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Catalyst Regeneration at SCR-Tech

For catalyst that has significantly deactivated and that may also be severely plugged, blinded or poisoned, SCR-Tech offers an off-site regeneration process that restores deactivated SCR catalyst back to its original specifications and catalytic activity, often to activity levels beyond original. SCR-Tech’s proprietary ReGen™ process involves removing the deactivated catalyst modules from the SCR unit and shipping them to SCR-Tech’s regeneration facility where the catalyst is both cleaned and chemically reactivated.

SCR-Tech’s Patented Cleaning and Regeneration Process

Multi-Step Process

The regeneration process at SCR-Tech consists primarily of four individual steps:

• Ultrasonic Deep Cleaning — We first use patented ultrasonic process to remove physical and microscopic pluggage
• Soaking and Washing — During this step, chemicals remove poisons that have contributed to catalyst deactivation
• Regeneration — Catalyst activity is restored through chemical reactivation
• Heat Treatment — This final step seals in the newly added activity

In practice, the full ReGen process consists of numerous individual process steps. Not all of these steps are applied to every batch of spent catalyst to be regenerated. Through various testing methods, a catalyst-specific cleaning, rejuvenation and regeneration program — or “recipe” — is developed for each batch of catalyst from a particular SCR facility.

Removal of catalyst poisons: Our processes are capable of removing even the most severe chemical catalyst poisons, such as arsenic, phosphorus, chromium and thallium. Less severe chemical catalyst poisons, such as sodium, potassium and calcium are also efficiently removed along with physical restrictions such as fly ash plugging, surface blinding layers and other surface blockages including popcorn ash plugging.

Regeneration: The module is immersed into a proprietary bath containing the chemicals needed to reactivate the catalyst, thereby restoring the original activity level.

Activity Beyond Original

During the chemical reactivation process, the catalyst is initially supplied with essentially two major activity components:

1. The necessary or basic activity to achieve the required NO_x reduction performance at initial operation, and
2. Additional or useful activity to allow the specification duty to be met through some useful life.

These are depicted in the Ko (original activity) bar of the graphic below as the gray and red regions, respectively. Aging of the catalyst reduces the useful activity through channel plugging by ash, and by the blinding of the active sites on a microscopic scale by fuel constituents and other fuel-related poisons that attach to active sites, chemically deactivating or sealing them and rendering these sites impotent. These deteriorating factors reduce the catalyst activity until the useful life has been depleted. At that time, the catalyst must be replenished, either through the purchase of new replacement catalyst or through regeneration. Replacement is a more costly alternative and results in disposing of the basic activity still left in the catalyst. Regeneration, on the other hand, fully restores the useful activity of the spent catalyst, while still taking full advantage of all the basic activity, for significantly less cost than replacement. By increasing the number of catalytic sites available for reaction, SCR-Tech's process has even been demonstrated in certain cases to increase catalytic activity beyond the original level by as much as 25%, providing the potential for significant economic upside.

Activity Often Enhanced Beyond Original

Once regenerated, SCR-Tech returns the catalyst modules to the customer for reinstallation in the SCR unit. Upon reinstallation, the long-time deactivation rates and NO_x reduction performance of regenerated catalyst have proven to be essentially identical to new catalyst.