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, UD's 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 Inc. of 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 Catalytic Regeneration, or CCR catalytic reforming process. But, Klein's research team is also 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); naptha 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 is currently 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.
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