Start Up of Propane Vaporizer
Start Up of Propane Vaporizer
(OP)
I was wondering in anyone has experience with the start up procedure of propane vaporizers. I have an issue with the heat load at start up. The vaporizer is for 25000 kg/hr super-heated propane @ 25 bar. LP steam is used as heat transfer input with condensate side control.
Start up load seems to be very load for this...Peak load is 4.5MW and start up has a very small load plus gas sent to flare.... How is it usually done?
Start up load seems to be very load for this...Peak load is 4.5MW and start up has a very small load plus gas sent to flare.... How is it usually done?





RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
What I am unsure about is how fast the vaporizer will built up pressure with the condensate side control system during startup.
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
Shouldnt there be a temp controller on the vaporiser exit that controls steam condensate level - how can you ensure the exit propane is at 100degC otherwise?
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
a) High set PC (set at say 27barg) on vaporiser exit to reset propane level LIC on the shellside. This LIC in turn resets the pump discharge PC set at approx 25barg.
b) Steam condensate level in condensate pot (and hence HX tubeside) is reset by vaporiser exit TC set at 100degC.
Since this is not a U tube HX, thermal stresses at startup need to kept at a minimum. Am guessing this propane is stored in a pressurised tank, and so propane temp is at ambient (15-25degC)?
An FF scheme may be possible for either one of the primary loops (a) or (b), but not both, if there is a flow feedback signal from vaporiser exit.
Does this match up with what you've got now ?
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
If the loops are configured properly and the steam condensate letdown valve(s) and the FT have adequate turndown, then there shouldnt be a problem with low load operation.
Agreed, the FF scheme would be better set up for the PC resetting propane level loop, since the turbine fuel gas supply pressure usually has a high pressure trip but not a high or low temp trip. Moreover, the bulk of the heating load would be for vaporising and less for superheating.
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
Agreed, for cases when a turbine trips, the controls may not react quickly enough to prevent overpressure on the supply to the turbines, due to the latent heat stored in the tube bundle metal mass - for this there should be a higher set PC to relieve excess pressure off to the flare header.
RE: Start Up of Propane Vaporizer
RE: Start Up of Propane Vaporizer
The level controller on the propane in the shellside could reset a level recycle valve around the pump (on a fixed speed pump) or reset pump speed on a VFD drive.