SCR Management Cycle

Evonik Steag, as well as other SCR users, developed and have used for two decades what we refer to as the perpetual cycle of SCR management which describes the tasks to be undertaken during each outage when the SCR reactor is accessible.

Evonik Steag has found that performing all the tasks as outlined in the SCR management cycle on a perpetual basis allows for achievement of the lowest overall SCR operating cost while ensuring the most sought after SCR efficient performance.

Particularly in the early years of SCR operation, the operator should take advantage of every opportunity to access the system and quickly establish an accurate data history of the reactor and the installed catalyst.

SCR management cycle includes the following steps:

Visual reactor inspection and sampling of catalyst from each catalyst layer
Independent catalyst activity testing in a bench scale reactor
Independent SO2/SO3 conversion rate testing in a bench scale reactor
Measurement of catalyst pressure drop in a bench scale reactor
Determination of the main deactivation causes (chemical and physical)
Determination of opportunities and limitations for catalyst refurbishment
Documentation of deactivation causes & tracking of catalyst activity and DeNOx potential
Development of catalyst management strategies (exchange frequency, layer, etc.)

As soon as a reasonably long operating history has been documented which typically takes three to four cycles, the plant operator can start consolidating the data and begin developing an optimized catalyst management strategy. Such a strategy can either be developed for a single unit or for an entire fleet of SCRs.

As a user of 30 SCRs, Evonik Steag quickly realized the enormous economic benefit of managing the entire inventory of catalyst on a fleet-wide basis with a pool of catalyst flowing freely among the various units. Such a strategy includes the catalyst exchange frequency, catalyst rejuvenation or regeneration, and the purchase of new catalyst layers as necessary.