University of Delaware
Office of Public Relations
UpDate - Vol. 16, No. 24, March 20


              Software improves refinery reaction process

     Boosting the octane number of gasoline just got easier,
thanks to new software that lets engineers and scientists
build a model of the naphtha reforming process in hours,
rather than months, UD researchers reported March 13 in
Houston during the American Institute of Chemical Engineers
(AIChE) meeting.
     Refineries depend on the complex process of catalytic
reforming to increase the octane number of gasoline, which
determines how well the fuel resists "knocking" during
combustion, explained Michael T. Klein, Elizabeth Inez
Kelley Professor of Chemical Engineering.
     Modeling the catalytic reforming process-and predicting
the effect of changes such as using a new feedstock-has
traditionally been a tedious, time-consuming task involving
intricate reaction models optimized only for a limited set
of circumstances, according to Klein and graduate student
Prasanna V. Joshi.
     The new model-building software, developed with support
from the refinery technology company UOP, headquartered in
Des Plaines, Ill., now makes it possible to generate a
simulated version of reforming scenarios, given basic data
inputs, in as few as 100 CPU seconds-"roughly the time it
takes to grab a cup of coffee," Klein said.
     "This software will let a research engineer or
scientist sit down and describe a particular reforming
situation by entering data into a computer, then let the
computer do the work while he or she works on another task,"
he added. "We can build a model in a day, instead of six
months."
     Senior Process Specialist Aronson "Ron" L. Huebner of
UOP said UD's NetGen reforming software should improve the
accuracy of reforming models, too. "This is a valuable tool
for scientists and engineers," he said. "Building a model of
such highly complex chemical systems can become an
overwhelming task when you're doing it manually. It takes
too long, and a large margin of error is inevitable."
     During the AIChE meeting, Joshi reported on NetGen
software for building models of UOP's continuous catalysis
regeneration reforming process. But, Klein's research team
also is developing software to help engineers and scientists
build models of various industrial processes, including
ethane pyrolysis; hydrocracking (breaking large hydrocarbon
molecules to generate useful fuels); naphtha pyrolysis and
gas-oil pyrolysis.
     Ultimately, Klein said, the group hopes to develop "a
generic model-building software, similar to popular
spreadsheet software used for accounting tasks, in terms of
its usefulness for tackling a broad range of problems."


Modeling 79 molecules and 464 reactions
     Operating on an IBM RISC 6000 workstation, the NetGen
reforming software contains numerical "fingerprints" of 79
molecules involved in the reforming process, Joshi said. The
molecules fall within four general categories: paraffins
(straight-chain type molecules), naphthenes featuring a five-
membered ring structure; naphthenes with six-membered rings
and aromatics. The reforming software also simulates 464
reactions, within seven reaction families: metal cracking,
acid cracking, paraffin isomerization, dehydrocyclization,
dehydrogenation, naphthene isomerization and dealkylation.
     A key to the software, Joshi said, is that it results
in a "kinetic" model, meaning that it "keeps track of the
rate of change of all these different compounds in the
mixture, while you're reforming or reconfiguring the
molecules."
     How does the NetGen reforming software work? First,
molecules are displayed on the computer screen as a series
of numbers describing the structure of each molecule. For
example, the numerical fingerprint for water shows that it
contains three atoms: an oxygen and two hydrogens, which are
linked to the oxygen by a single bond.
     Next, the software identifies the species of molecules
involved in the reaction process. Different molecules
trigger different reactions, Joshi noted, depending on
whether the molecules are paraffins, naphthenes or
aromatics. Algorithms built into the software then "take a
shortcut," he said, "revealing the initial molecules and the
product of the reactions, as well as the intermediate
products." Finally, the computer generates a model of the
process, including reactions, products and the changing
rates of each product.
     "This model builder lets you see the consequences of
changes," Joshi said. "It's like doing an experiment on the
computer, with no waste and no risk."
     Though the NetGen reforming software dramatically
simplifies the model-building process, Klein said, it
requires some technical expertise.
     The research team currently is working on a more user-
friendly version of the software. "We plan to put all of
this in a user-friendly package, with icons and easy-to-use
menus," he said.
                                          -Ginger Pinholster