Patent GB-1479033-A (GB)
Title: Electrostatic precipitating apparatus
IPC: B03C3/38
Filed: 1974-08-02
Abstract: 1479033 Electrostatic separators S MASUDA 2 Aug 1974 [14 Aug 1973 7 Sept 1973] 34143/  74 Heading B2J [Also in Division H2] An electrostatic precipitating apparatus having a charging section which comprises a housing through which a gas to be filtere passes; first discharge producing electrode positioned in the housing; second electrodes positioned adjacent to and in spaced relationship to the first electrodes, third electrodes positioned adjacent to and in spaced relationship to the first and second electrodes; means for applying a periodically varying high voltage between the first and third electrodes; means for applying a high direct voltage between the second and third electrodes and means for applying a direct bias voltage between the first and third electrodes for the suppression of corona discharge from the first electrodes when the periodically varying voltage approaches a minimum level. Electrostatic dust collecting apparatus comprises a chamber 2 having a gas ionising section 10 followed by a precipitating section 51. Dust laden gas being introduced into the apparatus by way of a port 1 and the cleaned gas being taken therefrom by a port 3, a foraminous plate 9 providing means to equalise the flow of gas through the apparatus. The ionising section of the apparatus includes groups of electrodes 13, 21, 23, the electrodes 13, 23 being tubular in form and the diameter of the electrodes 23 being large compared with that of the electrodes 13, whereas the electrodes 21 have a plate-like form and are placed between groups of the electrodes 13, 23. All the electrodes 13, 21, 23 are insulatedly mounted in the casing of the apparatus and the electrodes 13 are provided along the lengths thereof with thin painted elements 12 projecting at right angles from the electrodes. The electrodes 13 are connected to a source 17 of high voltage having a repetitively varying maximum value and the electrodes 23 are connected to the negative terminal 29 of a source of D.C. voltage 27, the positive terminal 28 of which is connected to the electrodes 21. The electrodes 23 are furthermore connected to the negative terminal 50 of a D.C. source 49 so as to bias these electrodes relatively to earth potential. After having become ionised in the section 10 the dust laden gas passes to the precipitation section 51 which comprises electrodes 53, 54 each consisting of U-shaped channel member, the open ends of which face each other in a staggered relationship. The electrodes 53 are insulated from the body of the apparatus and are connected to the negative terminal 57 of a D.C. source 56 whereas the electrodes 54 are integral with the body of the apparatus. Further towards the outlet port 3 are provided electrodes 66 of a construction similar to that of the electrodes 13 in the ionising section 10, and being connected to the negative terminal 57 of the D.C. source 56. The electrodes 54, 53, 21, 23 are provided with vibratory devices 61, 62, 63, 64 respectively whereby dust which collects in any of these electrodes is shaken off to collect in hoppers 5, 6, from which it is ejected by a helical conveying device 8. The high voltage periodically varying source 17 may comprise a motor driven disc 41 provided with a series of projections 40 which co-operate with a terminal 36 to form spark gaps by means of which the terminal 17 is successively earthed at a frequency determined by the spark rate in the precipitator which is sensed by a device 70 to control the speed of the motor 38 driving the disc 41. Alternatively, as shown in Figure 4 the source 17 may comprise a serial arrangement of D.C. and A.C. sources. In a second embodiment the electrodes 66 may be replaced by an arrangement of electrodes similar to the arrangement of electrodes 13, 23 and these electrodes connected to sources similar to 17, 50.