Sunday, November 20, 2016

TECH SPECIAL........ Lessons learned in commercial scale-up of new chemical processes (5)

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

No comments: