POWER February 2014 - 48

PLANT AUTOMATION
ing the most economic combination of pulverizers
to put into service at a particular load.
The expert rules have become much more
sophisticated in recent years and today there are
processes that " extract " knowledge from experienced
operators with intimate knowledge of the
operation of a particular unit. These rules can
now be reflected in software so the knowledge
is permanently stored yet easily retrievable. The
expert rules approach can then be seamlessly
combined with neural networks, MPC, firstprinciples
equations, and other methods in the
best possible combination to solve a particular
problem, such as an integrated boiler combustion
optimization system.
abt. power feb 14:Layout 1 1/8/14 4:31 PM Page 3Annual NH3 cost reduction
Optimize Back-End Systems Too
Integrated unit optimization must go beyond
boiler optimization. Other plant operations
must be considered in order to substantially
increase the efficiency, availability, and emissions
benefits obtained though combustion
optimization. For example, boiler optimization
will impact flue gas temperatures, stoichiometry,
and unburned carbon in the flue
gas that will in turn impact FGD sorbent and
reagent use, and therefore the effectiveness
of the FGD used for control of HAPS under
MATS. The same may be said of reagents,
Total combustion optimization savings
Table 1. Operating cost savings. This table shows fuel and reagent cost savings for a
600-MW unit with selective catalytic reduction and a 350-MW unit with selective noncatalytic
reduction with neural net combustion optimization, both burning Powder River Basin or other
subbituminous coal. The simple payback for the 600-MW unit is less than one year, based solely
on fuel and reagent cost savings. The cost savings that result from avoided MATS tune-ups and
avoided slagging and waterwall tube corrosion are unit-specific but will further reduce the payback
period, as will the cost of NOx allowances, if required. Source: NeuCo Inc.
Operating and economic data
Net capacity (MW)
Capacity factor
Annual output (MWh)
Boiler type
Design heat rate (Btu/kWh)
Annual heat input (mmBtu)
Fuel cost ($/mmBtu)
Annual CO2 output (tons)
Annual fuel cost
Heat rate improvement
Annual fuel savings
Baseline average boiler NOx (lb/mmBtu)
Baseline annual NOx (tons/year)
Nominal SCR/SNCR NOx reduction
Reagent cost ($/ton NOx)
Typical 600-MW plant
555
75%
3,646,350
Tangential
9,850
38,828,700
2.00
5,379,686
$77,657,400
-0.375%
$291,215
0.19
3,592
90%
3,009
$110,874
$402,090
Typical 350-MW plant
333
60%
1,747,620
Opposed
10,000
18,396,000
2.00
1,575,776
$36,792,000
-0.375%
$137,970
0.2
1,840
90%
500
$82,782
$220,752
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such as activated carbon, injected directly into
the boiler or flue gas for mercury removal.
The variable costs for these reagents can be
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quite high, particularly those injected directly
into the flue gas. The emissions removal efficiency
can be improved considerably by optimizing
the injection rates of these chemicals
in response to not only load, but also the very
same operating parameters addressed with
boiler optimization. The best unit combustion
optimization system must consider tradeoffs
between boiler efficiency, NOx
levels, reagent
use, and sorbent costs in order to minimize
total operating costs while adhering to emissions
and operational constraints.
MATS adds another layer of complexity
for operators of coal-fired plants beginning in
2015, so now is the time to begin developing a
compliance plan. A neural net combustion optimization
system is the only holistic tool available
that will help ensure MATS compliance
while at the same time paying for itself through
improved plant operating efficiency. An intangible
yet valuable side benefit is reducing the
testing and administrative reporting expense
TRAINI NG * F IELD SUPPOR T * TEC HNIC AL EXPER TISE
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48
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POWER | February 2014
that comes with MATS compliance. ■
-Peter Spinney (spinney@neuco.net) is director
of market and technology assessment
for NeuCo Inc. His background includes
more than 25 years of combined electric
power generation, economics consulting,
and government agency experience.

http://www.appliedbolting.com http://www.powermag.com

POWER February 2014

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