GCC

GCC makes use of heat balance for quick identification of feedstock changes.  Large fractionators my work for hours off mass balance, accumulating liquid on trays, but heat balance must always be satisfied, (or else – the column would explode).  In terms of keeping the unit under control, even difficult crude switches are accomplished within one hour, and during the switch product qualities are kept constant. Furthermore, there is no need to feed any data whatsoever before crude switches. Detection of crude characteristics is completely automatic.

• Simple to calibrate.

GCC requires only a simple calibration procedure, which makes use of steady state data. The technique itself is robust enough to work without calibration, but given inaccuracies of flow, pressure and temperature measurements, precision improves after steady state calibration.

• Self tuned.

Commissioning does not require elaborate tuning procedures. The model will work instantly, and it helps that the inferential responses are quick with short delay times. 

• Easily understood.

The model follows standard API procedures for heat balance, temperature / pressure correction and EFV / TBP conversion.

• Reliable enough to replace distillation analyzers.

Inferential precision is for example 2ºF for 90 % Naphtha distillation point, or 5 ºF for 90 % Diesel distillation point.  That said, GCC can also work with analyzers, resetting a bias in the calculation via a dead time compensator.

• Able to manipulate all column cooling circuits.

Control of the cooling load distribution ensures fractionation in all sections of the column.

• Multi variable dynamic capability.

The inferential calculations integrate easily with MVC (multi variable control) packages available on the market.  Indeed, the majority of our GCC models work to create inferences, whereas control action is applied by MVCs.