US1813306A - Electrical precipitation apparatus - Google Patents

Description

y 7, 1931. K. I. MARSHALL 1,813,306

ELECTRICAL PREC IPITATION APPARATUS Filed July 29. 1 29 4 Sheets-Sheet l Z I INVENTOR. K ennefb Marsha A TTORNEYJ' July 7, 1931. K, MARSHALL 1,813,306

ELECTRICAL PRECIPITATION APPARATUS Filed July 29, 1 29 4 Sheets-Sheet, 2

4y 1 k V 7.5-; i-V- 0 I JNVENTOR.

2 Kennef/f/ Mam/25W BY M fl/ M 4 TTO RNEY5 July 7, 1931.. K. I. MARSHALL 1,313,306

ELECTRICAL PRECIPITATIbN APPARATUS Filed July 29, 1 29 4 Sheets-Sheet,

l I v 47 INVENTOR;

Kennefh l Marsha ATTQRNEYS J y 7, 1931. K. MARSHALL 1,313,306

ELECTRICAL PRECIPITATION APPARATUS 7 Filed July 29, 1 29 4 Sheets-Sheet, 4

g- 8 I INVENTOR.

v Kennefh Z Marsbal/ ATTORNEXS Patented July 7, 1931 KENNETH I.

MARSHALL, 013 LOS AN GELES, CALIFORNIA, ASSIGNOR TO INTERNATIONAL xPRECIPITATION COMPANY, OF LOS ANGELES, CALIFORNIA, A CORPORATION OF CALIFORNIA Application filed. m 29,

This invention relates to apparatus. for electrical precipitati'oniof suspended material from gases and the principal object thereof is to provide improved means for cleaning the electrodes thereof, that is, for removing from said electrodes material precipitated or deposited thereon and adhering thereto.

'A particular object of the invention is to provide improved means for cleaning the electrodes by mechanically rapping or jarring the same, and particularly by jarring or rapping each electrode unit independently of the other electrode units, so that a sufficiently strong jarring action may be imparted to the electrode without requiring the application of a blow of excessive power.

In the rapping or jarring of electrodes in electrical precipitation apparatus it has here-' tofore been customary to mechanically and rigidly secure together a plurality of electrode units and toeffect the ra ping of such electrodes units by means 0 blows of a mechanically, pneumatically, or otherwise operated hammer or the like, delivered at a single point against an anvil or other part mechanically secured to all of said electrode units. It has been found, however, that such rapping means is ineflicient in utilizing the power applied, a large portion of such power being dissipated in the members of the frame means by which the electrode units are secured to one another and to the anvil member, so that some of the electrode units are not jarred actively enough to remove the adhering material therefrom. In certain cases where the precipitated material'is of such a nature as to be relatively ditficultly-removed from the electrodes, rapping means of the type above described have proven entirely inefiective in keeping such electrodes clean enough for efiicient operation.

An object of the present invention is to provide for more eflicient utilization of the power applied and for more effective rapping or arringof all of the electrode units than by the means heretofore used, and to accomplish this purpose I prefer to. provide each individual electrode unit with an anvil or impact member rigidly connected thereto and to provide novel means for separately ELECTRICAL PRECIPITATION APPARATUS 1929. Serial No. 382,043.

striking or rapping the anvil or impact members of the respective electrode units.

' It has heretofore been proposed to separately strike or rap the individual electrode units or individual impact members connected to the respective units, by providing a number of rapping or striking elements equal to the number of electrode units, and to operate all of such rapping or striking ele ments for a group of electrode units in unison. This,.however, required the provision of a large number of rapping or striking elements in an, electrical precipitator of large size, in addition to the mechanism required to operate all of such elements. Furthermore, only a small portion of the power delivered to the rapping mechanism was delivered to the individual electrode units, so that in order to deliver blows or vibrations to each electrode unit sufficiently powerful to efiectively dislodge collected material therefrom it was necessary to apply a large amount of power to the rapping mechanism and said mechanism consequently had to be relatively heavy in order to transmit this power. It has also been found that pneumatic hammers and particularly pneumatic hammers of the type adapted to deliver a rapid successionof sharp impulses, are particularly advantageous for use in rapping the electrodes, due to the sharp high frequency vibration thus imparted to the electrodes, and the expense of providing individual pneumatic hammer devices for all of the electrode units in a large precipitator would be prohibitive.

According to the present invention, a single rapping device is employed for successively rapping the anvil or impact members of a plurality of electrode units, such rapping device being mounted so as to be readily movable into position to operatively engage any one of said anvil or impact members. ablymounted to permit operation thereof upon any one of a plurality of anvil or im- The use of such a rapping device, movpact members is not necessarily restricted to separate rapping of each individual electrode element, but may also be advantageously employed in connection with separate rapping of a plurality of groups each comprising a small number of electrode units. In the latter case, the electrode units of each group may be rigidly and mechanically secured to one another and to a common anvil or impact member, there being one of said anvil or impact members for each group of connected electrode units, and a single rapping device may be mounted to permit movement thereof into operative engagement with any one of said anvil or impact members.

The invention is applicable to both the collecting electrodes and the discharge electrodes, and a common rapping device maybe used for rapping both the collecting electrode units and the discharge electrode units of any desired portion of the precipitator, or if preferred, separate rapping devices may be provided for the collecting electrode units and the discharge electrode units.

The rapping device may be of any suitable type and operated either mechanically, pneumatieally or in any other suitable manner, but I prefer to use a rapping-device comprising a pneumatic hammer adapted to deliver a rapid succession of sharp blows or impulses agalnst the electrodes or against suitable impact means connected thereto.

In order to readily permit movement of the rapping device into position to operatively engage any one of the electrode units to be rapped thereby, I prefer to mount said device outside the walls of the precipitator chamber proper in which the electrode units themselves are mounted, and a particularly advantageous embodiment of the present invention therefore comprises, in connection with the walls of a precipitator chamber and with a plurality of electrode units mounted within said chamber, impact members or anvils for the respective electrode units and projecting through a wall of said chamber, and a single rapping device mounted outside said wall and adapted to be moved into position to operatively engage any one of said impact members, the collecting electrodes are ordinarily grounded, so that the impact members for said electrodes may be rigidly secured thereto and project through the wall of the chamber, which is also ordinarily ground-,

tain the necessary insulation, and to provide means whereby, when it is desired to rap the discharge electrode units, each of said impact members may be first moved into position of engagement with the corresponding discharge electrode unit, and then rapped.

The accompanying drawings illustrate embodiments of my invention, and referring thereto: I

Fig. 1 is a longitudinal section through the upper portion of an electrical precipitating apparatus provided with rapping means according to this invention, taken on line 11 in Fig. 2.

Fig. 2 is a vertical section on line 22 in Fig. 1.

Fig. 3 is a detail section on line 33 in Fig. 1. i

Fig. 4 is adetail view showing the means for supporting the collecting electrodes.

Fig. 5 is a detail section on line 55 in Fig. 1.

Fig; 6 is a section on line 66 in Fig. 5.

Fig. 7 is a horizontal section on line 77 in Fig. 8, showing the connection of a plurality of electrode units to each impact member.

Fig. 8 is a vertical section on line 88 in F ig. 7.

In the drawings I have shown only the upper portion of one section of an electrical precipitator, it being understood that said precipitator comprises a suitable housing including side, top and bottom walls, in which the discharge and collecting electrode means of the several sections are mounted. The top wall of one section of the precipitator is shown as comprising a plurality of rectangular top sections or cover plates 1 having de ending flanges 2 at their longitudinal sides resting on asbestos or other suitable packing material3 in channel members 4 and depending flanges 2 at their ends also resting on packing material 3 in channels formed by angle bars 5 and 6. e

The above'described cover plates, together with the intervening channel members combine to form a substantially gas tight top wall for this section of the precipitator.

The collecting electrode units indicated at 8 are shown as being of the so-called rod curtain type, each of saidunits comprising a plurality of suitably spaced vertically extending rods or small pipes 9 suspended at their upper ends from supporting members 10 and connected at their lower ends to any suitable means (not shown) for maintaining the same inproperly spaced and aligned relationship. -Each supporting member 10 is bers 13, for supporting the same upon said strips. Each of'the supportingmembers 10, including angle bars 11 and strip 12, is supported at each end upon a channel member '14, said channel member extending entirely across this section of the precipitator and serving to support all of the collecting electrodes thereof. The'angle barsll and strips 12 may rest loosely upon the lower horizontal flange of each channel 14 and may be properlyspaced thereon by means of spacing pin 16, as shown in Fig. 4.

Each collecting electrode unit may be provided with one or more impact members or anvils. In the present instance I have shown one'imp'act member or anvil 18 mounted upon each of said collecting electrode units and substantially midway between the ends thereof. Each of said impact members is shown as comprising a base portion 19 extending across the horizontal flanges of the two angle bars 11 and secured thereto by means of rivets or bolts 20, a stem portion 21 extending upwardly from said base portion and projecting through an opening 23 in one or the other of the sectional cover plates 1, and provided at its upper end with an impact receiving head 22. Openings 23 around said impact members are preferably closed by suitable packing means such as leather washers or gaskets 24 adapted to make a substantially gas tight fit around the impact receiving portions 22, said packing means being held in position by clamping rings 25. The strips 12 are omitted at the central portion of the supporting member of each collecting electrode so as to permit the base portion 19 of the corresponding impact member to be mounted directly upon the angle bars 11, as shown for example in Figs. 1 and'5. Since the base portion of the impact member prevents the rods 9 from projecting above the angle bars for support in the regular manner, I have provided special means for supporting the particular rods indicated at 9', which are disposed directly beneath the impact members. For this purpose a short U-shaped supporting strap 27 is secured to this portion of the angle bars 11 so as to embrace the vertical flanges of said bars and extend across beneath the'same, and the rods 9 are passed up through the horizontal web of this supporting strap and supported thereon in any suitable manner, for example by being deformed as shown in Figs.

- .5 and 6, so 'as to'elongate the upperend 28 of each of said rods in a direction longitudinally of the collecting electrode and compress the same in a perpendicular direction.

'Each discharge electrode unit is shown as comprising a plurality of vertically extending elements 31 of small diameter, such as wires or fine rods suspended at their upper ends froma supporting member'such as a rod or pipe 32 and provided at their lower ends with any suitable means for maintaining the members being mounted The wires 31 may conveniently be supported.

on pipes 32 by carrying them up through holes in the bottom and top of said pipes and bending over the upper end of wires, as-

shown at 31. The supporting members 32 for the several, discharge electrode units are supported at their ends on pins or bolts 33 secured to beams or channels 34, which are in turn suspended by means of vertical beams 35 from supporting members 36 mounted on insulating supports 37. The discharge electrode units thus constituted are hung midway between the respective collecting electrode units 8, as shown at 38.

There may also be provided one or more impact members for each of the discharge electrode units, and said impact members are preferably so mounted as to be normally held out of contact with the discharge electrode means and sufficiently removed therefrom to substantially prevent electric discharge or arcing therebetween. I have shown, for example, one impact member 41, for each discharge electrode unit, each of said impact directly above the midpoint of the corresponding electrode unit. Each of said impact Iilembers may comprise a base portion 42 whose lower face 43 is preferably concave as shown so as to assist in holding the same in centered position upon the supporting member 32 of the corresponding discha'rge'electrode unit when brought into engagement therewith, a shank portion 44 extending upwardly from said base portion, and a stemportion 45 of somewhat reduced diameter extending upwardly through an opening suclr as 46 in the top wall of the precipitator and provided at its upper end with an impact receiving head 47. For the discharge electrode units which are disposedbencath the sectional cover plate 1, the openings 46 are provided in said cover plates. It will be noted, however, that certain of the discharge electrode elements are mounted directly beneath the channel members 4, and for these discharge electrode units there may be provided sleeves 48 extending upwardly from the channel members 4 between the flanges 2 of adjacent cover sections, the stem portions 45 of the corresponding impact members extending through openings 46' at the top of said sleeves. Suitable means such as compression springs 49 are provided, tending to hold the impact members 41 1n raised position, said springs i being held in position around the stem portions 45 with their lower ends engaging the cover plates 1 or the upper ends of sleeves 48 as the case may be,'and their upper ends engaging collars 51 adjacent the upper ends of said stem portions, said collars being preferably removably secured to said stem portions. Springs 45 and 49, therefore, serve to normally hold the impact members 41 in raised position, with the shoulders 52 against the cover plates 1 or the tops of the sleeve members 48, at which time the base portions 42 are far enough above the supporting member 32 of the discharge electrode units to prevent electric discharge therebetween. In Fig. 3 the stem portions 45 are partly broken awaybecause of lack of space, but it will be understood that these stem portions and springs 49 are of sufficient length to permit compression of said springs equal to the vertical downward stroke required to bring the concave lower faces 43 of the impact members into engagement with the supporting members 32 of the discharge electrode units. In order to better guide the impact members 41 in their vertical movement to and fromposition of engagement with the discharge electrode units, the base portions 19 of the impact members on the collecting electrodes may be provided with projecting arms 54 having notches 55 embracing and guiding the shank portions 44. The base portion 42 of each impact member 4]: is preferably recessed upwardly at the central portion of the lower face, as shown at 56, to accommodate the portions 31 of the discharge electrode elements 31 which project above the supporting members 32.

The rapping device is shown as comprising a pneumatic hammer 61 suspended by means of cord or cable 62 from a spring balance device 63 adapted to resiliently support the weight of said pneumatic hammer. Said spring balance device is hung by chain 64 Erom 'a carrier member mounted to travel horizontally on suitable track means so as to bring the rapping device successively into cooperative relation with the respective impact members. Said carrier means may consist of a carriage 65 provided with wheels or rollers 66 rlding upon a rail 67 extending across above the precipitator transversely of the electrode units and substantially directly above the row of impact members 18'and 41. The pneumatic hammer 61 is provided with handle means 68 whereby the same may be readily moved along the rail 67 to position to operatively engage any one of said impact members. The pneumatic hammer may be connected by flexible hose connection 69 to a pipe 71 for supplying air thereto at sufficient pressure to operate the hammer and the usual control valve 72 is provided for turning on or off the supply of air to the hammer.

It will be understood that the usual means are provided for connecting the discharge electrodes to the high tension side of a source of electric power at sufficient potential to maintain a silent or corona discharge'therefrom, while the collecting electrodes are connected to the other side of said power supply 1 source and are preferably also grounded. The precipitator will, therefore, operate in the usual manner of such apparatus to cause precipitation of suspended matter from gas passed therethrough, such. suspended matter being precipitated principally upon the surfaces of the collecting electrode units, but also collecting to some extent on the discharge elec .trodes.

switching means usually provided for this purpose whereupon the pneumatic hammer may be operated successively on the several impact members 41 for the respective discharge electrode units. In operating on each of said impact members, the pneumatic hammer is first brought into engagement with the impact receiving head 47 thereof and is pressed down so as to force said impact member downwardly until the base portion 42 thereof rests in engagement with thecorresponding supporting pipe 32. The air supply is then turned on and the pneumatic hammer operated to rapidly vibrate this discharge electrode unit sufliciently to dislodge the collected material therefrom. The air supply is then turned off and the downward pressureremoved from the pneumatic hammer, whereupon the impact member again returns to the normal or raised position.

- F igs.'7 and 8 illustrate a modification of the invention in which the collecting electrode means are rapped in groups instead of individually. In this case each of the impact members 18' is shown as rigidly connected to the angle barsor supporting members 11 of three collecting electrode units 8, but it will be understood that any suitable number 'of collecting electrode units'may be included in each group. The base portion 19' of each impact member is made of sufficient length to extend across the tops of the desired number of electrode units, said base portion rest ing upon and being secured to the horizontal flanges of'the supporting members of said electrode units. Each of said impact members is provided as before with an impact receiving portion 22 projecting above a cover plate 1, and it will be understood that the rapping device, such as pneumatic hammer 61, may be mounted in substantially thesame manner as above described so as to bemovable into aposition of operative engagement with said impact receivingportion of any one of the impact members. In order to stifi'en the impact members and assist in delivering the force of the vertical downward blow to the electrode units connected to the extremities of said impact members, I prefer to provide vertical ribs or stiffening flanges 75 extending from the central shank portion 21 to the corners or ends thereof. Except for the modification above described, the construction may be otherwise substantially the same as in the first form of the invention, and the operation of the pneumatic hammers or other rapping device on the several impact members may also be carried out in substantially the same manner.

While I have shown collecting electrode units of the rod curtain type, and discharge electrode units comprising wires, it will be understood that the rapping means of my invention. may be applied in connection with collecting 'and discharge electrode means of any type suitable for electrical precipita tion. It will also be understood that any suitable forms of impact members may be used, and that they may be mounted in any suitable manner in position for transmitting jarring action to the collecting and discharge,

electrode units. Furthermore, while I have shown the use of a pneumatic rapping hammer for jarring the impact members and electrodes, it will be understood that the same may be rapped by hand operating means, such as a heavy hammer, or by any other mechanically or electrically operated rapping means.

The impact receiving members ,for the collecting electrodes are arranged in rows or horizontal series, as shown, and the rapping device is adapted to be moved by the carrier means, horizontally, so as to bring it successively into cooperative relation with the respective impact member of a series or row. Similarly, the impact members from the discharge electrodes are arranged in horizontal rows, and the rapping device is mounted to move horizontally to cooperative relation with said impact members respectively.

I claim 1. In combination with'the electrode means of an electrical precipitator, a plurality of impact members mounted in position to transmit vibrations to different parts of said electrode means, track means, a carrier means mounted to travel on said track means, and a single rappingdevice mounted on said carrier means and movable therewith so as to bring the rapping device into position of operative engagement with any one of said impact members.

2; In an apparatus for electrical precipitation, a precipitation chamber, electrode means within said chamber, a plurality of impact members in position to transmit vibrations to different parts of said electrode meansand having impact receiving portions projecting outside a wall of said chamber, track means, a carrier means mounted to travel on said track means, and a single.rapping device mounted outside said wall and carried by said carrier means and movable therewith so as to bring said rapping device into position of operative engagement with any one of said impact members,

3. In combination with an electrical preci itating apparatus comprising a plurality o electrode units, impact members adapted to transmit mechanical vibrations to the respective electrode units, track means, carrier means mounted to travel on said track means, a'rapping device, means for supporting said rapping device on said carrier means and for moving said rapping device vertically so as 't'o bring the rapping device into position of 4. In an apparatus for electrical precipitation, collecting electrode means, discharge electrode means, a plurality of impact membersfor different portions of said collecting electrode means, a plurality of separate impact members for different parts of said discharge electrode means, track means, carrler means mounted to travel on said track means,

and a single rapping device movable vertically on said carrier means but mounted to travel horizontally therewith so as to bring said rapping device into position of operative enagement with any one of said impact memers. i

5. In an apparatus for electrical precipitation, a plurality of collecting electrode units, a plurality of discharge electrode units, a plurality of impact members rigidly connected to the indivldual collecting electrode units, a plurality of. impact members corresponding to the individual discharge electrode units and movable to a position of engagement therewith and to a position sufiiciently re-' moved therefrom to substantially prevent electric discharge therebetween, means tendin to hold said movable impact members in said last-mentioned position, and a single rapping. device movable into positlon 0t operative engagement with any one of said 1mpact members. r v

6. In combination with the collecting electrode means of an electrical precipitator, a plurality to different parts of said electrode means, a. single rapping device, means for supportmg said rapping device and, formoving the same of impact members rigidly secured horizontally so as to bring it into position for operative engagement with any one of said impact members, and means for'operating said rapping device in any such position.

In an apparatus for electrical precipitation, a plurality of separately mounted collecting electrode units, a plurality of impact members one rigidly connected to each of said electrode units, a carrier member mounted to move horizontally, a single rapping device mounted on said carrier member and movable therewith so as to bring it into position of operative engagement with any one of said impact members, and means for operating said rapping device in any such position.

8. In an apparatus for electrical precipitation, a plurality of separately supported discharge electrode units, a plurality of impact members one for each of said discharge elec-,

trode units, said impact members being movable into engagement -with the respective electrode units and also'movable out of such engagement, means tending t'ohold said impact members out of engagement with said electrode units and sufiiciently removed therefrom to substantially prevent electric discharge therebetween, and a single rapping device movable into position to engage any one ofsaid impact. members, said rapping device being operable to first move said impact member to position of engagement with the corresponding electrode unit and to then rap said impact member.

9. In an apparatus for electrical precipitation, a precipitation chamber, a plurality of electrode units separately supported within said chamber, a plurality of impact members extending through a wall of said chamber and adapted to transmit mechanical rapping action thereto, a single rapping device outside said wall, and movable into position of operative engagement with any one of said impact members, and means on said wall through which said impact members extend, providing a substantially tight seal around said impact'members while permitting substantially free movement of said impact members independent of said wall.

10. In an apparatus for electrical precipitation, a precipitation chamber, elec- I trode means within said chamber, and a plurality of impact members in position to transmit vibrations to difierent parts of said elec trode means having impact receiving portions projecting outside a wall of said .chamber for access of rapping means thereto and means for maintaining a substantially gas tight connection between the impact member and said wall while permitting-relative movement .of said impact member with respect to said wall and the space above said impact member being unobstructed to enable the rapping device to be brought into cooperative relation with any one of said impact members.

11. In an apparatus for electrical precipitation, a precipitation chamber, a plurality of electrode units mounted within said chamber, one of said Walls extending transversely of said electrode units, a plurality of impact members in position to transmit vibrations to the respective electrode units and having impact receiving portions projecting through said transversely extendin wall for access of rapping means thereto an means for maintaining a substantially gas tight connection between the impact member and said wall while permitting relative movement of said impact member with respect to said wall, and the space above said impact member being unobstructed to enable the rapping device to be brought into cooperative relation with any one of said impact members.

12. In combination with the electrode means of an electrical precipitator, a plurality of impact members adapted to transmit vibrations to different parts of said 6180? trode means, said impact members being arranged in a row and a single rapping device mounted to move along said row of impact members and adapted to cooperate with any one of said'impact members for operation-

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