“NOx Catalyst Performance on Mercury and SO3 is very Complex - Hot Topic Hour Conclusion on February 27, 2014

 

The speakers yesterday demonstrated lots of expertise and experience. The clear message is that the decisions about selecting and replacing NOx catalyst have a major impact on SO3 and mercury emissions. You can pay more for catalyst and obtain better performance on the combination of pollutants. You can vary the replacement cycle to address the combination of pollutants and not just NOx.

 

Other system decisions are intertwined with those involving catalyst.  Do you add halogens with the fuel?  How are you going to prevent mercury re-emissions?  What about fuel changes and even changes in goals such as the amount of pollutants to remove?

 

The speakers demonstrated that a lot of time and effort has gone into understanding the relationships among all these different variables.  Techniques for laboratory testing and micro and bench scale simulation are also improving. So the state of the art is progressing.

 

McIlvaine suggested that all these complex variables be segmented into three categories:

 

 

McIlvaine further questioned whether more attention should be paid to the “no shut down” variables. For example, one can compensate for the deteriorating performance of the catalyst by steadily increasing the halogen level in the fuel. Conversely, with fresh catalyst the halogen level in the fuel could be minimal.

 

This is exactly the opposite philosophy of “refined coal.” It provides a fixed halogen level in the fuel regardless of the system performance. One of the consequences of this operational mode may be accelerated corrosion of the air heater and other components. In other words, you have halogen overkill much of the time. But enough speculation, let’s move on to summarize the excellent presentations

 

Noel Rosha, P.E., Senior Applications Engineer at IBIDEN CERAM presented "SCR Catalyst Management Targeting Mercury Oxidation."

 

The company has developed a NOx catalyst management plan, CATLIFE® which calculates the number of catalyst events and the cost of those events depending on changing goals for pollutant reduction and variables such as fuel changes. Noel provided this summary.

 

Catalyst management planning becomes increasingly complex. Accurate catalyst management planning considers ALL aspects of SCR and boiler unit operations. MATS will change the approach to catalyst management. Catalyst management strategies can be optimized to support high mercury oxidation rates. Opportunities to optimize will be site specific and fuel dependent.

 

Chris Reeves, Ph.D., Development Project Manager at Cormetech, Inc, discussed advanced catalysts , COMET™ which  significantly improve Hg oxidation performance while  maintaining  high DeNOx activity and equivalent SO2 oxidation performance. Chris acknowledged the influence of layer position, halogen in the fuel, temperature, CO, O2, H2O and SO2.  Reactor condition is another variable. Lab studies with the new catalyst show considerable improvement in mercury oxidation. One graph shows the new catalyst with over 80 percent oxidation compared to less than 70 percent with the standard offering. 

 

Brydger Van Otten, Chemical Engineer in the Engineering Research and Development Department at Reaction Engineering International, focused on the problems caused by  SO3 using the MerSim Model.” The model has been validated from data sets at 28 plants and takes into account varying amounts of SO3 and the resultant change in mercury capture based on a standard set of conditions including ACI, particulate equipment, fuel etc. Some of the findings are

 

 

 

The entire February 27 recording can be heard at:  NOx Catalyst Performance on Mercury and SO3    86 minutes
You will need to enter your name and email address after clicking link to view recording

 

Bios, Abstracts and Photos are as follows:  BIOS, ABSTRACTS, PHOTOS - February 27, 2014.htm

 

The individual presentations are as follows: