(74e) Beyond "Classics":New Technologies to Boost Capacity In a Butadiene Unit

Classic means to increase capacity of a given system of columns include hardware modifications, particularly the redesign of packing or trays, distributers, heat exchangers, new or additional columns. Two new approaches going one step further were investigated.

Sandwich packing combines the advantages of trays and structured packing. Consisting of alternating layers of flooded and non flooded structured packing, it provides up to 50 % more separation efficiency and a higher capacity compared to conventional internals. This technology is proven in a 1.8 m diameter production column.

Energy management in an existing extractive distillation system provides capacity increase by detailed optimization of solubility, selectivity as well as vapor and liquid flow in each part of the system by intermediate cooling or heating of the liquid. This system is proven in the absorption system of two butadiene units, providing a capacity increase of up to 10 %.

A study concerning capacity increase of a 105 kt/y butadiene unit showed following results:

- “classic” means: 12 % capacity increase, investment 10 MM€

- Energy management (one exchanger) 4-10 % capacity increase (depending on the location), investment 0.3 MM€

- Packing partly replaced by sandwich packing: 20 % capacity increase, investment 8.5 MM€.

- combined energy management plus sandwich packing: 26 % capacity increase, investment 9 MM€.