Abstract:
The drive to achieve greater energy efficiencies is well-established in the fine
chemical industries with distillation processes being a key focus due to their
disproportionate energy consumption totaling more than 40% of the overall
plant. The objective of this paper is to specifically focus on the energy efficiency
benefits that would be realized by employing intensified distillation column
configurations on a high purity, multicomponent, high recovery
industrial methanol distillation where a middle boiling trace ethanol component
must be managed to ensure on specification production (<10 ppm
wt. ethanol in product and <5 ppm impurities in bottoms). Based on technology
maturity constraints, five column configurations were selected for further
analysis, comprising a direct synthesis configuration, a side draw column, a
Petlyuk inspired recovery column arrangement, a divided wall column, and a
cut divided wall column. These configurations were then simulated on an
industrial process simulator where all configurations were able to match the
strict industrial product specifications and design limits. The energy usage of
the column configurations was improved through a systematic analysis, and
the results revealed that all intensified columns have a superior energy usage
compared to the direct synthesis configuration but with the gains limited to
only 3%. An unbiased consideration of the energy efficiency results, together
with other external factors including cost of capital and operability, shows that
the recovery column configuration would be the most practical choice despite
the presence of the divided wall column configuration which represents a
greater level of intensification and integration.
