discharge electrodes, not shown, depends by vertical tube I42 from a high tension frame I44. Insulating bushing I43 serves as a closure for the opening between chamber H2 and insulating compartment I I3.

It will be seen that a common characteristic of the electrode supporting and rapping devices of the present invention is that the electrode is supported from a movable pivot point positioned substantially symmetrically on or in the center line of gravity of the electrode so that the electrode is normally supported in a definite and preing said electrode from its normal position and for suddenly releasing it from its displaced position.

2. In an electrical precipitator, an electrode, means supporting said electrode comprising a single movable pivot symmetrically positioned with respect to the eleptrcde and a member connecting the electrode with the pivot, anvil means positioned adjacent said electrode and means for displacing said electrode from its normal position and for suddenly releasing'it from its displaced position.

3. In an electrical precipitator, an electrode, means supporting said electrode comprising a single movable pivot, a plurality of anvil means positioned adjacent said ele'ctrode at least one of said anvil. means being adjustable in. position with respect to the electrode and means for displacing saidelectrode from its normal position and {or suddenly releasing it from its displaced position.

4. In an electrical precipitator, an electrode,

means supporting said electrode comprising a single movable pivot and a member connecting the electrode with the pivot, a plurality of anvil means positioned adjacent said electrode, means for periodically altering the position of one oi said anvil means with respect to the electrode and means for displacing said electrode from its normal position andior suddenly releasing it Irorn its displaced position. 1

.5. In an electrical precipitator, an electrode,

means supporting said electrode for movement about a single pivot, means supporting said pivot for movement, anvil means positioned adjacent said electrode, and means for displacing said a supporting member'pivctally connected to said electrode and for suddenly releasing it from its displaced position. 6.1a an electrical precipitator, an electrode,

electrode, means plvotally carrying said supporting member, means for eflecting pivotal motion of said supporting member whereby said electrode is displaced from its normal position and for releasing said electrode from its displaced position, and a plurality or anvil members posi-l a whip-like motion.

at a plurality of points thereon. I

7. In an electrical precipitator, an electrode, means supporting said electrode comprising a single movable-pivot, anvil means positioned adjacent said electrode and means for periodically displacing said electrode from its normal positioned to be struck by said electrode in succasion' I tion and for suddenly releasing it from its displaced position.

8. In an electrical precipitator, anelectrode, means supporting said electrode comprising a movable pivot and a member connecting the V electrode with the pivot, anvil means positioned adjacent said'electrode, means forperlodically altering the position of one of said anvil means with respect to the electrodeand means for pcriodically displacing said electrode from its normal position and vifor suddenly releasing it from its displaced position,

9. In an'electrical precipitator, anelectrode, means i, supporting said electrode for gyratory movement, comprising a single supporting member, a movable pivot connecting said supporting member'to the electrode, said pivot being positioned away from and vertically above the center of mass of the electrode.

10. In an electrical precipitator, an electrode,

anvil means positioned adjacent said electrode, V means for displacing said electrode from its normal position and suddenly releasing it from its displaced position, and means supporting said.

electrode, comprising a single supporting memher, a movable pivot connecting said supporting member to the electrode, said pivot being positioned away from and vertically above the center of mass of the electrode.

11. 'In an electrical precipitator,- an electrode, means supporting said electrode comprising a single movable pivot positioned away from the center'of mass 01' the electrode, anvil means po" sitioned adjacent said electrode, and means for displacing said electrode from itsnormal posi-. tion and for suddenly placed position. v r

12. A method oi cleaning an electrode or an electrical precipitator which comprises suspending the electrode from a single movable point. moving the electrode laterally by a force acting releasing it from its dlsadjacent the top 01' the. electrode, the stress in said force balancing the horizontal component set up in the suspending means due to displacement of the electrode, releasing said electrode from its displaced position thus "causing said horizontalcomponent in the suspension means to act upon the top of the electrode quickly pulling it laterally back towards its original position and causing the bottgm' or the electrode to follow with r. uns'ron.

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