TWO-PHASE FLOW IN A FEED LINE
TWO-PHASE FLOW IN A FEED LINE
(OP)
HI FOLKS,
We are dealing with the following problem:
The line that feeds a Crude Unit, coming from a heating train,which is 100 m away from the tower, handles a mixed phase product (vapor/liquid).
The product leaving the heater is at 453 °F, and the tower pressure is 15 psig. The pipe that interconnects the heater with the tower is 42".
Is there any limitation and criteria (velocity, density x (velocity^2), location of the heater with respect to the tower, etc...)for this line to handle two phase flow? We have the understanding that it should not exceed 80% of the sonic flow, but have no other means to determine whether the line is sized correctly or not.
Any help is appreciated.
Regards,
ChemE2912
We are dealing with the following problem:
The line that feeds a Crude Unit, coming from a heating train,which is 100 m away from the tower, handles a mixed phase product (vapor/liquid).
The product leaving the heater is at 453 °F, and the tower pressure is 15 psig. The pipe that interconnects the heater with the tower is 42".
Is there any limitation and criteria (velocity, density x (velocity^2), location of the heater with respect to the tower, etc...)for this line to handle two phase flow? We have the understanding that it should not exceed 80% of the sonic flow, but have no other means to determine whether the line is sized correctly or not.
Any help is appreciated.
Regards,
ChemE2912





RE: TWO-PHASE FLOW IN A FEED LINE
I dont think that you can use 80% of sonic velocity for a 2 phase flow in a 42" line in a plant for anyting - you should be much lower.
This seems like complicated work. If you dont have sufficient inhouse knowledge try to look for a consultant. Dont expect to get more that "good advice" here (even though its often quite good - you dont get any liability
Best regards
Morten
RE: TWO-PHASE FLOW IN A FEED LINE
RE: TWO-PHASE FLOW IN A FEED LINE
Propably also what ChemE2912 meant (i mean erosinal - not sonic allthough i didnt see that at first.
Best regards
RE: TWO-PHASE FLOW IN A FEED LINE
1. Pressure drop is acceptable.
2. Flow regime should be in the stable phase, avoid slug flow where possible. Generally, this is related to velocity, the higher the velocity, the better you can avoid slug flow. Check the flow map. And this is also another reason why you would not want a liquid pocket along the line. It doesn't necessarily needs to be sloping, just no pocket will do.
3. Lower than erosinal velocity (but this is primarily for material integrity protection, and where solids or erosive material is present)
RE: TWO-PHASE FLOW IN A FEED LINE
Regards,
ChemE2912