Lessons learned in commercial scale-up of new chemical processes (5)
Total system design
New
chemical processes often involve new reactor concepts. Unfortunately, the
reactor often becomes the sole focus of research, with little thought given to
the balance of the plant. This can be detrimental to the design. Consider the
common scenario of the startup company with limited cash struggling to fix the
back end of its inadequately designed pilot unit so that it can operate the new
reactor concept, prove the concept and raise more funds. Meanwhile, a crew of
operators are sitting idle, burning cash.
The
lesson here is that a successful chemical facility requires a robust design
across all sections. The author recommends using the total system design
approach, selecting contractor(s)/consultant(s) with proven applicable
experience to at least provide the process design package, and not using
“low cost” as the sole criteria for the
selection of consulting/engineering firms for design.
Cost growth
It is
common to see announcements by startups on how a new route will reduce the production cost of an existing
process, usually by a good margin, and often from a reduction in installed
plant cost. Variable costs associated with chemical processes such as
raw materials, utilities, operations, maintenance, waste disposal and
product sales are generally easy to estimate and with a high level of accuracy, based on
process yield and selectivity.
Capital costs are much more difficult to
assess. Most startups do not have the funding resources to hire an engineering
firm for this purpose, and so they must rely on either public domain
information or cost-estimating software. Public domain information issued by
government entities should be used with caution. This information is usually
acceptable if used to rank different schemes. However, it should not be used to
estimate production and/or plant costs, nor for
comparing new process data with non-governmental published data for existing commercial
plants run by competitors. The result often presents an unrealistically
favorable comparison.
Cost-estimating
software programs can be useful and are generally reasonably accurate; however,
they can produce misleading data. Often, it is unclear what pieces of
information may require manual adjustment to obtain a realistic output.
Engineering contracting firms rely heavily on these tools for initial cost
estimates, but they also invest considerable effort to
continuously benchmark their estimates against actual purchases to identify
where manual adjustments may be needed.
These two
factors can often lead to cost growth for the commercial plant between
early-stage estimates and actual estimates obtained during the design phase by
contractors, eliminating most, if not all, of the perceived economic benefit of
the new process.
The other
cost growth comes from incorrect early-stage design. Omissions may result in
missed equipment, as discussed in some of the aforementioned examples.
CONTINUES
Jazayeri, B., Reacxion http://www.hydrocarbonprocessing.com/magazine/2016/october-2016/process-control-and-instrumentation/lessons-learned-in-commercial-scale-up-of-new-chemical-processes
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