POWER May 2012 - 61

AIR EMISSIONS
3. Typical HRSG ammonia injection
grid. Ammonia reacts with the NOx
in the exhaust gas stream over a catalyst to
form molecular nitrogen and water vapor. If
too much ammonia is used, unreacted ammonia
may also leave the stack (ammonia slip).
Courtesy: Cormetech Inc.
4. Keep your catalyst clean. Ash and other contaminants can blind the insulation layer
around the catalyst. Shown are the catalyst modules when clean (right) and when the catalyst
performance is reduced by blinded insulation (left). Courtesy: Cormetech Inc.
June 2010 issue of POWER or the archives at
www.powermag.com).
Plan Plant Maintenance
Site environmental management for air and
water systems is important to the ongoing operation
at any power plant. These systems need
routine oversight and must be maintained. Failure
to properly manage them may result in permit
violations and associated fines, operating
restrictions, and bad publicity for the site.
Historically, many gas plants have been opwarranted
(see " Improving SCR Performance
on Simple-Cycle Combustion Turbines " in the
3266 MetFab 4c ad_Layout 1 11/3/11 10:03 AM Page 1
erated cyclically with extended dormant periods
due to high natural gas prices and a varying
demand for the electricity the plant provides.
For plants with an SCR system, stopping and
laying up the equipment may accelerate aging
of the catalyst system components, increasing
the importance of inspections and preventative
maintenance planning.
SCR catalyst systems may run with little
attention for three to five years and gradually
begin to show signs of performance loss and
system wear and tear. It is important to monitor
the equipment condition and evaluate the performance
demands against system capabilities to
ensure reliable operation and avoid emergency
outages. HRSG tube leaks, blinding of the cataDemand
the Best from Your
Environmental/Boiler OEM...
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Advantages of our Bin Activated PAC system over air fluidization technology include:
* No additional capital cost for compressors
* Virtually no use of expensive compressed
air over system life
* Flow on demand with a first in, first out
discharge pattern
* Delivery of consistent bulk density for
better accuracy with less PAC waste and
lower PAC cost annually
* No tunnel through of densified PAC
after outages
* Availability of increased vibrator force to
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after extended outage periods
For more information contact your OEM or call 800-764-2999, in NJ 973-764-2000,
e-mail: sales@metalfabinc.com or visit www.metalfabinc.com.
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Dry Solids Processing Made Better by Design
CIRCLE 36 ON READER SERVICE CARD
May 2012 | POWER
www.powermag.com
61
" gravimetric feeders, process controls, instrumentation, gate valves, and
piping into a PAC storage and handling system that is more accurate and economical than typical air
fluidization systems.
* Less material leakage to keep worker housekeeping
to a minimum

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POWER May 2012

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