| 摘要 |
A hydrocarbon-containing feed, e.g. naphtha, is converted in a treatment plant (1), in particular a refinery or olefin plant, into desired olefins, e.g. ethylene and propylene. At least part of the fractions comprising relatively long-chain olefins, in particular olefins having at least four carbon atoms, obtained from the treatment plant (1) is passed to an olefin conversion stage (12) In the olefin conversion stage (12), for example, a catalytic reactor, in particular a fixed-bed reactor, at least part of the relatively long-chain olefins is converted into relatively shorter-chain olefins. Reaction products are fed together with any unreacted hydrocarbons to a conversion product fractionation stage (17) in which the desired olefins, in particular ethylene and propylene, are separated off. To increase the yield of the desired olefins, a paraffin/olefin separation stage (23) is installed downstream of the conversion product fractionation stage (17). In this paraffin/olefin separation stage (23), the feed stream is separated into a paraffin stream, e.g. a stream comprising butane and pentane, and an olefin stream, e.g. a stream comprising butene and pentene, e.g., by extractive distillation. The paraffins obtained in this way are recirculated to the treatment plant (1), e.g., to the cracking furnace (3) of the olefin plant, and the olefins are recirculated to the olefin conversion stage (12).
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