NOVELTY - Reducing (P1) fouling in methanol to olefins (MTO) conversion process, comprises: e.g. (a) passing a process stream (8) from MTO reactor to quench tower (10) to generate first overhead stream (12) comprising olefins, and first bottoms stream; (b) passing first overhead stream to product separator unit (20) to generate second overhead stream (22), second bottoms stream, and intermediate stream; (c) passing second overhead stream to product treatment and recovery system; and (d) separating second overhead stream, in compression and separation steps, into hydrocarbon stream and water stream.    USE - The process is useful for reducing fouling in an MTO process and recovering olefins generated in an MTO process (claimed).    ADVANTAGE - The process: provides the recovery of olefins with improved purity, in an economical manner; and is efficient in removing contaminants or heavy components, and eliminates the occurrence of loss of energy.    DETAILED DESCRIPTION - Reducing (P1) fouling in an methanol to olefins (MTO) conversion process, comprises: (a) passing a process stream (8) from an MTO reactor to a quench tower (10) to generate a first overhead stream (12) comprising olefins, and a first bottoms stream comprising waste water; (b) passing the first overhead stream to a product separator unit (20) to generate a second overhead stream (22) comprising olefins and water, a second bottoms stream comprising water, and an intermediate stream comprising water and hydrocarbons; (c) passing the second overhead stream to a product treatment and recovery system; (d) separating the second overhead stream, in compression and separation steps, into a hydrocarbon stream and a water stream; and (e) passing the intermediate stream to a second separation unit. INDEPENDENT CLAIMS are also included for:    (1) recovering (P2) olefins generated in an MTO process, comprising: the steps (a) as above per se; passing the first overhead stream to a product separator unit to generate a second overhead stream comprising olefins, a second bottoms stream comprising water, and an intermediate stream comprising water and hydrocarbons; the step (c) as above per se; separating the intermediate stream, in a separation step, into a hydrocarbon stream and a water stream; and passing the water stream to a water stripper; and    (2) recovering (P3) olefins from an oxygenate conversion reactor, comprising: passing a reactor product stream from an oxygenate to olefins reactor to a quench tower to generate a first waste water stream and a first overhead vapor stream; passing the first vapor overhead stream to a product separator to generate a second waste water stream, a process overhead stream comprising light olefins, and an intermediate stream comprising water and hydrocarbons; passing the process overhead stream to a product compression and cooling unit to generate a compressed product stream and a condensed water stream; passing the compressed product stream to an oxygenate absorber to generate a product stream comprising light olefins and an absorber stream comprising water and oxygenates; and separating the intermediate stream to generate a hydrocarbon stream comprising hydrocarbons having more than 4C and a third waste water stream.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of the process of passage of an intermediate stream from the product separator to a water stripper.    Process stream (8)    Quench tower (10)    First overhead stream (12)    Product separator unit (20)    Second overhead stream (22)