Heat Exchanger Data Book - archive.mu.ac.in heat_exchanger_databook Mechanical.pdf · University of...

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AC 26/02/2015 Item no. 4.66

Heat Exchanger Data BookCHC603 Heat Transfer Operation – II

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Contents

I Formulae, graphs and tables 1

1 Shell and Tube Heat Exchanger 31.1 Log Mean Temperature difference . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.1.1 Correction factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.2 Heat transfer through tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.3 Shell-side heat-transfer coefficient(Kern’s Method) . . . . . . . . . . . . . . . . 61.4 Bell’s method for HTC shell side . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.4.1 HTC cross flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.4.2 Fn, tube row correction factor . . . . . . . . . . . . . . . . . . . . . . . 71.4.3 Fw, window correction factor . . . . . . . . . . . . . . . . . . . . . . . . 71.4.4 Fb, bypass correction factor . . . . . . . . . . . . . . . . . . . . . . . . 81.4.5 FL, Leakage correction factor . . . . . . . . . . . . . . . . . . . . . . . 8

1.5 Pressure Drop in shell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81.5.1 Cross-flow zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81.5.2 ∆Pi ideal tube bank pressure drop . . . . . . . . . . . . . . . . . . . . 91.5.3 F ′b , bypass correction factor for pressure drop . . . . . . . . . . . . . . 91.5.4 F ′L, leakage factor for pressure drop . . . . . . . . . . . . . . . . . . . . 111.5.5 Window-zone pressure drop . . . . . . . . . . . . . . . . . . . . . . . . 111.5.6 End zone pressure drop . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.5.7 Total shell-side pressure drop . . . . . . . . . . . . . . . . . . . . . . . 141.5.8 Shell and bundle geometry . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.6 Wills-Johnston Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161.6.1 Streams and flow areas . . . . . . . . . . . . . . . . . . . . . . . . . . . 161.6.2 Flow resistances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171.6.3 Total shell-side pressure drop . . . . . . . . . . . . . . . . . . . . . . . 19

1.7 Fouling factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191.8 Tube data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2 Plate Heat Exchanger 212.1 Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212.2 Heat transfer coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

2.2.1 Number of Transfer Units (NTU) . . . . . . . . . . . . . . . . . . . . . 232.2.2 Correction factor, Ft . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.3 Pressure drop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232.3.1 Pressure drop in flow through plates . . . . . . . . . . . . . . . . . . . 232.3.2 Pressure drop in flow through port . . . . . . . . . . . . . . . . . . . . 24

2.4 Plate sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

iii

University of Mumbai CHC603 Heat Exchanger Data Book

3 Condenser Design 273.1 HTC in Vertical condenser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.2 HTC in Horizontal Condenser . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.3 Condensation with subcooling . . . . . . . . . . . . . . . . . . . . . . . . . . . 283.4 Condensation with desuperheating . . . . . . . . . . . . . . . . . . . . . . . . 283.5 Condensation in vertical tubes with vapour downflow . . . . . . . . . . . . . . 293.6 Condensation outside horizontal tubes . . . . . . . . . . . . . . . . . . . . . . 29

4 Reboiler Design 314.1 Nucleate Boiling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.1.1 The Forster-Zuber correlation . . . . . . . . . . . . . . . . . . . . . . . 314.1.2 The Mostinski correlation . . . . . . . . . . . . . . . . . . . . . . . . . 314.1.3 The Cooper correlation . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.1.4 The Stephan-Abdelsalam correlation . . . . . . . . . . . . . . . . . . . 324.1.5 Boiling mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334.1.6 Convective effects in tube bundles . . . . . . . . . . . . . . . . . . . . . 33

4.2 Critical heat flux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344.2.1 Mostinski correlation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

4.3 Two Phase Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354.3.1 Pressure drop correlations . . . . . . . . . . . . . . . . . . . . . . . . . 35

4.4 Convective Boiling in Tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374.4.1 Heat transfer coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . 374.4.2 Critical heat flux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

4.5 Film Boiling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384.5.1 Heat transfer coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . 38

4.6 Design equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.6.1 Number of nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.6.2 Shell diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.7 Frictional losses in pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.7.1 Friction factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.7.2 Pressure drop in pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404.7.3 Maximum gas/vapour velocity in tubes . . . . . . . . . . . . . . . . . . 404.7.4 Maximum velocity of liquids in tubes . . . . . . . . . . . . . . . . . . . 404.7.5 Maximum velocity of two-phase flow in tubes/pipe . . . . . . . . . . . 41

4.8 Design of Vertical Thermosyphon Reboiler . . . . . . . . . . . . . . . . . . . . 414.8.1 Pressure balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414.8.2 Sensible heating zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424.8.3 Mist flow limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

II Data Sheet 45

iv

Part I

Formulae, graphs and tables

1

Chapter 1

Shell and Tube Heat Exchanger

1.1 Log Mean Temperature difference

For counter current flow,

∆Tlm =(Thin − Tcout)− (Thout − Tcin)

ln

(Thin − TcoutThout − Tcin

) (1.1)

∆Tm = Ft∆Tlm (1.2)

1.1.1 Correction factor

For one shell pass and two or more even tube passes shell and tube heat exchanger,

Ft =

√(R2 + 1)ln

[1− S

1−RS

]

(R− 1) ln

2− S(R + 1−

√(R2 + 1)

)2− S

(R + 1 +

√(R2 + 1)

)

(1.3)

where,

R =Tin − Touttout − tin

(1.4)

S =tout − tinTin − tin

(1.5)

T = Shell side temperaturet = Tube side temperatureTh = hot fluid temperatureTc = cold fluid temperature

3


4


5


Figure 1.1: LMTD Correction factor (1 Shell pass; 3 tube passes)

1.2 Heat transfer through tubes

Seider-Tate and Hausen equations,

for Re ≥ 104

Nu = 0.023Re0.8Pr1/3(µ/µw)0.14 (1.6)

for 2100 < Re ≥ 104

Nu = 0.116[Re2/3 − 125

]Pr1/3(µ/µw)0.14

[1− (D/L)2/3

](1.7)

for Re ≤ 2100

Nu = 1.86 [RePr (D/L)]1/3 (µ/µw)0.14 (1.8)

1.3 Shell-side heat-transfer coefficient(Kern’s Method)

jH = 0.5 (1 + lB/Ds)(0.08Re0.6821 + 0.7Re0.1772

)(1.9)

where,

jH =hodek

Pr−1/3(µ/µw)−0.14 (1.10)

lB = baffle spacingDs = shell IDde = equivalent diameter

6


Re =Gsdeµ

(1.11)

Gs =ms

As(1.12)

As =(pt − do)DslB

pt(1.13)

for a square pitch arrangement:

de =1.27

do

(p2t − 0.785d2o

)(1.14)

for an equilateral triangular pitch arrangement:

de =1.10

do

(p2t − 0.917d2o

)(1.15)

1.4 Bell’s method for HTC shell side

hs = hocFnFwFbFL (1.16)

hoc = heat transfer coefficient calculated for cross-flow over an ideal tube bank,no leakage or bypassing.

Fn = correction factor to allow for the effect of the number of vertical tube rows,Fw = window effect correction factor,Fb = bypass stream correction factor,FL = leakage correction factor.

1.4.1 HTC cross flow

See section – (1.3)

hocdokf

= jHPr1/3

(µ

µw

)0.14

(1.17)

1.4.2 Fn, tube row correction factor

1. Re > 2000, turbulent; take Fn from Figure 12.32.

2. Re > 100 to 2000, transition region, take Fn = 1.0;

3. Re < 100, laminar region,Fn ∝ (N ′c)−0.18

where N ′c is the number of rows crossed in series from end to end of the shell.

1.4.3 Fw, window correction factor

The correction factor is shown in Figure 12.33 plotted versus Rw, the ratio of the number oftubes in the window zones to the total number in the bundle. For Rw refer section – 1.5.8

7


1.4.4 Fb, bypass correction factor

Fb = exp

[−αAb

As

(1−

(2Ns

Ncv

)1/3)]

(1.18)

where,

α = 1.5 for laminar flow, Re < 100,α = 1.35 for transitional and turbulent flow Re > 100,Ab = clearance area between the bundle and the shell, refer equation – (1.35),As = maximum area for cross-flow,Ns = number of sealing strips encountered by the bypass stream in the cross-flow zone,Ncv = the number of constrictions, tube rows, encountered in the cross-flow section.

1.4.5 FL, Leakage correction factor

FL = 1− βL[Atb + 2Asb

AL

](1.19)

where,

βL = a factor obtained from Figure 12.35,Atb = the tube to baffle clearance area, per baffle,Asb = shell-to-baffle clearance area, per baffle,AL = total leakage area = (Atb + Asb).

1.5 Pressure Drop in shell

1.5.1 Cross-flow zones

∆Pc = ∆PiF′bF′L (1.20)

8


1.5.2 ∆Pi ideal tube bank pressure drop

∆Pi = 8jtNcvρu2s2

(µ

µw

)−0.14(1.21)

where,

Ncv = number of tube rows crossed (in the cross-flow region),us = shell side velocity, based on the clearance area at the bundle equator,jt = friction factor obtained from Figure 12.36, at the appropriate Reynolds number,

Re = (ρusdo/µ).

1.5.3 F ′b , bypass correction factor for pressure drop

The correction factor is calculated from the equation used to calculate the bypass correctionfactor for heat transfer, equation – (1.18) but with the following values for the constant α,

where,

α = 5 for laminar flow, Re < 100,α = 4 for transitional and turbulent flow Re > 100

The correction factor for exchangers without sealing strips is shown in Figure 12.37.

9


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1.5.4 F ′L, leakage factor for pressure drop

The factor is calculated using the equation for the heat-transfer leakage-correction factor,with the values for the coefficient βL taken from Figure 12.38.

1.5.5 Window-zone pressure drop

∆Pw = F ′L (2 + 0.6Nwv)ρu2z2

(1.22)

where

uz = the geometric mean velocity, =√uwus

uw = the velocity in the window zone, based on the window area less the area occupiedby the tubes, uw = Ws

Awρ

Ws = shell-side fluid mass flow, kg/s,Nwv = number of restrictions for cross-flow in window zone, approximately equal to the

number of tube rows.

1.5.6 End zone pressure drop

∆Pe = ∆Pi

[Nwv +Ncv

Ncv

]F ′b (1.23)

11


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13


1.5.7 Total shell-side pressure drop

∆Ps = 2∆Pe + ∆Pc (Nb − 1) +Nb∆Pw (1.24)

where, Nb = LlB− 1

L = Total tube length,lB = baffle spacing

1.5.8 Shell and bundle geometry

Bundle diameter

Db = do

(Nt

K1

)1/n1

(1.25)

where

Nt = number of tubes,Db = bundle diameter, mm,do = tube outside diameter, mm.

Table 1.1: Constants for use in equation – 1.25

Triangular pitch, PT = 1.25do

No. of passes 1 2 4 6 8

K1 0.319 0.249 0.175 0.0743 0.0365

n1 2.142 2.207 2.285 2.499 2.675

Square pitch, PT = 1.25do

No. of passes 1 2 4 6 8

K1 0.215 0.156 0.158 0.0402 0.0331

n1 2.207 2.291 2.263 2.617 2.643

Hb =Db

2−Ds (0.5−Bc) (1.26)

Ncv =Db − 2Hb

p′t(1.27)

Nwv =Hb

p′t(1.28)

Hc= baffle cut height = Ds ×Bc, where Bc is the baffle cut as a fraction,Hb= height from the baffle chord to the top of the tube bundle,Bb= bundle cut = Hb/Db,θb = angle subtended by the baffle chord, rads,Db= bundle diameter.Ds= Shell ID.p′t = pt for square pitch,p′t = 0.87pt for equilateral triangular pitch.

14


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The number of tubes in a window zone Nw is given by:

Nw = Nt ×R′a (1.29)

where, R′a is the ratio of the bundle cross-sectional area in the window zone to the total bundlecross-sectional area, R′a can be obtained from Figure 12.41, for the appropriate bundle cut,Bb.

The number of tubes in a cross-flow zone Nc is given by

Nc = Nt − 2Nw (1.30)

Rw =2Nw

Nt

(1.31)

Aw =

(πD2

s

4×Ra

)−(Nw

πd2o4

)(1.32)

Ra is obtained from Figure 12.41, for the appropriate baffle cut Bc

Atb =ctπdo

2(Nt −Nw) (1.33)

where ct is the diametrical tube-to-baffle clearance; the difference between the hole and tubediameter, typically 0.8 mm.

Asb =csDs

2(2π − θb) (1.34)

where cs is the baffle-to-shell clearance, see Figure – 1.2.θb can be obtained from Figure 12.41, for the appropriate baffle cut, Bc

Ab = lB (Ds −Db) (1.35)

15


1.6 Wills-Johnston Method

1.6.1 Streams and flow areas

The bypass flow areaSbp = B (Ds −Dot +Npδp) (1.36)

where,

Ds = Shell IDB = central baffle spacingDot = outer tube limit diameterNp = number of tube pass partitions aligned with the cross-flow directionδp = pass partition clearance

Tube-to-baffle leakage flowSt = ntπDoδtb (1.37)

Shell-to-baffle leakage flowSs = πDsδsb (1.38)

where

nt = number of tubes in bundleδtb = tube-to-baffle clearanceδsb = shell-to-baffle clearance

16


Figure 1.2: Typical baffle clearances.

SBW =BD2

ot (π − θot + sin θot)

4Ds (1− 2Bc)−BNpδp (1.39)

where,

θot = 2 cos−1[Ds (1− 2Bc)

Dot

](1.40)

Here, Bc is the fractional baffle cut and θot is expressed in radians.

1.6.2 Flow resistances

The cross-flow resistance The cross-flow resistance is given by the following equation

ξB =4aDoDsDv (1− 2Bc) (PT −Do)

−3(mBDo

µSBW

)−b2ρgcS2

BW

(1.41)

mB

mo

=

√ξxξoξyξB

(1.42)

where

a= 0.061, b= 0.088 for square and rotated-square pitcha = 0.450, b = 0.267 for triangular pitch

Dv =Ω1P

2T −D2

o

Do

(1.43)

Ω1 = 1.273 for square and rotated-square pitch= 1.103 for triangular pitch

The bypass flow resistance The bypass flow resistance is computed as follows:

ξCF =

0.3164Ds

(1− 2Bc

Ω2PT

)(moDe

µSbp

)−0.025+ 2Nss

2ρgcS2bp

(1.44)

17


mCF

mo

=

√ξxξoξyξCF

(1.45)

where

Nss = number of pairs of sealing stripsΩ2 = 1.0 for square pitch

= 1.414 for rotated-square pitch= 1.732 for triangular pitch

De = equivalent diameter for the bypass flow

De =2Sbp

Ds −Dotl + 2B +Np (B + δp)(1.46)

ξy = ξw + ξx (1.47)

ξx =1(

1√ξB

+ 1√ξCF

)2 (1.48)

The tube-to-baffle leakage flow resistance The flow resistance for the tube-to-baffleleakage stream is given by the following equation,

ξA =0.036Bt/δtb + 2.3 (Bt/δtb)

−0.177

2ρgcS2t

(1.49)

where Bt is the baffle thickness. Flow fraction,

mA

mo

=

√ξoξA

(1.50)

where, mo is total mass flow.

The shell-to-baffle leakage flow resistance The flow resistance for the shell-to-baffleleakage stream is given by an equation,

ξE =0.036Bt/δsb + 2.3 (Bt/δsb)

−0.177

2ρgcS2s

(1.51)

mE

mo

=

√ξoξE

(1.52)

The window flow resistance The window flow resistance is given by

ξw =1.9 exp (0.6856Sw/Sm)

2ρgcS2w

(1.53)

mw

mo

=

√ξoξy

(1.54)

18


Inlet and outlet baffle spaces The cross-flow resistance in the end spaces is estimatedby the following equation

ξe = 0.5ξx

(B

Be

)2 [1 +

Dotl

Ds (1− 2Bc)

](1.55)

the end baffle spaces. The flow resistance in the end windows is calculated as follows

ξwe =1.9 exp [0.6856SwB/(SmBe)]

2ρgcS2w

(1.56)

The pressure drop in the inlet or outlet baffle space is then given by:

∆Pe = ξem2e + 0.5ξwem

2w (1.57)

∆Pj = ξjm2j j = A,B,CF,E (1.58)

1.6.3 Total shell-side pressure drop

∆Po = ψ [(nb − 1) ∆Py + ∆Pin + ∆Pout] + ∆Pn (1.59)

ψ = 3.646Re−0.1934B ReB < 1000

= 1.0 ReB ≥ 1000

ReB =DomB

µSm∆Py = ξym

2w

where,

nb = number of baffles.∆Pin,∆Pout = the pressure drops in the inlet and outlet baffle spaces.∆Pn = the pressure drops in the nozzles.

1.7 Fouling factor

19


Fluid Coefficient (W.m-2.°C-1) Resistance (m2.°C.W-1)

River water 3000-12,000 0.0003-0.0001 Sea water 1000-3000 0.001-0.0003 Cooling water (towers) 3000-6000 0.0003-0.00017 Towns water (soft) 3000-5000 0.0003-0.0002 Towns water (hard) 1000-2000 0.001-0.0005 Steam condensate 1500-5000 0.00067-0.0002 Steam (oil free) 4000- 10,000 0.0025-0.0001 Steam (oil traces) 2000-5000 0.0005-0.0002 Refrigerated brine 3000-5000 0.0003-0.0002 Air and industrial gases 5000-10,000 0.0002-0.000-1 Flue gases 2000-5000 0.0005-0.0002 Organic vapors 5000 0.0002 Organic liquids 5000 0.0002 Light hydrocarbons 5000 0.0002 Heavy hydrocarbons 2000 0.0005 Boiling organics 2500 0.0004 Condensing organics 5000 0.0002 Heat transfer fluids 5000 0.0002 Aqueous salt solutions 3000-5000 0.0003-0.0002

Figure 1.3: Typical values of fouling coefficients and resistances

1.8 Tube data

Standard tube data:

Tube Size Outside diameter Wall thickness

inch inch mm BWG inch mm

14

0.250 6.350 8 0.165 4.191

38

0.375 9.525 9 0.148 3.759

12

0.500 12.700 10 0.134 3.404

58

0.625 15.875 12 0.109 2.769

34

0.750 19.050 14 0.083 2.108

78

0.875 22.225 16 0.065 1.651

1 1.000 25.400 18 0.049 1.245

114

1.250 31.750 20 0.035 0.889

112

1.500 38.100 22 0.028 0.711

2 2.000 50.800 24 0.022 0.559

20

Chapter 2

Plate Heat Exchanger

2.1 Plate

Figure 2.1: Plate

2.2 Heat transfer coefficient

hpde

k= 0.26Re0.65Pr0.4

(µ

µw

)0.14

(2.1)

Re =ρupde

µ

up =(m/nc)

ρAf

21


Af = flow area through plates = b× Lw,Lw = effective plate width,de = equivalent diameter = 2b,b = plate gap = p− t,p = pitch,t = plate thickness.nc = number of channels

Table 2.1: Heat transfer coefficient

Fluid Coefficient (W/m2-C)

River water 3000 – 12,000

Sea water 1000 – 3000

Cooling water (towers) 3000 – 6000

Towns water (soft) 3000 – 5000

Towns water (hard) 1000 – 2000

Steam condensate 1500 – 5000

Steam (oil free) 4000 – 10,000

Steam (oil traces) 2000 – 5000

Refrigerated brine 3000 – 5000

Air and industrial gases 5000 – 10,000

Flue gases 2000 – 5000

Organic vapours 5000

Organic liquids 5000

Light hydrocarbons 5000

Heavy hydrocarbons 2000

Boiling organic 2500

Condensaing organics 5000

Heat transfer fluids 5000

Aqueous salt solutions 3000 – 5000

Table 2.2: Fouling factor in PHE

Fluid Fouling factor (m2-C/W)

Process water 0.00003

Town water (soft) 0.00007

Town water (hard) 0.00017

Cooling water (treated) 0.00012

Sea water 0.00017

Lubricating oil 0.00017

Light organics 0.00010

Process fluids 0.0002 – 0.00005

22


2.2.1 Number of Transfer Units (NTU)

NTU =to − ti∆Tlm

(2.2)

Corrected mean temperature difference,

∆Tm = Ft∆Tlm (2.3)

2.2.2 Correction factor, Ft

Refer figure – 2.2

Figure 2.2: Log mean temperature correction factor for plate heat exchangers

2.3 Pressure drop

2.3.1 Pressure drop in flow through plates

∆Pp = 8jf

(Lpde

)ρu2p2

(2.4)

Lp = effective plate length, = Lv − dptjf = 0.6Re−0.3 for turbulent flow.

23


2.3.2 Pressure drop in flow through port

∆Ppt = 1.3

(ρu2pt

)2

NP (2.5)

NP = number of passes,

upt = velocity in port =m

ρAp, where Ap =

πd2pt4

2.4 Plate sizes

D

B

CE

APP

L2

24


Table 2.3: Plate dimensionsPlateNo.

MaxPressure

A B C D E L2 PP Portsize

bar mm mm mm mm mm mm mmPL01 16 460 160 336 65 85 150 – 600 pcs. × 2.4 1”PL02 16 800 160 675 65 85 150 – 600 pcs. × 2.4 1”PL03 16 837 310 590 135 132 250 – 1000 pcs. × 2.4 2”PL04 16 1066 310 819 135 132 250 – 1000 pcs. × 2.4 2”PL05 25 470 185 381 70 45 250 – 1000 pcs. × 2.7 1”PL06 25 765 185 676 70 45 250 – 1000 pcs. × 2.7 1”PL07 25 733 310 494 126 128 250 – 1000 pcs. × 2.9 2”PL08 25 933 310 694 126 128 250 – 1000 pcs. × 2.9 2”PL09 25 1182 310 894 126 128 250 – 1000 pcs. × 2.9 2”PL10 16 1080 440 650 202 200 500 – 2500 pcs. × 3.1 DN80PL11 25 1160 480 719 225 204 500 – 2500 pcs. × 3.1 DN100PL12 25 1332 480 894 225 204 500 – 3000 pcs. × 3.1 DN100PL13 25 1579 480 1141 225 204 500 – 3000 pcs. × 3.1 DN100PL14 25 1826 480 1388 225 204 500 – 3000 pcs. × 3.1 DN100PL15 25 2320 480 1882 225 204 500 – 3000 pcs. × 3.1 DN100PL16 25 1470 620 941 290 225 500 – 4000 pcs. × 3.5 DN150PL17 25 1835 620 1306 290 225 500 – 4000 pcs. × 3.5 DN150PL18 25 2200 620 1671 290 225 500 – 4000 pcs. × 3.5 DN150PL19 25 1470 620 941 290 225 500 – 4000 pcs. × 3.1 DN150PL20 25 1835 620 1306 290 225 500 – 4000 pcs. × 3.1 DN150PL21 25 2200 620 1671 290 225 500 – 4000 pcs. × 3.1 DN150PL22 25 2687 620 2157 290 225 500 – 4000 pcs. × 3.1 DN150PL23 25 1380 760 770 395 285 500 – 4000 pcs. × 3.1 DN200PL24 25 1740 760 1130 395 285 500 – 4000 pcs. × 3.1 DN200PL25 25 2100 760 1490 395 285 500 – 4000 pcs. × 3.1 DN200PL26 25 2460 760 1850 395 285 500 – 4000 pcs. × 3.1 DN200PL27 25 1930 980 1100 480 365 1780 – 5280 pcs. × 3.8 DN300PL28 25 2320 980 1490 480 365 1780 – 5280 pcs. × 3.8 DN300PL30 25 2710 980 1879 480 365 1780 – 5280 pcs. × 3.8 DN300PL31 25 3100 980 2267 480 365 1780 – 5280 pcs. × 3.8 DN300PL32 25 2500 1370 1466 672 480 1980 – 5980 pcs. × 4.1 DN500PL33 25 2855 1370 1822 672 480 1980 – 5980 pcs. × 4.1 DN500PL34 25 3211 1370 2178 672 480 1980 – 5980 pcs. × 4.1 DN500PL33 25 3567 1370 2534 672 480 1980 – 5980 pcs. × 4.1 DN500

25


Table 2.4: Pipe sizes for PHE

Outside

Diameter

Wall

Thickness

Inside

Diameter

NB DN OD - t - ID

(inches) mm (inches) (inches) (inches)

1/8 6 0.405 0.0680 0.2690

1/4 8 0.54 0.0880 0.3640

3/8 10 0.675 0.0910 0.4930

1/2 15 0.84 0.1090 0.6220

3/4 20 1.05 0.1130 0.8240

1 25 1.315 0.1330 1.0490

1 1/4 32 1.66 0.1400 1.3800

1 1/2 40 1.9 0.1450 1.6100

2 50 2.375 0.1540 2.0670

2 1/2 65 2.875 0.2030 2.4690

3 80 3.5 0.2160 3.0680

4 100 4.5 0.2370 4.0260

6 150 6.625 0.2800 6.0650

8 200 8.625 0.3220 7.9810

10 250 10.75 0.3650 10.0200

12 300 12.75 0.4060 11.9380

14 350 14 0.4380 13.1240

16 400 16 0.5000 15.0000

18 450 18 0.5620 16.8760

20 500 20 0.5940 18.8120

Pipe Size

26

Chapter 3

Condenser Design

3.1 HTC in Vertical condenser

Heat transfer coefficient for condensation on vertical tubes is given by Nusselt theory,

h = 1.47

[k3LρL (ρL − ρv) g

µ2LRe

]1/3for Re ≤ 30 (3.1)

h =Re [k3LρL (ρL − ρv) g/µ2

L]1/3

1.08Re1.22 − 5.2for 30 ≤ Re ≤ 1600 (3.2)

h =Re [k3LρL (ρL − ρv) g/µ2

L]1/3

8750 + 58Pr−0.5L (Re0.75 − 253)for Re ≥ 1600 and Pr ≤ 10 (3.3)

Re =4Γ

µL

where

Γ =m

ntπD

3.2 HTC in Horizontal Condenser

Heat transfer coefficient for condensation on horizontal single tube or a single row of tubes isgiven by Nusselt theory,

h = 1.52


µ2LRe

]1/3for Re ≤ 3200 (3.4)

Re =4Γ

µL

where

Γ =m

ntL

kL = thermal conductivity of condensate at average film temperatureρL = density of condensate at average film temperatureρv = density of vapour

27


µL = viscosity of condensate at average film temperaturem = rate of condensation at average film temperaturent = number of tubes in tube bankL = tube length

for Nr tube rows stacked vertically,

hNr =h

N1/6r

(3.5)

for circular tube bundles used in shell-and-tube condensers,

h = 1.52


4µLΓ∗

]1/3(3.6)

where,

Γ∗ =m

n2/3t L

Average film temperature,Tf = 0.75Tw + 0.25Tsat (3.7)

3.3 Condensation with subcooling

Sadisivan and Lienhard equation,

h

hNu=

[1 +

(0.683− 0.228

PrL

)ε

]1/4for PrL ≥ 0.6 (3.8)

where,

PrL =CpLµLkL

ε =CpL (Tsat − Tw)

λwhere

hNu = is the heat-transfer coefficient given by the basic Nusselt theory.Tsat = condensation temperatureTw = tube wall temperatureλ = latent heat of condensation.

3.4 Condensation with desuperheating

h

hNu=

[1 +

Cpv (Tv − Tsat)λ

]1/4(3.9)

where

hNu = is the heat-transfer coefficient given by the basic Nusselt theory.Cpv = specific heat of vapourTsat = condensation temperatureTv = vapour temperatureλ = latent heat of condensation.

28


3.5 Condensation in vertical tubes with vapour down-

flow

The correlation of Boyko and Kruzhilin,

h = hLo [1 + x (ρL − ρv) /ρv]0.5 (3.10)

where

x = vapour weight fractionhLo = heat-transfer coefficient for total flow as liquid

3.6 Condensation outside horizontal tubes

McNaught developed the following simple correlation for shear-controlled condensation intube bundles:

h

hL= 1.26X−0.78tt (3.11)

where,

Xtt = Lockhart-Martinelli parameter, (refer section – 4.3)hL = heat-transfer coefficient for the liquid phase flowing alone through the bundle.

(refer chapter – 1)

************

29


Chapter 4

Reboiler Design

4.1 Nucleate Boiling

4.1.1 The Forster-Zuber correlation

hnb = 0.00122k0.79L Cp0.45L ρ0.49L g0.25c ∆T 0.24

e ∆P 0.75sat

σ0.5µ0.29L λ0.24ρ0.24v

(4.1)

where,

hnb = nucleate boiling heat-transfer coefficient, Btu/h·ft2·F(W/m2·K)kL = liquid thermal conductivity, Btu/h·ft·F (W/m·K)CpL = liquid heat capacity, Btu/lbm ·F(J/kg· K)ρL = liquid density, lbm/ft3(kg/m3)µL = liquid viscosity, lbm/ft·h (kg/m·s)σ = surface tension, lbf/ft(N/m)ρv = liquid density, lbm/ft3(kg/m3)λ = latent heat of vaporization, Btu/lbm (J/kg)gc = unit conversion factor = 4.17× 108 lbm·ft/lbf·h2 (1.0 kg·m/N·s2)∆Te = Tw − Tsat, F(K)Tw = tube-wall temperature, F(K)Tsat = saturation temperature at system pressure, F(K)∆Psat = Psat(Tw)− Psat(Tsat), lbf/ft2 (Pa)Psat(T ) = vapor pressure of fluid at temperature T, lbf/ft2 (Pa)

Any consistent set of units can be used with Equation - 4.1, including the English and SIunits shown above.

4.1.2 The Mostinski correlation

In English unit,hnb = 0.00622P 0.69

c q0.7Fp (4.2)

where,

hnb = nucleate boiling heat-transfer coefficient, Btu/h·ft2·FPc = fluid critical pressure, psiaq = heat flux, Btu/h·ft2 = hnb∆TeFp = pressure correction factor, dimensionless

31


In SI units,hnb = 0.00417P 0.69

c q0.7Fp (4.3)

where,

hnb = nucleate boiling heat-transfer coefficient, W/m2·KPc = fluid critical pressure, kPaq = heat flux, W/m2 = hnb∆Te

The pressure correction factor given by:

Fp = 2.1P 0.27r +

[9 +

(1− P 2

r

)−1]P 2r (4.4)

where, Pr = P/Pc = reduced pressure.

4.1.3 The Cooper correlation

In English unit same as that of equation – 4.2,

hnb = 21q0.67P 0.12r (− log10 Pr)

−0.55M−0.5 (4.5)

In SI unit same as that of equation – 4.3,

hnb = 55q0.67P 0.12r (− log10 Pr)

−0.55M−0.5 (4.6)

where M is the molecular weight of the fluid.

4.1.4 The Stephan-Abdelsalam correlation

Z1 =qdBkLTsat

(4.7)

Z2 =α2LρL

gcσdB(4.8)

Z3 =gcλd

2B

α2L

(4.9)

Z4 =ρvρL

(4.10)

Z5 =ρL − ρvρL

(4.11)

dB = 0.0146θc

[2gcσ

g (ρL − ρv)

]0.5(4.12)

where,

dB = theoretical diameter of bubbles leaving surface, ft(m)θc = contact angle in degreesg = gravitational acceleration, ft/h2 (m/s2)gc = 4.17× 108 lbm·ft/lbf·h2 (1.0 kg·m/N·s2)

32


αL = liquid thermal diffusivity, ft2/s (m2/s)q ∝ Btu/h·ft2(W/m2)kL ∝ Btu/h·ft·F (W/m·K)Tsat ∝ R (K)σ ∝ lbf/ft (N/m)ρL, ρv ∝ lbm/ft3 (kg/m3)λ ∝ ft·lbf/lbm (J/kg)1 Btu = 778 ft·lbf

The heat-transfer coefficient is given by the following equation:

hnbdBkL

= 0.23Z0.6741 Z0.35

2 Z0.3713 Z0.297

4 Z−1.735 (4.13)

Fluid group Contact angle (θc) in

Water 45

Hydrocarbons (including alcohols) 35

Refrigerants (including CO2, propane, n-butane) 35

Cryogenic fluids (including methane, ethane) 1

4.1.5 Boiling mixtures

The coefficient, hideal, is an average of the pure component values that is calculated as follows:

hideal =

[n∑i=1

xihnb,i

](4.14)

where hnb,i is the heat-transfer coefficient for pure component i. So heat transfer coefficientfor mixture is,

hnb = hideal

1 +

(BR · hideal

q

)[1− exp

(−qρLλβ

)]−1(4.15)

where

BR = TD − TB = boiling rangeTD = dew-point temperatureTB = bubble-point temperatureβ = 0.0003 m/s (SI units) = 3.54 ft/h (English units)

4.1.6 Convective effects in tube bundles

The average boiling heat-transfer coefficient, hb, is expressed as follows:

hb = hnbFb + hnc (4.16)

where hnc is a heat-transfer coefficient for liquid-phase natural convection and Fb is a factorthat accounts for the effect of the thermosyphon-type circulation in the tube bundle. The

33


bundle convection factor is correlated in terms of bundle geometry by the following empiricalequation,

Fb = 1.0 + 0.1

[0.785Db

C1 (PT/Do)2Do

− 1.0

]0.75(4.17)

where,

Db = bundle diameter (outer tube-limit diameter)Do = tube ODPT = tube pitchC1 = 1.0 for square and rotated square layouts

= 0.866 for triangular layouts

For larger temperature differences, therefore, Palen suggests using a rough approximationfor hnc of 250 W/m2· K (44 Btu/h· ft2·F) for hydrocarbons and 1000 W/m2· K (176 Btu/h·ft2·F) for water and aqueous solutions.

4.2 Critical heat flux

The equation for critical heat flux is generally used in the following form:

qc = 0.149λ√ρv [σggc (ρL − ρv)]0.25 (4.18)

4.2.1 Mostinski correlation

Boiling on single tube. For English unit,

qc = 803PcP0.35r (1− Pr)0.9 (4.19)

where qc Btu/h·ft2 and Pc in psia.For SI unit,

qc = 367PcP0.35r (1− Pr)0.9 (4.20)

where qc W/m2 and Pc in kPa.For tube bundles, Palen presented the following correlation:

qc,bundle = qc,tubeφb (4.21)

where

qc,bundle = critical heat flux for tube bundleqc,tube = critical heat flux for a single tubeφb = bundle correction factor

= 3.1ψb for ψb < 1.0/3.1 ∼= 0.323= 1.0 otherwise

ψb = dimensionless bundle geometry parameter =πDbL

ADb = bundle diameterA = bundle surface area = ntπDoL for plain tubesDo = tube ODL = tube lengthnt = number of tubes in bundle

34


4.3 Two Phase Flow

4.3.1 Pressure drop correlations

The Lockhart-Martinelli correlation

The two-phase pressure gradient is expressed as,

(∆Pf/L)tp = φ2L (∆Pf/L)L (4.22)

where

φ2L = two-phase multiplier

(∆Pf/L)L = negative pressure gradient for liquid alone(∆Pf/L)tp = negative two-phase pressure gradient

The two-phase multiplier is a function of the parameter, X, which is defined as follows:

X =

[(∆Pf/L)L(∆Pf/L)v

]0.5(4.23)

where (∆Pf/L)v is the pressure gradient that would occur if the vapor phase flowed alone inthe conduit.The relationship between φ2

L and X was given in graphical form by Lockhart andMartinelli, and subsequently expressed analytically by Chisholm as follows:

φ2L = 1 +

C

X+

1

X2(4.24)

The constant, C, depends on whether the flow in each phase is laminar or turbulent, as shownin Table – 4.1.

Table 4.1: Values of the Constant in Equation – 4.24

Liquid Vapour Notation ReL ReV C

Turbulent Turbulent tt > 2000 > 2000 20

Viscous (laminar) Turbulent vt < 1000 > 2000 12

Turbulent Viscous (laminar) tv > 2000 < 1000 10

Viscous (laminar) Viscous (laminar) vv < 1000 < 1000 5

For the turbulent-turbulent case,

Xtt =

(1− xx

)0.9(ρvρL

)0.5(µLµv

)0.1

(4.25)

where, x is vapour mass fraction.

The Chisholm correlation

The two-phase pressure gradient is expressed as,

(∆Pf/L)tp = φ2LO (∆Pf/L)LO (4.26)

where,

35


φ2LO = two-phase multiplier

(∆Pf/L)LO = negative pressure gradient for liquid alone(∆Pf/L)tp = negative two-phase pressure gradient

The correlation for the two-phase multiplier is the following:

φ2LO = 1 +

(Y 2 − 1

)B [x (1− x)](2−n)/2 + x2−n

(4.27)

Y =

(ρLρv

)0.5(µvµL

)n/2(4.28)

where n = 0.2314For English unit with G in units of lbm/h · ft2:

B = 1500/√G (0 < Y ≤ 9.5)

= 14250/(Y√G)

(9.5 < Y ≤ 28) (4.29)

= 399000/(Y 2√G)

(Y > 28)

For calculations in SI units, the following conversion can be used:

G(lbm/h · ft2) ≡ 737.35G(kg/s ·m2)

The Friedel correlation

The two-phase pressure gradient is expressed in the same manner as the Chisholm method,Equation – 4.26 with the following correlation for the two-phase multiplier:

φ2LO = E +

3.24FH

Fr0.045We0.035(4.30)

where,

E = (1− x)2 + x2 (µv/µL)0.2314 (ρL/ρv)

F = x0.78 (1− x)0.24

H = (ρL/ρv)0.91 (µv/µL)0.19 (1− µv/µL)0.7

Fr =G2

gDiρ2tp= Froude numbar

We =G2Di

gcρtpσ= Weber number

Di = internal diameter of conduit

ρtp = two-phase density

For the purpose of this correlation, the two-phase density is calculated as follows:

ρtp = [x/ρv + (1− x) /ρL]−1 (4.31)

where, x is vapour mass fraction.

36


Slip ratio,

SR =

√ρLρtp

(4.32)

void fraction is computed

εv =x

x+ SR (1− x) ρv/ρL(4.33)

Finally, the average two-phase density is computed as,

ρtp = εvρv + (1− εv) ρL (4.34)

The Muller-Steinhagen and Heck(MSH) correlation

The correlation is reformulated in the Chisholm format of Equation – 4.26 with the two-phasemultiplier given by the following equation:

φ2LO = Y 2x3 +

[1 + 2x

(Y 2 − 1

)](1− x)1/3 (4.35)

where x is the vapor mass fraction and Y is the Chisholm parameter (equation – 4.28).

4.4 Convective Boiling in Tubes

4.4.1 Heat transfer coefficient

The Chen correlation

hb = SCHhnb + FxhL (4.36)

where

hb = convective boiling heat-transfer coefficienthnb = nucleate boiling heat-transfer coefficient

SCH = (1 + 2.53× 10−6Re1.17)−1

Fx = 2.35(X−1tt + 0.213

)0.736for (Xtt < 10)

= 1.0 for (Xtt ≥ 10)

Re = ReL (Fx)1.25

The heat flux is calculated as follows:

q = SCHhnb (Tw − Tsat) + hL (Tw − Tb) (4.37)

whereas convective heat transfer coefficient, hL, can be calculated using Dittus-Boelter equa-tion,

hL = 0.023 (kL/Di)Re0.8L Pr0.4L (4.38)

37


4.4.2 Critical heat flux

The following simple correlation for vertical thermosyphon reboilers was given by Palen

qc = 16070(D2/L

)0.35P 0.61c Pr0.25 (1− Pr) English Unit (4.39)

qc = 23660(D2/L

)0.35P 0.61c Pr0.25 (1− Pr) SI units (4.40)

where

qc = critical heat flux, Btu/h · ft2 (W/m2)D = tube ID, ft (m)L = tube length, ft(m)Pr = reduced pressure in tubePc = critical pressure of fluid, psia (kPa)

For flow in horizontal tubes, the dimensionless correlation of Merilo is recommended byHewitt et al.

qcGλ

= 575γ−0.34H

(L

D

)−0.511(ρL − ρvρv

)1.27

(1 + ∆Hin/λ)1.64 (4.41)

where

γH =

(GD

µL

)(µ2L

gcσDρL

)−1.58 [(ρL − ρv) gD2

gcσ

]−1.05(µLµv

)6.41

(4.42)

The correlation cover the ranges 5.3 ≤ D ≤ 19.1 mm, 700 ≤ G ≤ 8100 kg/s·m2, 13 ≤ ρL/ρv ≤21.

4.5 Film Boiling

4.5.1 Heat transfer coefficient

A combined heat-transfer coefficient, ht, for both convection and radiation can be calculatedfrom the following equation:

h4/3t = h

4/3fb + hrh

1/3t (4.43)

For saturated film boiling on the outside of a single horizontal tube,

hfbDo

kv= 0.62

[gρv (ρL − ρv)D3

o (λ+ 0.76Cp,v∆Te)

kvµv∆Te

]0.25(4.44)

Here, Do is the tube OD. hr is the radiative heat-transfer coefficient calculated from thefollowing equation:

hr =εσSB (T 4

w − T 4sat)

Tw − Tsat(4.45)

where,

ε = emissivity of tube wallσSB = Stefan-Boltzmann constant

= 5.67× 10−8 W/m2 ·K4 = 1.714× 10−9 Btu/h · ft2 · R4

If hr < hfb, Equation – 4.43 can be approximated by the following explicit formula for ht:

ht = hfb + 0.75hr (4.46)

38


4.6 Design equations

4.6.1 Number of nozzles

For a tube bundle of length L and diameter Db, the number, Nn, of nozzle pairs (feed andreturn) is determined from the following empirical equation,

Nn =L

5Db

(4.47)

4.6.2 Shell diameter

Vapour loading,

VL = 2290ρv

(σ

ρL − ρv

)0.5

(4.48)

where

VL = vapor loading (lbm/h · ft3)ρv, ρL = vapor and liquid densities (lbm/ft3)σ = surface tension (dyne/cm)

The dome segment area, SA, is calculated from the vapour loading as follows:

SA =mV

L× VL(4.49)

The segment area till semicircle is given by,

SA =D2s

8(θ − sin θ) (4.50)

θ = 2 cos−1(

1− 2h

Ds

)(4.51)

where, Ds Shell ID and h is height of the segment. When segment exceeds semicircle thesegment area is area of circle minus area of segment whose height in the circle diameter minusheight of the given segment.

4.7 Frictional losses in pipe

4.7.1 Friction factor

Reynold’s number

NRe =dvρ

µ

Friction factor in Laminar flow:

f =16

NRe

39


Friction factor in turbulent flow:

A. For smooth pipe/tubes (Turbulent)

i) f = 0.046NRe−0.2 for 50000 < NRe < 1× 106

ii) f = 0.0014 +0.125

NRe0.32 for 3000 < NRe < 3× 106

iii) von-Karman equation

1√f/2

= 2.5 ln(NRe

√f/8)

+ 1.75

B. For Commercial pipes (Turbulent)

i) Colebrook equation1√4f

= 2 log

(D

2κ

)+ 1.74

ii) Generalised equationf = 0.3673N−0.2314Re

4.7.2 Pressure drop in pipe

∆P = 4f

(L

d

)ρv2

2

4.7.3 Maximum gas/vapour velocity in tubes

For plain carbon steel tube in English unit,

vmax =1800√PM

(4.52)

in SI units,

vmax =1440√PM

(4.53)

where,

vmax = maximum velocity, ft/s (m/s)P = gas pressure, psia(kPa)M = molecular weight of gas

Multiply equation – (4.52) or (4.53) with 1.5 for stainless steel and 0.6 for copper tube.

4.7.4 Maximum velocity of liquids in tubes

i. Maximum recommended velocity of water in plain carbon steel tube is 10 ft/s (3 m/s).

ii. Multiply above value with 1.5 for stainless steel and 0.6 for copper tube.

iii. Multiply above value with the factor√

(ρwater/ρliquid) if liquid is other than water.

40


4.7.5 Maximum velocity of two-phase flow in tubes/pipe

English unit,

vmax =

√4000

ρtp(4.54)

SI unit,

vmax =

√5924

ρtp(4.55)

vmax = maximum velocity, ft/s (m/s)ρtp = density of two-phase mixture, lbm/ft3 (kg/m3)

4.8 Design of Vertical Thermosyphon Reboiler

Figure 4.1: Configuration of vertical thermosyphon reboiler system.

4.8.1 Pressure balance

PB − PA = ρL (g/gc) (zA − zB)− 4f

(LinDin

)G2in

2ρL(4.56)

The subscript in refers to the inlet line to the reboiler.

PC − PB = ρL (g/gc)LBC − 4f

(LBCDt

)G2t

2ρL(4.57)

41


The subscript t in this equation refers to the reboiler tubes.

PD − PC = −∆Pstatic,CD −∆Pf,CD −∆Pacc,CD (4.58)

∆Pstatic,CD = ρtp (g/gc)LCD (4.59)

∆Pf,CD = 4f

(LCDDt

)G2t φ

2LO

2ρL(4.60)

∆Pacc,CD =G2tγ

ρL(4.61)

Fair recommends calculating ρtp at a vapour weight fraction equal to one-thirds the value atthe reboiler exit using equation – (4.34). where,

γ =(1− xe)2

1− εv,e+ρLx

2e

ρvεv,e− 1

In this equation, xe and εv,e are the vapour mass fraction and the void fraction at the reboilerexit.

Fair recommends calculating φ2LO at a vapour weight fraction equal to two-thirds the value

at the reboiler exit.

PA − PD =(G2

t −G2ex) (γ + 1)

ρL−

4fexLexG2exφ

2LO,ex

2ρLDex

(4.62)

In this equation, the subscript ex designates conditions in the exit line from the reboiler.The relationship between the circulation rate and the exit vapour fraction in the reboiler

in SI units is,

m2i =

1.234D5t ρL(g/gc) (ρLLAC − ρtpLCD)

2Dt

[(γ + 1)

(Dt

Dex

)4

− 1

n2t

]

+ finLin

(Dt

Din

)5

+

(ftn2t

)(LBC + LCDφ

2LO

)+ fexLexφ

2LO,ex

(Dt

Dex

)5

(4.63)

where,

mi = tube-side mass flow rate (kg/s)nt = number of tubes in reboiler

4.8.2 Sensible heating zone

TC − TBPC − PB

=(∆T/L)

(∆P/L)(4.64)

Tsat − TAPsat − PA

= (∆T/∆P )sat (4.65)

42


LBCLBC + LCD

∼=(∆T/∆P )sat

(∆T/∆P )sat −(∆T/L)

(∆P/L)

(4.66)

The pressure gradient in the sensible heating zone is calculated as follows:

− (∆P/L) = ρL (g/gc) + ∆Pf,BC/L (4.67)

The temperature gradient in the sensible heating zone is estimated as follows:

∆T/L =ntπDoUD∆Tm

miCpL(4.68)

Here, UD and ∆Tm are the overall coefficient and mean driving force, respectively, for thesensible heating zone.

4.8.3 Mist flow limit

Tube-side mass flux at onset of mist flow,

Gt,mist = 1.8× 106Xtt (lbm/h · ft2) (4.69)

Gt,mist = 2.44× 103Xtt (kg/s ·m2) (4.70)

********************

43


Part II

Data Sheet

45

1 Heat Exchanger Specification Sheet2 Company:

3 Location:

4 Service of Unit:

5 Item No.: Prepared by:

6 Date: Rev No.: Job No.:

7 Size mm Type Connected in parallel series

8 Surf/unit(eff.) m2 Shells/unit Surf/shell (eff.) m2

9 PERFORMANCE OF ONE UNIT

10 Fluid allocation Shell Side Tube Side

11 Fluid name

12 Fluid quantity, Total kg/h

13 Vapor (In/Out) kg/h

14 Liquid kg/h

15 Noncondensable kg/h

16

17 Temperature (In/Out) C

18 Dew / Bubble point C

19 Density kg/m3

20 Viscosity cp

21 Molecular wt, Vap

22 Molecular wt, NC

23 Specific heat kJ/(kg*C)

24 Thermal conductivity W/(m*K)

25 Latent heat kJ/kg

26 Pressure mmH2O(g)

27 Velocity m/s

28 Pressure drop, allow./calc. mmH2O

29 Fouling resist. (min) m2*K/W

30 Heat exchanged kcal/h MTD corrected C

31 Transfer rate, Service Dirty Clean W/(m2*K)

32 CONSTRUCTION OF ONE SHELL Sketch

33 Shell Side Tube Side

34 Design/Test pressure kgf/cm2

35 Design temperature C

36 Number passes per shell

37 Corrosion allowance mm

38 Connections In

39 Size/rating Out

40 mm Intermediate

41 Tube No. OD Tks- avg mm Length mm Pitch mm

42 Tube type Material Tube pattern

43 Shell ID OD mm Shell cover

44 Channel or bonnet Channel cover

45 Tubesheet-stationary Tubesheet-floating

46 Floating head cover Impingement protection

47 Baffle-crossing Type Cut(%d) Spacing: c/c mm

48 Baffle-long Seal type Inlet mm

49 Supports-tube U-bend Type

50 Bypass seal Tube-tubesheet joint groove/expand

51 Expansion joint Type

52 RhoV2-Inlet nozzle Bundle entrance Bundle exit kg/(m*s2)

53 Gaskets - Shell side Tube Side

54 Floating head

55 Code requirements TEMA class

56 Weight/Shell Filled with water Bundle kg

57 Remarks

58

59

60

61

62

Company PLATE-AND-FRAME HEAT EXCHANGER DATA SHEET (SI UNITS)

PROCESS

Engineering contractor

PO No.: Doc. No.: Page 1 of

Customer: Vendor:

Project: Order/enq. No.:

Location: Model:

Item No.: Serial No.:

Service:

01 CASE HOT SIDE COLD SIDE

02 Fluid

03 Total flow (kg/s)

04 Flow per exchanger (kg/s)

05 Design temperature (max.) ( C)

06 Minimum design metal temp. ( C)

07 Design pressure [kPa (ga)]

08 Pressure drop allow./calc.- (kPa) / /

09 Wall temperature min./max. ( C) / /

10 Fouling margin a (%)

11 OPERATING DATA INLET OUTLET INLET OUTLET

12 Liquid flow (kg/s)

13 Vapour flow (kg/s)

14 Non-condensables flow (kg/s)

15 Operating temperature ( C)

16 Operating pressure [kPa (ga)]

17 LIQUID PROPERTIES

18 Density (kg/m3)

19 Specific heat capacity (kJ/kg·K)

20 Dynamic viscosity (mPa·s)

21 Thermal conductivity (W/m·K)

22 Surface tension (N/m)

23 VAPOUR PROPERTIES

24 Density (kg/m3)

25 Specific heat capacity (kJ/kg·K)

26 Dynamic viscosity (mPa·s)

27 Thermal conductivity (W/m·K)

28 Relative molecular mass (kg/kmol)

29 Relative molecular mass,

non-condensables

(kg/kmol)

30 Dew point/bubble point ( C)

31 Solids maximum size (mm)

32 Solids concentration (% volume)

33 Latent heat (kJ/kg)

34 Critical pressure [kPa (abs)]

35 Critical temperature ( C)

36

37 Total heat exchanged (kW)

38 U a (W/m2·K) Clean condition: Service:

39 LMTD ( C) /

40 Heat transfer area (m2)

41 Stream heat transfer coefficient (W/m2·K) a Fouling margin = [(Uclean /Uservice) 1] 100 % where U = Overall heat transfer coefficient (thermal transmittance).

Rev. No. Revision Date Prepared by Reviewed by

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