US2489786A - Electrical precipitator - Google Patents

Description

NOV. 29, 1949 l H, KLEMPERER 2,489,786

ELECTRICAL PREC IPITATOR Filed June 20, 1946 /A/VS KLEMPERER Patented Nov. 29, 1949 ELECTRICAL PRECIPITATOR Hans Klemperer, Belmont, Mass., assigner to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application June 20, 1946, Serial No. 678,154

1 This invention relates to electrical precipitators for separating dust and smoke from atmospheric air, ue gases and the like, and more particularly to a circuit for energizing such precipitators.

In precipitators oi the type to which the invention relates, the air or other gas to be cleaned is rst ionized in a suitable ionizing device, from whence it flows through a suitable precipitating means where dust and other impurities are separated. The ionizing device comprises at least one pair of ionizing electrodes adapted to be maintained at a suiiicient potential to ionize the air that passes therebetween. The precipitating means commonly comprises a plurality of spaced, parallel collector plates of substantial area between which the ionized air flows and on which the dust particles and other impurities are collected due to a dilerence in potential maintained between adjacent plates. The potential across adjacent plates may be of the order of 6,000 volts while the potential across the ionizing electrodes is substantially higher, for example, of the order of 12,000 volts or more. n

It is among the obiects of the present invention to provide a simpliiied circuit for supplying the desired potentials to the ionizing electrodes and the collector plates, in which circuit the collector plates function as a capacitance in a voltagedoubling circuit for substantially doubling the potential applied to the ionizing electrodes over the potential applied to the collector plates.

The above and other objects and features of the invention will be made fully apparent to those skilled in the art from a consideration of the following detailed description taken in conjunction with the accompanying drawing, in which the figure represents schematically an electrical precipitator together with a supply circuit.

Referring to the drawing, reference numeral I indicates generally an ionizing device of an electrical precipitator comprising a plurality of tubular electrodes II and a plurality of spaced, parallel iine wire electrodes I2, one between any two successive tubular electrodes I I, and between which tubular electrodes and fine wire electrodes an ionizing discharge is adapted to take place.

Adjacent the ionizing device I0 is a precipitating device I3 comprising a plurality of collector plates having extensive parallel surfaces and comprising a plurality of ground plates I4 and a plurality of intervening charge plates I5.

In order to supply suitable potentials between the ionizing electrodes II and I2 of the ionizing device I0 and a substantially lower potential between the charge plates I5 and the ground plates 5 anims.' (C1. 18s-7) I4 of the precipitating means I3, a transformer IB is provided having a primary winding Il, the terminals of which are connected across a suitable source of alternating current, and a secondary winding I8. One terminal of the secondary winding I8 is connected to the tubular electrodes II of the ionizing device and to the ground plates I4 of the precipitating means through a grounded conductor I9. A condenser 20 is connected across the terminals of the secondary winding I8 through a rectifier 2I. The rectifier 2l may be any suitable rectifier such as a well-known diode. In order to avoid the necessity of providing heating circuits for the cathodes of such rectiers, I

prefer to use a glow rectifying tube such as disclosed in copending application of Paul W. Stutsman for Gaseous discharge device, Serial No. 647,463, iiled February 14, 1946 now patent No.

2,435,246, dated February 3, 1948. The anode of the rectifier is connected to the grounded terminal of the secondary winding I8, and its cathode is connected to the opposite terminal of secondary winding I8 through the condenser 20. The

right-hand side of condenser 20 is thus the positive side. The positive side of condenser 20 is connected through a resistor 22, which may be of the order of 2 megohms, to the charge plates I5 of the precipitating means. The positive side l of the condenser 20 is also connected through a rectiiier 23 of the type described and a conductor 24 to the fine wire electrodes I 2 of the ionizing device. A condenser 25 is connected between the conductor 24 and ground.

In operation, assuming, for the moment, that the ionizing device and the collector plates aredisconnected, the voltage at the terminal C on the positive side of condenser 20 varies sinusoidally around -l-E/2 from 0 to -I-E with respect "fte ground. With the charge plates I5 connected at A, the voltage of A varies around a center value that is closely below E/2. The amplitude of variation is greatly reduced being divided between the resistive and capacitive components.

3 tlnuous eiective operation of the precipitating unit.

The operating resistor loss in this instance is about one watt, and the sustained short-circuit current through the plates and the same resistor is 3 ma.

The voltage applied at B is substantially equal `to -l-E relative to ground. This voltage which is applied across the ionizing electrodes l I and l2 is approximately twice that applied to the precipitator plates, and is, therefore, of the order of 12,000 volts. This voltage is suiicient to cause an ionizing discharge to ionize the Vair or other gases passing through the ionizing device in the direction of the collector plates where the dust, smoke and similar impurities are precipitated.

While there has been herein described a preferred embodiment of the invention, other embodiments within the scope of the appended claims will be obvious to those skilled in the art from a consideration of the form shown and the teachings hereof.

What is claimed is:

yl. An electrical precipitator for purifying gas comprising ionizing electrode means, a plurality of spaced, parallel collector plates comprising alternate charge and ground plates upon which impurities in said gas are collected, a source of alternating current, circuit means for deriving a unidirectional pulsating potential from said source, and circuit means including a resistor in series with said collector plates connected to an intermediate point of said pulsating potential deriving means whereby to employ the capacitance inherent in said Collector plates for deriving a potential from said pulsating potential of approximately the average value of said pulsating potential for energizing said collector plates, and means providing substantially the entire pulsating potential to said ionizing means.

2. An electrical precipitator for purifying gas comprising a plurality of ionizing electrodes between which an ionizing discharge is adapted to occur, a plurality voi spaced, parallel collector plates comprising alternate charge and ground Il plates upon which impurities in said gas are collected, a source oi alternating current, circuit means for deriving a unidirectional pulsating potential from said source, circuit means including a resistor and the capacitance inherent in said collector plates for deriving la potential from said pulsating Vpotential of approximately the average value of said pulsating potential for energizing said collector plates, and means for deriving a second potential from said pul- Ul sating potential approximately equal to the peak value of said pulsating potential for energizing `said ionizing electrodes` 3. An electrical precipitator for purifying gas comprising a plurality `oi ionizing electrodes between which an ionizing discharge is adapted to occur, a plurality of spaced, parallel collector plates comprising alternate charge Yand ground plates upon which impurities in said gas are collected, a source of alternating current, circuit means for deriving a pulsating potential varying between zero and a predetermined value in one direction from said source, circuit means including a resistor and the capacitance inherent in said collector plates for deriving a potential from said pulsating potential of approximately onehalf of the peak value of said pulsating potential for energizing said collector plates, and means Vfor deriving a second potential from said pulsating potential approximately equal to the peak value of said pulsating potential for energizing said ionizing electrodes.

4. VAn electrical precipitator for purifying gas comprising a plurality of ionizing electrodes between which an ionizing discharge is adapted to occur, a plurality of spaced, parallel collector plates comprising alternate charge and ground plates upon which impurities in said gas are collected, a source of alternating current, a circuit including a rectifier and a condenser for deriving a unidirectional pulsating potential from said source, circuit means including a resistor and the capacitance inherent in said collector plates'- for deriving a potential from said pulsating potential of approximately one-half of the peak value of said pulsating potential for energizing said collector plates, and means including a sec-` ond rectifier and a condenser for deriving a sec-Jv ond potential from said pulsating potential. approximately equal to the peak value of said. pulsating potential for energizing said ionizing. electrodes.. 'i

5. An electrical precipitator for purifying .gasl comprising a plurality of ionizing electrodes be-` tween which an ionizing discharge is adapted tcl occur, a plurality of spaced, parallel collectorplates comprising alternate charge vand ground plates upon which impurities in said gas are collected, a source of alternating current, a circuit including a rectier and condenser for deriving. a pulsating potential varying between zero and a predetermined value in one direction from said source, circuit means including a resistor and vthe capacitance inherent in said collector plates for deriving a potential from said pulsating po: tential of approximately one-half of the peakvalue of said pulsating potential for energizing.

said collector plates, and means including asecond rectifier and a condenser for deriving a sec-.

ond Vpotential from said pulsating potential apl proximately equal to the peak value of said pulv sating potential for energizing said ionizing electrodes.

HANS KLEMPERER.

REFERENCES CITED The following references are of record in the le of this patent:

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