Electrostatically augmented cartridge type dust collector and method

Apparatus for separating particulate matter from a gas stream comprising:

• (a) a housing having an inlet for receiving dirty gas and an outlet;
• (b) a wall in said housing dividing the interior of said housing into a dirty gas chamber in communication with said inlet and a clean gas chamber in communication with said outlet;
• (c) a plurality of filter elements each being hollow elongated in shape open at one end and closed at the other and having a body between said ends comprising an outer shell of electrically conducting material having openings therein permitting passage therethrough of said gas and particulate material and an inner filter medium of foraminous dielectric material, each of said filter elements being connected to said wall adjacent said open end thereof in a manner such that said open end is in communication with said clean gas chamber and said body is in said dirty gas chamber whereby dirty gas flows from said dirty gas chamber through said outer shell and through said filter medium then out said open end into said clean gas chamber;
• (d) a plurality of discharge electrodes mounted in said housing in spaced, neighboring relation external to said filter elements, each of said electrodes having a sharp corona producing formation;
• and
• (e) means for applying an electrical potential difference between said electrodes and said shells of said filter elements of sufficient magnitude to generate a corona discharge between said electrodes and said shells;
• (f) whereby as dirty gas flows from said housing inlet through said filters the particulate matter is electrostatically charged before entering said filter medium and a portion of said particulate matter is collected on said shell and the remainder is collected in said filter medium.

In a cartridge type filter comprising a hollow, elongated filter element closed at one end by a closure elements and open at the other having a perforated outer shell of rigid material and an inner filter medium of foraminous dielectric material and adapted to be included in apparatus for removing particulate matter from a gas stream such that dirty gas moves into said filter element through said shell and said filter medium and cleaned gas exits from said filter open end and periodically a pulse of compressed gas is introduced into said filter open end for causing a reverse flow of gas through said filter to clean said filter medium and said shell, the improvement comprising:

• a hollow elongated flow directing element of material impervious to flow of gas and located entirely within said hollow filter element, said flow directing element having an opening at one end adjacent to said open end of said filter element and having openings at the opposite end located between said ends of said filter element, said flow directing element having an internal cross-sectional area of substantially constant size along the entire length of said directing element, said flow directing element acting as a jet pump to induct a substantial reverse flow of gas through said filter element for cleaning same, said flow directing element having a member fixed to said opposite end and extending across said opposite end, said openings in said flow directing element being located adjacent said end member and being of a size allowing substantial fluid flow therethrough, and an elongated connecting element in said filter element connected at one end to said closure element and connected at the opposite end to said end member of said flow directing element for holding said closure element in place.

Apparatus for separating particulate matter from a gas stream comprising

• (a) a housing having an inlet for receiving dirty gas and an outlet;
• (b) at least one filter element within said housing, said at least one filter element being substantially cylindrical, closed at one end and open at the other, said at least one filter element comprising a metal outer shell having openings therein permitting passage therethrough to said gas and particulate matter and an inner filter medium of foraminous dielectric material;
• (c) means for holding and positioning said at least one filter element in said housing in a manner such that gas flows from the interior of said housing through said outer shell and then through said filter medium of said at least one filter element and then axially within and out through said open end of said at least one filter element into said housing outlet;
• (d) a plurality of corona discharge electrodes spaced radially outwardly of and circumferentially around said at least one filter element, each of said electrodes being in the form of a rod and disposed such that the longitudinal axis of said electrode is substantially parallel to the longitudinal axis of said at least one filter element, each of said electrodes having a sharp-edged corona producing formation extending along the outer surface thereof in a generally axial direction and;
• (e) means for applying an electrical potential difference between said electrodes and said shell of said at least one filter element of sufficient magnitude to generate a corona discharge between said electrodes and said shell;
• (f) whereby as dirty gas flows from said housing inlet through said at least one filter element the particulate matter is electrostatically charged before entering said filter medium and a portion of said particulate matter is collected on said shell and the remainder is collected in said filter medium.

A method of separating particulate matter from a gas stream utilizing a filter comprising an elongated, hollow element closed at one end and open at the other and having a body between said ends comprising an outer shell of electrically conducting material having openings therein permitting passage therethrough of said gas and particulate material and an inner filter medium of foraminous dielectric material, comprising the steps of:

• (a) providing a corona discharge between corona electrodes and the outer shell of said filter;
• (b) moving dirty gas first through said corona discharge and then through said filter in a direction from the outside through said shell, through said filter medium and through the interior of said filter;
• (c) collecting a portion of the particulate matter on said shell of said filter;
• (d) collecting the remainder of the particulate matter in said filter medium;
• and
• (e) withdrawing clean gas from said filter.