Sawsan311
Chemical
- Jun 21, 2019
- 303
Dear All,
GPSA is referring to a self venting design of liquid outlet nozzle to prevent gas carry under with a maximum of 1 vol% specially when a downstream pumping system is there. I understand that the prevention of gas carry under is not only pertaining when we have pump downstream, it is also to prevent the erosion induced by the gas carried down to the downstream.
In setting the lowest liquid level LALL in the vessel, do we have to always check against the Froude criteria to be < 0.31 as per GPSA. wouldn't this be too conservative? and what about the credit of vortex breakers? will maintaining the velocity through the nozzle at 1 m/s is sufficiently safe to prevent the gas carry under and hence self-venting check of the nozzle is not required ?
Additionally, I am interested to know if having a raised vortex breaker intruding inside the vessel would mandate a higher setting of the LALL , what should be the criteria? Additionally, when do we decide to elevate the vortex breaker ? is it for flushing purposes when we have a slurry stream and we need the circulation inside the vessel...? also in case there is no weir for a L/L separator.. do we need to elevate the vortex on the light liquid phase with a specific standpipe height in order to prevent short-circuiting of the water heavy phase into the light phase outlet nozzle??
Thanks
Regards,
GPSA is referring to a self venting design of liquid outlet nozzle to prevent gas carry under with a maximum of 1 vol% specially when a downstream pumping system is there. I understand that the prevention of gas carry under is not only pertaining when we have pump downstream, it is also to prevent the erosion induced by the gas carried down to the downstream.
In setting the lowest liquid level LALL in the vessel, do we have to always check against the Froude criteria to be < 0.31 as per GPSA. wouldn't this be too conservative? and what about the credit of vortex breakers? will maintaining the velocity through the nozzle at 1 m/s is sufficiently safe to prevent the gas carry under and hence self-venting check of the nozzle is not required ?
Additionally, I am interested to know if having a raised vortex breaker intruding inside the vessel would mandate a higher setting of the LALL , what should be the criteria? Additionally, when do we decide to elevate the vortex breaker ? is it for flushing purposes when we have a slurry stream and we need the circulation inside the vessel...? also in case there is no weir for a L/L separator.. do we need to elevate the vortex on the light liquid phase with a specific standpipe height in order to prevent short-circuiting of the water heavy phase into the light phase outlet nozzle??
Thanks
Regards,
