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Solutions and technologies shaping your business in the future

TopClaus® technology

Minimize sulfur recovery costs

Lower your ownership costs, protect your profit, and stay compliant with TopClaus®, an innovative solution that combines two proven technologies.

TopClaus® combines conventional Claus technology from Comprimo with the proven Wet gas Sulfuric Acid (WSA) process from TOPSOE™ to create a reliable and energy-efficient sulfur recovery unit. The result is a solution that will simplify sulfur recovery efficiency (SRE) compliance, reduce your CO2 footprint, and improve your bottom line.

Meet increasing industry demands
Claus installations with tail gas treatment in refineries and elsewhere are expected to reach SRE levels of 99.9 percent or more. Compliance with this requires an amine-based tall gas treatment unit (TGTU) to be placed downstream of the Claus unit.

It’s no secret that TGTUs are relatively expensive to install and operate. They also require high energy consumption to regenerate amine and incinerate the remaining H2S in a thermal oxidizer. That all adds up to high compliance costs and a larger environmental footprint.

With TopClaus®, SRE compliance is more straightforward than it is with a conventional TGTU. The solution significantly reduces the CO2-footprint of sulfur recovery, eliminating the need for amine regeneration and fuel gas to incinerate the tail gas.

In a TopClaus® unit it is possible to bypass ammonia-containing streams directly to the WSA unit. This avoids common ammonia issues in Claus units for higher reliability.

The TopClaus® process

1000xN_License_TopClaus_diagram Claus unit_v2

1000xN License_TopClaus_diagram WSA unit
How it works
TopClaus® is a combination of the Claus desulfurizing process and the wet gas sulfuric acid (WSA) process. Here’s how it works:

  1. Sour gas is treated in a simple, conventional Claus unit with 95–97% SRE to produce elemental sulfur.
  2. The Claus unit's tail gas proceeds to the WSA unit, where the remaining sulfur compounds are removed to yield a total SRE of 99.9 to 99.99%.
  3. The small amount of sulfuric acid produced in the WSA unit is returned directly to the Claus unit’s reaction furnace and reprocessed to elemental sulfur. This process allows all sulfur products to be produced in the form of elemental sulfur only. Thanks to TopClaus®’ flexibility, operators can also choose to export or consume the commercial-grade acid produced by the WSA unit.


The TopClaus® technology has been developed by TOPSOE™ and Comprimo, the leading licensor in gas treating and sulfur recovery technology. Learn more about Comprimo here.

Get in touch

Marie Vognsen
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