Propylene supplied needs to be separated from Butane and Butene in a debutanizer column to obtain a pure propylene.
Alkylation of benzene with propylene takes place in Alkylation reactors. Benzene must be recycled to maintain the profile of temperature and the benzene-propylene ratio high.
Effluent from the alkylation reactor is sent to the depropanizer column and its bottom is sent to the benzene column where benzene is collected overhead and recycled. The benzene column bottom is
sent to the Cumene column where Cumene product is recovered overhead. The bottom from this column, containing mostly diisopropylbenzene (DIPB), is sent to the DIPB column where DIPB is recovered and recycled to the transalkylation reactor. The bottom from the DIPB column consists of a small stream of heavy aromatic by-products which are normally blended into fuel oil. Steam or hot oil provides the heat for the product fractionation section.
sent to the Cumene column where Cumene product is recovered overhead. The bottom from this column, containing mostly diisopropylbenzene (DIPB), is sent to the DIPB column where DIPB is recovered and recycled to the transalkylation reactor. The bottom from the DIPB column consists of a small stream of heavy aromatic by-products which are normally blended into fuel oil. Steam or hot oil provides the heat for the product fractionation section.
A portion of the recycle benzene from the top of the benzene column is combined with the recycle DIPB from the overhead of the DIPB column and sent to the transalkylation reactor. In this reactor DIPB and benzene are converted to additional IPB. The effluent from the transalkylation reactor is sent to the benzene column.