Abstract: A partial oxidation process for the production of a stream of cooled and cleaned synthesis gas, reducing gas, or fuel gas substantially free from entrained particulate matter and slag. The hot raw gas stream from the partial oxidation gas generator is quench cooled with deaerated grey water in a quench tank to produce black quench water or cooled in a radiant and/or convection cooler. The cooled gas is scrubbed with deaerated grey water in a scrubbing zone to remove all of the entrained particulate matter and to produce black scrubbing waters. The black water is resolved in a flashing zone and reused by flashing it in two or three flash stages connected in series and separating the overhead flash vapors comprising vaporized grey water and sour gas from the bottoms comprising concentrated black water. The flash vapors from the first flash stage are used to heat a stream of deaerated grey water being recycled to the quench tank and gas scrubbing zone or to the gas scrubbing zone.