US3540191A - Electrostatic separator - Google Patents

Description

M. V. E. HERMAN ELECTROSTATIC SEPARATOR Nov. 17, 1970 3 Sheets-Sheet 1 Filed Jan. 29, 1968 Nov. 17, 1970 M. v. E. HERMAN 3,540,191

ELECTROSTATIC SEPARATOR Filed Jan. 29, 1968 3 Sheets-Sheet 2 FIG 3.

Nov. 17, 1970 MTV. E. HERMAN 3,540,191

ELECTROSTATIC SEPARATOR 3 Sheets-Sheet 3 Filed Jan. 29, 1968 United States Patent O 3,540,191 ELECTROSTATIC SEPARATOR Marc Victor Edgard Herman, 192 Rue Rogier, Brussels, Belgium Filed Jan. 29, 1968, Ser. No. 701,318 Claims priority, application Belgium, Jan. 31, 1967,

rm. or. nose 3/74 US. Cl. 55-121 9 Claims ABSTRACT OF THE DISCLOSURE An electrostatic separator comprising a pre-ionization zone and an attracting zone, each provided with two sets of electrodes, of which one set, in the pre-ionization zone, forms the emitting electrodes, each one thereof comprising a thin metal strip laid out in a transverse plane with reference to the direction of flow of the gas to be separated.

The present invention relates to an electrostatic separator comprising a pre-ionization zone and an attracting zone, each provided with two sets of electrodes, of which one set, in the pre-ionization Zone, forms the emitting electrodes.

Electrostatic separators are known wherein the emitting electrodes comprise metal filaments; these, generally produced from tungsten, oxidise rapidly and become brittle, which causes disturbances in the operation of the separator, such as short-circuits calling for stoppages of the separator in order to replace broken filaments, and the like.

The invention has for its object to overcome this disadvantage. For that purpose, in the electrostatic separator according to the invention, each emitting electrode comprises a thin metal strip laid out in a transverse plane with reference to the direction of flow of the gas to be separated.

The strips provide in themselves stiffer elements than the filaments previously used as emitting electrodes; they are therefore less sensitive to vibrations during the transport and operation of the dust separator, the more so as they provide better means of fastening to the members supporting them.

According to a preferred form of embodiment of the invention, the strip projects onto a metal surface positioned in a plane substantially parallel to the direction of flow of the gas to be separated, which ensures a predominantly unidirectional electron flux because of the repulsion of the electrons produced by the said surface.

Preferably according to the invention the emitting strips are inclined towards the attracting zone. This inclination offers the advantage that the electrons emitted by corona effect are directed towards the adjacent electrode of opposite potential, under an angle exceeding 90; this displacement of the electrons causes in turn an air draught through the electro-separator in the direction of flow of the [gas to be separated. This automatic air draught reduces correspondingly the head losses usually encountered in electrostatic separators.

According to an advantageous form of embodiment of the invention, between two non emiting electrodes in the preionization zone, is provided every time a double emitting electrode comprised of a fairly thin, channel-shaped metal section, the legs of which are each provided with a portion bent towards the adjacent non emitting electrode.

The invention has also for its object a device for the periodical cleansing of the electrodes of the electrostatic separator permanently connected with the separator device the design of which was favored by the particular 3,540,191 Patented Nov. 17, 1970 construction of the electrodes, which are the first object of the present application. According to the invention, the separator comprises cleansing members extending substan tially parallel to the direction of flow of the gas to be separated, these cleansing members being connected to means to move them inside channels determined between adjacent electrodes of opposite potential during the periods of cleaning the separator.

Other details and features of the invention will "become apparent from the description given hereinafter by way of non limiting examples, of forms of embodiment of the invention, with reference to the accompanying drawings wherein:

FIG. 1 shows an elevational sectional view along line I--I of FIG. 2' of an electrostatic separator according to the invention.

FIG. 2 shows a sectional view along line IIII of FIG. 1.

FIG. 3 shows a perspective view of a detail of FIG. 1.

FIG. 4 shows a front view of part of a modification of embodiment of a separator according to the invention.

FIG. 5 shows a sectional view along line VV of FIG. 4.

The electrostatic separator shown on the drawings comprises a metal vessel 1 with an admission opening 2 and a discharge opening 3 of the gas to be separated.

Inside the vessel are mounted two sets of electrodes: on the one hand, low tension electrodes 4, made from plates taking up nearly the entire width of the vessel, and threaded on three pairs of metal stems 5 fastened by means of screws 6 on the Walls 7 of the vessel; on the other hand, high tension electrodes, each comprising two plates 8, 8' in alignment, threaded on stems 9 fastened on insulators 10- carried on the walls 7. The length of the plates 8, 8 is less than half the length of the plates 4 and they are positioned so as to leave between them a free space 11 and leave uncovered a part 12 of the adjacent plates 4, on the side of the walls of the vessel 1. The plates 4 are kept at the required spacing the ones from the others by cylindrical distance pieces 13, threaded on the stems 5; similarly the plates 8, 8' are kept spaced one from the other by means of distance pieces 14 threaded on the stems 9. 7

On the rim 16 of each low tension plate 4 directed towards the admission '2 of the vessel, is mounted riderfashion, in sliding contact, a thin metal channel section 17, the legs of which are bent in direction of the adjacent plates 8, 8" and towards the discharge opening 3, so

as to provide a thin strip 18 projecting outwards on each of the faces of the plates 4.

At a slight distance from the sections 17, each of the faces of the plates 4 carries a second thin metal section with a portion 19 welded on the plate 4 and a projecting strip 20, inclined parallel to the adjacent strip 18.

The separator comprises cleansing members for the plates 4, 8, 8- as well as emitting electrodes 18, '20. These members comprise brushes 21 provided with a reciprocal movement in the channels determined each time between a plate 4 and the adjacent plates 8, '8'.

Each brush comprises a central stem 22 fastened at the top end thereof by a square 23 to a channel shaped runner 24 mounted so as to slide along the downstream rim 25 of the plates 4.

Each plate 4 carries indeed two sections 17 in alignment 17, 17, each of which corresponds to one half of the length of the plate; the ends of the section 17 are bent at right angles so as provide fins 36. On the side directed towards the wall of the vessel 1, the fins 36 of the sections 17, 17' are seized each time between a U-shaped sustaining component 37 and a small plate 38. Said plate 38 has a central recess 43 (FIG. 2) around the emitting channel section 17 and said plate 38 is rigidly connected to the fins 36 and the adjacent face of the sustaining component 37 by means of bolts 44. At the center, the fins 36 adjacent to the sections 17, 17 are pinched between two U-shaped sustaining components 39, 40.

The stem 22 of the brushes 21 provided at the inlet of the channels determined between the plates 4 and the plates 8 is fastened at its bottom end to the corresponding U-shaped sustaining component 37 while the stem 22 of the brushes provided at the inlet of the channels determined between the plates 4- and the plates 8' is fastened to the corresponding Ushaped sustaining component 39. A handle 27 connected to the small plates 38 located on the side of the wall 30' and to the end facing said wall 30 of the runners 24 by means of arms 28 passing through ports 29 in the wall 30 of the vessel, permits movement of the brushes 21, which at rest are aligned outside the said channels in order to prevent short circuits. In fact, when the handle 27 is actuated, it pulls simultaneously on the runners 24 and on the thin metal emitting channel section 17, thus the runners 24 and channel section 17 move along the corresponding rims of the plates together with the brushers 21.

When the separator is under tension, preferably in such a manner that the positive pole of the high tension source is connected to one end of one of the stems 9, mounted on one of the insulators .10, so that the plates 8, 8' are at high potential, while the second pole of the tension source and the vessel 1 are earthed, so that the plates 4 and the strips 18, are at the low potential, an electrostatic field is established between the electrodes 4 and the electrodes 8, 8 and the rims of the strips 18, 20 produce a corona effect of electron emission definitely directed towards the adjacent electrodes 8, 8' and in direction of the arrow 35 which corresponds to the direction of flow of the gas to be separated, which is forced through the electrostatic separator by means of a pump, not shown, located at the admission or the outlet of the separator. Downstream of the zone comprising the sections 17 and 19 zone, which is the re-ionization zone of the separator, the electronic charged dust particles will be deposited on the remaining portion of the electrodes 8, 8', this zone of the separator being the attracting zone.

Periodically, the tension of the separator is cut out and the plates are cleaned by producing a reciprocal movement of the brushes 21 along the rims 16 and of the plates 4 by any appropriate mechanical means.

The form of embodiment shown in the FIGS. 4, 5 relates to an electrostatic separator of the same type as that described hereinbefore, but wherein the direction of flow of the gas to be separated is horizontal.

In this case the plates 8 are made from one piece, likewise the sections 17 which are mounted in a stationary manner on the rims of the plates 4.

At the top, the vessel is closed by means of a removable cover 4-5, fastened by means of bolts 46 to the side walls 47. Flanges 48 carried on the walls 47 determine an admission opening 49 and an exhaust opening 50 for the gas. Y

The brushes 51 are carried on two arms 53, 54, fastenecl outside the vessel 1, to two angles 55 part of a frame 56 having a central transverse member 57 whereon is mounted a cylinder 58 of a hydraulic ram, the piston rod 59 thereof is fastened to the cover 45. The length of the arms 53 is about equal to the height of the plates 4, so that when the hydraulic ram is actuated, the brushes, normally positioned in the top part of the vessel, on the outside of the channels determined each time between the electrodes 4 and the adjacent electrodes 8, are impelled with a vertical reciprocal motion in the said channels.

It will be understood that the invention is not limited to the forms of embodiment described and that many modifications may be introduced therein without departing from the scope of the present patent application.

Thus, more than two emitting electrodes may be provided facing each of the electrodes of opposite potential. Thus also the emitting electrodes may be carried by the insulated plates, which are then connected for preference to the negative pole of the tension source, the vessel and the plates which are in electric contact therewith being connected to earth same as the positive pole of the tension source. Thus moreover the cleansing members may be carried out as scrapers mounted in the same manner as the brushes shown in the drawings.

I claim:

1. An electrostatic separator comprising:

a housing having an'inlet and an outlet with said housing defining therein a gas flow path from said inlet to said outlet;

laterally spaced parallel electrode plates, said electrode plates comprising a grounded set and an isolated set, alternately positioned across said housing, parallel to the general direction of the gas flow;

said plates having upstream and downstream rims transversely to the general direction of the gas flow;

channel-shaped thin metal profiles mounted riderfashion on the upstream rim of the plates of one set of plates;

said channel-shaped profiles having edges projecting downstream towards the corresponding adjacent plates of the other set, and means for supplying high voltage unidirectional current of opposite sign to the grounded and isolated plates, with the profile carrying plates being connected to the negative pole of the high voltage source, whereby the electric discharge from said projecting edges will charge impurities of the gas flow and will deflect them in the direction of the outlet of the housing.

2. An electrostatic filter as claimed in claim 1 in which at a distance from the channel-shaped profiles and parallel therewith a thin metal strip is attached to each face of the profile carrying plates, said trips having edges projecting downstream towards the corresponding adjacent plate of the other set of plates.

3. An electrostatic filter as claimed in claim 1, in which the profile carrying plates are the grounded ones.

4. An electrostatic filter as claimed in claim 1, in which the non profile carrying plates extend beyond the upstream rim of the profile carrying plates.

5. An electrostatic separator comprising:

a housing having an inlet and an outlet with said housing defining therein a gas flow path from said inlet to said outlet and defining an attracting zone and a preionization zone situated upstream of said attracting zone;

two sets of alternately-parallel to the general direction "of the gas flow-arranged, plate-shaped electrodes;

means for supplying high voltage of opposite sign to the electrodes of each set;

all the electrodes extending through both of said zones and having upstream and downstream rims substantially perpendicular to the gas flow path through the housing;

and channel-shaped thin metal profiles mounted riderfashion on the upstream rim of one set of said electrodes, with said electrodes being connected to the negative pole of the high voltage, said channelshaped profiles having edges projecting downstream towards the corresponding adjacent electrode of the other set, whereby the part of the electrodes which for one set carries said profiles and for the other set faces said profiles, comprises said ionization zone of the separator and the downstream part of the electrodes comprises the attracting zone.

6. An electrostatic separator according to claim 5, further comprising in the preionization zone additional emitting longitudinal thin metal strips mounted on said negative electrodes, downstream and parallel to said channel-shaped profiles, with said strips having edges projecting downstream towards the corresponding adjacent electrode.

7. An electrostatic separator according to claim 5, in which said housing has metallic walls and further including means for mounting said profiles carrying plates without insulation on said walls and isolator means for mounting said non profile carrying plates on said Walls.

8. An electrostatic separator comprising:

a, housing having an inlet and an outlet with said housing defining therein a substantially vertical gas flow path from said inlet upwards to said outlet;

laterally spaced parallel electrode plates defining between each other a channel, said electrode plates comprising a grounded set and an isolated set alternately positioned across said housing and parallel to the general direction of the gas flow;

said plates having lower-upstream and upper-downstream rims located transversely to the general direction of the gas flow and lateral rims substantially perpendicular to said direction;

channel-shaped thin metal profiles mounted riderfashion on the upstream rim of the plates of one set of plates;

said channel-shaped profiles having edges projecting downstream towards the corresponding adjacent plate of the other set, and means for supplying high voltage unidirectional current of opposite sign to the grounded and isolated plates with the profile carrying plates being connected to the negative pole of the high voltage supplying means whereby the electric discharge from said projecting edges will charge impurities of the gas flow and deflect said gas flow so that said impurities will deposit on the plates of the other set, upstream of part thereof which faces said channel-shaped profile, said separator further comprising;

at least one cleansing means arranged in each channel, a center stern carrying each cleansing means, said stems extending substantially parallel to said lateral rims and in a central plane between said chanel- Cir shaped profiles, runners slidably supported on the upper rim of each second electrode plate, each runner having a pair of bracket surfaces extending symmetrically in two neighboring channels, the stem of said cleansing means corresponding to the two said channels being attached at one end thereof to the said runner bracket surfaces, sustaining means for supporting the other end of said stems and for guiding them along the lower rim of the said runner supporting plates, means to reciprocate said runners, and sustaining members along the upper and lower rims of the plates.

9. An electrostatic separator as claimed in claim 8, in

which said sustaining members comprise a channel component bridging said profile and rigidly mounted therewith.

References Cited UNITED STATES PATENTS 470,608 3/ 1892 Wardhaugh 121 1,252,104 1/1918 Girvin 5513 1,333,790 3/1920 Bradley 55152 X 1,992,113 2/1935 Anderson 55150 X 1,791,338 2/1931 Wintermute 55121 1,980,521 11/1934 Hahn 552 1,992,113 2/1935 Anderson 55150 X 2,195,431 4/1940 Shively et al. 55152 X 2,547,902 4/1951 Burton 55121 X 2,585,777 2/1952 Hills 55152 X 2,698,669 1/1955 Wintermute 55138 2,711,224 6/1955 Herber 55147 2,726,731 12/1955 Brixius 55138 3,137,550 6/1964 Fruth 55156 X 3,158,453 11/1964 Maartman et al. 55--1 12 DENNIS E. TALBERT, JR., Primary Examiner US. Cl. X.R.

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