Chemithon SafeDeNOx® Process Completes First Successful Ozone Season at Consumers Energy Plant Karn

The first commercial Chemithon SafeDeNOx® Urea-to-Ammonia Process was commissioned at Consumers Energy Plant Karn in May 2003 and operated as a continuous process until the end of the ozone season in October 2003. During this first season of operation, Plant Karn obtained 782.6 tons of NOx credits based on NOx emissions of 0.03 lbs NOx/million BTU.

One of the critical factors that made this possible was the high percentage “on stream factor” of the SafeDeNOx® process. The following chart shows the availability of the SafeDeNOx® system by month for the first season of operation. Performance was excellent with an average on stream factor of 98%.



Another key to the successful run was the very fast response time of the SafeDeNOx® process to changes in ammonia demand. The following chart from the Plant Karn control system illustrates the response of the SafeDeNOx® process to changes in ammonia demand. Note that the ammonia flow closely tracks the ammonia demand signal during both “ramp up” and “ramp down”. This is due to the use of a patented urea conversion catalyst in the SafeDeNOx® process that increases the urea to ammonia reaction rate up to 20 times relative to non-catalyzed processes.

Further, it is apparent from the chart that the reactor temperature and pressure remain constant during changes in ammonia production rate. The constant temperature and pressure mean that the ammonia concentration in the product gas from the SafeDeNOx® process does not change with changes in ammonia demand. This allows much tighter control of the ammonia flow to the SCR, resulting in lower NOx levels in the outlet stream. Plant Karn reached a 15ppm NOx level.

The SafeDeNOx® process was developed at the Chemithon Seattle R&D facility in response to the demand for a safer, cost effective alternative to storing ammonia on site. Process advantages of this latest technology include these:

  • Responds quickly to changes in ammonia demand
  • Uses a self-regenerating catalyst that significantly reduces the residence time of the ammonia in the system (minutes vs. hours of ammonia production)
  • Produces ammonia at a constant concentration (no slip)
  • Minimizes energy consumption by using molten urea and direct steam injection





© 2007 Chemithon Enterprises, Inc.