Method and apparatus for removing particulates from a gas stream

Electrostatic spray apparatus comprising

• an electrode for generating a high-voltage corona,
• spray means for generating a spray of liquid droplets directed into said high-voltage corona whereby an electrical charge is imparted to the droplets,
• liquid conduit means for supplying liquid to said spray means,
• means for electrically grounding said liquid conduit means so that liquid supplied to said spray means is at ground potential,
• means for continuously maintaining said electrode substantially clean and dry as it generates said high-voltage corona comprising gas conduit means for directing high-velocity pressurized gas over and around the electrode,
• a conductor for delivering high-voltage electrical current to said electrode, said conductor being axially disposed inside said gas conduit means, and
• a tubular insulator around the conductor for electrically insulating the conductor from said gas conduit means.

A particle collection system comprising a particle collecting device disposed in a stream of dirty gas for removing particles of dirt from the gas stream, the improvement comprising electrostatic spray apparatus upstream from said particle removing device for generating electrically charged liquid droplets for introduction into said gas stream to cause agglomeration of said liquid droplets and particles of dirt thereby to increase the efficiency of the downstream particle collecting device, said electrostatic spray apparatus comprising

• an electrode for generating a high-voltage corona,
• spray means for generating a spray of liquid droplets directed into said high-voltage corona whereby an electrical charge is imparted to the droplets,
• an insulator for supporting the electrode so that said spray of liquid droplets is directed into the high-voltage corona,
• liquid conduit means for supplying liquid to said spray means,
• means for electrically grounding said liquid conduit means so that liquid supplied to said spray means is at ground potential, and
• means surrounding an outer surface of said insulator through which pressurized gas can be directed for continuously maintaining said electrode and insulator substantially clean and dry as the electrode generates said high-voltage corona and as the spray means directs said spray of droplets into the high-voltage corona.

A particle collection system comprising a particle collecting device disposed in a stream of dirty gas for removing particles of dirt from the gas stream, the improvement comprising electrostatic spray apparatus upstream from said particle removing device for generating electrically charged liquid droplets for introduction into said gas stream to cause agglomeration of said liquid droplets and particles of dirt thereby to increase the efficiency of the downstream particle collecting device, said electrostatic spray apparatus comprising

• an electrode for generating a high-voltage corona,
• spray means for generating a spray of liquid droplets directed into said high-voltage corona whereby an electrical charge is imparted to the droplets,
• liquid conduit means for supplying liquid to said spray means,
• means for electrically grounding said liquid conduit means so that liquid supplied to said spray means is at ground potential,
• means for continuously maintaining said electrode substantially clean and dry as it generates said high-voltage corona comprising gas conduit means for directing high-velocity pressurized gas over and around the electrode,
• a conductor for delivering high-voltage electrical current to said electrode, said conductor being axially disposed inside said gas conduit means, and
• a tubular insulator for electrically insulating the conductor from said gas conduit means and said liquid conduit means.

A process for removing particulate from a gas stream, said process comprising

• mounting an electrode adjacent said gas stream,
• delivering high-voltage electrical current to said electrode through a conductor surrounded by an insulator for generating a high-voltage corona,
• directing a spray of liquid droplets at ground electrical potential into said high-voltage corona to impart an electrical charge to the droplets, continuously maintaining outer surfaces of said electrode and insulator substantially clean and dry as said liquid droplets are directed into said high-voltage corona by directing a column of high-velocity purge gas over and around said electrode and insulator, and
• introducing said charged liquid droplets into said gas stream.