US 4,222,748 A · Electrostatically augmented fiber bed and method of using

Abstract

A method and apparatus for removal of particulates from gas streams with high collection efficiency on even submicron particulates. The apparatus includes a grounded fiber bed of 50 to 1000 micron average diameter fibers packed to a bed voidage of at least 90%, an electrostatic or ionizing field means upstream of the fiber bed to place an electrical charge on the particulates, and irrigation means for the fiber bed, and optionally the grounded electrodes of the electrostatic means as well, to flush collected particulates from the fiber bed and optionally from the grounded electrodes. The method is suitable for separation of any particulates but is particularly advantageous for separation of insoluble solid particulates from gas streams at high bed velocities of from 6 to 15 or more feet per second (i.e., 1.8 to 4.6 or more meters per second). The preferred fiber bed is of 100 to 500 micron diameter, and advantageously 100 to 250 micron diameter, glass fibers. In operation, particulates are charged in the electrostatic means and the charged particulates are collected in the fiber bed where the electrical charge is dissipated through the irrigating liquid/particulates mixture so that no significant space charge effect is allowed to develop in the fibers of the fiber bed and re-entrainment of particulates is avoided.

Claims28

Dependent claims

In a process for continuously removing particulates from a gas stream by flowing the gas sequentially through, first an electrostatic field to place a positive or negative charge on said particulates, and subsequently an irrigated packed bed collector wherein said charged particulates are collected, the improvement whereby even submicron particulates may be separated from the gas stream at high efficiency at high bed velocities while concurrently removing the collected solid particulates from the packed bed without interrupting the gas flow therethrough, which improvement comprises:

(a) flowing said gas stream containing said charged particulates through a bed of fibers having an average fiber diameter of from 50 to 1000 microns, said fiber bed having a voidage of from 90 to 98%, while concurrently
(b) irrigating said fiber bed with a liquid
(i) at a liquid flow rate such that at least a sufficient portion of the fiber bed contains sufficient liquid to dissipate the electrical charge from the fiber bed and the collected particulates contained therein, and
(ii) at least at a frequency such that no significant space charge is permitted to develop within the fibers and collected particulates in the fiber bed, and the collected solid particulates are removed from the fiber bed without substantial retention,
(c) dissipating said electrical charge to an electrical ground, and
(d) draining said liquid and the particulates contained therein from said fiber bed.

3 more elements

In an apparatus for continuously removing solid particulates from a gas stream comprising a housing having inlet and outlet ends, particulate charging section within said housing proximate said inlet and comprising a plurality of high voltage discharge electrodes connected to a D.C. voltage source at least one grounded electrode positioned and arranged with respect to said high voltage electrodes to create a substantially uniform electrostatic field therebetween, a packed bed collector for charged particulates disposed within said housing downstream of said particle charging section, and a means for irrigating said packed bed with a liquid, the improvement whereby even submicron particulates may be separated from the gas stream at high efficiency at high bed velocities while concurrently removing the collected solid particulates from the bed without interrupting the gas flow therethrough, which improvement comprises

(a) said packed bed comprising fibers having an average fiber diameter of from 50 to 1000 microns, said fiber bed having a voidage of from 90 to 98%;
(b) said irrigating means comprising means for a liquid flow such that at least a sufficient portion of the fiber bed contains sufficient liquid to dissipate the electrical charge from the fiber bed without permitting any significant space charge to develop within the fiber bed, and the collected solid particulates are removed from the fiber bed without substantial retention.

Dependencies are inferred from the claim text.

Electrostatically augmented fiber bed and method of using

Life of this patent

Electrostatically augmented fiber bed and method of using

Life of this patent

Abstract

Claims28