compared to the operat- ing case, are summarised in Table 2 . The stabiliser sec- tion operated normally under the reduced pressure condi- tions, with the following key observations: • The top and bottom temper- atures of the stabiliser column were successfully maintained by adjusting the reboiler steam flow and reflux rate. • Steam consumption, as meas- ured through condensate flow, was reduced significantly from 20 MT/h to 14.5 MT/h. The stabiliser section con- tinued to operate stably at the reduced pressure of 18 kg/cm²(g) and average tem- peratures (top: 78°C, bottom: 193°C) set during the demon- stration run. This resulted in a consistent steam saving of approximately 5.5 MT/h, as shown in Figures 5 and 6 .
Stabiliser section operating conditions
Parameter
Operating case
Low pressure case
Demonstration run
(model)
(plant)
Stabiliser top pressure, kg/cm²(g)
20.2
18.0
18.2
Stabiliser top temp, °C Stabiliser bottom temp, °C
88
76
75-78
201 58.4
189 56.2
190-194
Reflux rate, m3/hr
53.0 14.5
Stabiliser reboiler steam flow, MT/h
20
16
Fuel gas flow, Nm3/h
2,100
2,230
2,200
Table 2
20.5
24.0
Stabiliser top pressure
Steam f low rate
21.0
20.0
18.0
Steam saving ~5.5 MT/h
15.0
19.5
12.0
19.0
9.0
6.0
18.5
3.0
Further analysis confirmed that all product streams met the required quality specifica - tions at the reduced pressure of 18 kg/cm²(g). No detectable HCl was present in the stabi- liser bottom stream, and LPG composition remained within all required limits. Conclusion This study demonstrates that significant energy effi - ciency improvements in refinery column operations can be achieved through optimisation of operating parameters prior to capital-intensive equipment modifications. Using 0.0
Before demonstration run 18.0
After demonstration run
Figure 5 Stabiliser pressure profile
steps. The reboiler (E-01) duty was adjusted to maintain the top and bottom temperatures of the column at the model-predicted values of 76°C and 189°C, respectively. Reflux flow was tuned as required to stabilise the col - umn operation. Samples of FG, LPG, and stabiliser bot- tom streams were collected before and after the pressure reduction for compositional analysis. The key operating parameters during the demonstration run at 18 kg/cm²(g),
an ISOM stabiliser column as a case study, a structured meth- odology was applied, integrat- ing detailed process simulation (in Aspen HYSYS), tray-by-tray hydrodynamic validation, and controlled plant demonstration to evaluate reduced-pressure operation. Optimisation of the stabi- liser operating pressure from 20 to 18 kg/cm²(g) resulted in a sustained steam consump- tion reduction of 5.5 MT/h, corresponding to an energy efficiency improvement of approximately 27%, while maintaining product qual - ity specifications and stable
205
120
Stabiliser bottom temp
Stabiliser top temp
200
110
90
195
Average ~193˚C
80
190
Average ~78˚C
70
185
60
Before demonstration run 180
After demonstration run
Figure 6 Stabiliser temperature profile
82
PTQ Q2 2026
www.digitalrefining.com
Powered by FlippingBook