Modeling of Crude Distillation Unit

Modeling of CDU is today the foundation to almost any operation including design,
control, planning and retrofitting of the refinery plant. The purpose of this project is
to develop Rigorous model of Crude Distillation Unit (CDU) and also to study the
dynamic behavior of the model. In other to develop more accurate model, linearized
Francis Weir formula is selected to model liquid flow dynamic. Beside Francis Weir,
two different assumptions are studied to improve the model, which are constant molar
flow and non-constant flow. In constant molar flow model, the column is assumed to
be constant pressure so the vapor flow for each stage is the same and therefore the
energy equations is neglected. Since the dynamic model can be subjected to
disturbance and used for over a wide pressure, the assumption is not accurate and
therefore non constant molar flow assumption is important. The scope of work in this
project is firstly to perform Rigorous modeling for CDU where mass, energy balance,
equilibrium relation and Francis Weir formula where all the equations are developed.
Then, in other to get input properties for the model, process modeling simulator,
ASPEN HYSYS is used to simulate CDU. The famous computer algebra, MATLAB is
used to solve the dynamic rigorous model simultaneously. Lastly, the results of the
model dynamic behavior will be studied. In this report, only constant molar flow model
is solved and discussed where non constant molar flow is only discussed in Literature
Review and Methodology due to its complexity and also time constrain.
This report consists of 5 main chapters; the I'' chapter which is Introduction briefly
explains the problem statement, objectives of research, the scope works and work flow
of FYP I and also the Gantt chart. The 2"d chapter which is Literature Review covers
the background of Crude Distillation Unit (CDU) and also the theory of distillation to
model the CDU. The 3'd chapter which is Methodology will explain the steps on how to
develop mathematical modeling, how to determine the inputs from HYSYS and also
how to do MA TLAB computational. The 41
h chapter is Results and Discussion which all
the results from MA TLAB computational is shown and analyzed. The last chapter
consists of Conclusion and Future Recommendation.