PM_2.5 Compliance will be tough but not Impossible - Hot Topic Hour - May 12, 2011

Good discussions yesterday supplemented a strong trio of speakers as the various options for PM_2.5 compliance were reviewed.

Steven A. Jaasund, P.E. Manager of the Geoenergy Division of A. H. Lundberg Associates, Inc., explored the pros and cons of retrofit wet ESPs in the utility environment. Wet electrostatic precipitator technology is a logical add-on alternative to help meet these PM_2.5 compliance rules. This is particularly true if boiler emissions are already being treated with a wet FGD system. Steve says that some particulate mercury may be removed along with the fine droplets and particles but mercury in the vapor state will pass through. On the other hand arsenic, cadmium, lead and all the other particulate heavy metals will be captured. Steve cautioned the audience that while sulfuric acid mist is very efficiently removed there are condensibles falsely measured in the impinger in a test train which are not going to be reduced with a WESP. For example some SO₂ may be absorbed making the condensable measurement higher than it truly is.

John D. McKenna, Ph.D., principal and founder of ETS, Inc., discussed compliance strategy options and costs for PM_2.5 control for utility coal-fired boilers. Capital and operating cost were compared for three alternatives: electrostatic precipitators, pulse jet and reverse air baghouses. Precipitators offer lower cost solutions, but they are not likely to be efficient enough to meet proposed regulations. Membrane pulse jet filters e.g., membrane on PPS substrate) are less expensive than reverse air glass filters with membranes on a life cycle basis. Both can meet very low particulate levels. But if there are tube leaks or holes, efficiency can quickly fall and result in noncompliance with the new proposed standards.

Terence R. Ake, Product Manager for Turbosorp^® Circulating Dry Scrubbers (CDS) at Babcock Power, Inc., told us why a circulating dry scrubber is one of the best options to reduce particulate matter (PM) from utility coal-fired and waste-to-energy boilers. The new standards target total particulate - both filterable (PM_2.5) and condensable particulate, and a circulating dry scrubber is one of the best options to remove both filterable and condensable PM while also removing SO₂, HCl and Hg. The system integrates a circulating lime tower with a fabric filter. The lime is recirculated from the bottom of the filter back into the fluidized bed. A wet scrubber has lower SO₃ removal because the SO₃ becomes a sulfuric acid mist prior to reaching the scrubbing tower. The mist is not absorbed or impinged to any great extend. In the CDS the mist can be captured in the fabric filter if it does escape the fluidized bed.

The Bios, Abstracts and Photos are linked below.

BIOS, PHOTOS, ABSTRACTS - May 12, 202011.htm