NOVELTY - Propane is separated from reaction liquid (3) obtained from cumene production device by introducing the reaction liquid into debenzenizer tower (1) to obtain first overhead stream (4), benzene stream (8) and first bottom stream (5) containing cumene and polyisopropylbenzene; subjecting the first overhead stream into oil-water separation to obtain water (7) and propane-containing stream (6); and introducing the propane-containing stream into depropanizer tower (2) to obtain second overhead stream (9) containing propane, and second bottom stream (10) containing benzene.    USE - Method for separating propane from the reaction liquid obtained from cumene production device (claimed).    ADVANTAGE - The method employs debenzenizer tower to separate the benzene stream, the first bottom stream containing cumene and polyisopropylbenzene, and the first overhead stream, thus reducing the amount of residual benzene in the first overhead stream, the amount of material to be handled in the depropanizer tower, the size required for the depropanizer tower, the investment cost, and the energy consumption for cooling and heating processes; enabling effective separation of propane in the depropanizer tower; reducing the rate of benzene loss; solving the problems associated with the separation technique employed in the prior art (such as large depropanizer tower size and high investment cost, energy consumption and rate of benzene loss); and making the method suitable for industrial production.    DETAILED DESCRIPTION - Propane is separated from reaction liquid (3) containing benzene, cumene, polyisopropylbenzene and propane obtained from cumene production device by (A) introducing the reaction liquid into the middle part of debenzenizer tower (1), rectifying and separating to obtain first overhead stream (4) from the top of the debenzenizer tower, extracting benzene stream (8) from the middle side line of the debenzenizer tower, collecting first bottom stream (5) containing cumene and polyisopropylbenzene from the debenzenizer tower kettle, sending the benzene stream and first bottom stream into subsequent process; (B) subjecting the first overhead stream into oil-water separation process to obtain water (7) and propane-containing stream (6); (C) introducing the propane-containing stream into the middle part of depropanizer tower (2), rectifying and separating to obtain second overhead stream (9) containing propane from the top of the depropanizer tower, and second bottom stream (10) containing benzene from the depropanizer tower kettle.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic flow diagram illustrating the method for separating propane from the reaction liquid obtained from cumene production device.    Debenzenizer tower (1)    Depropanizer tower (2)    Reaction liquid (3)    First overhead stream (4)    First bottom stream (5)    Propane-containing stream (6)    Water (7)    Benzene stream (8)    Second overhead stream (9)    Second bottom stream (10)