The invention discloses a
separation method for producing light olefins from oxygenated chemicals. In the method, a product from a reactor for producing the light olefins from the oxygenated chemicals and / or a product generated from olefins catalytic
cracking are mixed, and the mixture is treated by a series of pretreatment steps of heat
recovery, compression, purification, cooling and the like and is separated into gas-phase
hydrocarbon and liquid-phase
hydrocarbon; the gas-phase
hydrocarbon and the liquid-phase hydrocarbon respectively enter different column plates of a depropanizing column to be in (C3-)-(C4+) separation; after being subjected to further compressing and cooling, light components of C3 and below on the top of the depropanizing column enter the depropanizing column, and ethane is used as an absorbent on the top of the depropanizing column to enhance the
recovery rate of the ethane; C2-C3 at the bottom of the depropanizing column enter a deethanizing column to separate C2 and C3; the C2 enters an
ethylene rectifying column,
ethylene is produced through side drawing, noncondensable gas on the top of the
ethylene rectifying column returns to a compressor, after totally cooling, the ethane at the bottom of the column is recovered as an absorbent of a demethanizing column or partly as
fuel gas; and C3 enters a propylene rectification
tower, propylene is recovered on the
tower top, and
propane is recovered at the
tower bottom, as an LPG (
Liquid Petroleum Gas) byproduct. The invention has the advantages of high ethylene yield, low
energy consumption, little investment and the like, and the byproduct can be effectively utilized.