Sizing 2-phase Horizontal Vessel
Sizing 2-phase Horizontal Vessel
(OP)
Hi guys,
I want to size an horizontal Surge Vessel to handle 50,000 bopd.
The % height of the LSL, LAL, LAH, LSH has been given. There respective respective retention times required has been given.
How can i determine the diameter and length of the vessel?
I try using DEP but bit confuse!
Useful information is appreciated.
Regards,
I want to size an horizontal Surge Vessel to handle 50,000 bopd.
The % height of the LSL, LAL, LAH, LSH has been given. There respective respective retention times required has been given.
How can i determine the diameter and length of the vessel?
I try using DEP but bit confuse!
Useful information is appreciated.
Regards,





RE: Sizing 2-phase Horizontal Vessel
For a surge vessel, you must know the maximum volume of liquids that will be slugged from (usually a 2-phase pipeline or a predominately gas pipeline with liquid condensates or minor voumes of condensates and oils) pipeline into the surge vessel. That will depend on the ratio of gas to liquid flow and the hydraulic characteristics of your pipeline (see 2-Phase flow regimes).
For a separator, if your flow is 50 KBOPD, and your retention time is 2 days, you will need 50Kbbl/day x 2 days =100,000 bbl capacity to start up the separator, during which time all flow will be diverted and feed into the separator. You will open the outlet in 2 days. Once the separator is started up, you can continue operating it at a steady state. You will probably also require some degassing volume above the oil's surface, so account for a reasonable vapor space to allow for degassing that 50Kbopd, according to the gas to liquid production ratios you expect to have, gas drawoff rate and the allowable pressure of the tank.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Sizing 2-phase Horizontal Vessel
Worst case is all your pipes slugging at the same time. A less conservative approach is to reasonably assume that all pipes will not slug at the same time; so you take your best educated guess, document it, and therefore you can possibly reduce the size of your slug catcher.
A helpful simulation program might assist in determining how much liquid might reasonably develop in the pipes.
I'm talking from a midstream background here, so if some of this does not apply my apologies.
Onwards,
Matt
RE: Sizing 2-phase Horizontal Vessel
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Sizing 2-phase Horizontal Vessel
The information i need is to determine the diameter and length of the required vessel.
Thanks
RE: Sizing 2-phase Horizontal Vessel
Neither does a retention time given for various levels of a tank, even if the dimensions are known. (at least it dosn't mean anything to me).
Retention time should be dependent on the solids that must be settled, hence dependent on density of the solids, average or maximum diameter of the solids and the viscosity of the oil in which they are being transported.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Sizing 2-phase Horizontal Vessel
RE: Sizing 2-phase Horizontal Vessel
If its a surge vessel for a liquid line, you must do a hydraulic surge analysis to find out if releasing that volume from the pipeline into the tank during a surge event will keep the pipeline's pressure below the pipeline's maximum allowed operating pressure.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Sizing 2-phase Horizontal Vessel
May be you don't understand me.
The detail given to me by the client is to design a vessel that will handle a 50K bopd of crude per day.
The initial vessel is a rectangular tank, but they want to change it to horizontal vessel.
They propose the size i.e. 13'x40' and gives the reaction time btw the level switches.
All i wanted to do was to check if the proposed size is sufficient.
RE: Sizing 2-phase Horizontal Vessel
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Sizing 2-phase Horizontal Vessel
RE: Sizing 2-phase Horizontal Vessel
As you do not give detailed information, I will do my own calculation here.
1) According to DEP 31.22.05.11(You mean Shell's DEP,right?)
LSL : > 150 mm
LSL to LAL : > 100 mm or 60 seconds holdup for control room and 5 mins for outside intervention.
LAL to LAH : Should be calculated from retention time
LAH to LSH : > 100 mm or 60 seconds holdup for control room and 5 mins for outside intervention.
LSH to Top of Vessel(Vap. Compartment) : should be enough for v/l separation (In this calculation this was ignored, virtually no vapor flow...)
2) Given Dimension : 13' x 40' (3962mm x 12192mm, L/D = 3)
LSL : 150/3962 = 4%
LAL : 250/3962 = 6%
LAH : 3712/3962 = 94%
LHL : 3812/3962 = 96%
BTM to LSL Partial Volume : 1.858 m3
LSL to LAL Partial Volume : 2.109 m3
LAL to LAH Partial Volume : 142.378 m3
LAH to LSH Partial Volume : 2.109 m3
LSH to TOP Partial Volume : 1.858 m3
You can change the dimensions above applying % of height given by your client.
W/ above dimensions, holdup+surge volume(from LAL to LHL) is 142.4m3.
3) 50,000 BPSD = 50000*0.158988 /24/60 = 5.52m3/min
Therefore the retention time from LAL to LAH = 142.4/5.52 = 25.8 minutes. (Check with the holdup+surge time criteria given by client)
4) If there is a need for V/L Separation, LSH shall be checked based on other variables such as density etc.
Regards,
ifreeman
RE: Sizing 2-phase Horizontal Vessel
Best regards
Morten