However, to comply with the still more stringent regulations being placed on the sulfuric acid industry to lower SO2 emissions, Topsøe has developed a new sulfuric acid catalyst designated VK-701 LEAP5™. This catalyst was introduced to the market in 2010. VK-701 LEAP5™ is based on a novel technology which circumvents the internal transport deficiencies of existing commercial sulfuric acid catalysts and thereby offers exceptionally high activity in strong gases. Since the introduction of this catalyst, sulfuric acid plants have used this catalyst to meet emission requirements lower than previously possible with any catalyst solution. During Cobras, Topsoe will present examples on reducing SO2 emissions during both Start-up and steady operation, by implementing a tailor-made catalyst solution using VK59, VK69 and VK-701 LEAP5™.

1. Topsoe WSA technology
for small compact
sulfuric acid production
units
COBRAS 2015, Fortaleza, Brazil
1

2. 2
Presentation – main contents
• Introduction to Rio Seco
• Introduction to the WSA technology
• Typical WSA plant design
• WSA plant equipment
• References
• Summary

3. 3
Rio Seco
• Part of the large Buenaventura group in Peru
• Procesadora Industrial Rio Seco S. A. plant, Hural 100 km from Lima
• Processing of silver ore by use of among other things sulfuric acid
• Magnesium sulphates are produced and an H2S stream is generated which needs cleaning
• The H2S stream and sulfur is burned in WSA plant for making 60 MTPD of 98 % acid for local
consumption at the site
• Gas cleaning and acid production in same unit
• High pressure steam from the WSA process is used for electricity production
• Remote location so local electricity production has value
• Avoid authority inspections/problems related to buying acid

4. 4
What is WSA?
Wet gas Sulfuric Acid
A catalytic process for purification of sulfur- containing streams while producing
concentrated sulfuric acid
S
H2S
RSH
COS
CS2
SO2
SO3
(NH4)2SO4
H2SO4
Sulfuric acid
Cleaned gas
HP Steam

5. 5
Why WSA?
• Up to 99.95 % of the sulfur content is recovered
• Treats the mixture of H2S and S
• Sulfur is recovered as concentrated sulfuric acid of commercial grade
• No waste products
• NH3 and hydrocarbons are accepted in the feed gas
• Excellent heat management
• Simple lay-out, few components
• Attractive operating cost and lower investment than competing technologies

6. 6
Chemical reactions – WSA for H2S gas
H2S
SO2
SO3
H2SO4 (gas)
H2SO4 (liquid)
Combustion H2S + 1.5 O2 → SO2 + H2O + heat
Conversion SO2 + 0.5 O2 → SO3 + heat
SO3 + H2O → H2SO4 (gas) + heat
H2SO4 (gas) → H2SO4 (liquid) + heat
Gas cooling
Condensation

7. 7
WSA process lay-out, H2S gas
H2S gas
SO2 converter
Acid cooler
Product acid
Combustion air
Stack gas
Blower
WSA
condenser
Interbed
cooler
Interbed
cooler
Gas
cooler
Combustor
Air
Blower
Reaction:
H2SO4 (g) → H2SO4 (liq)
Reaction:
SO3 + H2O → H2SO4 (g)
BFW
Steam
drum
WHB
Reaction:
SO2 + ½O2 → SO3
Reaction:
H2S + 1½O2 → SO2 + H2O
CW
Superheated steam

8. 8
Rio Seco WSA plant process layout

9. 9
WSA plant lay-out, H2S based

10. 10
Rio Seco WSA plant

11. 11
Rio Seco WSA plant

12. 12
Combustor and waste heat boiler

13. 13
Rio Seco combustor and waste heat boiler

14. 14
Rio Seco burner internals including waste heat boiler internal by-pass

15. 15
SO2 converter

16. 16
SO2 conversion catalyst series VK-W
VK-WSX / VK-WL
9 mm Daisy
VK-WSA
25 mm Daisy
VK-WSA / VK-WH
12 mm Daisy

17. 17
WSA condenser
Cooling air inlet
Clean gas outlet
Hot air outletSO3 gas inlet
Sulphuric acid

18. 18
WSA condenser – modular construction
Hot Air Outlet
Cooling Air
Inlet
Clean Gas Outlet
Product Acid Outlet
Acid Gas
Inlet

19. 19
WSA condenser design

20. 20
Rio Seco sulfuric acid product cooler

21. 21
Rio Seco plant data
• Acid capacity is 60 MTPD of 98 % acid. 50 % from H2S gas and 50 % from burning of S
• Electricity production approx 1 MW(e)
• Foot print is 30 m x 18 m
• Cooling water consumption (circulating) is very low
• H2S waste gas incinerated with the sulphur
• H2S = 28 % vol
• N2 = 25 % vol
• CO2 = 45 % vol
• H2O = 2 % vol

22. 22
Typical scope of supply
• License package
• Basic engineering
• Proprietary equipment
• Catalyst
• Supervision during erection and commissioning
Optional:
• Detailed engineering
• Supply of other equipment
• WSA condenser internals
• Acid vessel, pumps and cooler
• Acid piping and instruments
• Interbed heat exchangers
• Process gas cooler
• Mist control units

23. 23
WSA plants – applications
• Oil refining (39)
• Coking (33)
• Gasification (31)
• Metallurgical industry (14)
• Viscose fibre industry (8)
• Other applications (10)
• Total (135) – From the 135 plants 11 plants are burning sulphur as feed

24. 24
WSA/SNOXTM references
2
1
3
4
1
2
6
1
13
14
15
11 5
4
9 10
3
5
6
7
8
1
2
4
5
6
8 9
5
6
2
3
5
2
1
3
7
8
12
4
3
74
2
19
9
10
Oil refining
Coking
Gasification
Metallurgy
Viscose
Sundry applications
18
4
1
7
3
17
16
11
8
9
20
10
11
13
12
10
5
11
17
15
12
14
24
2322
12
26
25
27
16
21
January 2014
15 1619 18
6
14
13
17
2021
19
18
22
7
28
20
23
8
29
13
31
23
2825 27
26
30
6 7
25
32
33
24
24
21
34
2931
9
30 35
14
26
27
36
37
38
2829
3233
Acid production: 4 – 1,140 MTPD
More than 135 references

25. 25
WSA technology summary
• Clean, proven and reliable technology
• No consumption of chemicals or other additives, and no production of waste products
• High conversion of sulfur containing feeds into commercial-grade sulfuric acid, with
possibility for NOx reduction if required
• Effective heat recovery
• Simple layout with relatively small plot area
• Attractive operating economy