Heat Exchanger design

Process design

is

is

4.186 KJ/kg K ratio

46.2 KJ/kg K CS2 0.27723872

1.04 KJ/kg K CO 0.72276128

Overall Heat capacity of gas mixture 13.5601 KJ/kg K

flow rate on tube side 1518.213244 kg/h

Tube side

Shell side

38.8296984 C

R

S

0.81

heat capacity of water

heat capacity of CS2

Heat capacity of CO

100

LMTD

Heat Load ((flowrate *heat capacity of CS2(inlet - oulet))/(3600))

Flow of water Heat load/ (Heat capacity of methanol(outlet-inlet))

Use one shell pass and two tube pass

(0-40)/(25-100)

Tube side fluid mixture of Carbon monoxide and carbon disulfide

Shell side fluid

Outlet tempInlet temp

water

25

Inlet temp Outlet temp

10 20

0.133333333

(25-100)/(40-100)

0.9375

From the below graph we obtain Ft

428.8984163

10.24602046

C

450 W/m2 K U

Provsional Area A Heat load/((Delta Tm)*U)

30.30350707 m2

Choose 20 mm O.D. and 16 mm I.D. with 4.88

0.02 m 0.016 m

Allowing for tube length thickness use length 4.83 m

Area of one tube 4.83*20* Pi * (10^(-3)) = 0.303324

No of tube are provisional area/area of one tube 99.9047457

Db

= mm

= mm

= 55 mm

= 310+55 = 365 mm

= (Inlet+Outlet)/2 = 62.5

= (pi/4)*(16)^2 = 200.96

Tubes per pass = 100/2 = 50 tubes

Total Flow area = tubes per pass * tube cross sectional area in m2

= 0.010048 m2

Delta Tm LMTD * Ft

31.45205568

Overall Heat Transfer coeff of the process

As the shell side fluid are relatively clean use 1.25 triangular pitch

Bundle diameter 20*(146/.249)^(1/2.207)

Tube side co-efficient

Mean CS2+CO temperature

Tube cross sectional area

302.5672122

310

Use split ring floating heat type

From the below figure, bundle diametrical clearance

Shell diameter

= Flow of methanol / total flow area

= 1019.7074 Kg/m2 s

= 1.1813834 kg/m3 1.2632

1.15

= gas mass velocity/density

863.14691 m/s

Reynold number =

=

0.0029

= (Cp* viscosity )/Kf

Using the above equation and neglecting the (Mu/Mu w)

hi = 985.5636342 W/m2 C

= Ds/5 73 mm

= 1.25*20 25 mm

= ((25-20)/20)*(365)*(73*(10^(-6)))

= 0.0066613 m2

=

Kg/m2 s

de =

= 14.201 mm

(10.246/0.006661)

1538.152818

Shell side co-efficient

Choose baffle spacing

Tube pitch

Cross Flow area As

Mass Velocity Gs

(Density* velocity*diameter)/viscosity

9.07E+05

Heat transfer factor from the graph

Prandtle number

0.013020268

Gas mixture mass velocity

Density of gas mixture

Gas mixture linear velocity

Equivalent Diameter

= (10+20)/2 15 C

= 998 kg/m3

= 1.084 mNs/m2

= 4.186 KJ/kg C

= 0.592 W/m C

= (Gs*de)/mu

= 20150.653

= (Cp*mu)/Kf

= 7.6649054

jh = 0.0042

hs = 2201.7354 W/m2 C

= 62.5-15

= 47.5

= (U/h0)*(delta T)

= 9.70825 C

Mean wall temperature =

= C

= 50 W/m C

= 5000 W/m2 C

= 4000 W/m2 C

so 1/U0 =

= 0.002139511

U0 = 467.3966288 W/m2 C

The assumed value was 450 W/m2 c

Little above the assumed value

Mean Shell Side temperature

Density of water

Viscosity

heat capacity

across the water film

thermal conductivity

Reynold number

Prandtle number

Choose 25 % baffle cut, from graph find jh

Fouling co-efficient of gas mixture

37.79174905

(47.5)-(9.708251)

Overall HT Coefficient

Thermal Conductivity of cupro-nikle alloy

Fouling co-efficient of water

Without the viscosity correction term, find hs

Estimate the wall temperature

mean temperature difference across all resistence

From the graph Re = 9.07E+05

So friction factor is jf = 0.0029

Neglecting the viscosity term

delta Pt =

= 8364575.2 N/m2

= 8364.5752 K Pa

Linear velocity = Gs/ rho

= 1.541235288

jf = 0.0046

Delta Ps

= 74179.6 N/m2

= 74.1796 K Pa

Neglect the correction factor

Pressure Drop

Tube Side

Shell Side

From the figure, at Re at 20150.15

27722677 j/kmol

27722.68 KJ/Kmol

364.0057 kj/kg

KW

Kg/s

((flowrate *heat capacity of CS2(inlet - oulet))/(3600))

Heat load/ (Heat capacity of methanol(outlet-inlet))

heat of vaporization of CS2

m long tube of cupper-nikle

CU-ni Long tube length 4.88 m long tube of cupper-nikle

m2

= 100 Tubes

C

mm2

CS2

CO

Density

co 1.15

so2 2.71

Overall 1.58 kg/m3

Velocity 863 m/s

viscosity 0 Pa.s

Diameter 0.02 m

Thermal

conductivity 0.03 W/m C

C

1 2 3 4 5

0.001 0 4.46287E-05 0.000313 0.000568

c1 c2 c3 c4 Tr tc t

3.496 0.2986 0 0 0.540127 552 298.15

34960000

m long tube of cupper-nikle