Abstract: The invention is a process for recovering heat and removing impurities from a reactor effluent stream withdrawn from a fluidized exothermic reaction zone for conversion of oxygenates into light olefins from an oxygenate feedstream. The process comprises a two-stage quench tower system to remove water from the reactor effluent stream in the first tower and recover heat from the reactor effluent to at least partially vaporize the feedstream by indirect heat exchange between the oxygenate feedstream and either a first stage overhead stream or a first stage pumparound stream. A drag stream withdrawn from the first tower comprises the majority of the impurities and higher boiling oxygenates. The second stage tower further removes water and provides a purified water stream which requires minimal water stripping to produce a high purity water stream. The invention concentrates the impurities into a relatively small stream and results in significant energy and capital savings.