Three Reaction Gibbs Reactor

[nrgeng]

I am using the data from the example flowsheet, Methanol_iecr49p6150, to advance my skill with COCO. In using the Gibbs Minimization Reactor with a new, separate flowsheet, the two reactions specified in the example run, but when I add a third reaction the Unit reports “...not in mass balance.” Using any paring of two reactions runs but adding the third reaction creates a Unit mass balance error. Is there a two-reaction limit for the Unit? Please help if you can.

[jasper]

Can you attach the fsd file, or send by e-mail?

[nrgeng]

Please check your e-mail for the fsd file. Thanks.

[jasper]

Thank you for reporting the problem.

The Gibbs reactor does not actually require a reaction package; it only performs equilibrium reactions and can derive pseudo reactions with pseudo stoichiometries from an element balance. It does not require equilibrium constants or reaction rates. More info on this particular reactor is given in

van Baten, J.M., Szczepanski, R., A thermodynamic equilibrium reactor model as a CAPE-OPEN unit operation, Computers and Chemical Engineering 35 (2011) 1251-1256

You can operate it with reactions from a reaction package (which was obviously buggy, and fixed now), in case for example elemental information is not available from the thermo, or in case EnthalpyF is not available and the reaction package therefore supplies heats of reaction.

In any case, the problem is now fixed and available via CUP. Thank you again for your feedback.

[jasper]

Correction - the Gibbs reactor does not actually function without both enthalpyF and entropyF (as it requires the Gibbs free energy including formation terms), so the only reason to run it from a reaction package really is if the reactor cannot perform the elemental balance if this info is not available.