FGD and DeNOx
NEWSLETTER       

                                                                                                                    February  2002
                                                                                                                          No. 286

In-Situ Catalyst Regeneration

Regenerating the old catalyst instead of  replacing it can significantly reduce the cost of operating SCR units by increasing the effective life of the catalyst. A unique technology for in-situ catalyst re­generation (without removing catalyst from the SCR reactor) was devel­oped and patented by EnBW, one of the largest utility companies in Germany. During the last six years re­generation efficiency has been successfully dem­onstrated by EnBW for different types of catalysts (honeycomb and plate) installed at power plants burning various coals. Fourteen full-scale applications have regenerated over 1700 m3 of catalyst, and numerous lab scale tests with catalysts from U.S. power plants have shown ReAct™ to be applicable to U.S. SCR systems also. 

For optimal usage of ReAct™ and in planning the most reasonable catalyst management strategy, H. Maier and W. Götz of EnBW Engineering list the following parameters:

·         sufficient space around the SCR duct to place the regeneration equipment (10x30 ft)

·         man holes (2-3 ft diameter) to bring in the spray grid, collecting trough, and of course staff

·         Sufficient space between catalyst layers (about 6 ft)

·         exact knowledge of soot blowers position and the steel construction to adopt the construction of the regeneration equipment within the SCR duct.

·         information on activity (or even a sample) of the fresh catalyst

·         regular activity measurements of installed catalyst samples to establish a degradation pattern

·         frequent measurements of ammonia in the flyash as an indicator of current catalyst condition

·         availability of representative samples of catalyst for test regeneration.

For further information on EnBW's in-situ catalyst regeneration, see the July 2001 FGD & DeNOx Newsletter. To compare with SCR-Tech's catalyst regeneration, see the October 2001 Newsletter.

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