October 12, 2006

 

Catalyst Choices Analyzed in Two Hour Hot Topic Hour

 

Experts from supplier and engineering companies provided very current data and claims relative to catalysts for coal-fired boiler applications. Controversy emerged on whether regenerated catalyst will cause more frequent replacement, on pitch selection and on  plate vs. honeycomb design. There were a number of interesting observations on application to lignite boilers, SO3 conversion, mercury oxidation, and poisoning.

 

This Hot Topic discussion along with those in recent weeks will be accessible on our website as part of Power Plant Air Quality Decisions. Specifically the catalyst discussion will be part of the new NOx Decision Tree. Only a few branches of the Decision Tree are in place but all the support intelligence is accessible.

 

The presentations made on Thursday can be accessed through the Decision Tree or directly from the links below (if you are a Power Plant Air Quality Decisions subscriber). For those of you who subscribe to the Utility Upgrade Tracking System, you can access the FGD and Mercury Decision Trees with this service but not the Particulate and NOx Decision Trees. There is a modest charge for upgrading to both services.

 

When you click on the links you see the power point presentations which were made but you do not hear the discussion. However, the full audio/web discussion may also be available as early as next week but certainly within the next two weeks.

 

Start►DeNOx►Physical►Components►Catalyst►Source►Argillon►Products
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Argillon supplies both honeycomb and plate SCR catalyst under the SINOx line. It will be supplying catalyst for the new Oak Grove 1 and 2 which will burn lignite. It also recently supplied catalyst for a horizontal SCR reactor.

 

 

 Start►DeNOx►Physical►Components►Catalyst►Source►Ceram►Products

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Ceram supplies honeycomb SCR catalyst and has 70 references with catalyst life exceeding 60,000 hours of service. Since 2003, they have been supplying catalyst with SO2 oxidation rate less than 0.50 percent (now at ten U.S. installations). Ceram says the pitch of a catalyst needs to be selected as a function of ash loading and ash characteristics. Ceram recommends catalyst wall thicknesses of 0.8 to 1.1 mm when considering ash erosion or 0.9 to 1.2 mm when considering regeneration. Ceram has supplied catalyst for an installation running at less than 0.3 lb/MMBtu NOx.

 

 

Start►DeNOx►Physical►Components►Catalyst►Source►Cormetech►Products:  SO3 Mitigation     SCR Catalyst

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Cormetech supplies honeycomb SCR catalyst with high geometric surface area which reduces volume and lowers pressure drop. A thinner-walled Cormetech catalyst may be possible in a high dust situation and Cormetech stressed it has addressed the strength issues of this catalyst. Cormetech supplied catalyst for one SCR unit burning bituminous coal that is reaching 0.03 lb/MMBtu NOx. Cormetech catalyst can provide SO2 oxidation rates below 0.1 percent for a single layer.

 

 

 Start► DeNOx ►Procedural Maintenance & Operations► Catalyst Evaluation ►Source► FERco ►Products

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FERCo has tested an in-situ SCR catalyst activity testing technique that allows catalyst activity testing at any time during operation (for example, after an upset condition or when running the SCR yearlong instead of just during the ozone season). It hopes to have the system commercial in late 2006/early 2007. The in-situ measurement compares well to standard laboratory testing, but should not be thought of as a replacement for the laboratory testing.

 

 

Start► DeNOx► Physical► Components► Catalyst► Source► Haldor Topsoe► Products

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Haldor Topsoe provides a composite/hybrid (corregated) SCR catalyst with Tri-modal pore distribution. The Tri-modal pore distribution is advantageous especially where arsenic poisoning is a problem. For gas turbine application the hybrid catalyst is very responsive—on one application the gas turbine had to be in compliance within 10 minutes of start-up and start-up occurred 200-300 times a year.

 

 

Start► DeNOx► Physical► Components► Catalyst► Source►Hitachi►Products

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Babcock Hitachi supplies plate SCR catalyst. It says the center metal plate of plate catalyst provides higher mechanical strength and higher erosion resistance, and the larger open area of plate catalyst has less pluggage problems and lower pressure drop. It is testing a higher mercury oxidation rate catalyst and balancing that feature with the SO2 oxidation rate.

 

 

Start► DeNOx ►Procedural► Maintenance & Operations► Catalyst Cleaning ►Source►SCR Tech► Products

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SCR-Tech says regeneration does not equal more frequent outages. It has regenerated corrugated, plate and honeycomb catalyst and has large buildings on site for storing regenerated catalyst for customers. Its regeneration is customized based on analysis of the deactivation and on customer expectation. All testing is done by third parties.

 

 

Start ►DeNOx► Procedural► Preliminary Analysis► Flow Distribution► Source► Airflow Sciences► Products

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The presentation by Robert Mudry of Airflow Sciences was not received in time for inclusion in the discussion but is now in the Decision Tree. The conclusions are:

 

  1. Gas flow patterns have significant impact on the performance of SCRs.
  2. Analysis and design tools including physical and CFD modeling can be utilized.
  3. Models are used to optimize the design of flow control devices to achieve fluid dynamic goals.
  4. Design optimization includes location of turning vanes, baffles, and mixing devices. It also includes optimum location of points for reagent injection.

 

Marilyn Martin of Steag also summarized conclusions about catalyst performance. Bill Ellison of Ellison Consultants emphasized the critical importance of the fly ash/sulfur ratio and the negative effect of SO3 on air heater performance.