United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/S8-88/091 Nov. 1988
&EPA Project Summary
Industrial Boiler Low NOx
Combustion Retrofit Cost
Algorithm Development
Kevin L. Johnson
This report documents the
development of low NOX burner
(LNB) retrofit cost algorithms for
industrial boilers. Also included are
cost algorithms for overflre air (OFA)
and low excess air (LEA) systems.
Costs (in 1985 dollars) are estimated
for new systems as well as retrofit
applications. The boiler sizes
evaluated include those with
capacities ranging from 10 to 1300
million Btu/hr* heat input
Included are summaries of the
data sources and the methodology
used to generate the cost algorithms.
The approach to acquire detailed
cost data and the available literature
sources used as the basis for the
retrofit cost estimates are described.
Also summarized are the cost
algorithm development and the
boiler/burner design used to estimate
costs on a per burner or overtire air
port basis.
This Project Summary was
developed by EPA's Air and Energy
Engineering Research Laboratory,
Research Triangle Park, NC, to
announce key findings of the
research project that Is fully
documented In a separate report of
the same title (see Project Report
ordering information at back).
Introduction
The Industrial Combustion Emissions
(ICE) model has been developed to
(*) For readers more familiar with the metric
system, 1 Btu/hr = 0.29 W.
assess the costs of NOX controls applied
to existing stationary combustion
sources. However, the cost information in
the model needs substantial
improvement to provide accurate
assessments. Computerized algorithms
for low NOX burners have been
developed for large utility-size boilers,
but not for industrial-size boilers. Due to
major differences in boiler size, number
of burners, and control complexity
between utility and industrial boilers,
separate costs need to be developed for
low NOX burners applied to industrial-
sized boilers.
Procedure
A capital costing format for retrofit
NOX combustion modification controls
(for pulverized coal and gas/oil
applications) was developed for use by
boiler and burner manufacturers. Model
boiler sizes of 25, 100, 200, 500, and
1300 million Btu/hr were selected as
being representative of industrial boiler
applications. Detailed costs for low NOX
burners, overfire air, and low excess air
systems were to be estimated for
estimated NOX reductions of 50, 25, (40
for gas and oil), and 10%, respectively.
Since no detailed cost data were
obtained from manufacturers in this
study, cost algorithms had to be
developed based upon cost information
available in the literature. Major sources
of costs were presented as overall capital
costs for a given size unit. To convert
these costs to a per burner (or per
overfire air port) basis, various utility
survey reports and manufacturer contact
reports were utilized to develop estimates
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of the number of burners as a function of
boiler size. Other cost data sources
include past EPA studies evaluating NOX
controls for utility and industrial boilers.
Also, some costs from previous
communications with burner
manufacturers were utilized.
Results
To estimate the number and size of
burners as a function of boiler size,
information about several coal-fired
utility and industrial boilers was
compiled. In the industrial boiler size
range, there is a wide range of burner
sizes. For coal-fired industrial boilers of
capacities from 100 to 1300 million
Btu/hr heat input, burner sizes generally
range from about 25 to 125 million
Btu/hr. Based on this, the default values
in the cost algorithms for the number of
burners are as follows:
Industrial
Boiler
Size
Range,
10° Btu/hr
100-500
500-750
750 - 1000
Potential
Burner
Arrange-
ments,
No. of row x
Burners column
4 2x2
6 3x2 or 2x3
8 - 9 4x2, 2x4, or
3x3
No. of
OFA
Ports
(de-
fault
value)
2
3
4
1000-1300
12
4x3 or 3x4
These design bases allow the conversion
of utility low NOX burner and OFA total
system capital costs to a per burner or
per OFA port basis. Total capital costs
were first converted to a per unit basis.
Then, these unit costs were fit to a
logarithmic function of unit size. Total
industrial boiler system costs can then
be determined by multiplying these unit
costs by the number of low NOX burners
or OFA ports required for that particular
industrial boiler size. For oil- and gas-
fired boilers, typically there is a single
burner in boilers smaller than 200 million
Btu/hr heat input. For larger boilers, the
burner pattern is estimated to be the
same as that for pulverized coal.
Another capital cost impact of NOX
controls is the effect of staged
combustion (both low NOX burners and
overfire air) on packaged oil- and gas-
fired industrial boilers. The tight fireboxes
and resulting high heat release rates of
the larger packaged industrial boilers
limit the NOX reduction and steam
production capabilities of those systems.
To keep operating heat release rates
at a maximum level consistent with the
use of effective NOX controls, a new
packaged industrial boiler equipped with
a low NOX burner or overfire air would
have to be built physically larger to
maintain the same capacity. Many
existing packaged boilers would need to
have their maximum firing rate reduced
(i.e., capacity derate). Capacity derating
is an alternative that also can be applied
to new packaged boilers if a physically
larger unit could not be shipped (e.g.,
due to railcar space limitations).
Preliminary analyses indicate that
boiler capacity derate is roughly a linear
function with boiler size, ranging from no
derate at 75 million Btu/hr up to about 40
percent derate at 200 million Btu/hr. For
new oil- and gas-fired boilers in this
size range, the incremental capital cost
of a larger boiler must be added to the
capital costs of low NOX burner and
overfire air NOX controls. For retrofit
applications, the derate cost impact was
addressed in terms of capacity
replacement and NOX reduction
performance: for derate greater than
15%, additional capacity was estimated
at full NOX reduction performance; at
derate less than 15%, no replacement
capacity was required (resulting in
variable NOX reduction performance).
Essentially no detailed data available
on the operating costs associated with
the retrofit of NOX controls to utility and
industrial boilers: no additional labor, no
additional maintenance, no fuel penalty
for low NOX burners or OFA, and no fuel
savings for LEA.
The total annualized costs are the
sum of the annual O&M costs and the
annualized capital charges. The
annualized capital charges include the
payoff of the capital investment. The
annualized capital charges include the
payoff of the capital investment (capital
recovery), general and administrative
costs, taxes, and insurance. The capital
recovery cost is based on the equipment
life, real interest rate, and total capital
cost. For this analysis, a 10% real
interest rate and a 15-year equipment
life are assumed. This translates into a
capital recovery factor of 13.15%.
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Kevin L. Johnson is with Radian Corp., Research Triangle Park, NC 27709.
Larry G. Jones is the EPA Project Officer (see below).
The complete report, entitled "Industrial Boiler Low NOX Combustion Retrofit
Cost Algorithm Development," (Order No. PB 88-239 0741 AS; Cost:
$12.95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S8-88/091
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