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MANUFACTURING OFPHOSPHORIC ACID
Presented By
Sagar Mahajan Aniket Mali
Exam No. B120215939 Exam No. B120215940
BE Chemical
Under Guidance of
Prof. H L Kamble
Department of Chemical Engineering
AISSMS College of Engineering, Pune-01
1
1. Introduction
2. Literature Survey
3. Selection of Process
4. Process Description
5. Material Balance
6. Energy Balance
7. Equipment Design
8. Cost Estimation
9. Plant Layout
10. Safety
11. Conclusion
12. References
2
In this project, we are going to analyze the production of
phosphoric acid by wet process
Phosphoric Acid is made from Phosphate Rock
Figure 1: Structure 3
Food-grade phosphoric acid is used to acidify foodsand beverages such as various colas
Teeth whiteners to eliminate plaque.
As a chemical oxidizing agent for activated carbonproduction
As a cleaner by construction trades to remove mineraldeposits, cementations smears, and hard water stains
As a pH adjuster in cosmetics and skin-care products
As a dispersing agent in detergents and leathertreatment
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Sr . No.
Patent Title Author Patent No Process Raw Material Parameters
1. Process of manufacturing phosphoric acid
Casimer c Legal,Jr Pasadena
et al
US2504544Wet Process
Sulphuric acid & phosphate rock
P2O5=33%Cao=45.79%Composition:-Fluorine=3.66%Moisture=0.70%Conversion = 98%
2. Method of manufacturing wet process phosphoric acid
Asalchi Matsubara,Yoshito Yasutake
US3416887 Wet
Process
Phosphate rockH2SO4
P2O5=40%
So3=2-2.5%H2SO4=15-50%
Table 1: Literature Survey
6
Sr . No.
Paper Title Author Paper no Process Raw Material Parameters
3. Method of
preparing wet
process
phosphate acid
Feng
et al
US7172742
B2
Wet
Process
Decomposing
phosphate rock
in sulphuric
acid
Liq-solid ratio-2.3-2.7SO3 -0.09g/L
H3PO4-33-39wt%
P2O5-30-35%
Production=80%
4. Phosphoric
Acid
(Dryden’s
Outline of
Chemical
Technology,
3rd Ed.)
M. Gopal
Rao
Page No
150-153Wet
Process
Phosphate Rock
H2SO4
Phosphate Rock- 2.5 T
H2SO4 – 2.0T
CaSO4 – 2.7 T
Phosphoric Acid:
• Molecular formula : H3PO4
• Molecular weight : 98 gm/mole
• Melting point : 42.4ºC
• Boiling point : 213ºC
• pH: 1.5 (0.1 N aq. sol)
7
Different process are needed because of different rock and gypsum disposal systems
Two general types of processes are used
Wet Process
Thermal process
8
The processes that use phosphated minerals which are decomposed with an acid, are known as ‘Wet Process’
There are 3 Types of Wet Processes:
Nitric
Hydrochloric
Sulphuric
The process using sulphuric acid is most common and particularly used for fertilizer grade phosphoric acid
9
Main Reaction:
3CaO + P2O5 Ca3(PO4)2
Ca3(PO4)2 + 3H2SO4 3CaSO4 + 2H3PO4
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• SO3 + H2O H2SO4
• 2CaO + 2F2 2CaF2 + O2
• CaF2 + H2SO4 + 2H2O 2HF + CaSO4.2H2O
• 6HF + SiO2 H2SiF6 + 2H2O
• CaO + H2O Ca(OH)2
• Ca(OH)2 + H2SO4 CaSO4.2H2O
• Al2O3 + 3H2SO4 Al2(SO4)3 + 3H2O
• Fe2O3 + 3H2SO4 Fe2(SO4)3 + 3H2O
• CO2 + H2O H2CO3
11
Figure 2: PFD 12
Phosphate Rock: Ground to 200Mesh
Reaction Time: 4 – 6 Hr
98% conversion
By-Product: Gypsum(CaSO4.2H2O)
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14
1000 kg/day of Phosphoric Acid
Batch of 8hr
Slurry Feed ratio 1:2.5
Excess H2SO4 =1.4
98% Ca3(PO4)2 conversion
15
COMPOUND CONTRIBUTION (%)
P2O5 32
CaO 49
SiO2 5
F 4
Al2O3 2
Fe2O3 2
CO2 1
SO3 2
Moisture 1
16
% by mass
Table 2: Rock
1
2
3
4 Vent720.05 Kg Rock
+
1925.13 Kg Water
734.67 Kg H2SO4
Table 3: Material Balance for Reactor
To
Filter
17
3 5
6
Liquid to Sedimentation Tank
Gypsum
+
Waste
Assuming 85%
Filter efficiency
From
Reactor
Table 4: Material Balance for Filter
18
6
7To
Evaporator
Table 5: Material Balance for Sedimentation Tank
From
Filter
19
8
7
10
Water Vapours
To
Evaporator IIFrom
Sedimentation Tank
Table 6: Material Balance for Evaporator I
20
11
STEAM
9
483.29 Kg
483.29 Kg
9
13
From Evaporator I
Table 7: Material Balance for Evaporator I
21
14
10
12
483.29 Kg
483.29 Kg
Water Vapours
To
Evaporator III
12
16
Water Vapours
To
CondenserFrom Evaporator II
Table 8: Material Balance for Evaporator I
22
17
13
15
444.47 Kg
444.47 Kg
23
Table 9: Properties of Components
24
Ca3(PO4)2 + 3H2SO4 + H2O 3CaSO4.2H2O+ 2H3PO4
Formula ∶ ∆𝐺𝑓𝑅 = ∑(𝑝𝑖 × ∆𝐺𝑓𝑖)𝑝𝑟𝑜𝑑𝑢𝑐𝑡 − ∑(𝑟𝑖 × ∆𝐺𝑓𝑖)𝑟𝑒𝑎𝑐𝑡𝑎𝑛𝑡
where ∆𝐺𝑓𝑖 = Gibbs free energy of ith component
𝑝𝑖 = Stoichiometry of Product
• ∆𝐺𝑓𝑅 = 3 × −1797.44 + 2 × −1111.68 − [ 1 × −3884.84 +
3 × −690.06 + (6 × −237.18)]
• ∆𝑮𝒇𝑹 = -237.58KJ/Kmol
• Reaction is feasible
25
Base Temperature : 298 K
26
Table 10: Total Heat of Reaction for 1 Batch
∴ −∆𝐻𝑅 = 3448.526 KJ
27
1
2
3
4 Vent
To
Filter298 K
343 K
298 K
Table 11: Total Heat of Reaction for 1 Batch
Heat to be Added by Jacket = 354055.907 KJ
Steam of 105oC is used at 0.64 Kg/min-batch
28
3 5
6
Liquid to Sedimentation Tank
Gypsum
+
Waste
Assuming 5%
Energy Loss
From
Reactor343 K
339.5 K
339.5 K
Table 12: Energy Balance for Filter
6
7To
Pre-Heater
Table 13: Energy Balance for Sedimentation Tank
From
Filter
29
8
339.5 K
337.5 K
337.5 K
Assuming 3%
Energy Loss
First Effect: Wsʎs + WF(tf-t1) = W1ʎ1
Second Effect: W1ʎ1 + (WF-W1)(t1-t2) = W2ʎ2
Second Effect: W2ʎ2 + (WF-W1-W2)(t2-t3) = W3ʎ3
WF-W1-W2-W3 = WP
Steam Supplied: 483.2913 Kg
Vapours Out: 1329.191 Kg
Average Heat Transfer Area Required = 36m2
Steam Economy: 2.75
Table 14: Energy Balance for MEE
30
31
32
We calculated the total volume of input material
Volume of reactor is taken in 10% excess
Diameter, Height and Thickness of reactor
assuming 𝐿
𝐷=1.5
Various stability checks
Total weight of the reactor
33
Volume of cylinder = 𝜋𝑅2𝐻
Weight = 𝜋𝐷𝐻𝑡𝑝
Tangential Stress = 𝑓𝑡 =𝑃 (𝐷𝑖+𝑡)
2𝑡
Stress due to Internal Pressure = 𝑓1 =𝑃×𝐷𝑖
4𝑡
Stress due to Weight = 𝑓2 =𝑊
𝜋(𝐷𝑖+𝑡)×𝑡
𝑓𝑎 = 𝑓1 + 𝑓2
𝑓𝑟 = [𝑓12 − 𝑓1𝑓𝑎 + 𝑓𝑎
2 + 3𝑓22]0.5
34
Table 15: Design of Reactor
35
Calculated the total volume of input material
Volume of tank is taken in 20% excess
Calculations same as for reactor
Diameter, Height and Thickness of tank assuming 𝐿
𝐷=1.5
36
Table 16: Design of Sludge Separator
We calculated number of tubes required.
Pitch of tube: 75mm (Triangular)
𝐴 =𝑁×0.866×𝑆𝑇
2
𝛽𝛽 = 0.9
Area of Central down-take = 40% of CSA (Tubes)
Diameter of Tube Sheet
Thickness of Calendria
Thickness of Tube Sheet
𝐾 =𝐸𝑆×𝑡𝑆 𝐷𝑜−𝑡𝑆
𝐸𝑡×𝑁𝑡×𝑡𝑡(𝐷𝑡−𝑡𝑡)𝐹 =
𝐾
2+3(𝐾)
𝑡𝑡𝑠 = 𝐹 × 𝐷𝑜 ×0.25×𝑃
𝑓
37
Area of Drum
𝑅𝑑 =𝑉
𝐴
0.0172×𝜌𝑙−𝜌𝑣𝜌𝑣
Rd =0.8
Thickness of Vapour Space.
Design for all 3 evaporators will remain same
As the heat transfer area required is equal.
38
Table 17: Tubes and Calendria Specifications
39
40
Table 18: Vapour Space and Head Specifications
41
Figure 2: CFD – Geometry of Evaporator
42
Table 20: Equipment Cost
Final Equipment Cost is 30% excess for supports, pumps, etc.
Therefore, FCE = 1.3 × 2858522.5 = 3716079.3
43
Table 19: Material Cost
Fixed Capital (FCI)
Working Capital (WCI)
TCI = FCI + WCI
= 24773862 +17279693 = ₹ 4,20,53,555
44
Manufacturing Cost
General Expenses
TPC = Manufacturing Cost + General Expenses
= 24773862 +17279693 = ₹ 1,50,93,453
45
Selling Price of H3PO4(SP)= ₹ 80
Operating Time = 330 Days/Year
Capacity of Plant= 1000 Kg/Day
Taxes = 30% of GP
Income = SP × Capacity × Cycles
= 80 × 1000 × 330 = ₹ 2,64,00,000
Gross Profit (GP)= Income – TPC = ₹ 1,13,06,547
Net Profit = GP – Taxes = ₹ 79,14,583
46
Rate of Return:
𝑟 =Net Profit
Total Capital Investment× 10
=7914583
42053555.8× 100 = 𝟏𝟖. 𝟖𝟐%
Pay-out Period:
T =Total Capital Investment
Net Profit + Depreciation= 5.08 𝑌𝑒𝑎𝑟
47
48
After the process flow diagrams are completed and before
detailed piping, structural, and electrical design can begin,
the layout of process units in a plant must be planned
This layout can play an important part in determining
construction and manufacturing costs
Must be planned carefully with attention being given to
future problems that may arise
49
Operational convenience and accessibility
Economic distribution of utilities and services
Type of buildings and building-code requirements
Health and safety considerations
Waste-disposal requirements
Auxiliary equipment
Space available and space required
Roads and railroads
Possible future expansion
The principal factors to be considered are :-
50
51
Figure 3: Plant Layout
52
Keeping the number of incidences and accidents zero
Having a robust and dynamic safety program
Major Hazard is Fire
Using inherently safe equipment
Carrying out independent audit from competent organizations
Abide by all the Govt. laws and hold sacred all the engineering ethics
Regular training and drill of the employees and workers
Creating safety policies
Developing and monitoring safety programs
53
• Wet process was selected for the production of Salicylic Acid.
• Production capacity was selected as 1 Ton/Day after studying supply and demand data.
• From analysing the residence time of the process, three batches per day were selected.
• Energy balance was done for entire process.
• Design of the equipments was done.
• Costing of equipments was done.
• Plant layout is drawn.
54
55
R K Sinnott , “Chemical Engineering Design,” 4th ed.,
Elsevier Butterworth-Heinemann (2005)
J P Holman, “Heat Transfer”, 6th ed., McGraw Hill Book
Company (1986)
Donald Q Kern, “Process Heat Transfer,” McGraw Hill
Book Company (1988)
Robert H. Perry, “Perry's Chemical Engineers' Handbook,”
8th ed., McGraw Hill (1934)
V. V. Mahajani and S. B. Umarji, “Joshi’s Process
Equipment Design”, 5th edition, Trinity Publications.
56