Patented NOx Emissions Reduction System (SCR)
A newly patented process developed by industry experts and emissions specialists delivers one of the safest and most effective NOx reduction methods for boilers and fired vessels. This innovative system uses direct urea injection in combination with Selective Catalytic Reduction (SCR) to significantly reduce NOx emissions while maintaining boiler performance.
U.S. Patent and Trademark Approval
In November 2020, the U.S. Patent and Trademark Office granted a patent for this simplified, low-risk NOx-reduction process designed specifically for packaged boilers. The patent outlines a “process for direct urea injection with selective catalytic reduction (SCR) for NOx reduction in hot gas streams and related systems and assemblies.”
Why Urea? The Safest Ammonia-Based Reagent
SCR systems typically rely on ammonia-based reagents, which vary in safety and regulatory requirements. This patented process uses urea, the safest of the three ammonia-based options (urea, aqueous ammonia, and anhydrous ammonia).
- Urea is classified as non-hazardous under the Hazardous Materials Identification System (HMIS), with only minor health concerns like possible irritation.
- The same urea solution is widely used as Diesel Exhaust Fluid (DEF) in automotive applications and is readily available.
In this process, urea is injected at specific points within the boiler system. As the NOx and urea pass through the NOx Reduction Catalyst, a chemical reaction breaks down NOx into two harmless byproducts: Nitrogen (N₂) and Water Vapor (H₂O).
Urea vs. Other Reagents
| Reagent | Risk Level | Regulatory Burden |
|---|---|---|
| Anhydrous Ammonia | High | Strict |
| Aqueous Ammonia | Moderate | Moderate |
| Urea (DEF) | Low | Minimal |
Because of its low-risk profile, urea is especially recommended for facilities that house people — such as hospitals, universities, and care centers — where safety is critical. Hospitals use boilers for sterilization and space heating, while universities rely on them for campus-wide hot water and comfort heating.
SCR: A Proven Path to Ultra-Low NOx Emissions
As air quality regulations continue to tighten nationwide, more industrial and institutional facilities are turning to SCR systems to reduce emissions. SCR remains the most effective technology for achieving ultra-low NOx levels without sacrificing efficiency.
This patented direct urea injection SCR technology meets stringent emissions standards across the country — including those set by some of the strictest air quality districts, such as those in California’s San Joaquin Valley.
For more on emissions regulations and district-level air permitting, visit the California Air Resources Board (CARB).
