Abstract: A centrifugal vapor/liquid separator separates the vapor and liquid in a flash of hydrocarbon and steam mixture, such that only the vapor stream is fed and processed further downstream. The design of the separator ensures that all partially wetted surfaces in the separator, except at the vapor outlet pipe, are well-wetted and washed by the non-vaporized liquid portion of the feed or by injection of external liquid thus ensuring that no coke deposition occurs inside the separator. The flash temperature in the separator therefore can be increased beyond the typical limit thus achieving a deeper cut into the feed and recovering a larger fraction of the feed as vapor for further downstream processing.