PLANT DESIGN FOR SULFURIC ACID MANUFACTURE

CHU492 PROJECT Harshadul Faseem.P Minas. VP Muhammed Dhanish

Guide: Dr.Lity Alen Varghese

CONTENTS

• Objective• Process• Plan• Mass balance• Further steps

OBJECTIVES

• Design a plant for manufacturing sulfuric acid with a capacity of 1000 tones/day of 98% sulfuric acid

• Optimization of processes

• Maximize the heat recovery

• Reduce the emission of sulfur dioxide

PROCESS• Lead chamber process• Contact process

• Single absorption• Double absorption (DCDA)

Among these the DCDA process is the most modern process which has got increased yield and reduces stack emission of SO2

The DCDA process• Raw Materials

• Molten Sulfur• Air• Water

• Reactions

Process Flow Chart

PLAN• The whole project has been divided to seven

different stagesStage Work

1 Identification of the best process

2 Mass balance and heat balance of the selected process

3 Design of heat transfer equipments (two heat exchangers, two waste heat boilers)

4 Design of mass transfer equipments ( two absorption columns and drying tower)

5 Design of four stage catalytic converter and burner

6 Selection transport equipments (pumps and blower)

7 Optimization and cost analysis

MASS BALANCE

• Assumption• Complete burning of S in the burner• 99.8 % conversion of SO2 to SO3 in the reactor

• Overall absorption of SO3 in the process is 100%• 40% excess oxygen is provided • Humidity of entering air is 65% at 300 C

Simplified flowchart for mass balance

Dryer

Burner

Reactor Absorption column

Absorption column

Tank 1 Tank 2Molten sulfur

Calculation• Product = 1000 tones/day of 98% H2SO4

• Taking basis of 1hr operation • Primary estimations:

SUBSTANCE AMOUNT (kmole)

Final product :H2So4 416.67

Equivalent SO3 required 416.67

So2 needed (SO3/0.998) 417.502

O2 required 626.25

O2 supplied (40% excess) 876.75

Total amount of dry air 4175.01

N2 present 3298.26

Moisture present 110.98

Drying tower

2141.23 kmole98% H2SO4

2251 kmole97% H2SO4

4285.99 kmoleMoist air DRYER

4175.013 kmoleDry air

The Burner

BURNER3298.26 kmole N2

876.75 kmole O2

417.502 kmoleMolten sulfur

417.502kmole SO2

459.248 kmole O2

3298.26 kmole N2

Reactor (4 stage catalytic converter)

Stage % conversion1 74.02 18.43 4.34 3.1Overall conversion

99.8

417.502kmole SO2

459.248 kmole O2

3298.26 kmole N2

13.778 kmole SO2

257.385 kmole O2

403.724 kmoleSO3

3298.26 kmole N2

First three stages

Inter-pass absorber

Absorber 1

13.778 kmole SO2

257.385 kmole O2

403.724 kmoleSO3

3298.26 kmole N2

13.778 kmole SO2

257.385 kmole O2

158.01 kmoleSO3

3298.26 kmole N2

2450.718 kmole98 wt% H2SO4

2450.718 kmole100 % H2SO4

Reactor (fourth stage)

13.778 kmole SO2

257.385 kmole O2

158.01 kmoleSO3

3298.26 kmole N2

0.835 kmole SO2

250.91 kmole O2

170.95 kmoleSO3

3298.26 kmole N2

Final absorber

Absorber 2

0.835 kmole SO2

250.91 kmole O2

170.95 kmoleSO3

3298.26 kmole N2

0.835 kmole SO2

250.91 kmole O2

3298.26 kmole N2

1709.6 kmole98 wt% H2SO4

1709.6 kmole100 % H2SO4

Final absorber circulating tank

Tank 2

1709.6 kmole100 % H2SO4

1709.6kmole98 wt% H2SO4

189.95 kmole98 wt% H2SO4

189.95 kmolewater

Inter pass absorber circulating tank

Tank 12251 kmole97% H2SO4

2141.23 kmole98% H2SO4

462.25 kmole98% H2SO4

2450.718 kmole100 % H2SO4

2450.718 kmole98 wt% H2SO4

189.95 kmole98 wt% H2SO4

161.32 kmolewater

FURTHER STEPS

• Energy balance• Equipment design and selection• Optimization and cost analysis

Reference

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