Process for gas cleaning with reclaimed water

Abstract

Dispersions comprising water and particulate solids i.e. carbon and ash are produced in at least one gas cooling or scrubbing zone by quench cooling or scrubbing, or both the raw gas stream from a partial oxidation gas generator with water. Advantageously, the water may be reclaimed by the subject process. In one embodiment, the carbon-water dispersion containing any ash is mixed with a liquid organic extractant and a liquid aqueous emulsion. The emulsion breaks up, and in a decanting operation a carbon-extractant-water dispersion containing gaseous impurities separates out and floats on a dilute bottoms water layer containing gaseous impurities and some solids. The carbon-extractant-water dispersion is mixed with a heavy liquid hydrocarbon and introduced into a distillation column. The overhead from the distillation column is cooled and separated in a separation vessel into an upper layer of liquid organic extractant, an intermediate layer of aqueous emulsion, a bottom layer of water, and an overhead stream of uncondensed gaseous impurities if any. The liquid aqueous emulsion and the liquid extractant are recycled to the decanting operation. The water layer from the separation vessel and the bottoms water from the decanting operation are separately introduced into a flash column where the water is reclaimed. The flash column includes at least one stripping plate and two chambers at the bottom separated by a weir. The overhead from the flash column is cooled below the dew point and is introduced into said separation vessel. In another scheme, the emulsion is mixed with the bottoms water from the decanting operation and fed to a flash column for reclaiming water. Alternately, the aqueous emulsion is broken-up into water and liquid hydrocarbon by heating.