Dear All,
This is regarding relief valve sizing for stabilizer column for its re-boiler tube rupture scenario.
due to rupture in tube side hot oil will enters into the tube and eventually in column bottom. Due to high temperature of hot oil, bottom fluid will evaporate and causes over pressurization due to direct contact with hotoil.
please refer attachment for schematic.
I have calculated relieving rate considering overhead system (condenser, reflux and distillate etc.) at its turn down capacity and re-boiler at design duty and vapor generated due to direct contact between hot oil and column bottom.
Relieving rate = vapor generated due to re-boiler design duty + vapor generated due to hot oil enters in column bottom - turn down capacity of column overhead system*
* = turn down capacity of column overhead system has been considered for conservative approach as per shell standard.
(I have done simulation for this case in Unisim, hot oil rate obtained from tube rupture calculation, enters at column bottom along with reboiler rated duty.)
Data:
Column operating/ design pressure: 8.7 / 11 bar g
Column relief valve set pressure: 11 barg
Reboiler data:
shell side:
Fluid: hot oil
inlet/outlet temp: 282°C / 160°C
operating / design pressure: 14 / 23 ba rg
tube side:
Fluid: column bottom
inlet/outlet temp: 130°C / 132°C
operating / design pressure: 9.2 / 12.5 barg
Kindly advise me whether my understanding is correct.
Thanks and Regards,
Arvind