Catalyst Pluggage Due to Popcorn Ash - Cleaning and Regeneration Options

摘要

A number of bituminous coal-fired units equipped with SCRs have experienced severe catalyst pluggage problems often as a result of popcorn ash formation in the boiler and carry-over into the SCR reactor. These problems have made it necessary to take the SCRs off line after less than 3,000 operating hours due to undesirable pressure drop increases as a result of pluggage. Such cases have been known by some in Europe and have also been reported in the U.S. [1, 2]. The exact reasons for the formation of popcorn ash in the furnace are still not completely known, however, boiler operation and coal characteristics seem to play an important role. Typical popcorn ash particles as shown in Figure 1 may vary greatly in size (up to >1 inch) and specific gravity (between 0.2 and >1).