Dynamic modelling of a Hydrocracker

Abstract

Different types of petroleum refining processes were considered to be modelled in the Kongsberg dynamic modelling software K-Spice. Multiple oil and gas processing units exist in the model library, which begs the question whether the software may be utilized on petroleum refining, potentially opening a new market for sales of dynamic models such as operator training simulators.

In a literature study, petroleum refining configurations were studied with aim to fit the models to currently available modules in the steady-state simulator Petro-SIM. A single reactor configuration for hydrocracking of naphtha was chosen to fit the model library.

Removal of hydrocarbon impurities was examined to avoid catalyst poisoning. Sulphur, nitrogen and oxygen trapped in the more complex hydrocarbons will release from cracking to lighter ones, easily separable after reacting with the excess hydrogen. This further strengthened the process choice, as advanced purification methods were not within the scope of this thesis.

The inlet stream was considered to be composed of petrochemical hypothetical components defined in MultiFlash, with lighter components flowing out of the reactor. Different equations of state were discussed to be used to model the hypothetical components. The Peng-Robinson equation of state was chosen, giving a high precision from the components binary interaction parameters.

Further improvements to the model are recommended, including a broader range of hypothetical components, better kinetic models in the K-Spice reactor module and temperature optimization on the reactor loop.