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Schwechat’s steam cracker revamp -- Source, Sep 2007

Revamping an old cracker with only limited space available is a challenge. OMV’s team spent almost two years in the conceptual phase investigating different approaches. ARS
technology from Stone & Webster and side cracker options turned out to be either too expensive or too complex. Stepwise rigorous analysis of each individual column showed that nearly all columns could continue in service if the most advanced internals were used or the vapor to liquid ratio of the feed was optimized. Only the C₂ splitter had to be replaced, mainly because of the need to replace the random packing with trays and the impossibility of welding new tray collars. In Linde, OMV found an experienced and innovative partner. After modification, columns originally designed for 34 t/h of ethylene can now process 60 t/h. The propylene splitter is now also able to purify all FCCU C₃-cut, pushing the propylene yield of the cracker close to 50 t/h. The total olefin production was pushed from 650,000 to 900,000 t/y. At the same time, Borealis boosted the capacity of its neighboring plant to around 1 million (mn) t/y, making Schwechat one of the leading plastics locations in Europe. The two new furnaces that were needed are designed for naphtha. The growing popularity of diesel in Austria (about 2/3 of all new registrations are diesel cars) has caused the refinery to become long in naphtha. Converting naphtha to monomers avoids an expensive switch in the crude oil slate – a big advantage for an integrated refinery. Thanks to Linde and OMV’s team, the unit went on stream fairly smoothly, achieving all project targets including being on time and within budget.