| 摘要 |
The present invention is method for debottlenecking an existing steam cracker unit of which the operation is modified from high severity to low severity operation, having a cracking zone and a fractionation zone, said fractionation zone comprising a gasoline stripper, a de-methaniser (I), a de-ethaniser (I) a de-propaniser (I) and a de-butaniser (I), said de-propaniser (I) receiving product from the bottom of the de-ethaniser (I) and optionally product from the bottom of the gasoline stripper (I), wherein said debottlenecking method comprises the steps of: a) adding a selective hydrogenation unit (II), b) adding a cracking reactor (II) comprising a catalyst selective towards light olefins in the outlet, c) adding a re-run column and a de-propaniser (II), d) sending a part or all of the bottoms stream of the gasoline stripper (I) to the selective hydrogenation unit (II) and subsequently to the cracking reactor (II) at conditions effective to produce an outlet with an olefin content of lower molecular weight than that of the inlet, e) sending a part of the bottoms stream of the de-ethaniser (I) to the de-propaniser (II), such as, not to overload the de-propaniser (I) f) optionally sending a part or all of the overhead raw C4 fraction of the de-butaniser (I) to the selective hydrogenation unit (II), g) sending the cracking reactor (II) outlet to the re-run column to produce a C6+ bottom stream and a C1-C5 overhead, sending said overhead to the de-propaniser (II) to produce a C1-C3 overhead and a C4+ bottom stream recycled in whole or in part to the selective hydrogenation unit (II), optionally withdrawing a part of said C4+ bottom stream.
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