Abstract:
Compressors play significant roles in the oil and gas industries. Compressors’ operating points
shift to the surge line during startup or emergency shutdown as the flow decreases. Surge causes
a compressor to lose the ability to maintain peak head, causes the system to overheat, reduces
discharge pressure, damages thrust bearing, and make the entire system unstable. This study aims
to evaluate compressor anti-surge control in emergence shutdown using Aspen HYSYS. Aspen
HYSYS Dynamics extends models into dynamic model enabling process verification control scheme,
design, safety studies, relief valve sizing and rating, failure analysis, development of a startup,
shutdown, and operational model changes. Extensive numerical and graphical results generated
from dynamic models in Aspen HYSYS allow for in-depth analysis for each completed simulation.
The study used dynamic simulation to confirm the recycling valve’s performance and computing
surge control scaling of a boil-off gas compressor. The study investigated further if the anti-surge
valve would open during operation, keeping the compressor from surging and testing compressor
procedure during startup and shutdown. Simulation results show that when the inlet gas flow
decreases, compressor speed increases and all anti-surge valves opened to keep the compressor
away from a surge. Finally, the paper reveals compressor performance, such as efficiency, surge
control line, compressor duty, control tuning parameters, and valve flow coefficient can be predicted
using Aspen HYSYS. Thus, the use of Dynamic simulation is a great and efficient design tool for the
centrifugal compressors system, and it is highly recommended. For the simulation result to reflect
what happens in the plant, it is recommended to select an appropriate thermodynamic method.
Improper selection of the thermodynamic model and plant data inconsistent will produce an absurd
result. For oil and gas applications, it is advised to use the Peng-Robinson equation of state. It
provides accurate results, an extensive applicability range in terms of temperature and pressure,
and has a comprehensive binary interaction parameter database.
