US2911060A

US2911060A - Horizontal plane purge for precipitator

Info

Publication number: US2911060A
Application number: US690477A
Authority: US
Inventors: Roger F Rawe
Original assignee: Apra Precipitator Corp
Current assignee: Apra Precipitator Corp
Priority date: 1957-10-16
Filing date: 1957-10-16
Publication date: 1959-11-03
Anticipated expiration: 1976-11-03

Description

Nov. 3, 1959 R. F. RAWE 2,911,060

HORIZONTAL PLANE PURGE FOR PRECIPITATOR Filed Oct. 16, 1957 2092 f. Pan e United States Patent HORIZONTAL PLANE PURGE FOR PRECIPITATOR Roger F. Rawe, Alfred, N.Y., assignor to APRA Precipitator Corporation, New York, N.Y., a corporation of Delaware Application October 16, 1957, Serial No. 690,477 '5 Claims. (Cl. 183-7) This invention relates to gas cleaning apparatus of the electrostatic type and more specifically it relates to an arrangement for purging the collecting surfaces of an electrostatic precipitator that are arranged in a rectangular housing.

In gas cleaning apparatus of the general type defined that utilizes a continuous purging system, a large portion of the bulk of such apparatus is commonly allocated to house the mechanism and ductwork necessary for its satisfactory operation. Such apparatus is large and expensive to build and it frequently extends into the gas stream so as to provide substantial opposition to the gas flowing therethr'ough- This invention therefore is 'directed to a simple arrangement for a purging apparatus that is adapted to remove discrete material from collecting surfaces of the precipitatoron which it has been deposited by a process of electrostatic precipitation.

A primary object of this invention is to provide a purging system for an electrostatic precipitator that is continuous in operation yet does not'interfere with normal operation of the precipitator.

Another object of this invention is to provide a purging system that constitutes a minimum of interference in the path of the main fluid flow.

A further object of' this invention is to provide a purging system for an electrostatic precipitator that is easily manufactured and simple to maintain.

These and other objects of this invention willbecome more apparent when read in conjunction with the accompanying drawings in which:

Figure l is a perspective view of a precipitator having a purging system of the type herein defined.

Figure 2 is a side elevation of a precipitator having a modified form of purging arrangement.

Figure 1 of the drawings illustrates an electrostatic precipitator having an inlet section 12 receiving dust bearing gases from a source not illustrated. As the gas passes upward through the collecting compartments 14 of the precipitator, particulate matter entrained therein is ionized and attracted to the collecting surface of the several compartments and the cleaned residual gas is exhausted upward through outlet section 16 to an exhaust duct 18. Ionizing electrodes for the compartments 14 are not illustrated since they form no part of the present invention.

As the dust deposits accumulate on the walls of the collecting compartments the collecting efliciency of the apparatus is gradually lowered unless steps are inaugurated to systematically purge the compartment walls of their deposits.

To this end apparatusfor this purging process enclosed in outlet section 16 includes a series of ducts 22 with hoods 23 that are sized to cover a compartment 14 on which it is superposed to receive the dust bearing gas flowing thercthrough. The dust bearing gas flowing through the several compartments 14 flows at a normal therefrom and become electrostatically attracted to the.

compartment walls. When however the hood is superposed above a particular compartment the velocity of the dust bearing gas passing therethrough is increased to a high velocity whereby it re-entrains the particles from the compartment walls and carries them through the hood 23 and its connecting duct 22 to hopper 24. The opening 28 in wall 26 through which duct 22 slidably passes is provided with sealing means to preclude leakage of fluid around duct 22 between outlet section 16 and hopper 24.

'The flow of high velocity fluid is brought about by an induced draft fan 36 having its suction 32 in hopper 24 to which the ducts 22 exhaust. The high velocity fluid which effects removal of the dust particles from the walls of the collecting compartments is drawn from the inlet of housing 10 through compartment 14, hood 23 and duct 22 to hopper 24, where due to lowered velocity, it releases a large portion of the particulate matter removed from the walls of the chamber 14. Dust bearing gas drawn through induced draft fan 36 may be returned to the inlet of precipitator 10 for a repeat pass through the precipitator or it may be directed through other cleaning apparatus where it is subjected to further dust separation forces before it is exhausted to the atmosphere.

Actuating means 38 mounted on hopper 24 is adapted to reciprocate the ducts 22 and their integral hoppers 23 over the compartments 14 so as to sequentially subject each collecting unit to the flow of a high velocity fluid being induced by fan 36. The actuating means 38 illustrated includes a motor 42 and worm gear reducer 44 that rotates a lead screw mechanism 46 that in turn moves the ducts 22 and attached hoods 23 across the face of the compartments. Hydraulic or other mechanical equivalents may readily be substituted for the actuat ing means illustrated since the specific means is of no particular consequence to this invention.

At each side of the precipitator housing a dead space 52 is formed to provide a space on which the hoods 23 cated across the outlet section 16 in response to actuationby the motor 38.

To compensate for the space requirements of purging ducts 22 and hoods 23 in the outlet section 16, the size of the outlet section has been increased over that of the main precipitator 10. This increase in size provides a substantially constant flow area for fluids flowing from inlet 12 to outlet 18.

Figure 2 illustrates a modified arrangement where ducts 22 and hoods 23 are actuated from opposite sides ofrthe precipitator housing. This arrangement requires only one duct and interconnected hood assembly to be positioned in the fluid stream at any one time to thereby provide a minimum of interference to the flowing fluid.

In practice each precipitator may be subdivided into a series of juxtaposed sections each of which is adapted to be progressively covered by the purging mechanism as above described. Each motor 38 is actuated in response to a predetermined sequence of operation by a time delay switch or the like so that only one of the hood units will Patented Nov. 3, 1959 be actively engaged in a purging capacity at any given time. While one hood is disposed in a purging attitude all other hoods are held in a neutral position over a

dead compartment

52 or 54 until such-time as they will beactivated by the time delay switch.

While this purging mechanism has been described with reference to the several embodiments illustrated in. the drawing it is evident that numerous changes could be made without departing from the spirit of the invention and it is intended that all matter contained in the above description or shown in the accompanying drawings shall be, interpreted as illustrative and not in a limiting sense.

What I claim is:

l. Purging means for gas cleaning apparatus having a plurality of parallel banks of collecting compartments enclosed in a housing comprising; an outlet section superposed on said housing to provide a continuous enclosure for the flow of gaseous fluid therethrough; a dust hopper at one side of said outlet section having a wall therebetween including an opening adapted topermit communication between the collecting compartments and said hopper; duct means extending through said opening to direct fluid flow from a predetermined collecting compartment to said hopper; and actuating means associated with; the duct means adapted to reciprocate said duct through the opening to sequentially subject the collecting compartments to a purging fluid flowing therethrough.

2. Purging means for gas cleaning apparatus including a plurality of parallel banks of collecting elements enclosed in a housing comprising; an outlet section super posed on said housing to provide a continuousenclosure for the flow of a gaseous fluid therethrough; a dust hopper at one side of said outlet section having a wall therebetween including an opening adapted to permit communication between opposite sides thereof; duct means having a hood portion in communication with a bank of collecting elements adapted to reciprocate through said opening; and actuating means associated with said duct: adapted to move the duct relative to said parallelbanks of; collecting elements to sequentially subject said collecting elements to a purging fluid flowing therethrough.

3. Purging meansfor gas cleaning apparatus having a plurality of parallel banks of collecting elements enclosed in a housing comprising an outlet section superposed on said housing to provide a continuous enclosure for the flow of gaseous fluid therethrough; a dust hopper at one side of said outlet section having a walltherebetween perforated to provide an opening permitting communica: tion between the collecting elements and said hopper; duct means including a hood portion at one end adapted to cover a single bank of collecting elements to direct purging fluid through said opening between the collecting elements and the hopper; a source of suction adapted to exhaust gaseous fluid from said hopper to produce a high velocity purging fluid in the bank of collecting elements aligned with said hood; and means for reciprocating said duct through the opening to sequentially subject adjacent banks of collecting elements to the purging fluid, being directed therethrough.

4. Purging means for gascleaning apparatus having a plurality of parallel banks'of collecting elements enclosed in a housing comprising; an outlet section superposed on said housing providing a continuous enclosure for the flow of gaseous fluid therethrough; a dust hopper laterally adjacent said outlet section having an apertured wall therebetween to provide a plurality of ports therethrough;

duct means extending through each port to provide communication between spaced collecting elements and the dust hopper; and means for reciprocating the ducts through the openings to progressively subject the collecting elements to the flow of purging fluid being induced therethrough.

5. Purging means for gas cleaning apparatus having a plurality of parallel banks of collecting elements enclosed in a housing comprising; an outlet section superposed on said housing to provide a continuous enclosurefor the flow of gaseous fluid therethrough; hopper means-l laterally adjacent opposite sides of said outlet section each having a common wall therewith containing at. least one opening permitting communication between the outlet section and each of the hoppers; and ductmeans ex tending through said openings in opposite sides of the outlet section to subject the collecting elements aligned with said ductsto the purgingeflect of fluid flow being induced therethrough.

References Cited in the fileof this patent UNITED STATES PATENTS 1,957,560 Thomson May 8, 1934 2,731,107 Hersey Jan. 17, 1956 FOREIGN PATENTS 429,921 Germany June 8, 1926