Centrifugal Fan Applications for SCR Systems

Power plants and other industrial operations that involve combustion often use Selective Catalytic Reduction (SCR) systems for pollution control and environmental compliance. SCR systems pull flue gas out of the gas stream and inject it with a reagent (usually Ammonia or Urea) to reduce Nitrogen Oxide (NOx ) levels before exhausting to the atmosphere. SCR systems are a critical part of meeting acceptable emissions levels put forth by the Environmental Protection Agency (EPA).

Fans are a crucial part of the SCR process and require significant engineering consideration to ensure long life and reliable performance. These systems typically demand high static pressure at high temperatures, resulting in fans that operate at high tip speeds. Because of that, we often utilize a shrouded radial type wheel/impeller to accommodate the high tip speeds required while handling hot gas from the upstream combustion process.

Our representatives with Schaefer Industrial Air frequently work with SCR applications, so we spoke with them to get some insights for you.

Schaefer Industrial Air Insights on Fans for SCR Systems

Schaefer Industrial Air represents AirPro Fan & Blower Company across Northern Illinois and Northwest Indiana. The industrial roots in the region mean there are plenty of facilities producing power through combustion and using SCR systems to control their emissions.

Schaefer Industrial Air owner and AirPro representative Todd Schaefer outlined the important role of designing fans for the high speed and temperature at which fans in SCR systems must operate. An expanded page with all those details is coming soon. But here are some highlights from our conversation with Todd.

Keeping Your Bearings in an SCR System

In an SCR system, the fan is so important that there are often two identical units, one being redundant, in case of failure, because these essential systems cannot be offline. Downtime not only has an environmental impact, but also high costs in operations and penalties assessed by the Environmental Protection Agency’s Clean Air Act if emissions limits are exceeded.

In addition to redundancy, there are design, construction, and accessory considerations pros like Schaefer Industrial Air will be sure to specify when working with SCR system applications. A few of their top considerations are outlined below:

High Temperature & Tip Speed

In an SCR system application, the temperature is the biggest challenge, especially given the high tip speeds required to overcome the system resistance. There are critical protection points throughout and surrounding the fan, from internal clearances to insulation and shaft seals, all designed to protect the bearings from the application’s extreme temperatures, sometimes exceeding 1000°F.

Monitoring & Maintenance

Don’t leave your bearings to their own devices. Condition monitoring and proper maintenance are highly recommended. Bearing Resistance Temperature Detectors (RTD) and Vibration Sensors will allow you to monitor and protect your bearings. Any significant change in trending temperature or vibration levels should be investigated, as these are often early warnings of potential issues.

Design Customization

Every SCR system application has its own set of design requirements to consider when engineering the fan that’s moving the hot air and gas. Make sure you work with an application engineer who knows the nuances.

“This isn’t an application you want to do DIY. It’s just too important to get it right. AirPro engineers have a high degree of expertise with high temperature fans, and their fans are incredibly robust, making them very well-suited for SCR Systems. Just as importantly, they have a track record and a reputation that lets you know you can count on them to deliver on time and on point.” -Todd Schaefer, Schaefer Industrial Air

Learn More About Fans for SCR Systems

We want to thank our rep partners at Schaefer Industrial Air for their contributions to our SCR System application overview. To learn more from Schaefer, visit their website or contact them at (630) 672-4242.

If you have questions about industrial fans for SCR Systems or any other application, call 715-365-3267 or contact us, and one of our engineers will connect with you.

Content Related to SCR Applications

Here are related posts and case studies that might be of interest as you think about your application.

We’ll be highlighting several more of our applications and reps through the course of the year. Keep your eye on the All Things Fans blog and sign up for our newsletter to stay up to date, and please join the conversation on LinkedIn.

Contact us for a connection with your local rep or to schedule an appointment with an application engineer.