A feed vaporization process and apparatus for oxygenate to olefin conversion is provided, which uses a vapor-liquid disengaging drum to separate non-volatiles and/or low-volatiles from volatiles in the oxygenate feed and produce a vaporized effluent that is reduced in non-volatiles and/or low-volatiles while at the same time maintaining the effluent at optimal temperature and pressure as a feed for oxygenate to olefin conversion. The feed vaporization process and apparatus is particularly well suited for selectively removing non-volatile contaminants such as soot and rust from an oxygenate-containing feed, which may have become contaminated during shipping.