Sulfur removal

Topsoe’s commitment to the development of catalysts and process technology.

WSA and SNOX™ - desulfurization and nitrogen removal

The development of the Topsoe WSA process for removal of sulfur compounds from flue gases and production of sulfuric acid began in the late 70s. The WSA process builds on Topsoe’s extensive experience from the sulfuric acid business and on long-term commitment to development of catalysts and process technology. Major research areas are SO2 oxidation over sulfuric acid catalysts and acid condensation.


Fundamental studies

The ability to condense sulfuric acid vapors to produce concentrated sulfuric acid without emission of acid mist is a unique feature of the WSA process which has been achieved by comprehensive experimental and theoretical studies at Topsoe.

During cooling of gas containing sulfuric acid vapors, spontaneous homogeneous nucleation, heterogeneous condensation and wall condensation occur simultaneously. In order to develop and perfect the WSA condenser, Topsoe has studied these fundamental mechanisms of condensation thoroughly in lab scale investigations.


Proprietary glass tube technology developed by Topsoe is used in WSA for condensation of sulfuric acid vapors

Process development and optimization

Pilot and industrial scale testing combined with detailed mathematical modelling of the WSA condenser are used for investigation of the effect of condenser design and operating conditions on condenser performance in order to establish robust criteria for design and process control.

Another focus area of our development work is perfection of the WSA glass tube technology and continuous improvement of construction materials. The latter requires our expertise on materials testing in the harsh environments of sulfuric acid plants.

In order to utilize the full potential of the WSA technology, we use innovative flow sheeting in Topsoe’s proprietary calculation tools for optimization of different industrial applications. One of the drivers for this development is the increased global focus on energy consumption and CO2 emissions which calls for maximum heat recovery.


The SNOX™ process

For removal of both sulfur and nitrogen oxides from flue gases, Topsoe has developed the SNOX™ process which combines WSA and SCR DeNOx for optimum integration in power plants.