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NEW YORK STATE ELECTRIC AND GAS COMPANY
KINTIGH UNIT 1
SOMERSET, NEW YORK
EPA Contract No. 68D20163
Work Assignment No. I-34
Prepared by:
Research Division
Entropy, Inc.
Post Office Box 12291
Research Triangle Park, North Carolina 27709
Prepared for:
Lori Lay
U. S. Environmental Protection Agency
Emissions Measurement Branch
Research Triangle Park, North Carolina 27711
June 15, 1994
DISCLAIMER
This document was prepared by Entropy, Inc. under EPA Contract No. 68D20163,
Work Assignment No. I-34. This document has been reviewed by the U.S. Environmental
Protection Agency (EPA).
The opinions, conclusions, and recommendations expressed herein are
those of the authors, and do not necessarily represent those of EPA.
Mention of specific trade names or products within this report does
not constitute endorsement by EPA or Entropy, Inc.
TABLE OF CONTENTS
1.0 INTRODUCTION
1.1 BACKGROUND
1.2 DESCRIPTION OF THE PROJECT
1.3 PROJECT ORGANIZATION
2.0 PROCESS DESCRIPTION AND SAMPLE POINT LOCATIONS
2.1 PROCESS DESCRIPTION
2.2 AIR POLLUTION CONTROL DEVICES
2.3 SAMPLE POINT LOCATIONS
3.0 SUMMARY AND DISCUSSION OF RESULTS
3.1 OBJECTIVES AND TEST MATRIX
3.2 FIELD TEST CHANGES AND PROBLEMS
3.3 SUMMARY OF RESULTS
4.0 SAMPLING AND ANALYTICAL PROCEDURES
4.1 EXTRACTIVE SYSTEM FOR DIRECT GAS PHASE ANALYSIS
4.2 SAMPLE CONCENTRATION
4.3 CONTINUOUS EMISSIONS MONITORING
4.4 FLOW DETERMINATIONS
4.5 PROCESS DATA
4.6 ANALYTICAL PROCEDURES
5.0 INTERNAL QUALITY ASSURANCE/QUALITY CONTROL ACTIVITIES
5.1 QC PROCEDURES FOR MANUAL FLUE GAS TEST METHODS
5.2 QC PROCEDURES FOR INSTRUMENTAL METHODS
5.3 QA/QC CHECKS FOR DATA REDUCTION, VALIDATION, AND REPORTING
5.4 CORRECTIVE ACTIONS
6.0 CONCLUSIONS
7.0 REFERENCES
APPENDICES
NOTE: Appendices A-D are not available
1.0 INTRODUCTION
1.1 BACKGROUND
The U. S. Environmental Protection Agency (EPA) Office of Air Quality
Planning and Standards (OAQPS), Industrial Studies Branch (ISB), and Emission
Measurement Branch (EMB) directed Entropy, Inc. to conduct an emission
test at New York State Electric and Gas Company's (NYSEG) Kintigh Station
(Site 12), a coal-fired electric generating unit in Somerset, New York.
The test was conducted from July 26 to July 29 1993. The purpose of this
test was to identify which hazardous air pollutants (HAPs) listed in the
Clean Air Act Amendments of 1990 are emitted from this source. The measurement
method used Fourier transform infrared (FTIR) technology, which had been
developed for detecting and quantifying many organic HAPs in a flue gas
stream. Besides developing emission factors (for this source category),
the data will be included in an EPA report to Congress.
Before this test program, Entropy conducted screening tests using the
FTIR method at facilities representing several source categories, including
a coal-fired electric utility. These screening tests were part of the FTIR
Method Development project sponsored by EPA to evaluate the performance
and suitability of FTIR spectrometry for HAP emission measurements. These
tests helped determine sampling and analytical limitations, provided qualitative
information on emission stream composition, and allowed estimation of the
mass emission rates for a number of HAPs detected at many process locations.
The evaluation demonstrated that gas phase analysis using FTIR can detect
and quantify many HAPs at concentrations in the low part per million (ppm)
range and higher (sub-ppm for some HAPs), and a sample concentration technique
was able to detect HAPs at sub-ppm levels.
Following the screening tests, Entropy conducted a field validation
study at a coal-fired steam generation facility to assess the effectiveness
of the FTIR method for measuring HAPs, on a compound-by- compound basis.
The flue gas stream was spiked with HAPs at known concentrations so that
calculated concentrations, provided by the FTIR analysis, could be compared
with actual concentrations in the spiked gas stream. The analyte spiking
procedures of EPA Method 301 were adapted for experiments with 47 HAPs.
The analytical procedures of Method 301 were used to evaluate the accuracy
and precision of the results. Separate procedures were performed to validate
a direct gas phase analysis technique and a sample concentration technique
of the FTIR method. A complete report, describing the results of the field
validation test, has been submitted to EPA.[1]
This report was prepared by Entropy, Inc. under EPA Contract No. 68D20163,
Work Assignment No. I-34. Research Triangle Institute (RTI) provided process
information included in Sections 2.1, 2.2 and 3.3.3.
1.2 DESCRIPTION OF THE PROJECT
The FTIR-based method uses two different sampling techniques: (1) direct
analysis of the extracted gas stream (hereafter referred to as the gas
phase technique or gas phase analysis) and (2) sample concentration followed
by thermal desorption. Gas phase analysis involves extracting gas from
the sample point location and transporting the gas through sample lines
to a mobile laboratory where sample conditioning and FTIR analyses are
performed. The sample concentration system employs 10 g of Tenax® sorbent,
which can remove organic compounds from a flue gas stream. Organic compounds
adsorbed by Tenax® are thermally desorbed into the smaller volume of
the FTIR absorption cell; this technique allows detection of some compounds
down to ppb levels in the flue gas. For this test, approximately 850 to
1100 dry liters of flue gas were sampled during each sample concentration
run. Section 4.0 describes the sampling systems.
Entropy operated a mobile laboratory (FTIR truck) containing the instrumentation
and sampling equipment. The truck was driven to the site at Kintigh station
and parked near to each location. The test runs were performed over three
days.
Entropy tested the exhaust gases from the Unit 1 coal-fired boiler.
The furnace burns bituminous coal. Gases from the combustion furnace pass
through two electrostatic precipitators (ESPs) to control particulate.
Gases exiting the ESPs pass through a flue gas desulfurization unit (FGD),
to remove SO2, and are then exhausted through a stack. Section 2.0 contains
descriptions of the process and the sampling point locations.
Direct gas phase analysis was used to measure carbon monoxide (CO),
carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NOx), and
ppm levels of other species. EPA instrumental test methods were used to
provide concentrations of hydrocarbons (HC), CO, CO2, and O2. The sample
concentration technique was used to measure HAPs at ppb levels.
Entropy conducted three 4-hour sample concentration runs and one gas
phase run at the inlet and outlet of the ESP, a gas phase run at the FGD
outlet upstream of the stack, and three sample concentration runs at the
stack. Combustion gas volumetric flows were calculated from measurements
taken using a 3-dimensional pitot probe and an S-type pitot probe. Section
3.1 gives the test schedule.
1.3 PROJECT ORGANIZATION
This testing program is being funded and administered by the Industrial
Studies Branch (ISB) and the Emissions Measurement Branch (EMB) of the
Office of Air Quality Planning and Standards (OAQPS) of EPA. An RTI representative
collected process data. The following organizations and personnel have
been involved in coordinating and performing this project.
NYSEG Corporate Contact: Mr. Peter Carney (607) 729-2551
Mr. Mehdi Rahimi (607) 762-4212
Kintigh Station Mr. Donald Freed (716) 795-9501
Coordinator:
EMB Work Assignment Ms. Lori Lay (919) 541-4825
Managers: Mr. Dennis Holzschuh (919) 541-5239
ISB Contacts: Mr. Kenneth Durkee (919) 541-5425
Mr. Bill Maxwell (919) 541-5430
Entropy Project Manager: Dr. Thomas Geyer (919) 781-3851
Entropy Test Personnel: Mr. Greg Blanschan
Mr. Stuart Davis
Mr. Ricky Strausbaugh
Ms. Lisa Grosshandler
Mr. Scott Shanklin
Dr. Grant Plummer
Dr. Ed Potts
Mr. Mike Worthy
RTI Representative: Mr. Jeffrey Cole (919) 990-8606
2.0 PROCESS DESCRIPTION AND SAMPLE POINT
LOCATIONS
2.1 PROCESS DESCRIPTION
New York State Electric and Gas Company's (NYSEG) Kintigh Station in
Somerset, New York is about 30 miles Northeast of Buffalo on the south
shore of Lake Ontario. Unit One is a pulverized coal-fired (bituminous,
medium sulfur) base-loaded unit that normally operates 24 hours a day,
7 days a week, except for a 1- to 2-week planned outage for maintenance
once a year. Although Unit One is technically a base- loaded unit, a better
character-ization would be a load-following unit. The unit operates from
22 to 100 percent capacity (151 to 688 MWe) depending on the need for power.
The fuel source for Unit One is medium-sulfur coal from Pennsylvania
and West Virginia. Railroad cars bring the coal to the plant site where
the coal is first crushed and then fed by conveyer sequentially into one
of six coal storage bunkers. From these bunkers, the crushed coal is gravity
fed to six pulverizing mills directly below the storage bunkers. These
mills pulverize the crushed coal into talcum powder consistency. While
the coal is being transported to the silos by either of two belts, it is
sampled every 2.3 minutes by an automatic sampler. A second transfer belt
carries the sample to a mill that grinds the sampled coal and places it
in a sampling container. Proximate/ultimate analysis of a composite coal
sample are obtained every 24 hours. Table 2-1
shows coal analysis results from days the plant was tested and Table
2-2 shows an analysis of the limestone used for SO2 control. During
the test, the unit consumed coal at an average rate of 234.2 ton/hr.
Unit One is a pulverized coal-fired, dry bottom boiler with an opposed
firing configuration. Low NOx burners are used to control NOx emissions.
Normal operating temperature in the combustion zone is approximately 2,000
- 3,000 degF. The boiler produces 4,500,000 lb/hr of steam for a General
Electric steam turbine generator rated at 688 MWe.
Figure 2-1 is a diagram of the process. Combustion
air is supplied from two sources, the primary and secondary air systems.
Ambient air is drawn into the primary air inlet by a fan and passes through
the primary air preheater (PAH). The preheated air then mixes with the
pulverized coal and the mixture is blown into the combustion chamber through
the burners. The secondary air system starts at the secondary air inlet
where ambient air is drawn into the secondary air system by a forced draft
fan and passes through the secondary air preheater (SAH). The secondary
preheated air is ducted to windboxes where it is introduced above the burners
as secondary air used to complete combustion.
Combustion gases and particulate matter exiting the boiler pass through
the secondary and primary superheaters, economizer, and the air preheaters
to the electrostatic precipitator (ESP). There are four air preheaters,
two primary and two secondary. The primary and secondary air preheater
ducts meet just before the ESP entrance. The secondary system is larger
and accounts for approximately 85 percent of the gas flow. Air tempering
dampers are used on the primary preheaters to balance the air flow. From
the ESP, the combustion gases flow through three induced draft (ID) fans
and into the flue gas desulfurization unit (FGD). The flue gas then enters
a 625.5-ft stack and is exhausted to the atmosphere through the 26-ft 8-in
exit diameter.
2.2 AIR POLLUTION CONTROL DEVICES
2.2.1 Nitrogen Oxides (NOx) Control
This unit uses low NOx burners to control NOx. Low NOx burners are specially
designed burners that carefully control the amount of fuel and combustion
air to reduce combustion temperatures and lower NOx emissions.
2.2.2 Sulfur Dioxide (SO2) Control
A FGD is used to control SO2 emissions. These wet scrubbers (6 modules,
4 in use at full load) use limestone as a reagent. The modules are arranged
in parallel so that units can be activated and deactivated without effecting
other modules. The liquid-to-gas ratio of the FGD is approximately 94 gallons
per 1,000 acf and the reagent ratio is approximately 1.15 moles of reagent,
CACO3 in the limestone, per mole of SO2. Only fresh limestone is used;
therefore, there is no reagent recycling. The FGD system is approximately
70 to 90 percent efficient.
2.2.3 Particulate Control
A cold-side ESP is used to collect flyash that exits the air preheaters.
The total collection area and specific collection area (SCA) of the ESP
are 1,931,776 ft2 and 840 ft2/1000 acfm, respectively. The ESP has 5 fields
in 8 parallel sections resulting in 40 cells. The flue gas flow is divided
into four streams before the ESP and enters separate East and West sections.
These sections are physically separated and consist of 5 fields in 4 parallel
sections resulting in 20 cells. Only the inlet and outlet of the West section
was tested (Figure 2-2), but flow measurements
were taken at the East and West sections of the ESP. A rapping system is
used to dislodge dust from plates inside the ESP. The dust is collected
in hoppers. This system raps plates at different times to prevent large
amounts of particulate from re- entering the gas stream. The design efficiency
of the ESP is 99.86 percent.
2.3 SAMPLE POINT LOCATIONS
Figure 2-3 is a general schematic showing
the four test locations.
2.3.1 Boiler Outlet (ESP Inlet)
The main duct carrying gases from the boiler branches into four ducts
before passing through the ESPs. Two ducts carry flue gas through each
ESP. Entropy tested flue gas using ports on the western most duct of the
west-side ESP (Figure 2-4). A grating platform
provided access to the six, 4-inch diameter, sampling ports evenly spaced
across the top of the 13.25 ft deep, 12.5 ft wide horizontal duct. The
sampling location was 23 ft upstream of the ESP building and 66 ft above
ground level. The location was reached by stairs and a catwalk. The FTIR
truck was parked next to the ESP building and 200 ft of sample line was
used to connect the sample probe to the heated pump.
2.3.2 ESP Outlet (FGD Inlet)
The gas stream exits the two ESPs through four ducts, two ducts emanate
from each ESP. Each duct has six four-inch diameter sample ports located
about 23 ft downstream of the ESP buildings. Entropy extracted flue gas
from the western most duct of the west-side ESP outlet (Figure
2-5). The ports were equally spaced along the top of the 16.5 ft deep,
12.5 ft wide horizontal duct. Access to this location was provided by stairs
and a catwalk. This location was 66 ft above ground level and was reached
using 200 ft of sample line.
2.3.3 FGD Outlet
The four ducts exiting the ESPs recombine before the gas stream passes
through the induced draft (ID) fan which blows the gas through the flue
gas desulfurization unit (FGD) and out the stack. There are two sampling
locations available at the outlet of the FGD. One location is through ports
in the 17 ft 4-inch wide breaching connecting the scrubber and the stack
(Figure 2-6). The other location is at the 350-foot
level of the stack.
Gas phase sampling was performed through ports in the breaching. Four
six-inch diameter sample ports were arranged vertically along the side
of the breaching. Sampling was conducted through one of the two center
ports about 44 ft above ground level. Access was provided by ladder and
a platform. The FTIR truck was parked directly beneath and the location
was reached using 100 ft of sample line. No flow measurements were taken
because of the difficulty of performing velocity traverses using a 3-D
probe. It was assumed that volumetric flow at the stack and at the FGD
outlet were equivalent because there are no obstructions between these
locations. EPA agreed that flow data from the stack could be used for the
FGD outlet for the purpose of calculating mass emission rates.
2.3.4 Stack
The breaching carrying flue gas from the FGD connects to the base of
the stack. A platform is located at the 350 ft level of the 30.7 ft diameter
stack (Figure 2-7). Access to the platform was
provided by an elevator. There were four, 4-inch ID, sample ports evenly
spaced around the stack circumference. One of these was occupied by plant
CEM equipment. One of the remaining ports was used for the sample concentration
runs. velocity traverses were performed through all three ports before
and after each run using a standard S-type pitot.
3.0 SUMMARY AND DISCUSSION OF RESULTS
3.1 OBJECTIVES AND TEST MATRIX
The purpose of the test program was to obtain information that will
enable EPA to develop emission factors (for as many HAPs as possible) which
will apply to electric utilities employing coal-fired boilers using bituminous
coal. EPA will use these results to prepare a report for Congress.
The specific objectives were:
Measure HAP emissions (employing methods based on FTIR
spectrometry) in two concentration ranges, about 1 ppm and
higher using gas phase analysis, and at sub-ppm levels using
sample concentration/thermal desorption.
Determine maximum possible concentrations for undetected HAPs
based on detection limits of instrumental configuration and
limitations imposed by composition of flue gas matrix.
Measure O2, CO2, CO, and hydrocarbons using gas analyzers.
Perform simultaneous sample concentration runs at the inlet
and outlet of the west ESP and stack. Perform separate gas
phase runs at the inlet and outlet of both control devices.
Analyze data to determine effect (if any) of the control
devices on HAP (and other pollutant) emissions.
Obtain process information from Kintigh. This information
includes the rate of power production during the test runs and
operating parameters of the control devices.
Table 3-1 presents the testing schedule that
was followed at Kintigh.
3.2 FIELD TEST CHANGES AND PROBLEMS
Entropy had planned to collect gas phase samples sequentially at the
inlet and outlet of the ESP during Run 1. The distance between the two
locations was too long to connect heated line to both at the same time.
Instead, they were tested separately; the inlet during Run 1 and the outlet
during Run 2. The FGD outlet was sampled during Run 3.
3.3 SUMMARY OF RESULTS
3.3.1 FTIR Results
Gas phase and sample concentration data were analyzed for the presence
of HAPs and other species. All spectra were visually inspected and absorbance
bands were identified. The spectra were analyzed to determine concentrations
of detected species using procedures developed by Entropy. The results
are presented in Tables 3-2 and 3-3.
Maximum possible (minimum detectible) concentrations were determined for
undetected HAPs. These results are presented in Tables
3-4, 3-5, 3-6,
and 3-7.
3.3.1.1 Gas Phase Results -- Each gas phase FTIR spectrum was analyzed
for HAPs and other species. The spectra revealed that the gas phase samples
were composed of:
water vapor
CO2 was detected, but measured using a gas analyzer ( Table 3-8).
NO was not quantified in undiluted hot/wet samples because of water
interference, but was measured at about 520 ppm in condenser and
diluted samples.
CO was detected, but measured using a gas analyzer (Table 3-8).
NO2, and N2O, were detected and will be quantified in the final
report after reference spectra become available.
SO2 was measured at the ESP inlet and outlet at an average
concentration of about 1100 ppm, and at the FGD outlet at an
average concentration of about 220 ppm.
Calculated concentrations of NO, and SO2, for each spectrum are given
in Table 3-2. A set of subtracted spectra was
generated to analyze for the maximum possible (or minimum detectible) concentrations
of undetected HAPs. Reference spectra of water vapor, SO2, NO and CO2 were
scaled and subtracted from each sample spectrum. The resulting base lines
were analyzed using procedures described in Section 4.6.3. The upper limit
concentration of an undetected compound is referred to in Tables
3-4, 3-5, and 3-6
as the maximum possible concentration. This quantity was determined for
HAPs in the reference library. Results for hot/wet, condenser and diluted
samples are presented in Tables 3-4, 3-5, and 3-6, respectively. The results
are averages of the calculated values for all of the spectra in a sample
run.
Hot/wet gas phase spectra are the most difficult to analyze due to spectral
interference from water vapor. Even so, in results from the hot/wet gas
phase data, 90 compounds gave minimum detectible concentrations below 10
ppm; of these, 75 are below 5 ppm, and 25 are 1 ppm or lower.
Previously, Entropy generated program files to analyze for HAPs in FTIR
spectra of samples extracted from a coal-fired boiler stack. Statistical
analysis showed that the programs were successful in measuring some HAPs
in hot/wet and condenser samples.1 The same programs were run on gas phase
data from Kintigh. The results are presented in Appendix C.
3.3.1.2 Sample Concentration Results -- The concentrated samples are
integrated samples collected over 4-hours. The following compounds were
detected in addition to water vapor, CO, and CO2:
HCl was detected in samples from all three runs at all locations
with exception of Run 2 at the stack. Being volatile, HCl does not
adsorb to Tenax® well: therefore, HCl concentrations from Tenax
samples represent lower limit concentrations. The upper limit HCl
concentration is about 1 ppm from Table 3-4 for ESP inlet/outlet
samples. HCl is probably trapped in the water which condensed in
the tubes.
HCN traces were detected in samples from Run 3 at the ESP inlet,
from Run 1 at the ESP outlet, and from Runs 1 and 3 at the stack.
Concentrations were estimate using a spectrum from Infrared
Analysis. HCN is volatile so the Tenax® data provide a rough
estimate of the lower limit concentrations. An estimate of the
upper limit concentration is not shown in Table 3-4 because the HAP
library does not contain HCN spectra.
Traces of SO2 were detected in all of the samples. However, sample
concentration removes most of the SO2 from the FTIR sample and the
gas phase data (Table 3-2) provide a better estimate of the SO2
flue gas concentration.
Ammonia (NH3) was detected in the samples from Run 3 at the ESP
outlet, and Runs 1 and 3 at the stack. Tenax® results give a lower
limit estimate of the ammonia concentration. The upper limit is 1
to 2 ppm as given in Table 3-4.
Formaldehyde (CH2O) was detected in samples from Runs 1 and 2 at
the ESP inlet, from all 3 Runs at the ESP outlet, and from Run 2 at
the stack. Tenax® results give a lower limit estimate of the
formaldehyde concentration. The upper limit is 1 to 2 ppm as given
in Table 3-4.
Formic acid (CH2O2) was detected in Run 2 at the ESP inlet and
outlet. Formic acid is volatile so the Tenax® data provide a rough
estimate of the lower limit concentrations. An estimate of the
upper limit concentration is not shown in Table 3-4 because the HAP
library does not contain formic acid spectra.
Benzene was detected in the sample from Run 1 at the ESP outlet.
Carbonyl sulfide (OCS) was detected in the sample from Run 1 at the
ESP outlet.
Methane was detected in the sample from Run 1 at the outlet.
Freon(11) (CCl3F) was detected in samples from Runs 1 and 2 at all
three locations and Run 3 at the stack.
Evidence of hexane was detected in samples from all runs at all
three locations. Absorbance features assigned to hexane are likely
due to a mixture of aliphatic hydrocarbons, including hexane, the
sum of whose spectra is similar to that of hexane.
A cyclic siloxane was detected that Entropy first measured in
spectra of samples taken at the coal-fired boiler validation test.1
At that time it was shown to be a product of a reaction between HCl
or water vapor in the gas stream and materials in the filter
housing of the Method 5 box. Entropy took steps to eliminate this
problem and the cyclic siloxane, if it is a contaminant, is present
(in the samples from Kintigh) at very low levels relative to
validation data. It was detected in samples from Run 1 at the ESP
inlet, and all Runs at the ESP outlet and the stack.
Table 3-3 presents calculated concentrations
of HCl, hexane, formaldehyde, CCl3F, HCN, formic acid, OCS, methane and
NH3 in samples where these species were detected. Concentrations of CCL3F,
HCN, and formic acid were estimated using spectra prepared by Infrared
Analysis Inc. Flue gas concentrations in Table 3-3 were determined by dividing
the in-cell concentration by the concentration factor (Section 4.6.5) and
are based on the volume of gas sampled.
Table 3-7 gives minimum detectible concentrations
for HAPs undetected using Tenax®.
Other unidentified absorbance bands were observed in the spectra. None
of these features were attributed to HAPs listed in Table 3-7. The same
absorbance features did not consistently appear in every sample spectrum.
Spectral analysis programs were also developed for validation of sample
concentration spectra. The programs were run on the data collected at Kintigh
and the results for compounds that have been measured using thermal desorption
FTIR with Tenax® 1 are presented in Appendix C.
3.3.2 Instrumental and Manual Test Results
Table 3-8 summarizes the results of the EPA
Methods 3A, 10 and 25A tests as described in Section 4.3. All CEM results
in the table were determined from the average gas concentration measured
during the run and adjusted using the pre- and post-run calibration results
(Equation 6C-1 presented in EPA Method 6C, Section 8). Although not required
by Method 10, the same data reduction procedures as that in Method 3A were
used for the CO determinations to ensure data quality. All measurement
system calibration bias and calibration drift checks for each test run
met the applicable specifications contained in the test methods.
3.3.3 Process Operation During Test Runs
3.3.3.1 Process Data -- The process data collected during the test runs
have been tabulated and are presented in Appendix B. Process data are summarized
in Figures 3-1,
3-2,
3-3, 3-4, 3-5,
3-6, 3-7, and 3-8.
Occurrences during operations that may have affected the recorded data
are listed below:
1. During Run 1, a computer problem deleted the plant process data
that was being automatically collected. However, other logs with
similar data have been used to re-construct a record of the plant
operation during Run 1.
2. Data included in Appendix B, but not shown in graphical form, for
the scrubber inlet temperatures for all three runs showed a 100 degF
lower value for the absorber module 'A' than for the other three
modules. The lower value was assumed to be in error, presumably
because a sensor was defective or improperly placed.
The following problems and/or Variations occurred during the test:
1. During Run 1 (10:30 a.m. to 2:30 p.m., 7/27/93), the plant operated
at a steady state without any notable problems. Process data were
actually recorded until 3:45 p.m. to allow completion of flow
measurement testing.
2. During Run 2 (10:15 a.m. to 2:15 p.m., 7/28/93), the plant operated
at a steady state without notable problems.
3. During Run 3 (9:45 a.m. to 1:45 p.m., 7/29/93), the plant operated
at a steady state without notable problems.
3.3.3.2 Calculations -- The accompanying data sheets in Appendix B summarize
the calculated average values of the differential pressure across, and
inlet temperature to, the ESP. Also explained below are the calculations
for the average corona power input, total average corona power input, total
average corona power density, and the average cell corona power density.
Ignoring any pressure contribution by the primary air system, the average
differential pressure across the ESP, and associated ductwork, is equal
to the absolute value of the difference between the average ID fan inlet
pressure (in.wg) and the average SAH pressure (in.wg). The ESP inlet temperature
(degF) is equal to the SAH average gas temperature (degF) multiplied by
0.85 plus the average of the PAH 'A' gas temperature (degF) and the PAH
'B' gas temperature (degF) multiplied by 0.15. This second computation
is weighted because of the gas flow differences of the SAH and the PAH.
The Secondary currents and Secondary voltages, measured at 15 minute
intervals during each emission test, were averaged. These averaged numbers
were multiplied together to obtain the average corona power input used
by an ESP cell during the emissions test.
The average corona power input for each cell was used in two calculations.
In the first, all average corona power inputs were summed to obtain the
total average corona power input, which was then divided by the total plate
area (ft2) to obtain the total average corona power density. In the second
calculation, the average corona power input (for each cell) was divided
by each cell's plate area. This resulted in the average cell corona power
density and, with the total average corona power density, is displayed
in Figures 3-9,
3-10
and 3-11, respectively.
Since the total collection area of the ESP was known, the collection
area for each field was determined as follows.
Example:
Total Collection Area - 965,888 ft2 (West side only)
The collection area for each field would then be:
965,888 ft2 / 20 cells = 48,294.4 ft2
The number of plates in each field was not known. It was assumed to be
equal for the purposes of Figures 3-9, 3-10, and 3-11.
4.0 SAMPLING AND ANALYTICAL PROCEDURES
The FTIR analysis is done using two experimental techniques. The first,
referred to as direct gas phase analysis, involves transporting the gas
stream to the sample manifold so it can be sent directly to the infrared
cell. This technique provides a sample similar in composition to the flue
gas stream at the sample point location. Some compounds may be affected
because of contact with the sampling system components or reactions with
other species in the gas. A second technique, referred to as sample concentration,
involves concentrating the sample by passing a measured volume through
an absorbing material (Tenax®) packed into a U-shaped stainless steel
collection tube. After sampling, the tube is heated to desorb any collected
compounds into the FTIR cell. The desorbed sample is then diluted with
nitrogen to one atmosphere total pressure. Concentrations of any species
detected in the absorption cell are related to flue gas concentrations
by comparing the volume of gas collected to the volume of the FTIR cell.
Desorption into the smaller FTIR cell volume provides a volumetric concentration
related to the volume sampled. This, in turn, provides a corresponding
increase in sensitivity for the detection of species that can be measured
using Tenax®.
Infrared absorbance spectra of gas phase and concentrated samples were
recorded and analyzed. In conjunction with the FTIR sample analyses, measurements
of (HC), (CO), (O2), and (CO2) were obtained using gas analyzers. Components
of the emission test systems used by Entropy for this testing program are
described below.
4.1 EXTRACTIVE SYSTEM FOR DIRECT GAS PHASE ANALYSIS
An extractive system, depicted in Figure 4-1,
was used to transport the gas stream from the sample location to the infrared
cell.
4.1.1 Sampling System
Flue gas was extracted through a stainless steel probe. A Balston particulate
filter rated at 1 micron was installed at the inlet of the sample probe
(in-stack). Teflon® sample line (3/8-inch O.D.) was used to connect
the probe outlet to the heated sample pump (KNF Neuberger, Inc. model number
N010 ST.111) located inside the mobile laboratory. The temperature of the
sampling system components was maintained at about 300 degF. Digital temperature
controllers were used to control and monitor the temperature of the transport
lines. All connections were wrapped with electric heat tape and insulated
to ensure that there were no "cold spots" in the sampling system
where sample might condense. All components of the sample system were constructed
of Type 316 stainless steel or Teflon®. The heated sample flow manifold,
located in the FTIR truck, included a secondary particulate filter and
valves that allowed the operator to send sample gas directly to the absorption
cell or through a gas conditioning system.
The extractive system can deliver three types of samples to the absorption
cell. Sample sent directly to the FTIR cell is considered unconditioned,
or "hot/wet." This sample is thought to be most representative
of the actual effluent composition. The removal of water vapor from the
gas stream before analysis is sometimes desirable; therefore, a second
type of sample was provided by directing gas through a condenser system.
The condenser employed a standard Peltier dryer to cool the gas stream
to approximately 38 degF. The resulting condensate was collected in two
traps and removed from the conditioning system with peristaltic pumps.
This technique is known to leave the concentrations of inorganic and highly
volatile compounds very near to the (dry-basis) stack concentrations. A
third type of sample was obtained by dilution. The cell was partially filled
with sample gas and the partial pressure of the sample was recorded. The
cell was then filled to ambient pressure using dry nitrogen. The procedure
could also be reversed with the nitrogen being introduced to the cell first.
A dilution factor of 2:1 significantly reduced spectral interference from
water vapor without removing any species from the sample while minimizing
the possibility of reducing HAP concentrations below detectible levels.
Lowering the water vapor concentration, in addition to protecting the absorption
cell components, relieved spectral interferences, which could limit the
effectiveness of the FTIR analysis for particular compounds.
4.1.2 Analytical System
The FTIR equipment used in this test consists of a medium-resolution
interferometer, heated infrared absorption cell, liquid nitrogen cooled
mercury cadmium telluride (MCT) broad band infrared detector, and computer
(Figure 4-2). The interferometer, detector, and
computer were purchased from KVB/Analect, Inc., and comprise their base
Model RFX-40 system. The nominal spectral resolution of the system is one
wavenumber (1 cm-1). Samples were contained in a model 5-22H infrared absorption
cell manufactured by Infrared Analysis, Inc. The inside walls and mirror
housing of the cell were Teflon® coated. Cell temperature was maintained
at 240 degF using heated jackets and temperature controllers. The absorption
path length of the cell was set at 22 meters.
4.1.3 Sample Collection Procedure
One gas phase test run was performed at each location (ESP inlet, ESP
outlet and FGD outlet) concurrent with a sample concentration run. Table
3-1 presents the test schedule. Gas phase analysis was not performed
at the stack. During a run, flue gas continuously flowed through the heated
system to the sample manifold in the FTIR truck. A portion of the gas stream
was diverted to a secondary manifold located near the inlet of the FTIR
absorption cell (Figure 4-2). The cell was filled with sample to ambient
pressure and the FTIR spectrum recorded. After analysis, the cell was evacuated
so that a subsequent sample could be introduced. The process of collecting
and analyzing a sample, then evacuating the cell to prepare for the next
sample required less than 10 minutes. During each run, at least 12 gas
phase samples were analyzed.
4.2 SAMPLE CONCENTRATION
Sample concentration was performed using the adsorbent material Tenax®,
followed by thermal desorption into the FTIR cell. The sample collection
system employed equipment similar to that of the Modified Method 5 sample
train.
4.2.1 Sampling System
Figure 4-3 shows the apparatus used in this
test program. Components of the sampling train included a heated stainless
steel probe, heated filter and glass casing, stainless steel air-cooled
condenser, stainless steel adsorbent trap in an ice bath, followed by two
water-filled impingers, one knockout impinger, an impinger filled with
silica gel, a sample pump, and a dry gas meter. All heated components were
kept at a temperature above 120 degC to ensure no condensation of water
vapor within the system. The stainless steel condenser coil was used to
pre-cool the sample gas before it entered the adsorbent trap. The trap
was a specially designed stainless steel U-shaped collection tube filled
with 10 g of Tenax® and plugged at both ends with glass wool. Stainless
steel was used for the construction of the adsorbent tubes because it gives
a more uniform and more efficient heat transfer than glass.
A sample run lasted 4-hours at approximately 0.12 to 0.16 dcfm for a
total sampled volume of about 30 to 40 dcf. The rate depended on the sampling
train used and was close to the maximum that could be achieved. Collection
times provided a volumetric concentration that was proportional to the
total volume sampled. The resulting increase in sensitivity allowed detection
to concentrations below 1 ppm for some HAPs.
4.2.2 Analytical System
Before analysis, condensed water vapor was removed from the collection
tubes using a dry nitrogen purge for about 15 minutes. Sample analysis
was performed using thermal desorption-FTIR. The sample tubes were wrapped
with heat tape and placed in an insulated chamber. One end of the tube
was connected to the inlet of the evacuated FTIR absorption cell. The same
end of the tube that served as the inlet during the sample run served as
the outlet for the thermal desorption. Gas samples were desorbed by heating
the Tenax® to 250 degC. A preheated stream of UPC grade nitrogen was
passed through the adsorbent and into the FTIR absorption cell. About 7
liters of nitrogen (at 240 degF) carried the desorbed gases to the cell
and brought the total pressure of the FTIR sample to ambient pressure.
The infrared absorption spectrum was then recorded. The purging process
was repeated until no evidence of additional sample desorption was noted
in the infrared spectrum.
4.2.3 Sample Collection Procedure
During each run, concentrated samples were collected simultaneously
at the ESP inlet, ESP outlet and the stack. Table
3-1 presents the test schedule. A sample concentration apparatus was
set up at each location and ambient samples were collected to ensure each
train was uncontaminated. The procedure for obtaining the ambient sample
is described in Section 5.4.1. Entropy performed leak checks of the system
and the start time of each run was synchronized at all three locations.
Sample flow, temperature of the heated box, and the tube outlet temperature
were monitored continuously and recorded at 10-minute intervals. At the
end of each run, sampling was interrupted and the collection tube removed.
The open ends were tightly capped and the tube was stored on ice until
it was analyzed. The tubes were analyzed within 12 hours after the end
of the sample run.
4.3 CONTINUOUS EMISSIONS MONITORING
Entropy's extractive measurement system and the sampling and analytical
procedures used for the determinations of SO2, NOx, HC, CO, O2, and CO2
conform with the requirements of EPA Test Methods 6C, 7E, 25A, 10, and
3A, respectively, of 40 CFR 60, Appendix B. A heated extractive sampling
system and a set of gas analyzers were used to analyze flue gas samples
extracted from each location. The analyzers received gas samples delivered
from the same sampling system that supplied the FTIR cell. These gas analyzers
require that the flue gas be conditioned to eliminate any possible interference
(i.e., particulate matter and/or water vapor) before being transported
and analyzed. All components of the sampling system that contact the gas
sample were Type 316 stainless steel and Teflon®.
A gas flow distribution manifold downstream of the heated sample pump
was used to control the flow of sample gas to each analyzer. A refrigerated
condenser removed water vapor from the sample gas analyzed by all the analyzers
except for the HC analyzer. (Method 25A requires a wet basis analysis.)
The condenser was operated at approximately 38 degF. Condensate was continuously
removed from the traps to minimize contact with the gas sample.
The sampling system included a calibration gas injection point immediately
upstream of the analyzers for calibration error checks and also at the
outlet of the probe for sampling system bias and calibration drift checks.
The mid- and high-range calibration gases were certified by the vendor
according to EPA Protocol 1 specifications. Methane in air was used to
calibrate the HC analyzer.
A computer-based data acquisition system was used to provide an instantaneous
display of the analyzer responses, compile the measurement data collected
each second, calculate data averages over selected time periods, calculate
emission rates, and document the measurement system calibrations.
Table 4-1 presents
a list of the analyzers that Entropy used in this test program. Figure 4-1
presents a simplified schematic of Entropy's reference measurement system.
The test run values were determined from the average concentration measurements
displayed by the gas analyzers during the run and are adjusted based on
the zero and upscale sampling system bias check results using the equation
presented in Section 8 of Method 6C. The CEM data are presented in Appendix
A.
4.4 FLOW DETERMINATIONS
Flue gas flow rates were measured at the ESP inlet and outlet and the
stack. The exhaust duct from the boiler branched into four ducts (labeled
A - D in Figure 2-3)
upstream of the ESP inlet location. Two ducts carried flue gas through each
ESP building. The streams were recombined downstream of the ESP outlet location
before passing through the FGD. During Run 1 Entropy collected velocity data
using a 3-Dimensional (3-D) pitot probe at the inlet and outlet locations of
the A and B ducts on the west-side ESP. This information indicated the potential
for flow disturbances at the outlet. There were no indications of flow disturbances
at the ESP inlet location; therefore, during Runs 2 and 3, the inlet flow
determinations were made in accordance with EPA Methods 1, 2, and 3A using
the S-type pitot probe. Entropy adopted the following plan, with the approval
of Kintigh and EPA, to determine total flow on both sides of the ESPs.
Table 4-2 summarizes the schedule of flow measurements.
During Run 1 flow was measured using the 3-D probe through all 24
ports (in A and B ducts) on the inlet and outlet of the west-side
ESP.
During Runs 2 and 3 flow was measured using the S-type pitot
through all 12 ports (in the A and B ducts) on the inlet side of
the west-side ESP.
During Run 2 flow was also measured using the 3-D probe through all
24 ports (in the C and D ducts) on the inlet and outlet of the
East-side ESP.
During Run 3 the S-type pitot was used to measure flow through all
12 ports (in the A and B ducts) at the west side ESP inlet and the
3-D was used to measure flow through all 12 ports (in the A and B
ducts) at the West side ESP outlet.
Total flow, for each run, was determined by combining the flow through
the west-side ESP (measured each test run) with the flow through the east-
side ESP (measured only once during Run 2).
Gas flow was not measured at the breaching of the FGD outlet. This location
did not meet Method 1 criteria and access was difficult for 3-D measurements.
The stack location did meet Method 1 criteria and pre- and post-test flow
data were obtained using the S-type pitot. With EPA approval, it was assumed
that volumetric flow at the stack and the FGD outlet were the same. This
assumption is reasonable because there are no obstructions between the
FGD outlet and the stack locations.
The wet-bulb/dry-bulb technique was used for the measurement of the
flue gas moisture. Pitot traverse point locations and the measurements
made at these points are presented in the data sheets included in Appendix
A.
The 3-D probe was used to identify off-axial flow. Measurements were
obtained at 7 points through each port (42 data points for each duct) to
establish a flow profile in the sampling region.
During the sampling runs, an S-type pitot tube was positioned adjacent
to the point where the sample concentration probe was inserted. Single
point P values were recorded at 10 minute intervals to verify that flow
characteristics, at the sampling point, were not changing significantly
during the test run.
4.5 PROCESS DATA
RTI collected process data during the test. Results are included in
Section 3.3.3.
4.6 ANALYTICAL PROCEDURES
4.6.1 Description of K-Matrix Analyses
K-type calibration matrices were used to relate absorbance to concentration.
Several descriptions of this analytical technique can be found in the literature2.
The discussion presented here follows that of Haaland, Easterling, and
Vopicka[3].
For a set of m absorbance reference spectra of q different compounds
over n data points (corresponding to the discrete infrared wavenumber positions
chosen as the analytical region) at a fixed absorption pathlength b, Beer's
law can be written in matrix form as
![]()
where:
A = The n x m matrix representing the absorbance values of the m
reference spectra over the n wavenumber positions, containing
contributions from all or some of the q components;
K = The n by q matrix representing the relationship between absorbance
and concentration for the compounds in the wavenumber region(s) of
interest, as represented in the reference spectra. The matrix
element Knq = banq, where anq is the absorptivity of the qth
compound at the nth wavenumber position;
C = The q x m matrix containing the concentrations of the q compounds
in the m reference spectra;
E = The n x m matrix representing the random "errors" in Beer's law for
the analysis; these errors are not actually due to a failure of
Beer's law, but actually arise from factors such as
misrepresentation (instrumental distortion) of the absorbance
values of the reference spectra, or inaccuracies in the reference
spectrum concentrations.
The quantity which is sought in the design of this analysis is the matrix
K, since if an approximation to this matrix, denoted by K, can be
found, the concentrations in a sample spectrum can also be estimated. Using
the vector A* to represent the n measured absorbance values of a sample
spectrum over the wavenumber region(s) of interest, and the vector C to
represent the j estimated concentrations of the compounds comprising the
sample, C can be calculated from A* and K from the relation
![]()
Here the superscript t represents the transpose of the indicated matrix,
and the superscript -1 represents the matrix inverse.
![]()
The standard method for obtaining the best estimate K is to minimize
the square of the error terms represented by the matrix E. The equation
represents the estimate K which minimizes the analysis error.
Reference spectra for the K-matrix concentration determinations were
de- resolved to 1.0 cm-1 resolution from existing 0.25 cm-1 resolution
reference spectra. This was accomplished by truncating and re-apodizing4
the interfer- ograms of single beam reference spectra and their associated
background interferograms. The processed single beam spectra were recombined
and converted to absorbance (see Section 4.3).
4.6.2 Preparation of Analysis Programs
To provide quantitative results, K-matrix input must include absorbance
values from a set of reference spectra which, added together, qualitatively
resemble the appearance of the sample spectra. For this reason, all of
the Multicomponent analysis files included spectra representing interferant
species and criteria pollutants present in the flue gas.
Several factors affect the detection and analysis of an analyte in the
stack gas matrix. One is the composition of the stack gas. The major spectral
interferants in the coal-fired boiler effluent are water and CO2. At CO2
concentrations of about 10 percent and higher, weak absorbance bands that
are normally not visible begin to emerge. Some portions of the FTIR spectrum
were not available for analysis because of interference from water and
CO2, but most compounds exhibit at least one absorbance band that is suitable
for analysis. Significant amounts of SO2, NO, and NO2 were also present
in the samples and these species were accounted for in the analysis. A
second factor is the number of analytes to be detected because the program
becomes more limited in distinguishing overlapping bands as the number
of species increases. A third factor depends on how well the sample spectra
can be modeled. The best analysis can be made when reference spectra are
available to account for all of the species detected in the sample. If
reference spectra for a major sample component are unavailable, then it
may complicate the analysis of some species.
Before K-matrix analysis was applied to data, all of the spectra were
visually inspected. Program files included reference spectra of the detected
species were prepared and used to calculate flue gas concentrations. Four
baseline subtraction points were specified in each analytical region, identifying
an upper and a lower baseline averaging range. The absorbance data in each
range were averaged, a straight baseline was calculated through the range
midpoint using the average absorbance values, and the baseline was subtracted
from the data prior to K-matrix analysis.
4.6.3 Error Analysis of data
The principal constituents of the gas phase samples were water, CO2,
SO2, NO, and NO2. A program file was prepared to quantify these compounds.
Other than these species and N2O no major absorbance features were observed
in the gas phase data. After concentrations of the main constituents were
determined, the appropriate standard was scaled and subtracted from the
spectrum of the sample mixture. This helped verify the calculated concentrations
and generated a base line by successively subtracting scaled standard spectra
of water, CO2, SO2, NO, and NO2. The resulting "subtracted" spectrum
was analyzed for HAPs and used to calculate maximum possible concentrations
for undetected HAPs.
Maximum possible (minimum detectible) concentrations were determined
in several steps. The noise level in the appropriate analytical region
was quantified by calculating the root mean square deviation (RMSD) of
the baseline in the subtracted spectrum. The RMSD was multiplied by the
width (in cm-1) of the analytical region to give an equivalent "noise
area" in the subtracted spectrum. This value was compared to the integrated
area of the same analytical region in a standard spectrum of the pure compound.
The noise was calculated from the equation:
![]()
where:
RMSD = Root mean square deviation in the absorbance values within a
region.
n = Number of absorbance values in the region.
Ai = Absorbance value of the ith data point in the analytical
region.
AM = Mean of all the absorbance values in the region.
If a species is detected, then the error in the calculated concentration
is given by:
![]()
where:
Eppm = Noise related error in the calculated concentration, in ppm.
x2 = Upper limit, in cm-1, of the analytical region.
x1 = Lower limit, in cm-1, of the analytical region.
AreaR = Total band area (corrected for path length, temperature, and
pressure) in analytical region of reference spectrum of
compound of interest.
CONR = Known concentration of compound in the same reference
spectrum.
This ratio provided a concentration equivalent of the measured area
in the subtracted spectrum. For instances when a compound was not detected,
the value Eppm was equivalent to the minimum detectible concentration of
that (undetected) species in the sample.
Some concentrations given in Tables 3-4 to 3-6 are relatively high (greater
than 10 ppm) and there are several possible reasons for this.
The reference spectrum of the compound may show low absorbance at
relatively high concentrations so that its real limit of detection
is high. An example of this may be acetonitrile.
The region of the spectrum used for the analysis may have residual
bands or negative features resulting from the spectral subtraction.
In these cases the absorbance of the reference band may be large at
low concentrations, but the RMSD is also large (see Equation 7).
Condenser spectra give lower values because it is easier to perform
good spectral subtraction on the spectra of the dryer samples.
The chosen analytical region may be too large, unnecessarily
including regions of noise where there is no absorbance from the
compound of interest.
In the second and third cases the calculated maximum possible concentration
may be lowered by choosing a different analytical region, generating better
subtracted spectra, or by narrowing the limits of the analytical region.
Entropy has taken these steps to minimize the calculated values in Tables
3-4 to 3-7.
4.6.4 Concentration Correction Factors
Calculated concentrations in sample spectra were corrected for differences
in absorption pathlength between the reference and sample spectra according
to the following relation:
![]()
where:
Ccorr = The pathlength corrected concentration.
Ccalc = The initial calculated concentration (output of the Multicomp
program designed for the compound)
Lr = The pathlength associated with the reference spectra.
Ls = The pathlength (22m) associated with the sample spectra.
Ts = The absolute temperature of the sample gas (388 K).
Tr = The absolute gas temperature at which reference spectra were
recorded (300 to 373 K).
Corrections for variation in sample pressure were considered, and found
to affect the indicated HAP concentrations by no more that one to two percent.
Since this is a small effect in comparison to other sources of analytical
error, no sample pressure corrections were made.
4.6.5 Analysis of Sample Concentration Spectra
Sample concentration spectra were analyzed in the same way as the gas
phase samples. To derive flue gas concentrations it was necessary to divide
the calculated concentrations by the concentration factor (CF). As an illustration,
suppose that 10 ft3 (about 283 liters) of gas were sampled and then desorbed
into the FTIR cell volume of approximately 8.5 liters to give concentration
factor of about 33. If some compound was detected at a concentration of
50 ppm in the cell, then its corresponding flue gas concentration was about
1.5 ppm. The volume of flue gas sampled was determined from the following
equation:
![]()
where:
Vflue = Total volume of flue gas sampled.
Vcol = Volume of gas sampled as measured at the dry gas meter after
it passed through the collection tube.
Tflue = Absolute temperature of the flue gas at the sampling location.
Tcol = Absolute temperature of the sample gas at the dry gas meter.
W = Fraction (by volume) of flue gas stream that was water vapor.
The concentration factor, CF, was then determined using Vflue and the
volume of the FTIR cell (Vcell) which was measured at an absolute temperature
(Tcell) of about 300 K:
![]()
Finally, the in-stack concentration was determined using CF and the
calculated concentration of the sample contained in the FTIR cell, Ccell.
![]()
5.0 INTERNAL QUALITY ASSURANCE/QUALITY
CONTROL ACTIVITIES
Quality control (QC) is defined as the overall system of activities
designed to ensure a quality product or service. This may include routine
procedures for achieving prescribed standards of performance in the monitoring
and measurement process. Quality assurance (QA) is defined as a system
of activities that provides a mechanism of assessing the effectiveness
of the quality control procedures. It is an integrated program for assuring
the reliability of monitoring and measurement data.
The specific internal quality assurance and quality control procedures
used during this test program are described in this section. Each procedure
was an integral part of the test program activities.
5.1 QC PROCEDURES FOR MANUAL FLUE GAS TEST METHODS
This section details the QC procedures that were followed during the
manual testing activities.
5.1.1 Velocity/Volumetric Flow Rate QC Procedures
The QC procedures for velocity/volumetric flow rate determinations followed
guidelines set forth by EPA Method 2. Incorporated into this method are
sample point determinations by EPA Method 1. Gas moisture content was approximated
using the wet bulb-dry bulb technique.
The following QC steps were followed during these tests:
The S-type pitot tube was visually inspected before sampling.
Both legs of the pitot tube were leak checked before and after
sampling.
Proper orientation of the S-type pitot tube was maintained while
making measurements. The roll and pitch axis of the S-type pitot
tube was maintained at 90ø to the flow.
The magnehelic set was leveled and zeroed before each run.
The pitot tube/manometer umbilical lines were inspected before and
after sampling for leaks and moisture condensate (lines were cleared
if found).
Cyclonic or turbulent flow checks were performed prior to testing the
source.
Reported duct dimensions and cross-sectional duct area were verified
by on-site measurements.
If a negative static pressure was present at sampling ports, checks
were made for air in-leakage at the sample port which could have
resulted in possible flow and temperature errors. Leaks were sealed
when found.
The stack gas temperature measuring system was checked by observing
ambient temperatures prior to placement in the stack.
The QC procedures that were followed in regards to accurate sample gas
volume determination are:
The dry gas meter is fully calibrated every 6 months using an EPA
approved intermediate standard.
Pre-test and post-test leak checks were completed and were less than
0.02 cfm or 4 percent of the average sample rate.
The gas meter was read to a thousandth (.001) of a cubic foot for the
initial and final readings.
Readings of the dry gas meter, meter orifice pressure ( H), and meter
temperatures were taken every 10 minutes during sample collection.
Accurate barometric pressures were recorded at least once per day.
Post-test dry gas meter checks were completed to verify the accuracy
of the meter full calibration constant (Y).
5.1.2 Sample Concentration Sampling QC Procedures
QC procedures that allowed representative collection of organic compounds
by the sample concentration sampling system were:
Only properly cleaned glassware and prepared adsorbent tubes that had
been sealed with stainless steel caps were used for sampling.
The filter, Teflon® transfer line, and adsorbent tube were maintained
at +-10 degF of the specified temperatures.
An ambient sample was analyzed for background contamination.
Clean sample tubes were analyzed for contamination prior to their use
in testing.
5.1.3 Manual Sampling Equipment Calibration Procedures
5.1.3.1 Type-S Pitot Tube Calibration -- EPA has specified guidelines
concerning the construction and geometry of an acceptable Type-S pitot
tube. If the specified design and construction guidelines are met, a pitot
tube coefficient of 0.84 is used. Information pertaining to the design
and construction of the Type-S pitot tube is presented in detail in Section
3.1.1 of EPA document 600/4-77-027b. Only Type-S pitot tubes meeting the
required EPA specifications were used. The pitot tubes were inspected and
documented as meeting EPA specifications prior to field sampling.
5.1.3.2 Temperature Measuring Device Calibration -- Accurate temperature
measurements are required during source sampling. The bimetallic stem thermometers
and thermocouple temperature sensors used during the test program were
calibrated using the procedure described in Section 3.4.2 of EPA document
600/4-77-027b. Each temperature sensor is calibrated at a minimum of three
points over the anticipated range of use against a NIST-traceable mercury-in-glass
thermometer. All sensors were calibrated prior to field sampling.
5.1.3.3 Dry Gas Meter Calibration -- Dry gas meters (DGMs) were used
in the sample trains to monitor the sampling rate and to measure the sample
volume. All DGMs were fully calibrated to determine the volume correction
factor prior to their use in the field. Post-test calibration checks were
performed as soon as possible after the equipment was returned as a QA
check on the calibration coefficients. Pre- and post-test calibrations
should agree within 5 percent. The calibration procedure is documented
in Section 3.3.2 of EPA document 600/4-77-237b.
5.1.3.4 3-Dimensional Probe Calibration -- The following QC procedures
were performed when using the 3-dimensional probe.
The barometric pressure was recorded daily.
The entire sampling system was leak checked prior to each run.
The direction of gas flow was determined before sampling.
The angle finder was determined to be working properly.
The manometers were leveled and zeroed every day.
The probe was positioned at the measurement point and rotated in the
gas stream until zero deflection was indicated for the yaw angle;
this null position occurs when P2 = P3. Each yaw angle reading from
the protractor or other angle measuring device was recorded.
Holding the null reading position, readings were taken and recorded
for the (P1 - P2) and (P4 P5). Record the duct pressure or the (P2
- Pbar).
The procedure was repeated at each of the measurement points.
The pitch angle was determined from the F1 calibration curve and F2
was determined from the F2 calibration curve.
Calibration curves were generated from the procedures outlined in
Draft Method 2E.
5.2 QC PROCEDURES FOR INSTRUMENTAL METHODS
The flue gas was analyzed for carbon monoxide (CO), oxygen (O2), carbon
dioxide (CO2) and hydrocarbons (HC). Prior to sampling each day a pre-test
leak check of the sampling system from the probe tip to the heated manifold
was performed and was less than 4 percent of the average sample rate. Internal
QA/QC checks for the CEM systems are presented below.
5.2.1 Daily Calibrations, Drift Checks, and System Bias Checks
Method 3A require that the tester : (1) select appropriate apparatus
meeting the applicable equipment specifications of the method, (2) conduct
an interference response test prior to the test program, and (3) conduct
calibration error (linearity), calibration drift, and sampling system bias
determinations during the test program to demonstrate conformance with
the measurement system performance specifications. The performance specifica-
tions are identified in Table 5-1.
A three-point (i.e., zero, mid-, and high-range) analyzer calibration
error check is conducted before sampling by injecting the calibration gases
directly into the gas analyzer and recording the responses. Zero and upscale
calibration checks are conducted both before and after each test run in
order to quantify measurement system calibration drift and sampling system
bias. Upscale is either the mid- or high-range gas, whichever most closely
approximates the flue gas level. During these checks, the calibration gases
are introduced into the sampling system at the probe outlet so that the
calibration gases are analyzed in the same manner as flue gas samples.
Drift is the difference between the pre- and post-test run calibration
check responses. Sampling system bias is the difference between the test
run calibration check responses (system calibration) and the initial calibration
error responses (direct analyzer calibration) to the zero and upscale calibration
gases. If an acceptable post-test bias check result is obtained but the
zero or upscale drift result exceeds the drift limit, the test run result
is valid; however, the analyzer calibration error and bias check procedures
must be repeated before conducting the next test run. A run is considered
invalid and must be repeated if the post-test zero or upscale calibration
check result exceeds the bias specification. The calibration error and
bias checks must be repeated and acceptable results obtained before testing
can resume.
Although not required by Methods 10 and 25A, the same calibration and
data reduction procedures required by Method 3A were used for the CO and
HC determinations to ensure the quality of the reference data.
5.3 QA/QC CHECKS FOR DATA REDUCTION, VALIDATION, AND
REPORTING
Data quality audits were conducted using data quality indicators which
require the detailed review of: (1) the recording and transfer of raw data;
(2) data calculations; (3) the documentation of procedures; and (4) the
selection of appropriate data quality indicators.
All data and/or calculations for flow rates, moisture content, and sampling
rates were spot checked for accuracy and completeness.
In general, all measurement data were validated based on the following
criteria:
acceptable sample collection procedures
adherence to prescribed QC procedures.
Any suspect data were identified with respect to the nature of the problem
and potential effect on the data quality. Upon completion of testing, the
field coordinator was responsible for preparation of a data summary including
calculation results and raw data sheets.
5.3.1 Sample Concentration
The sample concentration custody procedures for this test program were
based on EPA recommended procedures. Because collected samples were analyzed
on-site, the custody procedures emphasized careful documentation of sample
collection and field analytical data. Use of chain-of-custody documentation
was not necessary. Instead, careful attention was paid to the sample identification
coding. These procedures are discussed in more detail below.
Each sample concentration spectrum was assigned a unique alphanumeric
identification code. For example, Tinl102A designates a desorption spectrum
of a Tenax® sample taken at the ESP inlet during Run 1 using tube number
02. The A means this was the spectrum of the first desorption from this
tube. Every collection tube was inscribed with a tube identification number.
The project manager was responsible for ensuring that proper custody
and documentation procedures were followed for the field sampling, sample
recovery, and for reviewing the sample inventory after each run to ensure
complete and up-to-date entries. A sample inventory was maintained to provide
an overview of all sample collection activities.
Every sample tube was cleaned and checked for contamination before use.
The contamination check consisted of desorbing the clean tube and recording
its FTIR spectrum. Each sampling train was checked for contamination before
testing and after all testing was completed. The trains were set up according
to the procedures of Section 4.2, except that the probe was not inserted
into the port. Ambient air was drawn through the entire sample concentration
apparatus for one hour (about 10 ft3 of air). This was sufficient to reveal
significant contamination in the sampling system components. The charged
ambient tube was stored and analyzed in the same manner as those obtained
during test runs. If relatively minor contamination was identified from
the ambient sample, it was accounted for in the subsequent analysis. Evidence
of major contamination was not identified in any instance.
Sample flow at the dry gas meter was recorded at 10 minute intervals.
Results from the analyzers and the spectra of the gas phase samples provided
a check on the consistency of the effluent composition during the sampling
period.
5.3.2 Gas Phase Analysis
During each test run a total of 12 gas phase samples were collected
and analyzed. Each spectrum was assigned a unique file name and a separate
data sheet identifying sample location and sampling conditions. A comparison
of all spectra in this data set provided information on the consistency
of effluent composition and a real-time check on the performance of the
sampling system. Effluent was directed through all sampling lines for at
least 5 minutes and the CEMs provided consistent readings over the same
period before sampling was attempted. This requirement was satisfied any
time there was a switch to a different conditioning system or a switch
between testing locations. The FTIR continuously scanned when the cell
was evacuating to provide a spectral profile of the empty cell. A new sample
was not introduced until no residual absorbance from the previous sample
was observed. The FTIR also continuously scanned during sample collection
to provide a real-time check on possible contamination in the system.
5.3.3 FTIR Spectra
For a detailed description of QA/QC procedures relating to data collection
and analysis, refer to the "Protocol For Applying FTIR Spectrometry
in Emission Testing" in Appendix D. A spectrum of the calibration
transfer standard (CTS) was recorded and a leak check of the FTIR cell
was performed at the beginning and end of each data collection session.
The CTS gas was 100 ppm ethylene in nitrogen. The CTS spectrum provided
a check on the operating conditions of the FTIR instrumentation, e.g. spectral
resolution and cell path length. Ambient pressure was recorded whenever
a CTS spectrum was collected.
Two copies of all interferograms and processed spectra of backgrounds,
samples, and the CTS were stored on separate computer disks. Additional
copies of sample and CTS absorbance spectra were also stored for use in
the data analysis. Sample spectra can be regenerated from the raw interfer-
ograms, if necessary. FTIR spectra are available for inspection or re-
analysis at any future date.
Pure, dry ("zero") air was periodically introduced through
the sampling system in order to check for contamination or if condensation
formed. Once, when water condensed in the FTIR manifold, the lines and
cell were purged with dry N2, until sampling could continue.
As successive spectra were collected the position and slope of the spectral
base line were monitored. If the base line within a data set for a run
began to deviate by more than 5 percent from 100 percent transmittance,
a new background was collected.
5.4 CORRECTIVE ACTIONS
During the test program, it was the responsibility of the field coordinator
and the sampling team members to ensure that all data measurement procedures
were followed as specified and that data met the prescribed acceptance
criteria. Specific procedures for corrective actions are described above.
6.0 CONCLUSIONS
Entropy conducted an emission test at NYSEG's Kintigh Unit 1 bituminous
coal-fired electric generating station in Somerset, New York. Entropy performed
direct gas phase analysis, and sample concentration testing over three
days. Gas analyzers were used to measure CO, O2, CO2, and hydrocarbons
in the gas streams. Three 4-hour sample concentrations runs were conducted
at the ESP inlet, ESP outlet, and the stack with each run performed simultaneously
at the three locations. One gas phase run was conducted at each of three
locations, the ESP inlet, ESP outlet, and the FGD outlet. CEM measurements
were performed simultaneously with the gas phase analyses. Each gas phase
run was performed concurrently with a sample concentration run.
Gas phase analysis revealed the presence of water vapor, CO, SO2, CO2,
and NOx. Sample concentration revealed the presence of a number of species.
Details are given in Section 3.3.2.
A primary goal of this project was to use FTIR instrumention in a major
test program to measure as many HAPs as possible or to place upper limits
on their concentrations. Four other electric utilities were tested besides
Kintigh. Utilities present a difficult testing challenge for FTIR techniques
because: (1) they are combustion sources so the flue gas contains high
levels of moisture and CO2 (both are spectral interferants) and (2) the
large volumetric flow rates typical at these facilities lead to mass emissions
above regulated limits even for HAPs at very low concentrations. This places
demand on the measurement method to achieve low detection limits.
This represents the first attempt to use FTIR spectroscopy in such an
ambitious test program. The program made significant achievements and demonstrated
some important and fundamental advantages of FTIR spectroscopy as an emissions
test method:
Quantitative data were provided for a large number of compounds
using one method.
Software was written to provide concentration and detection limit
results in a timely manner. The same or similar software can be
used for subsequent tests with very little investment of time for
minor modifications or improvements.
Preliminary data (qualitative and quantitative) is provided on-site
in real time.
With little effort at optimization (see below), detection limits in
the ppb range were calculated for 25 HAPs and below 5 ppm for a
total of 75 HAPs using direct gas phase measurements. Sample
concentration provided even lower detection limits for some HAPs.
A positive identification of a compound is unambiguous.
It is appropriate to include some discussion about the "maximum
possible concentrations" presented in Tables 3-4 to 3-6. These numbers
were specifically not labeled as detection limits because use of that term
could be misinterpreted.
In FTIR analysis maximum concentrations of non-detects are calculated
from the spectra (see Section 4.6.3 and the "FTIR Protocol").
These calculated numbers are not fundamental measurement limits, but they
give an indication of the measurement limits for the sampling and instrumental
conditions used in this test. A number of factors influence the maximum
concentrations:
Some instrumental factors
Spectral resolution.
Source intensity.
Detector response and sensitivity.
Path length that the infrared beam travels through the sample.
Scan time.
Efficiency of infrared transmission (through-put).
Signal gain.
Some sampling factors
Physical and chemical properties of compound.
Flue gas composition.
Flue gas temperature.
Flue gas moisture content.
Length of sample line (distance from location).
Temperature of sampling components.
Sample flow.
Instrumental components and settings can be chosen to optimize the measurement
capability for the sampling conditions and for particular compounds of
interest. For this program instrument settings were chosen to duplicate
conditions that were successfully used in previous screening tests and
the validation test. These conditions provide speed of analysis, durability
of instrumentation, and the best chance to measure a large number of compounds
with acceptable sensitivity. Sampling factors present similar challenges
to any test method.
An additional consideration is that the numbers presented in Tables
3-4 to 3-6 are all higher than the true measurement limits that can be
calculated from the 1 cm-1 data collected at TNP. This results from the
method of analysis: the noise calculations were made only after all spectral
subtractions were completed. Each spectral subtraction adds noise to the
resulting subtracted spectrum. For most compounds it is necessary to perform
only some (or none) of the spectral subtractions before the detection limit
can be calculated. With more sophisticated software it will be possible
to automate the process of performing selective spectral subtractions and
optimizing the detection limit calculation for each compound of interest.
(Such an undertaking was beyond the scope of the current project.) Furthermore,
the maximum concentrations are averages compiled from the results of all
the spectra collected at given location. A more realistic detection limit
is provided by the single spectrum whose analysis gives the lowest calculated
value. It would be more accurate to think of maximum concentrations as
placing upper boundaries on the HAP detection limits provided by these
data.
Perhaps the most important sampling consideration is the flue gas composition.
In Table 3-4 the maximum benzene concentration is reported as 6.83 ppm.
This was calculated by measuring the noise in the analytical region between
3020 and 3125 cm-1, where benzene has an absorbance band. Benzene exhibits
a much stronger infrared band at 673 cm-1, but this band was not used for
the analysis because absorbance from CO2 strongly interfered in this analytical
region. Using identical sampling components and FTIR instrumental settings
at a lower CO2 emission source would provide a detection limit below 1
ppm for benzene for direct gas analysis (even ignoring the consideration
discussed above).
There may be some question as to why certain species were not detected
in the direct gas measurements, particularly HCl. From Tenax® results
it can be concluded that the HCl concentration was at least 611 ppb. But
HCl results from sample concentration measurements are not quantitative
because some HCl is lost in the condensed water that passes through the
sample tube.
Table 2-1 presents the coal sampling analysis
data (supplied to RTI by NYSEG) for coal used during the test. According
to the analyses, the coal contained about .12 percent chlorine and about
1.9 to 2.0 percent sulfur (dry basis). The SO2 concentration before the
scrubber was as high as 1300 ppm. If chlorine content of the coal translates
in a similar way to a flue gas HCl concentration, then the HCl concentration
before the scrubber may have been as high as 80 ppm. The scrubber should
effectively remove HCl so any HCl concentration measured at the FGD outlet
or the stack would have been much lower.
The HCl concentration may actually have been below 970 ppb as given
in Table 3-4 for the ESP inlet. If HCl was present
above 1 ppm, which is detectible by direct FTIR gas analysis, its measurement
could have been affected by the moisture content of the flue gas. The sampling
system configuration (including temperature of components) was chosen because
the same configuration was used successfully at other tests. HCl was measured
at utilities and other emission sources during the FTIR development project,
and it was assumed that flue gas conditions at Kintigh would be similar.
The moisture content at the ESP locations varied between 8.5 and 11.5 percent
and was about 13.5 percent after the FGD and at the stack. This is higher
than the 7 percent moisture experienced at the screening and validation
tests. But, at least at the ESP locations, it should have been possible
to measure HCl at 1 ppm and above. High moisture makes HCl measurements
more difficult because of its solubility, but Entropy has detected HCl
in gas streams with up to 30 percent moisture after using dilution.
The sample components and the FTIR cell were maintained above 300 degF
and at 250 degF, respectively. Nothing would have been gained by using
a higher sampling temperature because the flue gas was between 280 and
300 degF at the ESP locations, and only about 120 degF at the stack. The
cell temperature was kept at 250 degF, because many of the reference spectra
were collected at that temperature. This did not present a problem because
no sample condensed in the cell.
Previous studies on HCl sampling and measurement in wet streams indicate
that high sample flow rates help to deliver HCl to the measurement system.
Entropy has participated in EPRI (Electric Power Research Institute) studies
performing FTIR CEM measurements at utilities. In these studies HCl was
measured using a sample flow of 10-15 lpm and heated lines at 300 degF.
At the Kintigh test it was not possible to achieve a sample flow rate above
6-7 lpm because Entropy was also delivering sample to gas analyzers. In
later FTIR field tests Entropy has performed QA spiking with HCl (and other
compounds) to verify sampling system integrity, and this would be a good
procedure to include in the test method. The important point to emphasize
is that moisture presents a sampling system difficulty that any test method
must address, not an analytical difficulty.
7.0 REFERENCES
1) "FTIR Method Validation at a Coal-Fired Boiler," EPA Contract
No.68D20163, Work Assignment 2, July, 1993.
2) "Computer-Assisted Quantitative Infrared Spectroscopy," Gregory
L. McClure (ed.), ASTM Special Publication 934 (ASTM), 1987.
3) "Multivariate Least-Squares Methods Applied to the Quantitative
Spectral Analysis of Multicomponent Mixtures," Applied Spectroscopy,
39(10), 73-84,1985.
4) "Fourier Transform Infrared Spectrometry," Peter R. Griffiths
and James de Haseth, Chemical Analysis, 83, 16-25,(1986), P. J. Elving,
J. D. Winefordner and I. M. Kolthoff (ed.), John Wiley and Sons,.
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