July 12, 2007

The morning Hot Topic Hour on July 12 was on NH₃, SO₃, and low NO_x measurement. There would be great value in being able to measure these contaminants continuously for the purpose of process control.

The lead off speaker was Rick Himes of EPRI. He has provided us with the following summary of those comments.

1)      Objective

a)      In the case of NH₃ and SO₃ a need has developed for the continuous measurement of each for process control.

b)      For each, there is also a need for a more representative measurement as opposed to a single point measurement.

2)      Instrument focus

a)      In situ approach versus extractive so as to avoid potential constituent reactions that could bias readings, especially for compounds present at ppm concentration levels.

b)      Near-IR TDL (NH₃) – benefit from development efforts in telecommunication industry which has brought down price of lasers.

c)      FTIR (SO₃, H₂SO₄, NO, NO₂, NH₃).

d)      From a research perspective also examining Mid-IR TDL with goal of better detection limits for some species such as CO, as well as making measurements of NO.

3)      Issues Encountered

a)      Flyash loadings associated with coal-fired boilers limit the viable path length over which measurements can be made with adequate signal to noise ratio.

b)      Vibrations and differential thermal expansion over load range on duct walls can create alignment problems, or tradeoffs with laser power.

c)      Optically aligned set of ports frequently not available, requiring an outage for installation.

d)      TDL offers multiplex capability, but narrow absorption range limits species measured to one or two.

e)      FTIR offers single line of sight, but broad range of species.

4)      EPRI Research Program

a)      Due to difficulties in conducting quantitative evaluations in the field (e.g. comparing a line of sight measurement against a series of time averaged wet chemistry point measurements), EPRI has sponsored the development of a laboratory for testing monitors at both UC Riverside and Stanford.

b)      Test monitors without particle loading over representative range of species concentrations, temperatures, and moisture levels.

c)      Field tests conducted at field test sites over range of path lengths and ash loadings (e.g. dry bottom or wet bottom furnaces or under open or closed path measurement volumes).

d)      Development of in situ cross-duct measurement probes to extend path length capabilities.

e)      Development of portable in situ measurement probes to enable multiple path measurements without need for installation of optically aligned ports.

f)        Development of an active alignment system for incorporation with current commercial systems to eliminate/minimize issue for measurements over the load range.

g)      Near term goal is to increase the applicability and acceptance of monitoring technology within the utility industry. Currently viewed as maintenance intensive at many sites that have implemented systems.

h)      Hierarchy of applications for future envisioned to be:

i.    Measurements used in advisory manner

ii.   Incorporate measurements in process control

iii.  Develop applications with multiple lines of sight for generating tomographic contours for process optimization.

 Joel Thompson of Sick Maihak talked of the extensive European experience with Differential Optical Absorption Spectroscopy (DOAS) to measure SO₂, NO, and NH₃. Advantages are immunity to dust, humidity and other gas components.

Paul Stenberg of Opsis explained that successful measurement and control of NH₃ slip is possible with the laser diode analyzer which features fast response times and low detection limits

CEMTEK participants showed NO_x CEMS on gas turbines were accurately measuring at levels as low as 0.007 lbs/MMBtu.

Tom McKarns of ECO PHYSICS - NO_x analyzers using chemiluminescence are monitoring very low levels of NO_x accurately.

Bob Spellicy of Industrial Monitor and Control (IMAC) told the participants that IMAC has been developing FTIR for NO_x, SO_x SO₃, H₂SO₄ and HCl at the SCR outlet. Measurements can be either in situ or through extraction.

Mercury CEMS Status is Dynamic but Positive

This is the conclusion one received when listening to presenters at the Mercury CEMS Hot Topic Hour yesterday. John Schakenbach, USEPA was the lead speaker. From an historical perspective he was also a lead speaker in a McIlvaine phone conference on flow monitors just prior to the implementation of the NO_x and SO_x CEMS requirements more than a decade ago. When asked whether this was a challenge equal to the former one, John said it was possibly more so. There are some complex issues. Nevertheless progress is being made. John summarized the status of both the sorbent trap instrumental reference methods. They are posted and will be final in October if no adverse comments are received.

Terry Marsh of Shaw focused on the Appendix K sorbent trap alternative to CEMS. He observed that selecting a reliable analytical method for trap analysis is a key to ensure data integrity, accuracy, repeatability, and reproducibility. A problem in spiking the traps is solved by using two mass flow controllers to control the bubbling rate and therefore precisely spike the targeted Hg concentration into the third section of the carbon trap.

Over 100 Mercury Freedom CEMS have been shipped by ThermoFisher. Michael Corvese also reported that 30 HgCl₂ generator modules have been shipped. Field operation shows greater than 70 percent oxidation.

DP&L J.M. Stuart is operating a Met Team Appendix K system on its 605 MW unit which includes SCR and ESP. Jim Wright of Clean Air Engineering reported that 1,500 hours of operation have been logged with minimal O&M problems. QA/QC targets are being met. Spike recovery issues are under control.

John Thompson cited features of the Sick Maihak mercury CEM and the extensive experience in Europe on municipal incinerators. Some units are operating on coal-fired boilers in Europe. Initial units are being installed in the U.S.

The presentations are in the Decision Trees. They can be viewed directly through the following links.

NOx DECISION TREE

Joel Thompson – Sick Maihak

Continuing Decision Process For: Products

Application SCR DeNOx Plant

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Sick MaihakMcIlvaine 7-12-07 Presentation.htm
 

Paul Stenberg - Opsis

Continuing Decision Process For: Products

Optical Measurement of NH₃ Slip

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Opsis -Paul Stenberg Optical Measurement of NH3 Slip rwm071207.htm
 

Ish Siddiqui - CEMTEK

Continuing Decision Process For: Products

Low Level NO_x + NH₃ Slip

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Cemtek Low Level NOx.pdf
 

FGD DECISION TREE

Robert Spellicy – Industrial Monitor & Control Corp.

Continuing Decision Process For: Products

Monitoring of NO_x, SO_x, SO₃ & H₂SO₄

http://www.mcilvainecompany.com/Mercury_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Robert Spellicy - Industrial Monitor and Control Corp. FTIR Monitoring of NOx, SOx, SO3, & H2SO4 July 12 2007.pdf
 

MERCURY DECISION TREE

John Schakenbach – USEPA

http://www.mcilvainecompany.com/Mercury_Decision_Tree/cems.htm

Mercury Monitoring Update

Mercury Update

Jim Wright – Clean Air Engineering

Continuing Decision Process For: Products

Appendix K Mercury Monitoring Experience

http://www.mcilvainecompany.com/Mercury_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Clean Air Jim Wright Mercury Monitoring Experience.htm
 

Mark Calloway – Tekran Instruments

Continuing Decision Process For: Products

Overview of Tekran Instruments Corporation Continuous Mercury Monitoring System

http://www.mcilvainecompany.com/Mercury_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Continuous Mercury Monitoring System.htm

Terry Marsh - Shaw

Continuing Decision Process For: Products

CMMS and Appendix K - July 12, 2007

http://www.mcilvainecompany.com/Mercury_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Shaw Appendix K Hot Topic Pres.htm
 

Michael Corvese - Thermo Fisher Scientific

Continuing Decision Process For: Products

Update with filter probe, HgCl2 generation, and reference method comments July 12, 2007

http://www.mcilvainecompany.com/Mercury_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Thermo Fisher McIlvaine 71207.pdf

More on Limestone Grinding from Hot Topic Hour July 5

Bob Sommerlad of Loesche contacted us regarding the Hot Topic Hour last week. “Regarding my presentation there is a correction and a clarification.

Correction - Wet grinding product can be stored as a slurry so that the wet mill and the
scrubber do not have to be in synch as I had claimed.

Clarification - When dry grinding limestone (or any other feed material with moisture
present), moisture needs to be driven off if you are to avoid dust handling problems downstream of the mill, and I think the finer the grind, the dryer the product needs to be. Storage of large quantities of ground product also demands low moisture levels if hang-ups and build-ups are to be avoided in bins and mechanical handling equipment. As moisture in the limestone feed
is generally almost all surface moisture, some form of drying will always be required in my opinion. Easiest way is in the mill with warm air.

Comment - The above weakens the case for dry grinding for on-site FGD applications but
my colleagues in the limestone business claim that operating and maintenance costs are the major cost elements in limestone grinding and are thus dry grinding advocates. Again, I would ask the system designers or A/Es to consider drying grinding and join with Loesche for a technical and economic comparison of dry versus wet grinding.”