Dear All,
I have performed depressurisation calculation in TGnet software for a 32", 33 km buried gas pipeline operating at 90 bar (g) and depressurisation initial temperature is 20°C. The depressurisation time calculated in TGnet is 60 hours.
It is manual stage wise depressurisation performed by sequential opening of the valves/RO's after certain time intervals in such a way that the peak flow doesn't go above design flowrate of the existing vent stack.
I wanted to check whether there was hydrate formation during the depressurisation. So I plotted the graphs of TGnet depressurisation and Unisim hydrate formation together in an excel sheet.
The hydrate formation curve is pressure v/s temperature whilst the depressurisation curve is pressure/temperature v/s time. Hence, I have plotted the temperature/pressure points (at respective time) of depressurisation in the hydrate formation graph in an excel sheet and I see both the graphs intersecting each other. It means that there will be hydrate formation during the intial phase of depressurisation.
Please find the graph attached.
I wanted to know whether this is a correct method of checking hydrate formation during the depressurisation activity.
If yes, what are the other prevention measures against hydrate formation other than methanol injection.
Anyone has done similar activity and has any experience regarding this matter. Please share.
Regards,
Trupti