This
study focuses on the energy-efficient separation process of
styrene monomer, avoiding the formation of an azeotrope by using a
vacuum distillation, derived from the pyrolysis of waste polystyrene
(PS). The direct-indirect sequence, which positions the separation
column of ethylbenzene and styrene monomer as the last step, exhibited
a 30% reduction in the total utility consumption and a 37% reduction
in the total annual cost compared to that of the direct-direct sequence
that separates lighter components sequentially. A dividing wall column
(DWC) configuration derived from the direct-indirect sequence showed
the most significant reduction of 40% in utility consumption. However,
when the feed capacity was low, the increased capital cost of DWC
resulted in a total annual cost similar to that of the direct-indirect
sequence. As the capacity of the entire distillation system increased,
the reduction in the total operating cost of the DWC was amplified,
indicating the advantages of using the DWC in high product throughputs
from both energy and economic perspectives. Therefore, implementing
the DWC in large-scale PS recycling processes demonstrates superior
performance compared to the conventional distillation process, resulting
in a more streamlined process with substantial energy savings and
CO2 emissions.