With sulfur emission rules tightening, industrial, chemical, oil refining, and metallurgical enterprises face an increasingly challenging task when it comes to satisfying environmental requirements while remaining profitable.
WSA is a highly versatile technology that has been specifically designed to keep emissions in check by removing a broad range of sulfurous compounds from key industrial processes. This proprietary system is ideal for bridging compliance gaps and replacing outdated legacy equipment that no longer meets modern environmental standards.
WSA technology can also be used to extend or enhance the performance of existing installations you want to retain. And for those aiming to exceed compliance requirements, it offers a way to create a competitive edge by improving your sulfur emissions profile.
No matter what the application, WSA can support regulatory compliance while helping to lower operating costs, reduce risk, and enhance your overall environmental performance.
With more than 90 % of the energy content in the feed streams recovered or recycled, and surplus energy exported as high-pressure, superheated steam, WSA is a climate-conscious solution that delivers both environmental and economic value.
Source: Topsoe
| WSA applications |
Typical feed streams |
| Oil refining |
H2S gas, Claus unit tail gas, sour water stripper gas, spent sulfuric acid (SmartSAR™ process), boiler flue gas (SNOX™ process) |
| Natural gas |
Sour gases |
| Gasification |
Sour gases (H2S, CO2, COS, etc.) |
| Coking |
Sour gases, waste gases and liquids from BTX refining |
| Viscose |
Lean gas and rich gas (H2S and CS2) |
| Pulp and paper |
Concentrated non-condensable gases (H2S, C2H2S, CH4S, CH3OH) |
| Metallurgy |
SO2 gases |
| Boilers |
Flue gas (SNOX™ process) |
| Other |
Sour gases, molten sulfur, chemical spent sulfuric acid |
WSA Uses Clean Gas, High-Pressure Steam, and Sulfuric Acid
WSA is a wet-gas catalytic process that is used to remove the wasted energy associated with drying the process gas. It also avoids the generation of wastewater or waste acid, making it a cleaner solution overall.
Step one is to generate SO2 gas at the appropriate working temperature of the catalyst in the SO2 converter. If the sulfur in the feed is SO2, simple preheating is all that is needed. If the feed is flammable, the sulfur compounds are oxidized to SO2 during burning.
The generated SO2 gas is then cooled in a waste heat boiler. The heat from this activity is collected as steam, which can be used elsewhere.
The second phase is catalytic conversion of SO2 to SO3, which normally occurs in two or three catalyst beds using Topsoe's proprietary VK-W type catalysts.
The heat energy released during this reaction is collected between the catalyst beds. After the last conversion stage, the gas is cooled, and the SO3 combines with water vapor to produce gas-phase sulfuric acid.
Finally, in the third phase, the process gas is cooled using a counter-current air flow in the WSA condenser. Clean gas escapes the condenser at the top, while condensed commercial-grade sulfuric acid collects at the bottom, where it is extracted, cooled, and stored.
To guarantee optimal energy efficiency, hot air from the WSA condenser can be used as preheated combustion air in the combustor or to preheat feed streams.
Compact, Reliable, and Safe
A WSA unit is compact and easy to integrate into existing plants. This straightforward, well-established technology offers a highly reliable solution with minimal complexity.
The entire system operates at or near atmospheric pressure (with the exception of the steam system), and it requires no activated carbon, heat transfer salts, or chemical absorbents, making it both safe and simple to operate.
Tailored to Your Requirements
WSA units can be customized to meet your specific process needs and emissions compliance targets. Topsoe can also adapt the design to fit seamlessly within your existing plant layout and equipment configuration.
The basic WSA arrangement for treating H2S gas is shown below.
Figure 2. How WSA works. Image Credit: Topsoe
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This information has been sourced, reviewed and adapted from materials provided by Topsoe.
For more information on this source, please visit Topsoe.