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August
2019
39
HYDROCARBON
ENGINEERING
P
art one of this article, published in the April 2019 issue
of
Hydrocarbon Engineering
, reviewed the design
challenges of large super-fractionator towers.
1
Areas of
key importance were identified in tray design
optimisation and the mechanical design challenges of large
diameter distillation towers. The following process and
mechanical technology solutions were also introduced:
High performance SUPERFRAC® XT trays.
The SECTIONALISED BEAM support structure.
The PINNED-TRUSS beam.
OMNI-FIT® technology for tower revamps.
This concluding second part will showcase the application
of these technologies in time-sensitive splitter revamp
projects, as well as a grassroots project.
Case study 1 - revamp of a C3 splitter
propane dehydrogenation (PDH) plant
The tower shown in Figure 1 was originally installed with 4-pass
fixed valve trays. On initial start-up the tray efficiency was
poor, generating too few stages to allow the splitter to
produce polymer grade propylene product. Despite one
attempted fix, the trays were still plagued by low tray
efficiencies, resulting in a significant shortfall in polymer grade
propylene production. The plant eventually installed a
prefractionation tower to make up for the deficit in stages
being provided in the main propylene product splitter.
Following successful commissioning of the prefractionator
tower, market conditions were favourable for another increase
in capacity. The owner targeted a revamp solution that would
ensure 100% of the propylene product to be polymer grade at
In this concluding article,
Izak Nieuwoudt and Neil Sandford, Koch-Glitsch,
USA,
use case studies to question whether there needs to be a trade-off
between capacity and efficiency in large diameter trayed towers.