US2494822A

US2494822A - Electrical precipitator

Info

Publication number: US2494822A
Application number: US735403A
Authority: US
Inventors: Kenneth W Mackenzie
Original assignee: Raytheon Manufacturing Co
Current assignee: Raytheon Co
Priority date: 1947-03-18
Filing date: 1947-03-18
Publication date: 1950-01-17
Anticipated expiration: 1967-01-17

Description

Jan. 17, 1950 K. w. M 'KENZlE ELECTRICAL PRECIPITATORS 2 Sheets-Sheet 1 Filed March 18, 1941 /NVENTO/? KENNGTH W MAcL avz/E Q 5v Jan. 17, 1950 K. w. M KENzlE 2,494,822

ELECTRICAL PRECIPITATORS Filed March 18,1947 2 Sheets-Sheet 2 m C 0Q 0) M. a r h v a I L/ r 3;

I "4 I: w J b m m g g I! Q f m a Ln m N? 8 N N I H i m '5 N m \l A /NVENTOR A ENNETH W MACKENZIE E ATTDI'PNEV Patented Jan. 17, 1950 ELECTRICAL. PRE GIPITATOR Kenneth. W; MacKenzie, Newton Highlands, Mass assignor: to; Raytheon. Manufacturing. Gompany; Newton Mass;, acorporation of'Delaware.

Application March 18, 1947, Serial No. 735,403

Thisinvention relates-to electrical ,precipitators for; separating particulate matter from atmosa pheric-air, and moreparticularly to a: systemfor: controlling. the operation of? such. preclpitators'.

Electrical dust precipitators, of the: type inwhichthe air tobe cleaned is first ionized in an. ionizing; zone; where thedust particles receive anelectrical charge; andisthen passed toacollecting zone Where the chargedparticles-am deposited. upon; suitable= collecting electrodes, must be cleaned. at: intervals; otherwisethe: accumulated desposits=williinterierewith the operati'onoi the system. Where the precipitator is intended for. use in a home or oth'erplace-Where'it would be impractical to: employ: a skilled attendant formaintaining the-system; it is desirable to limit the operations required of the user and. to-soasimplifythese that thepossibility of mistakes-and'misusewill be minimized. In-mycopending application, Serial No; 713 221; filed November 30'; 1946; now- Patent No; 2,47 6,248, datediJuly 12; 1949, there shown an electrical. dust precipitat'or" suitable for' home use in which the: collecting electrodes may be washed in situ by a fluidlspraylng meansassociated with thei system.-

The present invention contemplates the pro vision of a control system-which will effect-the washing operation at: the Will'- of the operator without requiring material attention or-timeon: the part of the operator:

To these ends-it is an object-oi thisinventiom toprovide a control system for precipitators of the type described, which maybeset: in operation to eilect thecleaning process by the actuation ofa switch, and which will then effeot the required' operations .in the desired-sequence-and' with the proper timing.

It is a'further-object' of the invention toprovide a control system of the=type-described which will insure that thepowersupply to the ionizing and collecting electrodes will bediscontinued prior to the initiation-of the supply of'cl'eaning-" fluid to the electrodes;

It is 1 a further obj ect of the inventiontoprovide.

a control-systemofthe type'described which=will' permit the static chargeon the-preeipitator"elec trodes to be dissipatedprior-tothe spraying of such electrodesw-ithcleaning 'fluid.

It is afurther object-of the' invention toprovide aconstruction in which th-e powersupply'to the motorof Y the fair orequivalent means forforcing air through the-precipitatoris discon-' tinned during; the period" cleaning-fluid is sprayed" onptheprecipitatorgelectrodes; andin which; upon thetermination-oi-thesupplyof-claningflhid; the

7 Claims; (Cl. 183-7) fan. will force air: through. the precipitator. fora predetermined periodlprior to the energizationofthe. precipitator electrodes: to. entirely dry said electrodes before; the appearance-of highv voltages 1 therebetween.

In. some domesticrisystemsit. is desired: to. pro- Vide' a construction in. which; th dust precipi. tatingi means is associated with. the" furnace, to

the endthat the. air tobepurifiedisfirst.forcedthrough. the precipitating means: and thence.-

passed inheat absorbinggrelation; to; the furnace; thus providing. a. combined? air purifying and heating system.

Itis a further object of. the. presentinvention toprovide, in sucliza: combined system, a, control circuit. in which the"- fuelv supply to the furnace and the control means icapable ofeff ectingsuch fuel supply are deenergizediduring the per-iod'iniwhich the=e1ectrodes of theprecipitat'or are beingsprayed with cleaningfiuid;

It is a. further objectofi'the'invention to :provide; a" control 1 system of." the: type" described in which the entire cleaning: operation becomes automatic" upon the actuation of aswitch by the; operator,. and in which the-washing zand drying process will proceed; be accurately timed, and the precipitator returned to its normaloperationupon completions of the process without; further attention onthe part of the operator.

The foregoing and'toth'er: objects" and featuresof the invention will be madefully apparent to those skilled in the art from a consideration of the following detaileddescription; taken incona junction with the accompanying drawings in WhlChZ Fig. 1 is a perspective view; with parts broken. away to show internal vconstruction, .ofa combined aircl'eaning and heating system; and

Fig. 2is a schematic.viewshowinglanelectricala control system for combined" air cleaning and heating systems in accordancewith the invention. Referring to the drawings, referencenumeral Ill indicates generally aprecipitator'which may,.

for example, be of 'the" type disclosedin my co.-

pending applicationpreviously mentioned; The; air to be purified-is forced through the precipitator: ID by means of a fan I l and the air is then passed through a conduit l2 into heat'absorbingrelation'. to a furnace 53 from which .the air. passes through: Y a hot airsupply duct I l-to the air distributingi system.

65- water-,- with or 'Without soap .or r other: detergents;

is supplied by way of a supply pipe l5 controlled by a solenoid valve l 6. Upon the opening of the solenoid valve IS, the water is supplied under pressure to a manifold ll positioned above the ionizing electrodes 8 and I3 and collecting e1ectrodes 9 and I9. Manifold I! is provided with a plurality of spray nozzles 20 directed toward the electrodes 8, l8 and 9, I9 in a manner to cause the cleaning fluid to impinge upon all parts of said electrodes.

In such a system, if the washing operation is left to the discretion of the operator, it is possible that the power supply'for the energization of the electrodes will be left on'at the time the solenoid valve I6 is energized to the detriment of the system. Also the operator might fail to cut off the power supply to the fan H prior to the initiation of the cleaning operation. In this event much of the spray from the nozzles 20 would be blown into the conduits of the heating and ventilating system, or be discharged from this system into the living quarters of the house, instead of falling to the collecting sump at the bottom of the precipitator. Other errors could be made such as failing to let the electrodes 8, l8 and 9, I 9 dry after the spraying operation, before turning on the power supply to energize the electrodes. Also it would be undesirable to continue the fuel supply to the oil burner 21 of the furnace when the fan H is not in operation. Such errors are avoided and the operation made completely automatic by the control system shown in Fig. 2.

Referring to Fig. 2, a motor 22 has its shaft connected to the driving shaft of a speed reduction gear 23 having a drivenshaft 24. A pair of cams 25 and 2B are mounted upon the shaft 24 to be driven at a very low speed through the reduction gear 23. For example, one revolution of the shaft 24 may require approximately twenty minutes. Cam 25 has an active portion 21, which active portion extends for only a few degrees of the angular movement of the cam, for example about four degrees. The active portion 21 actuates a rod 28 against the action of a spring 29. The cam 26 has an active portion 3!, which active portion extends over substantially 270 degrees of the circumference cam. The active portion 3| of the cam 26 is adapted to actuate a rod 32 against the action of a spring 33. The rod 28 controls a pair of normally closed contacts 34 and two pairs of normally

open contacts

35 and 35. By the term normally I refer to the position of the mechanism as shown in Fig. 2, which is the state of the system when the precipitator and the furnace are performing their normal functions of cleaning and heating the air forced therethrough by the fan I I rather than to the condition in which these functions are discontinued to permit the cleaning of the collecting electrodes of the precipitator. The rod 32 controls a pair of normally closed contacts 31 and a pair of normally open contacts 38. In the position shown, a circuit is provided across the terminals l and 2 of a source of power supply, which circuit comprises the conductors 4| and 42, the closed contacts 31, conductor 43, fan switch 44, conductor 45, closed contacts 34, conductor 46, the primary winding 41 of a transformer 48, and conductor 50 leading to terminal 2. The secondary winding 49 of the transformer 48 is connected across the energizing circuit of the electrodes l8 and 19. The fan motor II is connected across the

conductors

45 and 50. Thus, assuming that the fan switch 44, which is actuated by a thermostat in the bonnet or hot air reservoir of the furnace, is closed, the precipitator electrodes 8, I8 and 9, l9 will be energized, the heat control system of the furnace will be in operation, and a circuit will be closed thorugh the fan motor II to force air through the system.

The power supply circuit for energizing the electrodes is more fully set forth in my copending application, Serial No. 692,893, filed August 24, 1946, now Patent No. 2,476,247, dated July 12, 1949. As shown, the system comprises a pair of

rectifier tubes

52 and 53 connected in inverse relation to' one terminal of the secondary winding 49. The other terminal of the secondary winding 49 is connected through a conductor 54 to ground. The tube 52 has its cathode con nected by way of a conductor 55 to the fine wire electrodes :8 of the ionizing means. The tube 53 has its anode connected by a conductor 56 to the surface electrodes 8 of the ionizing means and to the charge electrodes IQ of the collecting system. The charge electrodes I 9 are alternate plates of the collecting system, the intervening plates 9 of which are connected to ground. A condenser 51 and a resistor 58 are connected between the conductor 54 and the conductor 55. A resistor 59 is connected between the conductor 54 and the conductor 56.

The operation of the power supply system described in the foregoing is more fully set forth in my copending application, Serial No. 692,893, filed August 24, 19%. It is suificient for the present purpose to note that the line 55 will be maintained at a predetermined positive potential of the order of 6 kv. Line 56 will be maintained at a negative potential of 6 kv and accordingly the potential difference between the fine wire electrodes [8 and the surface electrodes 8 which are connected to the line 55 will be of the order of 12 kv. The difference in potential between the collecting plates l9 which are connected to line 56 and intervening plates 9 which are connected to ground will be 6 kv.

When the parts are in the position shown, the circuit through the timing motor 22 is open and accordingly the

cams

25 and 26 are at rest. The circuit for the motor 22 from the terminal I of the source of supply includes the conductor 4!, a conductor 65, the contacts 36, and a conductor 66 connected to one terminal of the motor 22, the opposite terminal of which motor is connected to the conductor 59 and accordingly to the terminal 2. This circuit is normally open at the contacts 36. A push button switch 61 between the conductors 65 and 66 may be actuated by the operator to close a circuit by-passing the open contacts 36. When the push button switch 8'! is closed, the motor 22 then drives the

cams

25 and 26 very slowly in a clockwise direction through the speed reducing gear 23. Within a few seconds after the closure of the switch 6?, for example for about ten seconds, the active portion 21 of the cam 25 will disengage the rod 28, permitting the rod to move upwardly, opening the contacts 34 and closing the contacts 35 and 36. The closure of the contacts 36 permits the operator to release the push button switch 67 and the circuit through the motor 22 will remain closed through said contacts 35. Preferably a neon lamp 68, connected across the motor 22, is provided to visually indicate to the operator that the circuit through the motor 22 is closed. If the operator releases the push button 61 before the contacts 36 have been closed, the lamp (i8 will be acuums extinguished. The operator:" will again depress the push button flvfor' 'ai few; seconds until the lamp 68 continues to= glow 'upon the' release' of the push button, }-'iridicating that 'the w circuit 1 through the contacts 35 is closed. At the instant the contacts 36 are closed-"to-maintain a'circuit through the motor- 22, contacts 3d are -opened cutting off the power supply to the ionizing "and collecting electrodes of the aprecipitator. "Simultaneously the contacts 35" are closed. These contacts 35 close a circuit bypassing the switch-M itator, as for example in the condenser 51': or in the 1 capacitance'provided bythe collector plates l9,':to leak off or be dissipated through the resistorsf'58 and 59 before the introduction of cleaning fiuid into the, precipitator. .Byfthe endofjthis'peridd of twenty seconds the cam 26 has rotated through a sufficient angle in a clockwise. directionso that the active portion 3| of the camno longer holds the rod 32, inthe position shown butppermits. the

rod to move upward1y,.loreaking the contacts 31 p .and closing the contacts. 38. The opening of the contacts 31- opens the circuit which durin'gsthe previous twenty seconds permitted the. fiowW-of energy to the fanmotor l I through therconductor 42, the contacts 31; the contacts35, andthe conductor 45. Thus the iancan 1no 'longerforoe air through the precipitator. The circuit through the heat control system isalso broken. :Itwillrbe understood that the heat control systemiwill include the means. for controlling thesupplyrofiuel to the oil burner: and any limitswitcheseor thermostatic .deviceszcapable of normally-controlling the supplyof fuel to the burner.

The closure of the'contacts 38"closes'"a'- circuit from the conductor -42 through a conductor l-fl leading to the energizing coilll of thes'olen'oid valve 16 and thence byway ofconductor 1 2 and conductor 58 to the-terminal '2 *of the'supply source. The energizationof the coil -"H "opens the valve 16, permitting cleaning 'fluidfrom the j.

pipe 5 to' besprayed'upon the ionizing'and collecting electrodes 'ofthe pre'cipitator. I

The cleaningfiuidwill continue'to bespraye'd upon the electrodes for aperiod or approximately five minutes, while'the cam 26 rotates through an angle :of approximately 90 degrees. At the end of this five-minute period, the active portion 3| of the cam 26 again engages'the rod 32 to actuate this rod downwardly, breaking the contacts 38' and again closing'the'contacts 31. The circuit through the coil H being broken, the valve [6 closes, and cleaning fluid is no'ilong'er sprayed upon'the collecting" electrodes. Thezclosure of the contacts "'31 now closes a-circu-it through thefan motor Hby way or the contacts 35 which are closed at this time so that the circuit through the fan is closed regardless of the position of the fan motor switch 44. A circuit also exists at this time from the terminal I through the conductor 42, the contacts 31 and "ass "minutes.

: conductor-1143 through the zheat control system permitting-the oil'burner or the furnace to again she :placed in operation under the control of the 'usual thermostaticdevices. The fan motor thus forces air through" the-precipitator while the power supply'to' the ionizing and collecting electrodes remains broken *at' the contacts" 34. "This condition continues while the cams 25 and'26 *rotate through'an 'angle'of approximately 265 degre'es, and requiring approximately fifteen K At the end of-this fifteen-minute" period," the active portion 21 of the'cam 25 again contacts the rod"28to'efiect the closure or the contacts 34"andthe' opening of the contacts 35 and 36. The'partsarethus back in the'positionshown'in'Fig 2of the'drawings. The circuit throughthexhbtot '22 being broken, the cams 25arid 26 come to rest. 'Thus' the 'system is again' in its normal operative 'stategpoWer be- "ing'supplied to the tran'sform'er 48 of the precipitatorpower supply provided the" fan switch '44::is closed.

From" the foregoing itwill be apparent that the invention. provides acontrol system in which 'theentire cleaning operation is conducted automaticall'y'inra manner to .assure that the sequence or. operations will occur in -the desired order.

, :{While there has. been herein described a. preferred embodimentaofiithe. invention, other em bodiments .within the scope of .the appended claims will be app'arent to those skilled in the -art from aconsideration :of the form show-n and the teachings hereof.

What is. claimed is:

1. An 1.- air a cleaning 1? and heating system comprising ans-electrical dustprecipitator, a furnace, aheat.controlrsystemior said furnace, a fan for 'fforcing: air through said precipitatorlfor separating particulate matter therefrom, means conductingzsaid air from said precipitator in heat absorbing relation to said furnace, washing means to cleandeposits I of particulate matter from said precipitatonand means effective upon theroperation of said washing means to stop the operation of.-said. fan-and render said heat controllmeansinoperative to-cfiectthelsupply of fuel to said furnace, and amotor-driven-timingsystem -for cdeenergizingr said i electrical dust pre- .cipitator 'a shortfixed-time prior to theinitiation of operationiofthe washing means.

2..A control system for electrical dust precipitators of.the type including a plurality of ionizing and. collectingelectrodes, a, power supply circuit for energizingsaid electrodes, and means forwashing said electrodes. in .situ, comprising a timingv motor, .7 a I manually controlled switch for initiating the operation 'of said motor, a normally =open circuit =by-passing said manually controlled :switch, a first switching mechanism operated by said timing motor for opening said power supplycircuit iand simultaneously closing said-normally opencirouit to maintain said motor: inoperation regardless of. the position of said manually controlled .switch, .a second switching mechanism:operated'xby said timing rnotor' after 'aJpredetrminedtime-idelay fromzthe opening of said poweri-supply circuitzior supplying cleaning fluid. to saidwashing means for a predetermined 7'6 M e, said; first isvvitching :mechanism' being effective to again close said power supply circuit and stop said motor after a predetermined interval from the termination of said supply of cleaning fluid.

3. In an air heating and cleaning system comprising a dust precipitator, a furnace, a heat control system for said furnace, a fan for blow- 'ing air through said precipitator for separating particulate matter therefrom, and into heatabsorbing relation with said furnace, a heat control switch for controlling said fan, washing means to clean deposits of particulate matter from said precipitator, a motor-driven timing system for controlling the operation of said washing means, a switch operated by said timing system for deenergizing said fan and said heat control during the operation of said Washing means, and a switch operated by said timing sys tem for positively energizing said fan, regardless of the position of said heat controlled fan switch, for a predetermined time immediately following cessation of operation of said washing means.

4. In an air heating and cleaningsystem comprising a dust precipitator, a furnace, a heat control system for said furnace, a fan for blowing air through said precipitator for separating particulate matter therefrom, and into heat-absorbing relation with said furnace, a heat control switch for controlling said fan, washing means to clean deposits of particulate matter from said precipitator, a motor-driven timing system for controlling the operation of said washing means, a switch operated by said timing system for deenergizing said fan and said heat control during the operation of said washing means, and a switch operated by said timing system for positively energizing said fan, regardless of the position of said heat controlled fan switch, for a predetermined time immediately following cessation of operation of said washing means, and a power supply for application of voltage to the plates of said precipitator, and a switch controlled by said timing system for deenergizing said power supply a short fixed time previous to the initiation of said washing operation to allow the precipitator plates to discharge to a low value.

5. In an air heating and cleaning system comprising a dust precipitator, a furnace, a heat control system for said furnace, a fan for blowing air through said precipitator for separating particulate matter therefrom, and into heat-absorbing relation with said furnace, a heat control switch for controlling said fan, washing means to clean deposits of particulate matter from said precipitator, a motor-driven timing system for controlling the operation of said washing means, a switch operated by said timing system for deenergizing said fan and said heat control during the operation of said washing means, and a switch operated by said timing system for positively energizing said fan, regardless of the position of said heat controlled fan switch, for a predetermined time immediately following cessation of operation of said washing means, and a power supply for application of voltage to the plates of said precipitator, and a switch controlled by said timing system for deenergizing said power supply a short fixed time previous to the initiation of said washing operation to allow the precipitator plates to discharge to a low value, and said fan being energized during the period when said source of voltage is being deenergized.

6. In an air heating and cleaning system comprising a dust precipitator, a furnace, a heat control system for said furnace, a fan for blowing air through said precipitator for separating particulate matter therefrom, and into heat-absorbing relation with said furnace, a heat control switch for controlling said fan, washing means to clean deposits of particulate matter from said precipitator, a motor-driven timing system for controlling the operation of said washing means, a switch operated by said timing system for deenergizing said fan and said heat control during the operation of said washing means, and a switch operated by said timing system for positively energizing said fan, regardless of the position of said heat controlled fan switch, for a predetermined time immediately following cessation of operation of said washing means, and a power supply for application of voltage to the plates of said precipitator, and a switch controlled by said timing system for deenergizing said power supply a short fixed time previous to the initiation of said washing operation to allow the precipitator plates to discharge to a low value, and said fan being energized during the period when said source of voltage is being deenergized, and a manually operated push button switch for initiating the automatic sequencing of the entire cleaning operation by the timing system.

7. In an air heating and cleaning system comprising a dust precipitator, a furnace, a heat control system for said furnace, a fan for blowing air through said precipitator for separating particulate matter therefrom, and into heat-absorbing relation with said furnace, a heat control switch for controlling said fan, washing means to clean deposits of particulate matter from said precipitator, a motor-driven timing system for controlling the operation of said washing means, a switch operated by said timing system for deenergizing said fan and said heat control during the operation of said washing means, and a switch operated by said timing system for positively energizing said fan, regardless of the position of said heat controlled fan switch, for a predetermined time immediately following cessation of operation of said washing means, and a power supply for application of voltage to the plates of said precipitator, and a switch controlled by said timing system for deenergizing said power supply a short fixed time previous to the initiation of said washing operation to allow the precipitator plates to discharge to a low value, and said fan being energized during the period when said source of voltage is being deenergized, and a manually operated push button switch for initiating the automatic sequencing of the entire cleaning operation by the timing system, and an indicating device associated with said timing system for indicating when said timing system is in operation.

KENNETH W. MACKENZIE.

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

UNITED STATES PATENTS Number Name Date 2,233,639 Pegg Mar. 4, 1941 2,255,677 Penney Sept. 9, 1941 2,333,551 Pegg Nov. 2, 1943