1. Design Of Stirred Batch ReactorPresented By: SAQIB RAUF
2. What is bio-reactor A bioreactor may refer to any
manufactured or engineered device or system that supports a
biologically active environment In one case, a bioreactor is a
vessel in which a chemical process is carried out which involves
organisms or biochemically active substances derived from such
organisms. This process can either be aerobic or anaerobic. These
bioreactors are commonly cylindrical, ranging in size from litres
to cubic metres, and are often made of stainless steel.
3. Cont.. A bioreactor may also refer to a device or system
meant to grow cells or tissues in the context of cell culture.
These devices are being developed for use in tissue engineering or
biochemical engineering
4. Classification of bio-reactors On the basis of mode of
operation, bioreactor may be classified as Batch Fed batch
continuous Organisms growing in bioreactors may be Suspended
Immobilized
5. WHAT IS FERMENTATION?Enzymes break down starch into simple
sugars, and yeast fermentssugars into ethanol, giving off carbon
dioxide gas as a by product. Theprocess has been used since
civilization began. Starch is made up oflong chains of glucose
molecules coiled together. The starch must bebroken down into
sugars that are only one or two molecules long forthe yeast to feed
on.REACTION 305 KC6H12O6 (l)------------------> 2C2H5OH (l) +
2CO2 (g) 180 kPaH0r = -285 kJ /kg C2H5OH
6. REACTOR DESIGN Reactor Selection Process Design Mechanical
Design Heat Calculation Specification SheetREF: Chemical Process
Engineering Design and Economics By Harry Silla
7. SELECTION OF REACTOROur system is gas-liquid system. We
select a batch stirred tank reactor.This is due to the following
reasons: We need to have the bio mass and molasses in contact with
eachother for a long time.Need to mix the nutrients, bio mass and
molasses well together.Visited MURREY BREWERY INDUSTRY RAWALPINDI
where batchprocess was taking place.Concentration and temperature
of the species is uniform through out. REF: Chemical Process
Engineering Design and Economics By Harry Silla
8. SELECTION OF REACTORThe following table tells us that a
stirred batch reactor is common for gas-liquidsystems.REF: Chemical
Process Engineering Design and Economics By Harry Silla
9. BATCH REACTORREF: Chemical Process Engineering Design and
Economics By Harry Silla
10. BATCH REACTORFermenter modeled as a batch reactor.Batch
reactor consists of an agitator and ajacket around it for cooling
purposes.Reactants are filled in and allowed to react for acertain
period of time without them exiting.Jacket consists of agitation
nozzles forproviding higher turbulence and hence betterheat
transfer.REF: Chemical Process Engineering Design and Economics By
Harry Silla
11. BATCH REACTORFermenter modeled as a batch reactor.Batch
reactor consists of an agitator and ajacket around it for cooling
purposes.Reactants are filled in and allowed to react for acertain
period of time without them exiting.Jacket consists of agitation
nozzles forproviding higher turbulence and hence betterheat
transfer.REF: Chemical Process Engineering Design and Economics By
Harry Silla
12. BATCH REACTORThere are 2 fermenters installed in
parallel.According to a journal, the conversion is 70 %and for that
conversion the reaction time is 48hrs.2 fermenters are used because
1 would give usvery large dimensions.
13. PROCESS DESIGNIn sizing of a batch reactor, the following
rate equations have to be followed tocalculate the reaction time;
REF: Chemical Reaction Engineering By Octave Levenspiel
14. PROCESS DESIGNThe yeast being used is Saccharomyces
cerevisiae. According to anexperimental research paper, for a
conversion of 70%, the time takenfor the batch reaction is 48 hrs.
The following equation was then usedto calculate the entire batch
time.Where;tF = Time needed for filling.tR = Time taken for
reaction.tC = Time taken to cool.tE = Time taken for emptying and
cleaning.tB = Time taken for the entire batch operation. REF:
Journal of Tokyo University of Fisheries, Vol 90, pp. 23-30, 2003
REF: Chemical Process Engineering Design and Economics By Harry
Silla
15. Time required for the entire batch operation: Charging time
(tF ): 2 hrs. Cooling time (tC) : 1.5 hrs. Reaction time (tR): 48
hrs. Emptying and cleaning time (tE) : 0.5 hrs.Total time for batch
(tB): 2 + 1.5 + 48 + 0.5 = 52 hrs. REF: Crystalline Chemical
Industries
16. PROCESS DESIGNVolume of Fermenter:Conversion = 70%.Reaction
Time = 48 hrs.Batch Time (tB) = 52 hrs.No. of Fermenters used
=2Working Pressure of Vessel (P) = 180 kPaTemperature of Reaction =
32 oC.pH = 4.8Mass flow rate in (ml) = 6700 Kg/hr.Density of
Material in Fermenter () = 1200 Kg/m3.
17. VOLUME OF FERMENTERNow;tB = 52 hrs.Density of Feed () =
1200 Kg/m3.Now;ml = 6700 Kg/hrTherefore; Vr = 6700 x 52 1200 Vr =
290 m3. REF: Chemical Process Engineering Design and Economics By
Harry Silla
18. Now;We allow 30% of volume of fluid as the free space in
the fermenter.Hence;With 30% allowance; VT = 1.30 x Vr = 1.30 x 290
= 377 m3.REF: Chemical Process Engineering Design and Economics By
Harry Silla
19. Dimensions:H/D = 1.5VT = x (D2/4) x L = x (D2/4) x 1.5D =
(3/8) x (D3)VT = 377 m3.Hence, putting in above equation;D = 6.8
m.H = 10 m
20. Now;Height of Dished Bottom =1m( From
Literature)Therefore;Total Height = 10 + 1 = 11 m.
21. MECHANICAL DESIGNWALL THICKNESSFor the calculation of wall
thickness we have to calculate the total pressurewhich is the sum
of static pressure and operating pressure of the fermenter. Static
Pressure (Ps) = x g x H = (1200 x 9.81 x 10)/1000 = 129 kPa. Total
Pressure at base = Ps + P = 309 kPa. Maximum allowable pressure =
1.33 (309) = 410 kPa. REF: Plant Design and Economics for Chemical
Engineers Max S. Peters et al.
22. WALL THICKNESSWall thickness = P x ri + Cc SEj 0.6PMaterial
= Carbon Steel.Working Stress of Carbon Steel,S = 94408 KN/m2.Joint
Efficiency, Ej = 0.85Internal Radius, ri = 3.4 mCorrosion allowance
= 2mm.Therefore wall thickness = 0.017 + Cc = 0.017 + 0.002 = 0.019
m = 19 mm.Therefore outside diameter = Di + 2t = 6.84 m. REF: Plant
Design and Economics for Chemical Engineers Max S. Peters et
al.
23. REACTOR HEADThere are three types of heads:Ellipsoidal
Head.Torispherical Head.Hemispherical Head.Ellipsoidal head is used
for pressure greater than 150 psi and for lessthan that pressure we
use Torispherical head. That is why we haveselected a Torispherical
head. REF: Chemical Process Engineering Design and Economics By
Harry Silla REF: Coulson & Richard Chemical Engineering, Vol
6.
24. TORISPHERICAL HEAD = 0.019 + 0.002 = 0.021 m = 21 mm.REF:
Chemical Process Engineering Design and Economics By Harry Silla
REF: Coulson & Richard Chemical Engineering, Vol 6.
25. MECHANICAL DESIGN AGITATOR DESIGN Agitator Dimensions are:
Impeller Diameter Da = Dt/3 = 2.2 m Impeller Height above Vessel
floor E = Da = 2.2 m Length of Impeller Blade L = Da /4 = 0.6 m
Width of Impeller Blade W = Da /5 = 0.4 m Width of Baffle J = Dt/10
= 0.68 m No. of Impellers =3 No. of Impeller blades =6 Distance
between 2 consecutive impellers = 2.2 m Shape Factors are S1 =
Da/Dt = 1/3 S2 = E/Dt = 1/3 S3 = L/Da = 0.27 S4 = W/Da = 1/5 S5 =
J/Dt = 1/10 S6 = H/Dt = 1.5 Tip Velocity = 3 6 m/sec Tip Velocity =
5 m/sec Tip Velocity = x Da x N Speed of Impeller = N = [5/( x
2.2)] x 60 = 44 RPM REF: Heuristics in Chemical Engineering Edited
for On-Line Use by G. J. Suppes, 2002REF: Unit Processes in
Chemical Engineering By Mccabe, Smith & Harriot
26. POWER REQUIREMENTPower no (Np )= 6.Shaft RPM (N)= 44 RPM =
0.7 rev/secPower = (Np x N3 x Da5 x )/gc = 52 hp.Now,Assuming the
impeller is 85 % efficient:Actual Power required = 52/0.85 = 60
hp.
27. BAFFLE DESIGNNo. of baffles = 4.Width of one baffle = Dt /
10 = 0.68 m.Height of baffle = 10 m.
28. VISUAL DISPLAY OF AGITATOR WITH DIMENSIONS
29. VISUAL DISPLAY OF FERMENTER WITH DIMENSIONSFRONT VIEW
30. VISUAL DISPLAY OF FERMENTER WITH DIMENSIONSCooling
AgitatoJacket r 0.68 Width of 2.2 m m Baffle 6.80 m 6.84 mTOP
VIEW
31. HEAT TRANSFER CALCULATIONCooling fluid used = Cooling
Water.Cooling Jacket area available (A) = 17 m2This area is
obtained from Table 7.3 in Chemical Process Engineering Design and
Economics by Harry SillaCW inlet temp = 20 oCCW outlet temp = 28
oCApproaches; T1= 32 20 = 12 0C T2= 32 28 = 4 0C LMTD = 7.3 0C =
7.3 0K REF: Chemical Process Engineering Design and Economics By
Harry Silla
32. HEAT TRANSFER CALCULATIONHeat of Reaction; Q = Hr = 1.1 x
106 kJ/hr Design Overall Coefficient = UD = 170 W/ m2. 0KNow; Heat
Removable by Jacket; Qj = UD x A x LMTD = 23579 W = 8.5 x 107
kJ/hrSince the heat of reaction (1.1 x 106 kJ/hr) < heat
removable by jacket (8.5 x 107 kJ/hr )Our design for a cooling
jacket is justified in comparison with a cooling coil.Now Cooling
water Flow rate can be calculated as:Heat to be removed from
reactor = 1.1 x 106 kJ/hrMass flow rate of water = Q/( CpTM) = 33
Tons/hr REF: Chemical Process Engineering Design and Economics By
Harry Silla
33. Identification Item Fermenter Item Name R-101 No. Required
8 Function Production of Industrial Alcohol by Fermentation
Operation Batch Type Jacketed, Stirred Tank Reactor Volume 377 m3
Height 10 m Diameter 6.8 m Temperature 32oC Working Pressure 1.8
atm Batch Time 52 hrs Height to Diameter Ratio 1.5 Type of Head
Torispherical Depth of Dished Bottom 1m Wall Thickness 0.019 m Head
Thickness 0.021 m No. of Baffles 4 Width of Baffle 0.68 m Height of
Baffle 10 mMaterial of Construction of Fermenter Carbon Steel
34. IdentificationItem AgitatorType Three 6-bladed Flat
TurbineNumber of Blades 6Impeller Diameter 2.2 mLength of Blade 0.6
mWidth of Blade 0.4 mImpeller Above Vessel Floor 2.2 mSpeed of
Impeller 44 RPMPower Required 60 hpIdentificationItem Cooling
JacketFluid Handled Cooling WaterInlet Temperature 20oCOutlet
Temperature 28oCFlow Rate 33 Tons/hr.Heat Transfer Area 17 m2UD 30
BTU/hr.ft2.oFRD 0.001 hr.ft2.oF/BTU