Efb, Inc.

Massachusetts Institute of Technology

Karim Zahedi

Jeffrey C Alexander

James R Melcher

Jeffery C Alexander

Peter B Zieve

Kenneth S Sachar

Jeffrey Alexander

Apparatus and method for removal of particles and VOC from an airstream, in which particles carried by the airstream are charged by a corona ionizer and then collected by an electrically enhanced filter downstream of the ionizer. A catalytic filter downstream of the electrically enhanced filter removes VOC as well as ozone generated by the ionizer.

Method for removal of particles and VOC from an airstream

Apparatus for removal of particles and VOC from an airstream

A gaseous constituent such as SO.sub.2, HCl, or HF is removed from a gas stream in a granular bed filter containing granules coated with a sorbent material which is reactive with the gaseous constituent. Granules carrying reacted sorbent material are removed from the granular bed filter, cleaned of reacted sorbent material and coated with further sorbent material for reuse in the granular bed filter. Electrification of the filter bed permits simultaneous, highly efficient removal of particulates entrained in the gas stream.

Method for treating gas streams

A gaseous constituent, such as sulfur dioxide, is removed from a gas stream in a granular bed filter containing granules coated with a sorbent material which is reactive with the gaseous constituent. Granules carrying reacted sorbent material are removed from the granular bed filter, cleaned of reacted sorbent material and coated with further sorbent material for reuse in the granular bed filter. Electrification of the filter bed permits simultaneous, highly efficient removal of particulates entrained in the gas stream.

Electrified filter bed apparatus includes inner and outer cylindrical bed-retaining structures for confining a granular bed therebetween. The inner cylindrical structure may comprise a cage of superposed frusto-conical louvers and the outer structure may comprise a similar cage or a perforated cylindrical, liquid-drainage sheet. A cylindrical bed electrode for electrically charging the bed granules is suspended between the retaining structures. The tubular bed surrounds an internal gas passage from which polluted gas flows through the bed from the inside out. Gas enters the internal passage from above through an ionizer section of the apparatus. The ionizer section may include a disc-type ionizer assembly in an ionizer tube. The tube may form an extension of the inner louver cage. A corona discharge may be formed between the disc and the ionizer tube by providing electric current to the discs, whereby the corona discharge electrically charges particulate material within the gas stream. The discs may carry radially protruding needles defining circumferential corona discharge points. A blowdown system may be provided for cleaning the ionizer discs and the tube wall in the region of the discs. The apparatus may include means for avoiding blowout of bed granules from between the outer louvers, and a system for washing pollutant-coated bed granules.

Filter apparatus

Fly ash and fine dust in a gas stream from a coal combustor, for example, are efficiently collected in a 2-stage, tubular, granular bed filter. The stages of the filter are arranged one above the other so that the granules may move from the upper stage to the lower stage under the influence of gravity. Larger particulate in the gas stream is first collected by the lower stage, and then the remaining particulate is electrically charged and collected by the upper stage. Both stages are electrified sufficiently to rigidify the granular beds and adhere the particulate to the granules, so that the granules and the collected particulate move downwardly through the filters as a plug. Granules that exit from the lower stage are cleaned and returned to the upper stage. Non-porous granules may be used to prevent fine particulate from becoming embedded in the granules.

Filter apparatus and method for collecting fly ash and fine dust

A fluidized bed, particulate collector system wherein, in one embodiment, the bed particles have applied thereto at the surface thereof, an additive that serves to adhere particulate, once collected, to the bed particles. The bed particles and/or additive may be combustible or may be incombustible. In one embodiment, the system includes two fluidized beds, in tandem, the first of which collects particulate mostly in the supermicron sizes and the second of which is an electrofluidized bed that collects particulate mostly in the submicron sizes.

Fluidized bed particulate collectors

An electrofluidized bed agglomerator and method of agglomerating which comprises agglomerating submicron (and/or supermicron) particulates with a liquid, said liquid acting as a bond between particulates of the agglomerate thus formed to maintain the integrity thereof.

Electrofluidized bed agglomerator and method of agglomerating

Pollutant emissions produced in the manufacture of asphaltic roofing are controlled by the use of electrified bed filters. Filter bed granules coated with pollutants are removed from the beds periodically and are used in the manufacture of the roofing. A prefilter is employed to remove varnishing pollutant components in the supermicron size range to prevent fouling of an electrical charger.

Apparatus and method for controlling pollutant emissions and for

Apparatus for the high performance collection of gas entrained particulate, especially submicron particulate, consisting of a fluidized bed of collection sites with an electric field imposed on the bed so that the particulate to be collected, which is charged prior to entering the bed with the fluidizing gas, is electrically induced to agglomerate with the bed particles and the collected matter is removed in a fluidized state with the bed particles, which can consist of the collected material itself.

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Brookline, MA, United States of America

Karim Zahedi