(193e) Bottom Dividing Wall Column in a BTX Unit

DWC’s have been successfully applied in BTX separation units before, but almost all designs have been of middle DWC type i.e. where the dividing wall is placed in the middle part of the column. In a conventional post-fractionation section of a BTX extraction unit, a sequence of two distillation columns in series is used to get three high purity products – a B/T column, where benzene is recovered as top product with a purity level of 99.9 wt%, and a T/X column where toluene is recovered at the top with a purity level of 99.5 wt% min. C8 aromatics (mixed xylenes + EB) are drawn as the bottom product of the T/X column with a typical purity range of 95.0 – 98.5 wt%, depending on the quality of feed sent to the unit. Combining these two columns is particularly challenging due to high purity level of the products while still justifying the energy saving benefits associated with the DWC design.

GTC Technology has designed the first of its kind - Bottoms DWC for this application, and the presentation will touch upon the following items:

• key aspects of B-DWC design,
• its advantage over middle DWC for this application, and
• Control scheme needed to successfully operate this column.

The above mentioned column is currently being fabricated and is expected to be operational in Q4 of 2019.