GB475443A - Improvements in or relating to electrical precipitating apparatus for purifying air - Google Patents

Abstract

475,443. Electrical precipitation apparatus. WESTINGHOUSE ELECTRIC & MANUFACTURING CO. Sept. 8, 1936, No. 24488. Convention date, Oct. 15, 1935. [Class 39 (i)] Apparatus for electrically purifying air with the minimum production of ozone comprises an ionizing chamber 4, Fig. 8, and a precipitating chamber 5 through which the air flows in succession, the ionizing chamber comprising one or more insulated fine wires 7 spaced between relatively large electrodes 8, and means for unidirectionally charging the wires relatively to the electrodes. The wires 7 and electrodes 8 are disposed in a plane transverse to the flow of the air. Preferably the electrodes 8 are of cylindrical shape, and the unidirectional charge on the wires is positive. The precipitating chamber contains two sets of alternately disposed plates 19, 20 closely spaced; one set 19 being earthed through the casing and the other set 20 being insulated and unidirectionally charged. In the construction described the plates are built up into units and are slid into position in the casing in the manner of drawers. The power supply unit is housed in a small casing attached to the casing containing the air treating elements, and consists of a transformer 27 provided with a leakage path 31. The primary coil 33 is supplied from a commercial supply circuit 26. The charging of the wires 7 is obtained in the arrangement shown from the part of the secondary between the terminal 60 and the tapping 55 and the circuit includes the two rectifiers 36, 37 in series. The charging of the plates of the precipitator elements is derived from the part of the secondary between the terminal 44 and the tapping 55. Condensers 40, 41 are disposed in series with the rectifiers. A change over switch 62 is provided and is actuated by an electromagnet 69 energized when the switch 70 is closed either by hand or automatically. A switch 72 is disposed in the lead 45 to the charged plates 20, so as to throw this element out of action when desired. One of the electrodes 81 of the ionizing chamber may be insulated and connected to earth through a lamp 75 to indicate short-circuiting through the accumulation of dust and the necessity for cleaning. Earthing of the casing may be through a high resistance 78 to one of the leads of the primary circuit. The primary circuit has a switch 80 which is normally open and is closed only by the closing of the door of the casing of the power unit. The doors of the casing containing the ionizing and precipitating elements and of the power unit casing are also interlocked so that the latter cannot be closed until the former is closed. Opening of the door of the power unit casing also allows spring actuated contacts to de-energize the condensers 40, 41. The usual electrode cleaning devices such as rapping or flushing means may be provided.