Condensation cleaning of exhaust gases

Claim 1

A process for the removal of solid and gaseous contaminants from a hot particulate-laden exhaust gas stream which comprises: passing the gas stream upwardly through an open scrubbing tower; subjecting the upwardly flowing gas stream to a downwardly directed water spray only of sufficient duration and amount to saturate the gas stream and to cool it to a temperature below the boiling point of water; passing the saturated and cooled gas stream, now carrying entrained water droplets and fine particulate matter, directly to and downwardly through a spiral flow-cross flow heat exchanger having a heat exchange element oriented with its axis in a vertical direction, said heat exchange element defining a single closed, spiral liquid passage and an open, annular gas passage, said liquid and gas passages having vertically oriented and parallel boundaries; maintaining said heat exchange element at a temperature substantially below the temperature of the incoming gas stream by passing a cooling liquid therethrough; condensing water vapor contained in said gas stream on the heat exchange element surfaces, said condensation trapping and removing particulate matter and soluble and condensible gases contained in said gas stream; removing a condensate stream carrying contaminants from the heat exchanger, and removing a cleaned gas stream from the heat exchanger at a point below the heat exchange element.