Dry Ice Blasting & Cleaning Blog

The Advantages of Cleaning SCR Catalysts with Sponge Blasting

Selective Catalytic Reduction (SCR) Unit Cleaning with Sponge Blasting

Good flow and distribution, a good ammonia-to-NOx balance, and maximum catalyst surface area for NOx and mercury oxidation are key to achieving maximum catalyst efficiency in a selective catalyst reduction (SCR) unit in power plants.

Sponge blasting does all three, removing hardened ash in ways that traditional hand-cleaning, vacuuming and vibration cleaning can’t – with less risk and at lower cost. Here’s how it works.

How Sponge Blasting Cleans SCR Units

Sponge blasting utilizes polyurethane foam media to safely remove potentially harmful, hardened ash from the surface and interior of the catalyst modules, with results that cannot be achieved by traditional methods.

SCR Catalyst Before In-Situ Sponge Blasting

SCR Unit Before Sponge Blasting

SCR Catalyst After in-Situ Sponge Blasting

SCR Unit After Sponge Blasting

Bottom of SCR Catalyst Layer Before In-Situ Sponge Blasting

SCR Unit Bottom Before Sponge Blasting

Bottom of SCR Catalyst Layer After In-Situ Sponge Blasting

SCR Unit Bottom After Sponge Blasting

Cost of Reduction in Catalyst Activity

Using cost averages of between $800,000 (regenerated  catalyst) and $1,200,000 (new catalyst – not including installation) with 192 modules per layer and a 25% loss over an 18-month outage cycle, sponge blasting can save $450,000 by recovering 60% of the loss—and costs significantly less than the savings:

Layer Investment Loss at 25% 60% Recovery
1 $1,000,000 $250,000 $150,000
2 $1,000,000 $250,000 $150,000
3 $1,000,000 $250,000 $150,000
Total $3,000,000 $750,000 $450,000


Traditional, hand-cleaning only recovers 20% of the loss, so sponge blasting saves an additional $300,000 in savings by comparison. And, as blockage percentage compounds over time (80% vs. 90%), the rate of erosion increases.

Costly effects of blockages:

  • Decreased catalyst efficiency
  • Reduced catalyst life
  • More frequent catalyst replacement
  • Increased pressure drop across the SCR
  • Increased fan power consumption
  • Poor ammonia distribution
  • Ammonia slip
  • Increase regent usage
  • Formation of ammonium bisulfate (ABS) in the air preheater
  • Increased air preheater fouling
  • Increased back-end corrosion
  • Reduced efficiency of mercury removal
  • Interrupted power production and revenues

Sponge Blasting Service

While we’ve made our name in dry ice blasting, sponge blasting is a more abrasive alternative to ice with the added advantage of not refracting or damaging the protective equipment of the person spraying it.

Sponge blasting is ideal for SCR catalyst cleaning and our team has deep experience in using it to provide superior results for our customers.

To learn more, contact us: we’ll discuss your situation and problems, estimate your costs, savings and ROI, and determine if a site visit is needed to finalize a quote.

Contact us to learn more about sponge and dry ice blasting


All photos courtesy of ReNOx