Walther method

The Walther process for flue gas cleaning is a process that is suitable for both desulphurisation and denitrification . The process works on the principle of wet washing and uses ammonia solution . In the desulfurization, ammonium sulfate is produced after the following reaction , which is used as a fertilizer:

${\displaystyle \mathrm {NH_{3}+SO_{2}+H_{2}O\to \ NH_{4}HSO_{3}} }$

${\displaystyle \mathrm {NH_{4}HSO_{3}+NH_{3}\to \ (NH_{4})_{2}SO_{3}} }$

${\displaystyle \mathrm {(NH_{4})_{2}SO_{3}+0,5O_{2}\to \ (NH_{4})_{2}SO_{4}} }$

Similarly, in a second part of the plant, ammonium nitrate should be produced as a fertilizer during denitrification.

The process was technically developed by the Walther company from the 1970s. It was first used on a large scale as desulphurisation in 1983 in the Mannheim large power station (GKM). The originally planned denitrification system including pelleting system for the ammonium nitrate produced was never implemented.

Due to various material problems, a lack of engineering knowledge and the risk of explosion due to the by-product ammonium nitrate, several downtimes and retrofits were necessary to enable continuous operation. As the deadline for the new boilers to be equipped with flue gas desulphurisation was getting closer and the prototype plant was being disrupted again and again, the GKM decided to build a lime washing plant and then shut down the Walther plant.

Web links

• Swallow smaller toad . In: Der Spiegel . No. 22 , 1985 ( online - about problems with desulfurization systems).