Ui States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-85/014 May 1985
Project Summary
Technical and Economic
Evaluation of Organic Acid
Addition to a Commercial
FGD System
Jack M. Burke
This report summarizes the results of
organic acid addition tests at a com-
mercial FGD system. The tests were
conducted at San Miguel Electric Co-
operative's 410 MW lignite-fired Unit
1, outside Jourdanton, TX. During the
program, several organic acid mixtures
were tested over a range of operating
conditions to determine if the use of
organic acids would allow San Miguel
to reduce FGD system operating costs.
Based on the test results, a cost analysis
indicated that the use of organic acid
addition at San Miguel will result in a
first-year cost savings of over $600.000.
In terms of cumulative net present
worth, the estimated savings over a 15-
year period wHI be $7.2 million in 1984
dollars.
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 docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
A test program was conducted to
evaluate the technical and economic
aspects of organic acid addition to San
Miguel Electric Cooperative's Unit 1 wet
limestone FGD system. This program,
sponsored by EPA's Air and Energy
Engineering Research Laboratory, marked
the first time organic acids have been
used in an FGD system in an attempt to
reduce operating costs. As part of the
program, three different organic acids
were tested over a range of operating
conditions, and measurements were
made to permit changes in operating
costs to be quantified. The results of this
program have shown that a substantial
reduction in costs can be realized by San
Miguel through the continued use of
organic acids in the FGD system. The
estimated first year cost savings for San
Miguel are $600,000. Over a 15-year
period, this translates into a net present
worth of $7.2 million in 1984 dollars.
Most of these savings are either directly
or indirectly attributable to a reduction in
limestone consumption by the San Miguel
FGD system. As a result of the test
program at San Miguel, the utility has
installed a permanent organic acid addi-
tion system and has plans for continued
use of organic acids.
Background
As part of an earlier economic study
sponsored by EPA, the San Miguel FGD
system was identified as a good candidate
for a program designed to reduce oper-
ating costs through the use of organic
acids. The primary reason San Miguel
was so identified was that the system
was operating at a very high limestone
stoichiometry. Based on the limestone
stoichiometries reported by San Miguel
and previous data on the effects of organic
acids in FGD systems, an initial analysis
showed that the cost savings which could
result from reduced limestone consump-
tion would more than offset costs associ-
ated with the use of organic acids. The
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initial study also showed the potential for
San Miguel to improve FGD system
operation and reduce maintenance ex-
penditures by operating at low stoichi-
ometries (which should have been possi-
ble once organic acids were added to the
system). Because of the potential benefits
associated with organic acid addition,
San Miguel agreed to participate in a test
program to evaluate the use of organic
acids in the Unit 1 FGD system.
Test Program
The test program conducted at San
Miguel included eight tests with organic
acids and baseline measurements to
quantify the performance of the FGD
system without organic acids present.
The three organic acids tested were:
• A mixture of dibasic acids supplied by
DuPont Petrochemicals of Victoria,
Texas. The major components of this
mixture were adipic(15 wt%), succinic
(25 wt%), and glutaric (60 wt%) acids.
• A mixture of dibasic and monobasic
acids supplied by Badische Corporation
of Freeport, Texas. The major compo-
nents of .this mixture were adipic (45
wt%) and hydroxycaproic (35 wt%)
acids. > ,
• An organic acid stream composed
primarily (80 wt%) of dibasic maleic
acid supplied by Badische Corporation.
The results of thetests with these three
acid mixtures over a range of test condi-
tions permitted an economic analysis to
identify the most cost effective additive
and mode of operation for the San Miguel
FGD system.
Test Results
The major results of the San Miguel
test program can best be summarized by a
cost comparison of the three additives
tested. These results are shown in Table
1. This table presents estimated 15-year
net present worth of the cost savings for
each additive tested. The costs and
savings are calculated for actual test
conditions and they represent annualiza-
tion of measurements made during in-
dividual tests. For the two Badische
additives, the costs represent the only
conditions examined during the test
program.
As shown in Table 1, the estimated cost
savings for each additive include costs for
the organic acid and capital charges for
the organic acid addition system. As
mentioned earlier, the savings shown
Table 1. Fifteen-Year Cumulative Net Present Worth for the Three Additives Tested at San
Miguel
Estimated Savings (costs) in $ 1000s
Acid/ Buffer Capacity
Cost Component"
Capital Investment
Organic Acid
Limestone Reagent
Limestone Grinding
Sludge Disposal
Maintenance
Dewatering
Bypass Credit
Total
DuPont DBA/
600 ppm
(215)
(6093)
6939
1306
2523
752
353
1650
7215
EP-306/
460 ppm
1215)
(3395)
5949
1120
2163
__
303
914
6839
EP-501/
125 ppm
(215)
(5054)
4562
859
1659
—
232
914
2957
"All costs in mid-1984 dollars.
result primarily from reduced limestone
consumption. These savings include:
• Reduced limestone reagent costs.
'• Reduced costs for operation of the
limestone grinding circuit.
• Reduced costs, for sludge disposal
. since less limestone is present in the
FGD waste.
• Reduced costs for operation of the
dewatering area of the FGD system for
the same reason.
These represent the major savings.
Sayings also resulted from San Miguel's
ability to bypass flue gas around the FGD
system, thereby reducing the energy
required for reheating the scrubbed flue
gas. This bypass was made possible by
the improved SOz removal in the FGD
system which resulted from organic acid
addition.
An additional saying shown for the
DuPont acid is a .reduction in scrubber
maintenance costs. This reduction is a
result of reduced absorber and mist
eliminator plugging which was attributed
to the low pH (low stoichiometry) oper-
ating conditions made possible by using
the DuPont acid. An equivalent saving is
not shown for the Badische acids since it
was not possible to operate at the same
low pH's at the concentrations at which
these additives were tested.
the net result of the organic acid
addition test program at San Miguel is the
potential for a substantial reduction in
FGD system operating costs with any of
the organic acids tested. The maximum
saving is projected to result from use of
the DuPont DBA. As a result of the test
program at San Miguel and the economic
analysis summarized in this document,
San Miguel has made the use of the
DuPont DBA material a part of the normal
operation of the Unit 1 FGD system.
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J. M. Burke is with Radian Corporation, Austin, TX 78766.
J. David Mobley is the EPA Project Officer (see below).
The complete report, entitled "Technical and Economic Evaluation of Organic A cid
Addition to a CommercialFGD System," (Order No. PB 85-191 724/AS; Cost:
$13.00. subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Sp'ingfield,VA22161
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
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