SO3 Measurement and Control is the Hot Topic Hour on Thursday, July 15, 2010
Combustion of fossil fuels containing sulfur will result in the formation of a
small amount of SO3 in the flue gases depending on the sulfur content of the
fuel, combustion conditions and flue gas characteristics. More recently,
additions of scrubbers and SCR/SNCR systems at coal-fired power plants have, in
some instances, increased the formation of SO3 in flue gas. SO3 in the flue gas
stream from a fossil fueled boiler has long been a concern for plant operators
because of the potential for fouling and corrosion in the air heater and
corrosion in ducts and equipment downstream caused by the sulfuric acid formed
from the SO3. Excessive SO3 in emissions from the stack can also cause opacity
(“blue plume”) and acid mist deposition problems. In addition, the presence of
SO3 adversely affects the removal of mercury from the flue gas.
Switching to lower sulfur fuels, improvements in catalyst materials to reduce
SO2 to SO3 conversion, reduction in air heater temperature, a number of
additives and wet precipitators are all options that have been successfully used
to control SO3 at various points in the flue gas train. However, will these
methods be enough in the future? The recent changes in the National Ambient Air
Quality Standards (NAAQS) for particulates and ozone and the expected utility
MACT may force even greater control of SO3. Control of SO3 is a complex problem
that can be highly dependent on the control technology utilized for NOx, SO2,
mercury and particulates. While you may want to minimize SO3 to enhance mercury
removal, you may also need to have sufficient SO3 in the flue gas to enhance
your fine particulate capture. This means that you may want different
concentrations of SO3 at different points in the flue gas path while avoiding
any corrosion problems and minimizing any SO3 emitted from the stack. In
addition, measurement of SO3 can be difficult which further complicates the
control problem.
The following speakers will describe the pros and cons of these various control
options, provide an update on the success and cost effectiveness of the options,
predict how effective these options may be in meeting future regulations and
describe new improvements to existing technologies or new methods being
developed or tested as well as the latest advances in measurement of SO3 in flue
gas:
Scott Evans, Vice-President for Regulatory Affairs at Clean Air Engineering will
discuss the measurement of SO3. The measurement of SO3 is challenging and at the
current time, there is no method that is universally applicable to all sources.
His presentation will cover the problems associated with the measurement of
SO3/H2SO4, an update on the progress of ASTM in issuing a new controlled
condensation method, potential new instrumental monitoring approaches, and the
possibility of field spiking to validate SO3 test results.
Dr. Curtis Laush, a Senior Scientist at Industrial Monitor & Control Corporation
(IMAC) will discuss continuous and real-time measurement of ppm level SO3 and
related compounds (by FTIR) and sub-ppm level SO3 and SO2 by Quantum Cascade
Laser. Measurements were conducted of flue gases in-situ to yield SCR emissions
as operational conditions were changed.
Curt Biehn, Manager of Technical Sales & Marketing at Mississippi Lime Company
will describe pre-APH injection of hydrated lime to obtain the most efficient
use of SO3 sorbent. Many existing SO3 mitigation systems use hydrated lime to
control corrosion and eliminate blue plume. There are advantages to removing SO3
earlier in the air pollution control process, including sorbent utilization
benefits and heat recovery. Recent test programs have identified that hydrated
lime can effectively control SO3 when injected prior to the air pre-heater. His
presentation will cite examples of good SO3 control using hydrated lime injected
at the SCR outlet.
Brian Adair, PhD, Catalyst Technology Manager at SCR-Tech, A CoaLogix Company
will describe a holistic approach to SO3 control. SO3 measurement and control
has been a long standing challenge for our industry. The January 2011 EPA PM2.5
regulation translates into 0.005 lbs/MBtu of particulate, equivalent to 1-2 ppm
SO3 at the stack. During the presentation, Dr. Adair will discuss the overall
SO3 impact and control and measurement options on the back end of a coal-fired
power plant.
Sterling M. Gray, Manager of SBS Injection Technology at URS Corporation will
discuss the SBS injection process for removing SO3 from flue gases. SO3 can
adversely affect many aspects of power plant operation including energy
efficiency, reliability and environmental performance. As a result, effectively
removing SO3 prior to the air heater can generate many co-benefits for a plant.
The SBS Injection process has been in commercial operation since 2003 and has
been successfully installed on over 10,000 MW of generating capacity. Features
of the technology, as well as recent operating experience will be highlighted.
To register for the "Hot Topic Hour" on July 15, 2010 at 10 a.m. CDT (Chicago
time), click on: http://www.mcilvainecompany.com/brochures/FGDnetoppbroch/Default1.htm
Bob McIlvaine
President
847 784 0012 ext 112
rmcilvaine@mcilvainecompany.com
www.mcilvainecompany.com