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Two Phase Separator Sizing - Horizontal (beta)
Step 1 - Input Process Conditions
Operating Pressure, Pg
psig
Atmospheric pressure, Pa
psia
Operating Temperature, Tf
deg.F
Standard volumetric flow of gas, Qgs
mmscfd
Molecular Weight of gas, MW
lb/lbmol
Compressibility Factor, Z
Viscosity of gas, mu_g
cP
Volumetric flow rate of liquid, Ql
ft3/min
Density of liquid, rho_l
lb/ft3
Viscosity of liquid, mu_l
cP
Mixed fluid density rho_m
lb/ft3
Calculated density of gas, rho_g
lb/ft3
Mass flow rate of gas, mg
lb/min
Actual volumetric flow rate of gas, Qg
ft3/min
Calculate1
Step 2 - Input Surge Times
Low Level Response time - LLLL to LLL, t1 (typ. 1-2 min)
min
Control Surge time - LLL to HLL, t3 (typ. 2-10 min, depending on application) - See Help
min
LLL to NLL, t2 (initial value - 50% of t3)
min
High Level Surge time - HLL to HHLL, t4 (typ. 1-2 min)
min
Total surge time (LLLL to HHLL), ts (ts = t1 + t3 + t4)
min
Liquid retention time (Bottom to NLL), t5 (t5 = t1 + t2)
min
Calculate2
Step 3 - Calculate inside diameter / length
Select Length over diameter ratio, L/D (range 1.5 to 6, typical-3)
Ratio of total surge volume (LLLL to HHLL) to total volume, Vr
(typ 0.6)
Calculate inside diameter of vessel, Di_calc_in
in
Calculated inside diameter of vessel, Di_calc
ft
Calculated length of vessel, Lcalc (seam to seam or tan to tan)
ft
Calculate3
Step 4 - Select vessel length / diameter
Selected inside diameter of vessel, Di_in
in
Selected inside diameter of vessel, Di
ft
Selected length of vessel, L (seam to seam or tan to tan)
ft
Calculate4
Step 5 - Set Levels
Liquid Levels
Bottom to LLLL, h1 (min 12 in)
in
LLLL to LLL, h2 (min 4 in)
in
LLL to NLL, h3 (min 6 in)
in
NLL to HLL, h4
in
HLL to HHLL, h5
in
Vapor Space
Vapor space, Hv
in
Recommended vapor space, Hvr (Larger of 0.2*D or 2 ft)
in
Verify1 (Hv >= Hvr) :
HHLL to vertical meshpad, h6 (minimum 1 ft)
in
Cumulative Levels from bottom and heights
LLLL, ht1
in
LLL, ht2
in
NLL, ht3
in
HLL, ht4
in
HHLL, ht5
in
Bottom of vertical meshpad, ht6
in
Total inside height, ht
in
Vessel Inside diameter, Di_in
in
Verify2 (ht == Din) :
Calculate5
Step 6 - Verify Levels
LLLL to LLL
LLLL to LLL, h2
in
Actual volume of liquid from LLLL to LLL, V1
ft3
Required retention volume of liquid, Vr1
ft3
Verify3, compare the two volumes :
LLL to NLL
LLL to NLL, h3
in
Actual volume of liquid from LLL to NLL, V2
ft3
Required retention volume of liquid, Vr2
ft3
Verify4, compare the two volumes :
LLL to HLL
LLL to HLL, h7
in
Actual volume of liquid from LLL to HLL, V3
ft3
Required retention volume of liquid, Vr3
ft3
Verify5, compare the two volumes :
HLL to HHLL
HLL to HHLL, h5
in
Actual volume of liquid from HLL to HHLL, V4
ft3
Required retention volume of liquid, Vr4
ft3
Verify6, compare the two volumes :
Bottom to NLL
Bottom to NLL, ht3
in
Actual volume of liquid from Bottom to NLL, V5
ft3
Required retention volume of liquid, Vr5
ft3
Verify7, compare the two volumes :
Calculate6
Step 7 - Verify vapour velocity
Selected base K value, Kb (typ value: 0.4 to 0.45)
ft/s
K value adjusted for vessel length, Kadj
ft/s
Calculated particle terminal velocity, Vmax
ft/s
Actual vapour velocity, Vact
ft/s
Verify8 (Vact <= Vmax) :
Liquid dropout time, td
s
Minimum Length reqd for vap-liquid disengagement, Ld
ft
Length considered for separation, Lset (eg, (2/3) of L)
ft
Verify9 (Ld <= Lset) :
Calculate7
Step 8 - Settling of liquid particles (200 micron bubble) in gas phase
Vapour velocity in horizontal direction, Vh ( Vh = Vact )
ft/s
Settling height, Hset (Hset = Hv / 12)
ft
Effective gravity settling length, Lset
ft
Terminal velocity, Vt
ft/s
Velocity during settling, Vset
ft/s
Verify10 (Vh <= Vset)
Calculate8
Step 9 - Calculate meshpad area
Selected K value, Ksv (typ 0.35 for vertical flow thru mesh)
ft/s
K value after de-rating for pressure, Kv
ft/s
Calculate area of mesh, Acalc_m
ft2
Length / Width of a square mesh pad, DimSQ_m
ft
Height of meshpad above HHLL, h6 (minimum 1 ft
in
Calculate9
Step 10 - Check Inlet Velocity Head
Nozzle Pipe Nominal Size and Schedule
Selected Pipe Outside Diameter, NDo1
in
Selected Pipe Nominal Wall Thickness, Tn1
in
Selected Pipe Inside Diameter, NDi1
in
Inlet Velocity, Vin
ft/s
Gas velocity head, J1
lb/(ft*s2)
Gas velocity head limit, J1_Limit (See Help)
lb/(ft*s2)
Verify11 (Vl <= Vt):)
in
Calculate10
Step 11 - Check Outlet Velocity Head
Nozzle Pipe Nominal Size and Schedule
Selected Pipe Outside Diameter, NDo2
in
Selected Pipe Nominal Wall Thickness, Tn2
in
Selected Pipe Inside Diameter, NDi2
in
Outlet Velocity, Vout
ft/s
Gas velocity head, J2
lb/(ft*s2)
Gas velocity head limit, J2_Limit (See Help)
lb/(ft*s2)
Verify12 (J2 <= J2_Limit):
in
Calculate11
Step 12 - Final Design
Diameter/Length of the vessel
Selected inside diameter, Di
ft
Selected inside diameter, Di_in
in
Total Vessel Length (Seam to Seam) or (tan to tan), L
in
Cumulative levels from the I/S bottom and heights
Low low liquid level (LLLL), ht1
in
Low liquid level (LLL), ht2
in
Normal liquid level (NLL), ht3
ft/s
High liquid level (HLL), ht4
in
High high liquid level (HHLL), ht5
in
Mist eliminator bottom, ht6
in
HHLL to I/S top of vessel (vapour space), Hv
in
Retention Volume and Retention Time
Vessel Bottom to NLL, ht3
in
Retention Volume (vessel bottom to NLL), V5
ft3
Retention time, tr
min
Calculate12
Sketch
Help
General Notes:
Note: Refer to the "Terms and Conditions" in the 'About' section before using the software.
1) Two Phase Horizontal Separator Sizing is a software program that can be used to size 2 phase horizontal liquid / vapour (gas) separators.
2) The procedure is based on Chapter 7 - Separation Equipment, presented in GPSA 14th edition.
3) The separator in consideration is assumed to be equipped with a mist extractor. The software is not designed and hence should not be used for other types such as vane type separators. Heads on either ends of the shell are not considered for volume calculations such as surge volumes, retention volumes etc., for the sake of simplicity.
4) The user needs to select / fill in relevant input data under Step1' and then click 'Calculate1' button so the program calculates the relevant parameters. The user then needs to fill in relevant data under 'Step2' and click 'Calculate2' button and so on. The procedure needs to be followed sequentially. When an update to any input is made, the procedure needs to be followed sequentially again by clicking the buttons in sequence, so the calculations are updated under each step.
5) Typical control surge times (LLL to HLL) for liquids for various types of separator vessels are as below.
Compressor Drum : 2 minutes
Flash Drum : 2 - 5 minutes
Reflux Drum: 5 minutes on product plus reflux
Surge Drum upstream of a Tower: 5-10 minutes
Surge Drum upstream of a Fired heat: 10 minutes
Net Product to Storage: 5 minutes
Refrigeration Accumulator: 5 minutes, or based on system or storage requirements
Refrigeration Economizer: 3 minutes
Heat Medium Surge Drum: Maximum liquid expansion, based on 25% to 75% full
6) Typical retention times (empty to NLL) for liquids for various types of separator vessels as as below.
Amine Flash Drum : 5 - 10 minutes, depending on presence of hydrocarbons
Glycol Flash Drum : 10 - 20 minutes, depending on presence of hydrocarbons
Cold Separator: Gas / NGL / Ethylene Glycol : 15 - 30 minutes, depending on internals
7) Suggested mixed phase velocity head range for the inlet nozzle, J_Limit
Diffuser distributor: 4,000 - 6,000 max lb/ft • sec2
No inlet distributor : 650 - 1,500 max lb/ft • sec²
Inlet half pipe or elbow distributor: 1,000 - 2,500 max lb/ft • sec2
V-baffle or other simple invert diverter designs: 1,000 - 2,500 max lb/ft sec2
Cyclonic inlet device: upto 10,000 lb/ft • sec2
Suggested outlet velocity head range, J_Limit: 3000 - 3600 max lb/ft • sec2
8) All numbers / amounts need to be entered without commas or $ sign. Empty boxes, non-numerical values are not allowed where numbers are expected.
9) Please provide any constructive feedback so we can improve the quality of the software.