Particulate Training Hot Topic Hour Covers WESPs, Dry ESPs, Fabric Filters, Opacity Monitors and PEM CEMS on August 21

Six experts provided overviews of various particulate monitoring and control technology in a good 2-hour session. Bob McIlvaine raised some initial questions with his statement that “semantics proliferate when it comes to particulate.” The regulations are written around a specific particle size labeled 2.5 microns in diameter. However, most particles are not spheres but odd shaped particles. So the label applies to particles which are captured on the same plate in a cascade impactor. This capture is affected by particle density as well as size. So the bottom line is that whatever the cascade impactor catches on a specific plate is larger than 2.5 microns and everything passing through is smaller.

With the development of nano technology we have a whole new problem. The total weight is determined by a HEPA filter. Cleanroom operators use HEPA filters for primary collection and measure the inefficiency with particle counters. The problem is that particle counters cannot measure very small particles below 100 nanometers. An ultra-clean cleanroom is based on measurement of particles 100 nanometers and larger. For all intents and purposes particles below this size do not exist in either EPA dust measurement or in OSHA and FDA particle measurement.

It is ironic that the efficiency curves show the efficiency of dust collector media increasing as the particle diameter decreases below the 100 nanometer range. Is this because HEPA filters do not catch smaller particles or because the efficiency really increases? As the particle size decreases to five nanometers or so it is very possible that particles act as gases and penetrate openings as gases would. In any case all of this is speculation because of lack of measurement techniques.

The new cement MACT is using PM as a surrogate for heavy metals. Power plants are going to be regulated to reduce heavy metals. So the question arises as to how important are specific metals such as cadmium or arsenic? McIlvaine has created the universal metric QELD and that allows comparison on the impact of any pollutant. This is described at

http://mcilvainecompany.com/SURS/subscriber/Text/UEBI.htm

Mike Beltran of Beltran described the operation and performance of wet ESPs. Because of the cascading water down the collection plates or tubes in wet ESPs, they can capture high resistivity dusts. They are also effective in capturing SO₃ mist.

Particulate Continuing Decision Process For: Products

Operations and performance of wet ESPs. Presented by Mike Beltran, August 21, 2009 Particulate Training Session
http://www.mcilvainecompany.com/Particulate_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Mike Beltran - Beltran 8-21.pdf
 

John Caine of Southern Environmental was persuasive in his argument that old dry precipitators are not reliable and not likely to perform at lower efficiency during the period between outages. He cites the switch mode power supplies, the 16 inch spacing, the more sophisticated designs relative to gas distribution and other new design features which make replacements much more reliable than the 30-year-old precipitators operating still in many plants.
 

ESP Synergism of Old & New Concepts. Presented by John Caine at August 21, 2009 Particulate Training Session

http://www.mcilvainecompany.com/Particulate_Decision_Tree/subscriber/Tree/DescriptionTextLinks/John Caine - Southern 8-21.pdf
 

Devereaux Van Dyne of Albany Filtration, told attendees that Star bags increase the bag surface area by 1.6 to 2.4 times compared to the tubular bag. They are now available in all the fabric options that are used in tubular bags. Their space-saving features make them attractive as a retrofit to increase output of an existing production unit.

Particulate Continuing Decision Process For: Products

What is gained by the use of Star Bags, presented by Devereaux Van Dyne. Particulate Training Session August 21, 2009.

http://www.mcilvainecompany.com/Particulate_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Devereaux Van Dyne - Star-Bags - Aug 21 Training Session.pdf

 

John Brown of Midwesco (MFRI) points out that EPA ETV testing has allowed better evaluation of fabrics.  Two membranes were compared. The outlet emissions and efficiencies were similar but initial and residual pressure drops were significantly different. This results in substantial differences in energy consumption and bag life.

Particulate Continuing Decision Process For: Products

PM _2.5 Compliance presented by John Brown, Midwesco. August 21, 2009 Particulate Training Session

http://www.mcilvainecompany.com/Particulate_Decision_Tree/subscriber/Tree/DescriptionTextLinks/John Brown Midwesco.pdf
 

Derek Stuart of Ametek / Land Instruments

Derek made the case that transmissometers can accurately measure both opacity and weight of particulate. They are low in maintenance since there are no components in the stack. They have to be calibrated but are used extensively in Europe to demonstrate compliance with weight limitations.

Particulate Continuing Decision Process For: Products

Measuring Particulate Matter using Transmissiometry, presented by Derek Stuart. August 21, 2009 Particulate Training Session
http://www.mcilvainecompany.com/Particulate_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Derek Stuart Transmissometry - Ametek.pdf
 

Rich Brown of Altech made the case that PM CEMS rather than opacity monitors should be the choice of power plants. Since most power plants are being fitted with FGD systems it does not make sense to measure opacity prior to the FGD and assume that this is the particulate emissions. With the new HAPS rules under consideration it will be necessary to have more precise measure-ments.  Some FGD system suppliers have guaranteed to remove 50 percent of the particulate reaching the scrubber. The beta gauge type PM CEMS can be used to accurately measure particulate in the wet stack.

 Particulate Continuing Decision Process For: Products

PM CEMS rather than opacity monitors should be the choice of power plants. Presented by Rich Brown. August 21, 2009 Particulate Training Session

http://www.mcilvainecompany.com/Particulate_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Rich Brown - Altech 8-21.pdf