H2SO4 Flow chart

2. ABSTRACT
• Detailed designing of a four stage adiabatic catalytic
bed reactor for a H2SO4 plant.
• Plant capacity 1500 TPD
• Feed is at 1 atm and 410 degree centigrade.
• DCDA process is used to produce H2SO4.
• Process achievable conversion is 99.8 %
• Comprise mainly basic parts of manufacturing plant ,
their material and energy balances, heat duty of heat
exchangers.

3. INTRODUCTION
• Sulfuric Acid is a colorless highly corrosive strong mineral acid.
• Historical name : Oil of Vitriol
• Molecular weight :98.08
• Molecular formula: H2SO4
• Melting point: 10.5 degree C
• Boiling point: 340 degree C
• Solubility: Completely miscible with water.

4. Uses of Sulphuric Acid
Fertilizer Production 56%
11% Agricultural Chemistry
23% Other Applications
11% Manufacture of Chemicals

5. SULPHURIC ACID - WORLD MARKET

6. DCDA PROCESS :
Double Contact Double Adsorption Process
It is also called Contact Process.
Highly used as yield obtained is high.
More economical and preferable over chamber
process.

7. Chemical Reactions:
Produce Sulphur dioxide:
S (l) + O2 (g)→SO2 (g) Δ H= -298.3 kJ
Oxidies SO2 to SO3:
V2 O5
SO2 (g) + ½ O2 (g) SO3 (g) Δ H= -98.3 Kj
Adding excess O2 to the sulfer dioxide in the presence of
Vanadium pentoxide.
Formation of H2SO4:
SO3 (g) + H2 O(l) → H2 SO4 (l) ΔH= -130.4 kJ

8. Fig: Double Absorption Contact Process
The process flow sheet:

9. 1.Combustion Chamber
2.Converters
3.Absorbers
4.Heat Exchangers
The four stage catalytic reactor
Contact Process Equipments:
Total Pressure = 1 atm
Feed composition (Mole
Percent)
SO2 10
O2 11
N2 79
Overall Conversion = 99.8 %.
Fig: Four Stage Catalytic Reactor for Contact Process
Specification:

10. MATERIAL BALANCE:
Assumptions:
Complete burning of S
99.8% Conversion of S02 to SO3
Overall absorption of SO2 in process is 100%
 Humidity of entering air is 65% at 300 degree C
COMBUSTION
CHAMBER
S+O2 →SO2
Sin = 610.596
Airin =610.596
O2in = 915.894
O2out = 671.656
S O2 0UT =610.596
COMBUSTION CHAMBER BALANCE

11. FIRST THREE CATALYTIC BEDS(OVERALL BALANCE)
1st + 2nd + 3rd C.B
SO2 (g)+1/2 O2↔SO3 (g)
SO2in = 610.596
PRIMARY
ADSORPSTION
TOWER
4th Catalytic
Bed
O2in = 671.656
O2out =376.433
SO2out=20.15
SO3out=590.446
PRIMARY ABSORPTION
TOWER
SO3 (g)+H2 O(l)→H2 SO4
S O3in =236.178
SO2in=8.06
O2 in =150.573
H 2Oin
H2SO4formed=236.178
O2 to 4th bed
PRIMARY ADSORPTION TOWER BALANCE

12. FOURTH CATALYTIC BED BALANCE
FOURTH CATALYTIC BED
SO2(g) +1/2 O2(g)→SO3 (g)
SO2in =20.15
O2in=376.433
SO3in=354.268
SO2out = 1.221
O2out =366.969
SO3in= 373.197
SO2reacted =18.929
O2reacted =9.464
FINAL ADSORPTION TOWER BALANCE
FINAL ADSORPTION TOWER
SO3 (g)+H2 O(l)→H2SO4 (l)
SO3in=373.197
SO2in=1.221
O2in=366.969
H2SO4 formed=373.197
Total H2SO4 formed=
(Primary+Final)=609.375

13. ENERGY BALANCE:
LAW OF CONSERVATION ENERGY:
Energy can neither be created nor be destroyed, it can only be
Changed from one form to another.
HEAT BALANCE :
The energy or heat coming into a process in the inlet
materials plus any net energy added to the process is equal to the energy leaving
in the materials.
∑HR + (-∆H⁰
298 ) + q = ∑HP …(1)
Where,
∑HR =The sum of enthalpies of all materials entering the reaction process
(-∆H⁰
298 )= Standard heat of reaction at 298K and 101.32KPa
q= Net heat or heat added to the system
∑HP = The sum of enthalpies of all materials leaving the reaction process

14. NET ENTHALPY CHANGE AT CATALYTIC BED:
The temperature dependency of the heat capacity
C⁰P = a+ bT+ Ct2 +… …(2)
ΔH⁰RT = T∫298 ∑ (ni C⁰Pi) ReactantdT + ΔH⁰298 +298∫T ∑ (ni C⁰pi) ProductsdT….(3)
Where, ΔH⁰RT is the standard heat of reaction at temperature T (⁰K)
ΔH⁰RT = ΔH⁰298 +298∫T ( ∑ (ni C⁰Pi) Products -∑ (ni C⁰Pi) ReactantsdT….(4)
Enthalpy change,
∑H = ΔH⁰RT – ΔH⁰298 = ( ∑ ai ni )(T–298) + ((∑ bi ni)/2)(T2 – 2982) + …
…(5)
Enthalpy change between T1 K and T2 K
∑H = ( ∑ ai ni )(T1 –T2 ) + ((∑ bi ni)/2)(T1
2 – T2
2 ) + … …(6)
Standard heat of reaction at 298 K (ΔH⁰298 ) from heat of formation,
ΔH⁰298 = [ ∑ (ni ΔH⁰f) ]Products – [ ∑ (ni ΔH⁰f )]Reactants
Where,
[ ∑ (ni ΔH⁰f) ]products = standard heat of formation of products and
[ ∑ (ni ΔH⁰f )]reactants = standard heat of formation of reactants

15. FIRST CATALYTIC BED
Fig: ENTHALPHY BALANCE OVER FIRST CATALYTIC BED
Enthalpy in
(∑HR )=19880.838KW
Enthalpy out
(∑HP ) =31229.197KW
Enthalpy to be removed
(q)= -1065.99KW
Standard heat of reaction at 298K
(∆H⁰298 )=-12414.358KW

16. SECOND CATALYTIC BED
Enthalpy in
(∑HR )=22917.5705KW
Enthalpy to be removed
(q)= -529.504KW
Enthalpy out
(∑HP ) =25474.992KW
Standard heat of reaction at 298K
(∆H⁰298 )=-3O86.926KW
Fig: ENTHALPHY BALANCE OVER SECOND CATALYTIC BED

17. THIRD CATALYTIC BED
Enthalpy to be removed
(q)= -11.2604KW
Enthalpy in
(∑HR )=21728.873KW
Enthalpy out
(∑HP ) =22439.106KW
Standard heat of reaction at 298K
(∆H⁰298 )=-721.493KW
Fig: ENTHALPHY BALANCE OVER THIRD CATALYTIC BED

18. FOURTH CATALYTIC
BED
Enthalpy to be removed
(q)= -1.689KW
Enthalpy in
(∑HR )=19197.066KW
Enthalpy out
(∑HP ) =19715.176KW
Standard heat of reaction at 298K
(∆H⁰298 )=-519.799KW
Fig: ENTHALPHY BALANCE OVER FOURTH CATALYTIC BED

19. HEAT LOAD FOR HEAT EXCHANGERS:
Enthalpy change
First bed
outlet
Second bed
inlet
875K to 711K ∆H1 =-
9303.2204KW
Second bed
outlet
Third bed
inlet
771K to 705K ∆H2 = -
3746.1182KW
Third bed
outlet
Fourth bed
inlet
717K to 700K ∆H3 =-839.760KW
Heat load required between
beds
Temperature change
∑H = ( ∑ aini )(T1 –T2 ) + ((∑ bini)/2)(T2
1– T2
2) + …

20. REFERENCES:
1.Levenspiel, Octave, (1999). Chemical Reaction Engineering,
Third Edition
2.Fogler, H.S., 1999. Elements of chemical reaction engineering,
Third edition
3. Douglas K. Louie, (2005).Handbook of Sulphuric Acid Manufacturing ,
Second Edition
4. Bhatt, B.I., Vora, S.M., 1996. Stoichiometry. Third edition. Mc-Graw
Hill, New Delhi.