Wet gas Sulfuric Acid (WSA) technology

Able to remove a wide range of sulfurous compounds from off-gases and waste streams in a string of different applications, WSA is a truly flexible solution. You can use it to keep emissions from your key processes compliant, with the possibility of more than 99.9% sulfur removal efficiencies.

Recycling or recovering more than 90% of the feed streams' energy content and exporting the excess in the form of high-pressure superheated steam, WSA technology is truly climate- friendly. And with limited capital expenditure and low operating costs, it provides you with a reliable path to low lifecycle costs.

Overall, the Topsoe WSA technology helps you stay compliant while limiting overall operating costs, reducing risks, and strengthening your operation's environmental profile. That's why it has achieved more than 40 years of well-documented commercial success in numerous operations worldwide.

WSA is a wet gas catalytic process that eliminates the energy waste and waste water production associated with drying the process gas. Here’s how it works:

1. The first step is production of an SO₂ gas at around 400°C. If the sulfur in the feed is already SO₂, preheating is all that is required. Other sulfurous feeds can be oxidized to SO₂ by combustion followed by cooling in a waste heat boiler, producing steam that can be used elsewhere.
   
   

2. Catalytic conversion of SO₂ to SO₃ takes place in one or more catalyst beds. The thermal energy given off by this reaction is recovered between the catalyst beds. After the last conversion step, the gas is cooled, and the SO₃ reacts with water vapor to form gas-phase sulfuric acid.
   
   

3. The process gas is cooled by a counter-current flow of air in the WSA condenser. Clean gas leaves from the top of this condenser and is sent to the stack. Condensed commercial-grade sulfuric acid exits from the bottom of the condenser, where it is cooled and sent to storage. The hot air generated in the WSA condenser can be used as preheated combustion air in the combustor or for preheating process gas or boiler feed water to ensure maximum energy efficiency. 

The output is the result or end product you're looking to get out of your refinery or chemical process. The output helps determine which technologies and catalysts you need.