1

Advisor:Professor Dr.A.R.Saleemi

Co Advisor:Hafiz Zaheer Aslam

2

Group Members

Asif Masih Sharazi 2005-Chem-61

Mohammad Mohsin 2005-Chem-75

Saadi Hassan Mufti 2005-Chem-109

Saira Rasheed Khan 2005-Chem-29

Sundus Fatima 2005-Chem-43

3

Presentation ContentsProcess DescriptionDesign of CSTRDesign of SeparatorDesign of AbsorberDesign of Heat ExchangerDesign of Distillation Column

4

Equipment Coding

R = ReactorE = Heat ExchangerC = ColumnP = PumpM = MixerV = Vessel

5

6

7

Selection of ReactorReaction KineticsVolume of CSTRSelection of agitatorWall thicknessHead thicknessJacket area

8

Selection of ReactorType of reactionTemperature and pressure of reactionNeed for removal or addition of reactants and productsCatalyst use considerationRelative cost of reactorAvailable space Safety

9

10

11

12

0.02< <2 and E =1 Reaction takes place in the liquid phase Reaction is moderate

These conditions requires High interfacial area High liquid hold-up

To fulfill these requirements CSTR is the best

Ref:Coulson, Richardson, Chemical Engineering, Butterworth-Heinemann, Vol: 3, Edit: 3, (196-212), 1994.

13

Advantages of CSTR Very less chances of coalescence High liquid hold up High interfacial area Less resistance in gas diffusion

Bubble Column: Greater chances of coalescence

Packed Bubble Column: Greater pressure drop

Ref:Coulson, Richardson, Chemical Engineering, Butterworth-Heinemann,

Vol: 3, Edit: 3, (196-212), 1994.

14

Chemical Reaction CH3COOCH3+ CO (CH3CO)2

(CH3CO)2 + H2 CH3CHO + CH3COOH

Complete Reaction

CH3COOCH3+CO+ H2 CH3COOH+CH3CHO

Heat of Reaction 7.9x103 KJ/Kg mol

Catalyst CH3COOPd

15

160◦C

310.2KPa

Slow

Fast

16

310.2KPa160 ◦C

368KPa160 ◦C

310.2KPa160 ◦C

190◦ C1255.1Kpa

312Kpa25 ◦C

T=160°CP=310KPa

T=25°CP=312KPa

T=160°CP=368KPa

T=160°CP=310KPa

Reaction KineticsrB= (k1K1K2PBWA*)/(1+K1P+K1K1PA*)

k1 = Rate constantK1 = Adsorption coefficient for COK2 = Adsorption coefficient for H2

P = CH3I ConcentrationB = CH3COOCH3 concentrationW = Catalyst (CH3COOPd) concentrationA* = Equilibrium dissolved concentration of CO

Ref: Ashutosh, A.Kelkar, Rengaswamy Jaganathan, and Raghunath V.Chaudhari ,Industrial & Engineering Chemistry Research, ACS,Vol.40,No.7,2001

17

k1= 0.112 m3/Kgmol.sec

K1 = 1.75 m3/Kg mol

K2 = 2.86 m3/Kg mol

P = 0.09 Kg mol/m3

B = 0.09 Kg mol/m3

W = 8.89 Kg mol/m3

A* = 0.004939 Kg mol/m3

rB = k1K1K2PBWA*/(1+K1P+K1K1PA*)

= 0.0016 kg mol/m3.sec

18

Volume of Reaction Mixture

Vr/FBO = XB/rB

Vr = 21.2 m3

Ref: Octave Levenspiel, Chemical Reaction Engineering, Edition:3, (91-113)

19

Space time & Space Velocityτ = Vr/Vo

= 463 sec

s = 1/τ

= 2.16 x 10-3 sec-1

20

Length & DiameterLength and Diameter Calculation

V=(D2/4) x L

L/D = 1

So

L = 5.20m

D = 5.20m

21

Volume of ReactorIf Rated Capacity<1.89m3

Allowable head space is taken 15%

If rated capacity >1.89m3

Allowable head space is taken 10%

Allowable head space= 21.2 x0.1 = 2.12m

Reactor Volume = 21.2+21.12

= 23.32m3

Ref:Coulson, Richardson, Chemical Engineering, Butterworth-Heinemann, Vol: 3, Edit: 3, (196-212), 1994.

22

Selection of Agitator

Factors affecting the selection

Mixing pattern(axial, radial)Capacity of vesselDensity and viscosity of fluid viscosity

23

Three basic types of Impeller

1.Flat blade (Rushton) turbines(Suitable for shear controlled processes)

2.Propeller and Pitched blade turbines(suitable for bulk fluid mixing)

3.Anchor and Helical ribbon agitators90Suitable for highly viscous fluids)

Ref: Coulson, Richardson, Chemical Engineering, Butterworth-Heinemann, Vol: 3, Edit: 3, (196-212), 1994.

24

Agitator DesignFor turbine agitatorDa/DT = 1/3 , Da = Impeller diameter

J/DT = 1/12 , J = Width of Baffles

W/Da = 1/5 , W = Impeller Width

La/Da = 1/4 , La = Length of Impeller blades

E/DT = 1/3 , E = Impeller Height above vessel floor

25

Da/DT = 1/3 , Da = 1.73m

J/DT = 1/12 , J = 0.43m

E/DT = 1/3 , E = 1.73m

W/Da = 1/5 , W = 0.35m

La/Da = 1/4 , La = 0.43m

26

Power Calculation

Re = Da2 NP /

= 8.37 x 106

Np = KT Reb Frc

NP = KT = 6.30

P = NpDa5N3/g

= 7290W

= 9.8hp

27

28

Material of ConstructionFactors affecting the selection of material1. Mechanical properties such as tensile strength2. The effect of high and low temperatures on the

mechanical properties3. Corrosion resistance4. Any special properties required; such as thermal

conductivity, electrical resistance, magnetic properties5. Ease of fabrication-forming, welding, casting 6. Availability in standard sizes-plates, sections, tubes7. Cost

29

Austenitic Stainless Steel High Tensile StrengthHigh Corrosion resistance

Material Specification IS:1570-1961

Designation:

Cr=19% Ni=9%

Mo=3% Ti=20%

Ref: Bhattacharyya, Chemical Equipment Design Mechanical Aspects,CBS,Edition:1,(261-265),2001

30

Design TemperatureThe strength of metals decreases with

increasing temperature so the maximum allowable design stress will depend on the material temperature.

The design temperature at which the design stress is evaluated should be taken as the maximum working temperature of the material.

We chose austenitic stainless steel for the fabrication of CSTR for which the design stress is evaluated at 200C. So the Design temperature of the CSTR is 200C.

31

Design PressureThis is normally be 5 to 10 per cent above the normal

working pressure, to avoid spurious operation during minor process upsets.

When deciding the design pressure, the hydrostatic pressure in the base of the column should be added to the operating pressure, if significant.

Ref: Coulson, Richardson, Chemical Engineering, Butterworth-Heinemann, Vol: 3, Edit: 3, (807), 1994.

32

PHydrostatic = g h

= 56259.8Pa

= 56.3KPa

POperating = 56.3+310.2

= 366.5KPa

PDesign = 366.5+(366.5 x 0.05)

= 384.83 KPa

33

Wall ThicknessThe thickness of process vessel is chosen so that it is not

only adequate against the induced stresses caused by internal pressure, but also ensures safety against stresses caused by extraneous agencies.

The thickness of wall depends on the pressure and temperature of vessel.

34

tw = P Di/(2fJ-P)

tw = wall thickness

P = design pressureDi = inner diameter of vessel

f = allowable design stress for material specified

J = joint efficiency factortw = 8.86 x10-3m = 8.86mm

Standard plate thickness = 9mm

35

Selection of HeadFactors affecting selection of Head Process temperature and pressureNature of the materials to be handledPosition of the vessel(Horizontal or vertical)Nature of the support Economy

Ref: Bhattacharyya, Chemical Equipment Design Mechanical Aspects,CBS,Edition:1,(39-42),2001

36

Head Type Characteristics

Flat High discontinuity stresses , high material cost

Ellipsoidal Suitable for pressure above 1.5MN/m2

Hemispherical Suitable for heavy duty high pressure vessels, most expensive

Conical Suitable for removal of solids from process vessels, commonly used ads reducers

Torispherical Suitable for low pressure vertical vessels

37

Head Thickness

tH = P Do C/2fJSolution of above equation will require iteration because ‘C’(stress concentration factor) is a function of ‘tH’.

ri = 0.06 x Do

assume Ri = Ro = Do

Ref: Bhattacharyya, Chemical Equipment Design Mechanical Aspects,CBS,Edition:1,(51-56),2001

38

ho = Ro –[( Ro - Do /2) x (Ro + Do/2 – 2ro )]1/2

= 0.88m

Do2/(4Ro) = 1.302m

(Do ro/2)1/2 = 0.903m

Effective external height of head

hE = 0.903m

hE/Do = 0.17

39

tH/Do = PC/2fJ = 1.704 x 10-3C

By iteration

C=1.32 and tH/Do = 0.002

tH = 11.9 x 10-3m

= 11.9mm

Standard sheet available is of thickness12mm

40

Torispherical Head

41

Jacket Area

42

Area of Jacket = п Di L + п Di2/4

As L=Di so

Area of Jacket = 5 п Di2/4

= 106.13m2

Jacket Temperature = 14°CReaction Temperature = 160°CHeat Duty of CSTR = 6.5 x 106 KJ/h

Ref: D.Q.Kern, Process Heat Transfer, (716-720, 791-846)

43

Heating Media = Water at 10°C

Heat Transferred through jacket

Qj = Uj Aj (Tj-TR)

= 3.16 x 107 KJ/h

Qj > QR so only jacket is enough to provide the required heat to maintain the temperature at 160°C

Ref: Harry Silla, Chemical Engineering Design and Economics, Library of Congress Cataloging-in-Publication Data, (240,375-394), 2003.

44

Specification SheetItem CSTR

Number of Item 1

Item Code R-100

Capacity 23.32m3

Operating Temperature 160◦C

Operating Pressure 366.5KPa

Length 5.20m

Diameter 5.20m

Impeller Diameter 1.73m

Wall thickness 9 x 10-3m

Material of Construction Austenitic Stainless Steel

Head type Torispherical

Head thickness 12 x 10-3m

Jacket area 106.13m245