The high-performance scrubber REAplus

Ever since the 1980s, flue-gas desulphurization (FGD, or its German equivalent REA) plants have been filtering sulphur dioxide (SO₂) out of the flue gas from lignite-fired power stations. The scrubbing method, in which the SO₂ is washed out using limestone slurry, has long since proved its worth. Today, more than 95% of the desulphurization plants in power stations and industrial facilities worldwide are being reliably and successfully operated on the basis of this technology.

However, the high efficacy of today's flue-gas scrubbing is no reason for RWE to rest on its laurels. Its success is the spur that drives us on to develop new processes designed to make coal-based power generation even more environmentally compatible. This is where the REAplus concept comes in. This has been implemented in a pilot plant at the Coal Innovation Centre in collaboration with Andritz Energy & Environment (AE&E), a plant builder.

What counts in this concept is that we optimize even further the chemical processes in the desulphurization to achieve the highest possible degree of SO₂ capture. The progress here, compared with the previous method, lies in the staggered sequence of the scrubbing process and in improved contact between lime slurry and flue-gas SO₂. The pilot scrubs 50,000 cubic metres of flue gas an hour from the BoA power plant. Trialling is focusing on the capture targets to be achieved and the suitability for continuous operations.

REAplus' highly efficient desulphurization renders superfluous any pre-treatment of flue gases in the pilot CO₂ scrubbing plant that is likewise linked to BoA 1. The combination of REAplus and post-combustion capture creates conditions at Niederaussem that are unique worldwide for trialling modern, trail-blazing power-plant engineering.