September 13, 2007

Fabrics for Coal-fired Boiler Baghouses: Higher Efficiency and Higher Performance (Hot Topic Hour Yesterday)

A number of the world experts on fabrics for coal-fired boiler baghouses participated on September 30 in discussions as well as a few formal presentations. One of the conclusions is that the improvements in the fabrics results in very high efficiency whether it is membranes or small diameter fibers. Various combinations of fibers and membranes in both the filtering surface and the scrim or substrate provide strength, corrosion and temperature resistance at lower cost than previous offerings.

Todd Brown of Daikin revealed the latest developments on Admirex. A PTFE fiber matrix provides the surface filtration. The support material can be glass or PPS or other material. One important feature is the slower deterioration in permeability compared to PTFE membranes. In a steel plant test the Admirex showed much less loss in permeability over a year’s campaign. Daikin has been making the roll goods at 40” diameter but as of this next month will be offering a 120” product as well.

There was considerable interest and questions from the participants in this new and promising product. Sargent & Lundy wanted to know if these bags were operating in a coal-fired power plant. The answer was “Yes” in Japan, but “No” in the U.S.

Todd displayed an interesting comparison of ETV performance testing on a number of different fabrics. They show Admirex as more efficient than the membranes. John Darrow of W.L Gore complimented Todd on the presentation but stated that more extensive testing with new fabrics has been undertaken since the time of the tests depicted in the chart and these tests have been reported on the ETV website. Tests on the L3650 Goretex membrane fiberglass laminate as posted show outlets with five zeros after the decimal place (g/dscm) as opposed to four in the chart.

The link to the verification statements for all the fabrics is

http://www.epa.gov/etv/verifications/vcenter5-2.html

The link to the Gore verification is

http://www.epa.gov/etv/pdfs/vrvs/600etv06042/600etv06042s.pdf

Terry McKenna recently moved from Toray to Ticona and is involved with the FORTRON PPS resins. PPS has been used with the COHPAC filter at TXU Big Brown Units 1 & 2 since 1996. EPRI has conducted extensive testing. PPS felt with a PPS scrim has showed good results. By switching from a 2.7 denier to a 7 denier, permeability is raised by 300-400 percent. PPS is being used in the TOXECON at We Energies Presque Isle. This provides a unique opportunity to record fabric performance when activated carbon is the main particulate. Terry was asked about the temperature limit of PPS. He indicated that it was related to the oxygen and that the fulcrum was 15 percent O₂ and 375°F.

Mark Aitken of Inspec Fibres pointed out the advantages of P84 (PI) in combination with other fibers. P84 is blended with Dolanit (PAN) in low temperature applications. It is blended with Procon (PPS) for high temperature applications. It can be used with PTFE. Most recently the advantages of a three blend composite with P84, Procon and PTFE have been shown.

 The power points of the presenters are already in the Particulate Decision Tree and can be viewed through the links below.

Todd Brown - Daikin

Continuing Decision Process For: Products

Admirex Performance - Todd Brown Hot Topic Hour Sept. 13, 2007

http://www.mcilvainecompany.com/Particulate_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Todd Brown - Daikin McIlvaine Hot Topic 09-13 Presentation.htm

 

 Mark Aitken – Inspec Fibres

Continuing Decision Process For: Products

Filter Media Selection for Coal-fired Boilers - Mark Aitken Hot Topic Hour Sept. 13, 2007

http://www.mcilvainecompany.com/Particulate_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Inspec Fibres Presentation Hot Topic Hour McIlvaine Sept 13, 2007.htm

Terry McKenna - Ticona

Continuing Decision Process For: Products

Fortron PPS Terry McKenna, Hot Topic Hour Sept. 13, 2007

http://www.mcilvainecompany.com/Particulate_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Terry McKenna - Fortron.htm

 

Hot Topic Blog on Sorbent Traps in Wet Stacks

Question from Juan Ramirez of Seminole Electric

We've been using Appendix K for a month now on our Unit 1 stack in Palatka, FL.  It is a "wet stack" with very high moisture -13%-16% H₂O. We are trying to extend our run times to the maximum number of days possible for the sorbent trap. Do you know of anyone doing this on a wet stack?  Just curious.

Thanks,

Juan Ramirez
Senior Environmental Engineer
Seminole Electric Cooperative Inc.
16313 N. Dale Mabry, Tampa, FL  33618       jramirez@seminole-electric.com

 

Reply from Jim Wright of CleanAir Engineeering

CleanAir has had some limited R&D-level experience with long-term sorbent trap monitoring in scrubbed stacks. Although we can't say for sure what the maximum number of days would be, we know that, under the conditions in which we have tested, we were able to get good results after 8-9 days of sampling. Our conditions were Eastern bituminous coal, wet scrubber, large utility, 15% water, moderate entrained scrubbant, 3-7 ug/dscm Hg, 1-gram carbon beds, 500 cc/min nominal sampling rate. "Good" results defined as 75-125% spike recoveries, <5% breakthrough, <10%RD paired trap agreement, and results within 2 stdev of average from long-term study using short-duration traps.

In practice, the "maximum" length for a sorbent trap run will depend on many factors and will need to be considered plant-by-plant. These factors include the coal type, the APC design, the chlorine and SO₃ contents in the flue gas, the sorbent formulation, the trap spiking procedure, the trap heating design, trap particulate shield effectiveness, the amount of entrained liquid in the gas, etc. The over-riding factor, however, may be the amount of risk which the facility is willing to take with the data. The longer the run, the more substantive the data loss in case something goes wrong and invalidates the run. Even if a plant could run traps for 10 days or more does not mean that they should, based solely from a data risk perspective.

Jim Wright

Mercury Monitoring Products and Services

Clean Air Engineering

412-787-9130 x 227

jwright@cleanair.com

McIlvaine is making it easy to input your questions and comments about any of the subjects covered in our Hot Topic discussions. All you have to do is email us at rmcilvaine@mcilvianecompany.com with your input and we will take it from there. Initial coverage will appear in this Alert, in the Monitoring Newsletter and then be added to the online Decision Tree as follows:

Coal-Gen Audio Interviews are a Major New Resource

Forty-two audio interviews were conducted at Coal-Gen and are available. You can listen to them while multi-tasking or download them to your Ipod. Here is a list of the companies interviewed.

To hear any of these interviews click here