Chapter 6-Equipment Design(Production of Lactic Acid From Sugarcane Bagasse)
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Chapter 6-Equipment Design(Production of Lactic Acid From Sugarcane Bagasse)...
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I. INTRODUCTION
Several factors are considered in properly designing an efficient and economical production plant. Equipment design and its importance are significant in the industrial manufacturing plants that is at par with the production o f cost-effective and high quality products. With the reference with the previous chapters, an ideal process flow diagram was produced that determine the plant capacity and detailed computation of the mass and energy balances of the equipment. Equipment will be subject to determine their capability while being subjected to different parameters such as temperature, pressure and the likes. This manuscript will be providing an optimum design for the Fermentor, Rotary Drum Filter, Carbon adsorber and Evaporator. The importance of appropriate materials of construction must also be recogn ized. Products desired cannot be manufactured without considering the selection of appropriate and optimum materials of construction. This will be used to consider the container safe, economical for manufacturing and maintaining of the product quality. The materials to be selected must resist corrosion and sufficient strength to prevent breakdown caused by external parameters and processing of the product. Operating conditions con ditions are also one on e of the major considerations consider ations for the design of equipment. The design must be capable of producing the desired condition and must withstand any stresses and extreme conditions of the operation. Designing involves in the preparation of individual equipment specification sheet that is derived from the fabrication of different kinds of units with the help of available brochures. Modernization and development of new processes requires the use of chemical engineering principles and theories that is blended with actual limits with concern on the environmental and safety standards. 279
II. SPECIFICATION SHEETS A. Specification Sheet for Fermenter SPECIFICATION SHEET IDENTIFICATION Name of Equipment Equipment Code Equipment Type Operation Number required BASIC DESIGN DATA Function Operating Temperature Operating Pressure Material Handled VESSEL DESIGN Vessel Capacity Height Diameter Material of Construction Shell Thickness Head Thickness Welding Type IMPELLER DESIGN Impeller Type Rotational Speed No. of Baffles Baffle Width Impeller Clearance at the Bottom POWER REQUIREMENT Motor Size COOLING SYSTEM DESIGN Jacket Area Jacket Diameter Distance of Outer Shell to Jacket Thickness of Jacket Material of Construction Cooling Medium Cooling Temperature
Fermenter R – 2 2 Stirred-Type Bioreactor Batch Operation 2 units To ferment glucose into lactic acid 24 - 37°C 1.20 atm C6H12O6 (glucose), H2O, Na2SO4, Yeast Extract, CaCO3 6 m3 5.50 m 3.00 m SS304 3.00 mm 3.00 mm Double Welded Butt Joints (fully radiographed) 4-Pitched Blade 150 rpm 4 0.25 m 1m
No. of Impeller Impeller Diameter Impeller Width Impeller Length Distance between Impeller
3 1m 0.2 m 0.25 m 1.25 m
5 hp 3.25 m2 11.00 m 4.50 m 2.00 mm SS304 Water 25°C
280
Inoculation Pipe
Stirrer Shaft Seal
Vent
Working level
Impeller HT HL Baffle
Y Sampling point
Da
E
Drain Point
D
281
W La
282
ASSUMPTIONS 1. The fermentation will be conducted in a batch reactor. 2. 1 units of fermenter will be used per batch. 3.
An allowance of 5-6 hours for the cleaning and start-up of the fermenter will be allocated.
4. The material of construction of the fermenter will be S S304 for corrosion resistance. 5. ASME-UPV vessel design code will be used for the vessel design. 6. The impellers to be used will be Four-Pitched Blade turbines. 7. Motor efficiency of the agitator is 80 %. 8. The cooling system of the fermenter will be a jack eted type.
Design Equations: Residence Time of Fermentation From Bioprocess Engineering (2nd Edition) by Doran, P. M.:
t = μ1 ln1 μxq p p q =Yμm where: µ max – maximum specific growth rate x0 – initial cell density q p – specific rate of product formation pf/0 – final(f) / initial (0) product concentration 283
t b – batch culture time ms - maintenance coefficient
Vessel Design (Ref: Principles of Fermentation Technology by Stanbury, P.F. et al:Table 7.2. Details of Geometrical Ratios of Fermenters with Three Multi-bladed impellers)
•
Height of the Liquid (L):
V = H •
Internal Pressure (P):
P=P ρH gg •
Shell Thickness: For Cylindrical shell (Ref: Plant Design and Economics by Peters and Timmerhaus, Table 4 p.537)
t = SE 0.Pr 6P C
284
•
Head Thickness: For Ellipsoidal head (Ref: Plant Design and Economics by Peters and Timmerhaus, Table 4 p.537)
t = 2SEPD0. 2P C Impeller Design (Ref: Principles of Fermentation Technology by Stanbury, P.F. et al:Table 7.2)
•
Impeller Diameter:
= 13 •
Impeller distance from Vessel floor:
= 13 •
Length of Impeller Blade:
= 14 •
Width of Impeller Blades:
= 15 •
Baffle Width:
= 121 285
•
Distance between Impellers:
= 1.3 (Ref: Plant Design and Economics by Peters and Timmerhaus, page 241)
•
Power Requirement: For NRe>10,000 (Ref: Unit Operations of Chemical Engineering by McCabe and Smith, 5 th Edition)
P= N = Da – impeller diameter
•
Viscosity of Fermentation Broth: (Ref: Chemical Engineering Design Principles, Practice, and Economics of Plant and Process Design by G. Towler, et al. p. 440 Eq. 8-11.)
= ∑
286
Cooling System (Jacket) Design ( Ref: Ch.E. Handbook 8 th Edition, p. Eq. 5-31)
•
Surface Area of Jacket (Heating Area):
A = UΔTQ •
Log Mean Temperature Difference: (Ref: Ch.E. Handbook 8 th Edition, p. 5-7 Eq. 11-5a)
′ " ′ " (t t )t t ∆T = ln (t′′ t"" ) t t
Where 1- inlet condition, 2- outlet condition ’-hot fluid , ”-cold fluid
Diameter of Vessel with Jacket
πD V π D 2t Area of Jacket= H = 4 4
Outer Shell to Jacket Distance
d− = Jacketed Vessel DiameterOut2 er Shell Diameter of Tank t = SE Pr0. 6P C
Thickness of Jacket
287
NOMENCLATURE A j – Jacket Area, m2 c – Corrosion allowance, in Da – Impeller Diameter, m DT – Inside Diameter of Tank, m E – Distance of impeller from the bottom of the vessel g – Gravitational constant, m/s2 HT – Height of tank, m J – Baffle width, m L – Blade Length of Impeller, m mS – maintenance coefficient, h-1 P – Internal pressure, psi Q – Heat released during reaction, W q p – specific rate of product formation, h-1 Sw – Working Stress, psi tB – Batch time, h tH – Head thickness, mm tR – Reaction time, h tS – Shell thickness, mm Vliquid – Volume of liquid, m3 VT – Volume of tank, m3 W – Impeller width, m XA – Conversion Xo – initial cell density, g/L Y – Impeller distance, m µ - Viscosity of fermented broth, Pa-s µ max – maximum specific growth rate, h-1 ρ – density of fermented broth, kg/m3
288
Design Calculations:
0.017... =0.014... 0.003 0.001 2 t = μ1 ln1 μxq p p
Residence Time of Fermentation
From “Optimization and modeling of Lactic acid production” by Rasfid Roslina
p = . × p = . × p = p = 0 81.3667 g/L
, no product at the beginning of fermentation
Y p/s= 0.8248 kg Lactic acid per kg glucose, ms=0.098/h
q = q = x =
(0.09033 h-1) (0.8248) + 0.098 0.1725 h-1
9.26565 g/L
µ max = 0.09033/h.
289
0. 0 9033 1 ℎ 81. t = 0.09033 l n 1 3 6670 9. 2 6565 0. 1 725 ℎ ℎ = 42.62 hours (1.77days)
Total batch time:
= (Ref: Chemical Process Engineering, Design and Economics by Silla, Table 7.10 p. 397 )
Assuming that it takes the maximum time for all variables, therefore: tf = 2.38 h tc = 2.0 h te = 1.0 h t b = 42.62 h + 2.38 h + 2.0 h + 1.0 h
tb = 48 h (2 days)
290
Number of Units Required
=1 × ×2 days
Number of Units = 2 units Vessel Design In Fermented Broth: Component
Mass (kg)
Density(kg/m3)
Volume(m3)
Calcium Lactate
576.83
1,490
0.3871
Calcium Carbonate
7.44
2,710
0.0027
Calcium Sulfate
7.89
2,320
0.003
97.55
1,540
0.063
Water
5,395.31
1,000
5.395
Sodium Carbonate
6.14
2,540
0.0024
Total
6,094.39
Glucose
5.8535
Total Volume of Feed = 5.8535 m 3 /batch Total Mass = 6,094.39 kg/batch
ρ = ρ = 6,5.0894.53539mkg =
Average Density:
1,041.14 kg/m 3
291
Volume of Feed per unit of Fermenter:
V = 5 . 8 535 m V = 1 unit/bat/batchch = 5.8535 m3 /unit
From Brochure Mobius Bioreactors Specification Sheet, and upscaling the rated capacity of the bioreactor to 6000L:
D = 2.52 m = 99.21 in
(R=49.60 in)
H = 5.05 m
Height of Liquid:
H =
H = .. = P=P ρH gg P=101,325 Pa1,041.14 1.1685 m 9.81 = 1.1685 m
Internal Pressure:
113,259.57 Pa = 16.431 psi
292
Shell Thickness: For Cylindrical shell:
t = SE 0.Pr 6P C For Fully Radiographed Double-butt Welded: EJ = 1.00. For SS304, working stress (SW = 123 MPa = 17,844.56 psi) (Ref: ChE Handbook, 8 th ed., Table 25-11, p. 25-36)
t = ,..−... t =0.0457 in t =0.0457 in 161 in = ≈ , < 0.25 in
0.1081 in
2.748 mm (3mm)
Head Thickness: For Ellipsoidal head:
t = 2SEPD0. 2P C For Fully Radiographed Double-butt Welded: EJ = 1.00. For SS304, working stress (SW = 123 MPa = 17,844.56 psi) (Ref: ChE Handbook, 8 th ed., Table 25-11, p. 25-36)
t = ,..−. .. 293
t =0.0457 in t =0.0457 in in = ≈
, 10,000
P= N = Viscosity of Fermentation Broth:
= ∑ 295
Component
Mass (kg)
Mass Fraction
Viscosity
xμ
Calcium Lactate
576.83
0.0946
-
-
Calcium
7.44
0.0012
-
7.89
0.0013
-
-
97.55
0.016
0.00555
2.883
5,395.31
0.8853
0.000864
1,024.653
Carbonate Calcium Sulfate Glucose Water Sodium
1.212 6.14
0.001
6,094.39
1.00
0.000825
Carbonate Total
1,028.748
= ∑ =1,028.748
=
9.72E-04 Pa-s
Computation of the Reynold’s Number:
N = Dμvρ
296
From the brochure Mobius Bioreactors Specification Sheet, the type of impeller used is a 4-pitched blade turbine. The fermenter will be agitated at 150rpm.
,. . × N = .- −
=
2,254,732 > 10,000
Power Requirement
K n D = g ρ For Four-Pitched Blade turbine, K T = 1.27. (Ref: Unit Operations and Processes in Environmental Engineering 2 nd Edition by Reynolds and Richards, Table 8.2 p. 236)
K n D = g ρ . ,. . × P = P = 2,783.33 W ≈ 3.73 hp
297
Approximate Efficiency of an Electric Motor varies between sizes. In this equipment, a less than 5 kW turbine have a motor efficiency ƞ = 80%
(Ref: Chemical Engineering Design by Sinnott R.K., Table 3.1 p. 93 )
= = ..
= 4.66 hp ≈ 5 hp
From, the nearest standard size electric motor is 5 hp.
(Ref: Chemical Process Engineering, Design and Economics by Silla, Table 5.10 p. 240 )
Cooling System (Jacket) Design Surface Area (Heating Area):
A = UΔTQ 298
Q =4,173,629.01 × × × × = 16,101.96 W/unit
Log Mean Temperature Difference:
Fermentation Broth
Cooling Water
Inlet Temperature (°C)
Outlet Temperature (°C)
Inlet Temperature (°C)
Outlet Temperature (°C)
50
37
25
35
′ " ′ " (t t )t t ∆T = ln (t′′ t"" ) t t 5035 3725 ∆T = 5035 ln 3725 ∆ = 13.44 K
The cooling water will flow counter-current to the feed:
Counter-current Flow 60
50
C , e r u t a r 40 e p m e T
30
20 Feed
Cooling Water
299
From Chemical Process Engineering Design and Economics Tab le 7.6; for stirred tank (jacketed) using cooling water with organic solution. U = 50 – 80 Btu/h-ft2-°F. For an average value of U = 65 Btu/h-ft2-°F (369.07 W/m2-K):
(Ref: Chemical Process Engineering, Design and Economics by Harry Silla. 2003, Table 7.6 p. 386)
t A = 369.16,071m01.W9K6 W/uni 13.44 K = ≈ 3.246 m2
3.25 m2
300
Diameter of Vessel with Jacket: Cooling water flowrate is at 99,800 kg/day for Fermenter.
πD V π D 2t Area of Jacket= H = 4 4 × , V = V = m π2.525523×10 −m 99.1.186850 unimt = πD 4 4 ≈ 99.8 m3/unit
= 10.548 m
10.75 m
Outer Shell to Jacket Distance:
d− = Jacketed Vessel DiameterOut2 er Shell Diameter of Tank . − . +× d− = − = ≈ 4.01 m
4.25 m
301
Thickness of Jacket: For SS304, the working stress (SW) = 17,844.56 psi (Ref: ChE Handbook, 8 th ed., Table 25-11, p. 25-36)
t = SE 0.Pr 6P C P=1000 9.81 1.852 m P= 18,168.12 Pa = 2.636 psi
.. t = ,..−. t =0.0073 in t =0.0073 in 161 in = ≈ , < 0.25 in
0.0698 in
1.774 mm (2mm)
302
B. Specification Sheet for Microfilter SPECIFICATION SHEET IDENTIFICATION Name of Equipment Equipment Code Number of Elements Number of tubes per element Function Operation Type Materials Handled
Number Required BASIC DESIGN DATA Pressure Pressure Drop Temperature Filtrate Flow Permeate Flux Permeability Rate of Filtration Filtration Time Membrane Permeability Power Requirement Total Filtering Time Shell Thickness MEMBRANE DESIGN Filter Membrane Used Total element Area No. of tubes Area of membrane/per module Pore Size Membrane Diameter Length Operating Mode HOUSING DESIGN Type Materials of Construction Module Length PUMP DESIGN Pump Type
Microfilter F-3 2 100 To separate the cell mass and other solids from the fermented medium Continuous Tubular Microfiltration Membrane Calcium Lactate, Cell Mass, Calcium Carbonate, Sodium Carbonate, Calcium Sulfate, Residual sugars and Water 1 unit 1.5 bar 1.9738 atm ≈ 2 bar 25 – 30 °C 0.2438 m3/h 18.7402 L/m2-hr 329.3533 L/ m2-hr-atm 13.7 m3/hr 0.4276 hours 329.3533 L/m2-hr-atm 0.2438 hp 0.7276 hours/day 2.0199 x 10-3 m Polyether sulfone (PES) 9.3 m2 100 0.093 m2 0.1 micron 1.55 x 10-3 m 1.022 m Crossflow Filtration 2-port style Stainless steel AISI 316/316L 1.044 m Centrifugal Pump
303
DIAGRAM FOR MICROFILTER (F-3): D0 = 160.6 mm L0= 1022 mm
L0 = 1040 mm I0 = 125 mm
304
ASSUMPTIONS:
1. The Microfiltration is operated at constant pressure filtration. 2. Material of Construction – Stainless steel AISI 316/316L - Pentair X-Flow R-100 Microfiltration Membrane Brochure 3. Type of Microfiltration Membrane: Tubular Membrane - Membrane Filtration Handbook, pg.16 4. Operating Pressure:
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