The steam active reforming (STAR) process produces (a) propylene as feedstock for polypropylene, propylene oxide, cumene, acrylonitrile or other propylene derivatives, and (b) butylenes as feedstock for methyl tertiary butyl ether (MTBE), alkylate, isooctane, polybutylenes or other butylene derivatives.
Feed: Liquefied petroleum gas (LPG) from gas fields, gas condensate fields and refineries.
Product: Propylene (polymer- or chemical-grade); isobutylene; n-butylenes; high-purity hydrogen (H2) may also be produced as a byproduct.
The fresh paraffin feedstock is combined with paraffin recycle and internally generated steam. After preheating, the feed is sent to the reaction section. This section consists of an externally fired tubular fixed-bed reactor (Uhde reformer) connected in series with an adiabatic fixed-bed oxyreactor (secondary reformer type). In the reformer, the
endothermic dehydrogenation reaction takes place over a proprietary, noble metal catalyst.
In the adiabatic oxyreactor, part of the hydrogen from the intermediate product leaving the reformer is selectively converted with added oxygen or air, thereby forming steam. This is followed by further dehydrogenation over the same catalyst. Exothermic selective H2 conversion in the oxyreactor increases olefin product space-time yield and supplies heat for further endothermic dehydrogenation. The reaction takes place at temperature between 500°C–600°C and at 4 bar–6 bar.
The Uhde reformer is top-fired and has a proprietary “cold” outlet manifold system to enhance reliability. Heat recovery utilizes process heat for high-pressure steam generation, feed preheat and for heat required in the fractionation section.
After cooling and condensate separation, the product is subsequently compressed, light-ends are separated and the olefin product is separated from unconverted paraffins in the fractionation section.
Apart from light-ends, which are internally used as fuel gas, the olefin is the only product. High-purity H2 may optionally be recoverd from light-ends in the gas separation section.
Licensor: Uhde GmbH, Dortmund, Germany
