LECTURE NINE
054410 PLANT DESIGN
054410 Plant Design
LECTURE 9:
SEPARATION TOWER DESIGN
Daniel R. Lewin
Department of Chemical Engineering
Technion, Haifa, Israel
Refs: Seider, Seader and Lewin (2004), Chapters 14 and 16
Seader and Henley “Separation Process Principles” (1998), Chaps. 6 and 7
Kister, “Distillation Design” (1992), Chaps. 6 and 7
9-1
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Lecture Objectives
After this lecture, you should be:
n Familiar with the constraints affecting the
performance of trayed distillation column.
o Able to estimate the efficiency of a trayed
distillation column
p Able to compute the optimal diameter of a trayed
distillation column.
q Able to define all of the dimensions of a distillation
column, including the minimum wall thickness.
For a review of distillation, see:
a) Multimedia section on HYSYS-Separations
b) http://lorien.ncl.ac.uk/ming/distil/distil0.htm
9-2
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
Distillation Column Design Overview
Steps involved:
n Selection of operating pressure, to allow the usage of
cooling water for condenser, if possible.
o Short-cut method used to estimate RR, number of
ideal stages, NT,I = NR,I + NS,I , and location of feed tray.
p Rigorous solution of material and energy balances to
meet the number of specifications = DOFs.
q Estimate tray efficiency, E0, and number of actual
trays: NR,A = NR,I E0 and NS,A = NS,I E0
r Estimate tower height, diameter, and wall thickness.
It is assumed that you are familiar with steps n, o and
p. This lecture focuses on steps q and r.
9-3
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Focus of this lecture…
The focus of this lecture
is on the additional details
required to permit the
mechanical design of
multicomponent
separation
towers.
9-4
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
n A Look Inside a Distillation Column
Liquid
a
Outlet weir
a
a
a
Active tray area
Downcomer
Vapor
9-5
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
n Bubble-caps, Valves or Sieves…
Bubble-cap tray
Bubble-caps
Valves
Sieves
Relative cost
2.0
1.2
1.0
Pressure drop
Highest
Intermediate
Lowest
Efficiency
Highest
Highest
Lowest
Vapor capacity
Lowest
Highest
Highest
5
4
2
Typical turndown ratio
9-6
3
Sieve tray
Valve tray
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
n Bubble-caps, Valves or Sieves…
Bubble-cap tray
9-7
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
n Bubble-caps, Valves or Sieves…
Valve tray
9-8
4
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
n Bubble-caps, Valves or Sieves…
Sieve tray
9-9
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
n Tray Performance Constraints
Adverse vapor/liquid flow conditions can
cause:
 Foaming
 Entrainment
 Flooding
 Weeping/dumping
 Downcomer
flooding
9 - 10
5
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
n Tray Performance Constraints
Foaming
 Foaming refers to the expansion of liquid due to
passage of vapor or gas, caused by high vapor flow
rates.
 Although it provides high
interfacial liquid-vapor contact,
excessive foaming often leads to
liquid buildup on trays. In some
cases, foaming may be so bad
that the foam mixes with liquid
on the tray above.
 Whatever the cause, separation
efficiency is always reduced.
9 - 11
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
n Tray Performance Constraints
Entrainment
 Caused by excessively high vapor flow rates.
 Entrainment refers to the liquid carried by vapor to
the tray above.
 It is detrimental
because tray
efficiency is reduced:
lower volatile material
is carried to a plate
holding liquid of
higher volatility.
 Excessive entrainment
can lead to flooding.
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
n Tray Performance Constraints
Flooding
 Flooding is brought about by excessive vapor flow,
causing liquid to be entrained in the vapor up the
column.
 The increased pressure from excessive vapor also
backs up the liquid in the downcomer, causing an
increase in liquid holdup on the plate above.
 Depending on the degree of flooding, the maximum
capacity of the column may be severely reduced.
 Flooding is detected by sharp increases in column
differential pressure and significant decrease in
separation efficiency.
9 - 13
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
n Tray Performance Constraints
Weeping/Dumping
 Caused by excessively low vapor flow.
 The pressure exerted by the vapor is insufficient to
hold up the liquid on the tray. Therefore, liquid starts
to leak through perforations.
 Excessive weeping will lead to dumping - the liquid on
all trays will crash (dump) through to the base of the
column (via a domino effect) and the column will have
to be re-started.
 Weeping is indicated by a sharp pressure drop in the
column and reduced separation efficiency.
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
n Tray Performance Constraints
Downcomer Flooding
 Caused by excessively high liquid flow and/or a
mismatch between the liquid flow rate and the
downcomer area.
 This can be avoided by ensuring that the downcomer
back-up (level) is below 50% of the tray spacing. This
can be checked by performing tray sizing using a
process simulator.
 If necessary, design multipass trays (see later).
9 - 15
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
o Tray Efficiency Estimation
 The actual number of trays required for a particular
separation duty is determined by the efficiency of
the plate.
 Any factors that cause a decrease in tray efficiency
will also change the performance of the column.
 Tray efficiencies are affected by fouling, wear and
tear and corrosion, and the rates at which these
occur depends on the properties of the liquids being
processed. Thus appropriate materials should be
specified for tray construction.
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
o Empirical Efficiency Estimation
O’Connell correlation: EO = 0.492 ( µL α )
−0.245
± 10%
µ L = viscosity
⎫⎪
α = relative volatility ⎬ at average column conditions
of key component ⎪⎭
9 - 17
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Example 1: Tray Efficiency Calculation
Estimate the tray efficiency for the simulated column shown in
the table below.
α LH = 1.945
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
Example 1: Tray Efficiency Calculation
Solution.
The average column temperature is (70 + 309)/2 = 190 oF.
The closest match to this temperature is at stage 8, at which
the viscosity is 0.133 cP (note that the viscosity does not
change all that much over the entire column).
Hence, EO = 0.492 ( µL α )
−0.245
= 0.492 ( 0.133 × 1.945 )
−0.245
= 0.69
Given that the estimate is subject to ±10% error, a reasonable
estimate would be 0.62. Thus, the total number of trays will be:
⎧29 × 7 18 = 11 trays in the rectifying section
18/0.62 = 29 trays ⎨
⎩29 × 11 18 = 18 trays in the stripping section
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
p Tray Section Capacity
Defining column diameter.
 Most of the factors that affect column operation
are due to vapor flow conditions: either excessive or
too low.
 Vapor flow velocity is dependent on column diameter.
Weeping determines the minimum vapor flow
required while flooding determines the maximum
vapor flow allowed, hence column capacity.
 If the column diameter is not sized properly, the
column will not perform well. Not only will operational
problems occur, the desired separation duties may
not be achieved.
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
p Estimating Flooding Velocity
The flooding velocity is computed based on a force balance on
a suspended liquid droplet. This is the critical velocity at which
liquid droplets become suspended, a result of a perfect
balance between gravitational, buoyant and drag forces
(Sounders and Brown, 1934):
drag
( )
πd 3
ρL 6p g
gravity
( )
( )
πd 2
πd 3
u2
− ρG 6p g − CD 4p f ρG = 0
2 buoyancy
buoyancy
drag
Solving for flooding velocity:
12
⎛ ρL − ρG ⎞
⎟
⎝ ρG ⎠
uf = C ⎜
9 - 21
gravity
⎛ 4d p g ⎞
where C = ⎜
⎟
⎝ 3CD ⎠
PLANT DESIGN - Daniel R. Lewin
uf
Separation Tower Design
p Estimating Flooding Velocity
In practice, C is treated as an empirical parameter determined
using experimental data.
C = C SB FST FF FHA
where CSB is an empirical function of the ratio:
FLG = ( L G ) ρG ρL
and FST = ( σ 20 )
0.2
, σ = liquid surface tension [dyne/cm]
⎧1, for non-foaming systems
⎪⎪(e.g., most distillation applications)
FF = ⎨
⎪0.5-0.75, for foaming systems
⎪⎩ (e.g., absorption with heavy oils.
1, for Ah Aa ≥ 0.1
⎧
FHA = ⎨
⎩5 ( Ah Aa ) + 0.5, for 0.06 ≤ Ah Aa < 0.1
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
p Estimating Flooding Velocity
12
⎛ ρL − ρG ⎞
⎟
⎝ ρG ⎠
uf = C SB ( σ 20 ) FF FHA ⎜
0.2
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
p Tray Section Capacity
Tower inside cross-sectional area, AT, is computed at a
fraction f (typically 0.75-0.85) of the vapor flooding
velocity, uf :
G = (fuf ) (AT − Ad ) ρG
(14.10)
Substituting AT = π (DT ) 4 into Eq.(14.10) and solving
2
for DT :
⎡
4G
DT = ⎢
⎢⎣ (fuf ) π (1 − Ad AT ) ρG
⎧0.1 ,
⎪
(F − 0.1) ,
Ad ⎪
= ⎨0.1 + LG
AT ⎪
9
⎪⎩0.2 ,
9 - 24
12
⎤
⎥
⎥⎦
1/2
(14.11)
FLG ≤ 0.1
⎫
⎪
⎪
0.1 ≤ FLG ≤ 1.0 ⎬ FLG = ( L G ) ρG ρL
⎪
FLG ≥ 1.0
⎪⎭
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
p Selection of Multipass Trays
9 - 25
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Example 2: Tray Diameter Calculation
Compute the diameter of a valved-distillation column with the
following data - Liquid phase: = 7.1 dyne/cm, L = 215,000 lb/hr,
ρL =32.4 lb/ft3, Vapor phase: G = 244,000 lb/hr, ρG =1.095 lb/ft3.
Solution.
FLG = (215,000/244,000)(1.095/32.4)0.5 = 0.162
9-23 , for 24” tray spacing, CSB = 0.09 m/s
From Slide
slide 9-23
FF = 1 (no foaming), FHA = 1 (valves), so:
32.24 − 1.095
= 0.39 m/s = 4,610 ft/hr
1.095
− 0.1 ) 9 = 0.107. Assuming operation at 80% flooding:
Uf = 0.09 ( 7.1 20 )
Ad AT = 0.1 + (FLG
0.2
(1 )(1 )
1/2
⎡
⎤
4 (244, 000 )
DT = ⎢
⎥ = 9.3 ft
⎣ 0.8 ( 4, 610 ) π (1 − 0.107 ) 1.095 ⎦
Note: (a) In general, diameters in rectifier and stripper may differ.
(b) If DT < 2 ft, use a packed column.
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
Example 2: Tray Diameter Calculation
For this large diameter column, we should consider installing a
multipass tray. Recall from data: L = 215,000 lb/hr and ρL =32.4 lb/ft3
= 4.33 lb/gal
Volumetric flow rate = (215,000/60 ) / 4.33 = 828 gpm
9.3
828
9 - 27
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Example 3: Tray Diameter Calculation
Compute the tray diameter for the simulated column shown in
9-18 . Assume valve trays and light
the table on Slide
slide 9-18
hydrocarbon service. FF = 1 (no foaming), FHA = 1 (valves)
Solution.
The first thing we need to do is to identify the critical tray in
both the rectifier and stripping sections, defined as the trays
in which the loads for each section are maximized.
Rectifier Section - based on Stage 3
Stripper Section - based on stage 19
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
Example 3: Tray Diameter Calculation
Rectifier Section (based on Stage 3).
FLG = (85,360/121,184)(2.478/27.944)0.5 = 0.2098
Uf = 0.21 (3.3 20 )
0.2
(1 )(1 )
27.979 − 2.478
= 0.47 m/s = 5,551 ft/hr
2.478
Ad AT = 0.1 + (FLG − 0.1 ) 9 = 0.112. Assuming operation at 80% flooding:
1/2
⎡
⎤
4 (121,184 )
DT,R = ⎢
⎥ = 3.97 ft
⎣ 0.8 ( 5, 551 ) π (1 − 0.112 ) 2.478 ⎦
Stripper Section (based on stage 19).
FLG = (185,434/129,112)(3.614/27.191)0.5 = 0.5236
Uf = 0.16 (2.84 20 )
0.2
27.191 − 3.614
= 0.277 m/s = 3,272 ft/hr
3.614
1/2
⎡
⎤
4 (129,112 )
=⎢
⎥ = 5.40 ft
⎣ 0.8 (3,272 ) π (1 − 0.117 ) 3.614 ⎦
(1 )(1 )
Ad AT = 0.147. Hence, DT,S
Since the difference more than 20%, note that the rectifier diameter is
4 ft
and the
stripper
is 5.5 ft (to nearest ½’).
9 - 29
PLANT
DESIGN - diameter
Daniel R. Lewin
Separation Tower Design
p Estimating Column Pressure Drop
Typically, tray pressure drop for flow of vapor in a tower
is between 0.05-0.15 psi/tray.
For a sieve tray, the head
loss is due to the friction
for vapor flow through the
tray perforations, the
holduo of the liquid, and the
loss due to surface tension:
ht = hd + hA + hσ
ht = total pressure drop [in]
hd = dry tray pressure drop [in]
hA = equivalent head on tray [in]
hσ = pressure drop due to s.t. [in]
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
p Estimating Column Pressure Drop
Dry sieve tray pressure drop is computed using a
modified orifice equation:
⎛ uo2 ⎞ ⎛ ρG ⎞
⎟
2 ⎟⎜
⎝ C o ⎠ ⎝ ρL ⎠
hd = 0.186 ⎜
u0 = hole velocity [ft/s]
C 0 − depends on percent hole area and the ratio of tray thickness
to hole diameter. Range: 0.65-0.85. Typical value: 0.73.
9 - 31
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
p Estimating Column Pressure Drop
Equivalent height of clear liquid holdup on tray:
23
⎡
⎛ q ⎞ ⎤
hA = φe ⎢hw + C ⎜ L ⎟ ⎥
⎢⎣
⎝ Lw φe ⎠ ⎥⎦
hw = weir height [in]
φe = effective relative froth density (ht. of clear liquid/froth height)
= exp ( −4.257KS0.91 )
⎛
12
ρG ⎞
⎟
⎝ ρL − ρG ⎠
= superficial vapor velocity [ft/s] based on active bubbling area, Aa
= AT − Ad
= weir length [in] (for Ad AT = 0.1, taken as 73% of DT )
= liquid flow rate across tray [gal/min]
= 0.362 + 0.317 exp ( −3.5hW )
KS = capacity parameter [ft/s] = ua ⎜
ua
Aa
LW
qL
C
9 - 32
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
p Estimating Column Pressure Drop
As the gas emerges from the tray perforations, the
bubbles must overcome surface tension. The pressure
drop due to the surface tension is given by the
difference between the pressure inside the bubble and
that due to the liquid:
6σ
hσ =
g ρLDB (max )
Generally, the maximum bubble diameter, DB(max), may be
taken as the tray hole diameter.
9 - 33
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Example 4: Estimating Tray ∆P
Estimate the tray vapor pressure drop for a 1m diameter
absorber equipped with sieve trays. Given: hw = 2”, DH = 3/16”
Liquid phase: σ = 70 dyne/cm, L = 2,883 kg/hr, ρL = 986 kg/m3
Vapor phase: G = 7,920 kg/hr, ρG = 1.92 kg/m3.
Solution.
At the bottom of the tower, vapor velocity based on the total
cross-sectional area of the tower is:
7, 920 3, 600
2
(1.92) π (1 )
4
= 1.46 m/s
For a 10% hole area, based on total cross-section of the tower:
1.46
u0 =
= 14.6 m/s = 47.9 ft/s
0.1
⎛ 47.92 ⎞ ⎛ 1.92 ⎞
Hence, hd = 0.186 ⎜
⎟ = 1.56"
2 ⎟⎜
⎝ 0.73 ⎠ ⎝ 986 ⎠
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
Example 4: Estimating Tray ∆P
Solution (cont’d).
Taking weir length as 73% of DT gives LW = 0.73 m = 28.7”
2, 883 60
= 12.9 gpm
986 × 0.003785
Liquid flow rate in gpm, qL =
Ad/AT = 0.1, Aa/AT = 0.9, so ua = 1.46/0.9 = 1.62 m/s = 5.32 ft/s.
⇒ KS = ua ( ρG
( ρL − ρG ) )
12
⇒ φe = exp ( −4.257KS
0.91
= 0.235 ft/s
) = 0.32
C = 0.362 + 0.317 exp ( −3.5hW ) = 0.362
23
Hence, hA = φe ⎡hw + C (qL ( Lw φe ) ) ⎤ = 0.67 "
⎣
⎦
9 - 35
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Example 4: Estimating Tray ∆P
Solution (cont’d).
Assuming DB(max) = DH = 3/16” = 0.00476 m
σ = 70 dynes/cm = 0.07 N/m = 0.07 kg/s2 and g = 9.8 m/s2
Hence, hσ =
6σ
g ρLDB (max )
= 0.000913 m = 0.36"
Thus, total head loss/tray, ht = hd + hA + hσ
= 1.56 + 0.67 + 0.36
= 2.59"
Recalling that ρL = 986 kg/m3 = 0.0356 lb/in3
Thus, the tray vapor pressure drop = htρL = 0.092 psi
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
q Complete Column Sizing
Disengagement
4 ft
Rectifying Section
2×Nr ft
Dr ft
Stripping Section
2×Ns ft
Ds ft
Skirt
≥ 10 ft
9 - 37
Sump
Maximum height of column = 175’, Maximum L/D ratio = 30
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
q ASME Pressure Vessel Code
In the absence of wind and earthquake conditions and
excluding vacuum operation:
12Pd ⋅ DI
Tp =
(16.60)
2 ⋅ S ⋅ E − 1.2 ⋅ Pd
Tp = wall thickness [in] to withstand internal pressure
Pd = internal design pressure [psig]
DI = inside shell diameter [ft]
S = maximum allowable stress at design temp. [psig]
E = weld integrity (E = 0.85 for wall thicknesses < 1.25".
A value of 1 is used for thicknesses more than 1.25")
Conditions
S (psig)
CS SA-285, grade C
13,750
-20-750 oF with H2
1%Cr, 0.5%Mo Steel, SA-387B
15,000
to 800 oF with H2
1%Cr, 0.5%Mo Steel, SA-387B
14,750
oF
1%Cr, 0.5%Mo Steel, SA-387B
13,100
to 900
9 - 38
19
Recommended material
-20-650 oF no H2
with H2
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
q ASME Pressure Vessel Code
For vertical vessels, the vessel walls need to withstand wind
load, computed using:
0.22 (Do + 18 ) L2
Tw =
2
SDo
where Do is outside shell diameter (inches), L is vessel height
(tangent to tangent length, in inches), and the factor of 18
allows for the column cage ladders, which adds additional
effective diameter to the column.
When there is wind load, the girth seam must withstand the
combined load of the wind and the internal pressure, the latter
computed using:
12Pg DI
Tg =
2SE + 0.4Pg
An estimate for the required wall thickness at the bottom of
the tower is then: Tb = Tw + Tg
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
q ASME Pressure Vessel Code
To estimate the vessel thickness (assumed constant), use the
average of the top and bottom thicknesses, plus the corrosion
allowance, Tc, usually 0.125". Thus the values of wall thickness
are computed as follows:
HORIZONTAL VESSELS.
Ts =Tp +Tc
VERTICAL VESSELS.
Ts = 0.5 (Tb +Tp ) +Tc
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
q ASME Pressure Vessel Code
At low pressures, wall thickness computed using the above
equations may be too small to give sufficient rigidity to vessels.
The minimum wall thickness below should be used.
DI [ft]
Up to 4
4-6
6-8
8-10
10-12
Minimum value for tp [in]
1/4
5/16
3/8
7/16
1/2
Finally, the values computed need to be rounded up to the
nearest standard plate thickness, as given by the table below:
Ts up to [in]
1
2
3
>3
9 - 41
Rounding increment [in]
1/32
1/16
1/8
1/4
PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Example 5: Wall Thickness Calculation
Compute the wall thickness for a distillation column with height
175 ft and inside diameter 10 ft. The operating pressure is 110
psia and 150 oF at the bottom of the tower and 100 psia and
120 oF at the top. Material of construction is CS.
Solution. Design basis: Pd = 1.2×max P = 1.30×(110-14.7) = 123 psig
Td = max T + 50 oF = 200 oF.
Using Eq. (16.60) assuming CS shell:
120 × 123
Tp =
= 0.635"
2 × 13,750 × 0.85 − 1.2 × 123
The vessel thickness at the bottom of the tower is:
0.22 (10 × 12 + 18 ) 1752
123 × 10 × 12
Tb =
+
= 1.21"
2
13, 750 × 10
2 × 13, 750 × 1.0 + 0.4 × 123
(
)
Thus: Ts = 0.5 Tb +Tp +Tc = 0.5 (1.21 + 0.635 ) + 0.125 = 1.049"
Rounding up, this gives Ts = 1.0625” (1 1/16”)
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion
LECTURE NINE
054410 PLANT DESIGN
Summary
After reviewing the materials of this lecture, you
should be:
n Familiar with the constraints affecting the
performance of trayed distillation column.
o Able to estimate the efficiency of a trayed
distillation column.
p Able to compute the optimal diameter of a
trayed distillation column.
q Able to define all of the dimensions of a
distillation column, including the minimum wall
thickness.
9 - 43
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PLANT DESIGN - Daniel R. Lewin
Separation Tower Design
Daniel R. Lewin, Technion