United States EPA-600 /R-92-141
Environmental Protection
A9encv July 1992
'EPA Research and
Development
RECOMMENDED OPERATING
PROCEDURE NO. 56: COLLECTION
OF GASEOUS GRAB SAMPLES
FROM COMBUSTION SOURCES FOR
NITROUS OXIDE MEASUREMENT
Prepared for
Office of Environmental Engineering
and Technology Demonstration
Prepared by
Air and Energy Engineering Research
Laboratory
Research Triangle Park NC 27711
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EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the contents necessarily
reflect the views and policy of the Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
DISCLAIMER
This recommended operating procedure (ROP) has been prepared for the sole use of the Air
and Energy Engineering Research Laboratory (AEERL), U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, and may not be specifically applicable to the activities of other
organizations.
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EPA-600/R-92-141
July 1992
RECOMMENDED OPERATING PROCEDURE NO. 56:
COLLECTION OF GASEOUS GRAB SAMPLES FROM COMBUSTION
SOURCES FOR NITROUS OXIDE MEASUREMENT
Prepared by:
Jeffrey V. Ryan
Shawn A. Karns
Acurex Environmental
4915 Prospectus Drive
P.O. Box 13109
Research Triangle Park, NC 27709
EPA Contract No. 68-DO-0141
Technical Directive No. 92-066
EPA Project Officer: William P. Linak
Combustion Research Branch
Air and Energy Engineering Research Laboratory
Research Triangle Park, North Carolina 27711
Prepared for:
U.S. Environmental Protection Agency
Office of Research and Development
Washington, DC 20460
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ACKNOWLEDGMENTS
Assisting in the preparation of this procedure were Constance V. Wall and Shirley J. Wasson of
Research Triangle Institute, Research Triangle Park, NC, under EPA Contract 68-02-4291 for Quality
Assurance Support to AEERL. Judith S. Ford, the QA Manager for AEERL, is responsible for the
development of operating procedures, including ROPs, for this EPA Laboratory.
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TABLE OF CONTENTS
Section Page
ACKNOWLEDGMENTS ii
1 INTRODUCTION 1-1
1.1 Scope and Application 1-1
1.2 Summary of Method 1-2
1.3 Limitations 1-2
1.3.1 Limitations of Recommended Operating Procedures 1-2
1.3.2 Limitations of this Procedure 1-3
1.4 Definitions 1-4
2 START-UP 2-1
2.1 Personnel Requirements 2-1
2.2 Facilities 2-1
2.3 Safety Precautions 2-1
2.4 Apparatus 2-1
3 PREPARATION OF SAMPLING MATERIALS AND EQUIPMENT 3-1
3.1 Sample Container 3-1
3.1.1 Sample Container Assembly 3-1
3.1.2 Sample Container Conditioning 3-1
3.2 SO2 Sorbent Cartridge 3-3
3.2.1 Sorbent Cartridge Preparation 3-3
3.2.2 Dispersion Tubes 3-3
3.2.3 SO2 Sorbent Preparation 3-4
3.2.4 Filling SO2 Sorbent Cartridge 3-4
3.3 H2O Sorbent Cartridge 3-5
3.3.1 Cartridge Preparation 3-5
3.3.2 H2O Sorbent Preparation 3-6
3.3.3 Filling H2O Sorbent Cartridge 3-6
4 SAMPLING PROCEDURE 4-1
4.1 Summary of Procedure 4-1
4.2 Sampling Procedure 4-2
5 REFERENCES 5-1
Hi
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LIST OF FIGURES
jure Page
3-1. Sample container schematic 3-7
3-2. SO2 sorbent cartridge assembly 3-8
3-2A. SO2 sorbent cartridge components 3-8
3-2B. Dispersion tube hardware 3-8
3-2C. Complete SO2 sorbent cartridge 3-8
4-1. N2O sampling system configuration 4-4
4-1A. Location of sampling system 4-4
4-1B. Sorbent/sample container schematic 4-4
4-2. N2O field data form 4-5
4-3. Sample custody sheet 4-6
iv
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SECTION 1
INTRODUCTION
1.1 SCOPE AND APPLICATION
This procedure is applicable to the collection of gaseous grab samples from fossil fuel
combustion sources for subsequent analysis of nitrous oxide (N2O). This procedure details only the
grab sampling methodology and associated equipment. Analysis of the collected grab samples is not
within the scope of this procedure. A number of analytical procedures exist that are suitable for the
measurement of N2O from grab samples.1'2
Any gaseous stream resulting from the combustion of fossil fuels may be considered a post-
combustion process stream. Gas streams from utility boilers, furnaces, and fluidized bed combustors,
firing on natural gas, fuel oils, or coals are examples. This procedure has not been evaluated on waste
incineration processes.
The integrity of grab samples collected for N2O measurement has been demonstrated to be
compromised under most common combustion sampling conditions. A sampling artifact has been
observed when nitrogen oxides (NOX), sulfur dioxide (SO2), and moisture (H2O), present in most
combustion samples, react in the sampling containers to produce N2O.3 N2O generation in grab
sample containers approaching 200 ppm has been observed.4
Much of the data reported on N2O measurements from fossil fuel combustion sources were
obtained using grab sampling methods conducive to the sampling artifact.4-5 Because the previously
reported data are suspect, an economical method for assessing N2O emissions from fossil fuel
combustion sources was needed. As a result, this procedure was developed. The goal of the
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procedure is to minimize, but not eliminate, the N2O sampling artifact to levels acceptable for fossil fuel
combustion source screening purposes. When this procedure is followed, the N2O generation within
grab sample containers is less than 10 ppm in samples analyzed within 2 weeks of collection.
1.2 SUMMARY OF METHOD
This method is designed so that it can be used compatibly with continuous emission monitoring
(OEM) sample delivery/conditioning systems or as a stand alone procedure. Specifically, this method
employs selective extraction to negate gaseous components to the point that the N2O generation in
stored (1-2 weeks) sample containers is minimized to £ 10 ppm. Sequentially, SO2 is neutralized and
H2O removed from a flue gas sample stream before entering a Teflon®-lined stainless steel container.
The neutralization and removal of SO2 requires the presence of H2O in the flue gas stream. Therefore,
the flue gas is collected before (upstream of) any moisture removal systems (e.g., refrigeration
condensers, silica gel) that may be present in CEM flue gas conditioning systems.
The flue gas sample is extracted using a vacuum pump. The pump will pull a flue gas sample
from a post-combustion process stream and subsequently push the sample through the two-cartridge
solid-sorbent system. The first cartridge will neutralize and extract the SO2. The second cartridge will
extract the H2O. The SO2 cartridge must be placed before the H2O cartridge to ensure that a "wet*
sample enters the SO2 cartridge. The flue gas sample will then flow into a grab sample container. The
grab sample container or "sample bomb" can then be sealed and stored for up to 2 weeks at room
temperature. The sample containers can be analyzed for N2O at any point during the 2-week holding
period.
1.3 LIMITATIONS
1.3.1 Limitations of Recommended Operating Procedures
Recommended operating procedures (ROPs) describe non-routine or experimental research
operations where some judgement in application may be warranted. ROPs may not be applicable to
activities conducted by other research groups, and should not be used in place of standard operating
procedures or EPA-approved test methods. Use of ROPs must be accompanied by an understanding
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of their purpose and scope. Questions should be directed to the preparers or project personnel listed
in the Acknowledgments.
1.3.2 Limitations of this Procedure
This procedure was developed to provide a method for evaluating the N2O emissions from
suspected high N2O emitting fossil fuel combustion sources. Researchers in the U.S. EPA's Air and
Energy Engineering Research Laboratory (AEERL) found that N2O generation in grab sample
containers, limited to less than 10 ppm, would be acceptable for the screening of fossil fuel combustion
sources. This procedure may not be suitable for use on combustion sources where low concentrations
of N2O are anticipated. For those combustion sources, use of a grab sampling method where N2O
generation within grab sample containers has been demonstrated to be eliminated or use of an on-line
monitoring method is recommended.
This procedure was developed for use with flue gases from conventional combustion sources
and processes. Samples were designed to be collected upstream of any pollution control equipment or
on systems where pollution control equipment did not exist. This procedure may not be applicable for
use where sampling is performed downstream of pollution control devices or processes. This
procedure has been evaluated under both laboratory and field conditions. Publication of these findings
is expected in the fall of 1992.
During the development of the procedure, laboratory tests were conducted to determine the flue
gas NOX, SO2, and H2O concentration ranges where N2O generation would be consistently minimized
to less than 10 ppm over a 2 week period. This method was found suitable for use on combustion
systems with flue gas concentrations in the following ranges:
SO2: 0 - 2500 ppm
NOX: 0 -1000 ppm
H2O: 5 - 25% (by volume)
These flue gas concentration ranges were verified under actual field test conditions as well.
During these tests, the flue gas components of carbon monoxide (CO), carbon dioxide (CO2), and
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unbumed hydrocarbons, typically present in fossil fuel combustion process streams, were found to not
interfere with the sampling method performance. Other common flue gas components such as
hydrogen chloride (HCI) and ammonia (NH3) were not evaluated and may act as interferences. Use of
this procedure where these compounds are present in the flue gas stream may not be applicable and
would require additional evaluation.
Laboratory and field tests have found a two-cartridge sorbent system suitable for the collection
of three or four grab samples within a total operation time of 30 minutes. Any additional grab samples
taken with the sorbent system may result in the generation of higher N2O concentrations due to SO2
breakthrough in the first cartridge.
1.4 DEFINITIONS
Grab sample: a gaseous sample "grabbed" or pulled from a post-combustion process stream
and stored in an inert, closed container.
Sample container: (sample cylinder, sample bomb) Tefk>n®-lined stainless steel container
designed for safe containment of gas samples during drawing, storage, and handling or
transport.
Sorbent: a substance that will hold or take up another substance (gases, solutes, or
liquids) with which they are in contact.
Compression fitting: a compression type tube fitting that uses a nut and one or two ferrules
to provide a leakproof, torque-free seal.
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SECTION 2
START-UP
2.1 PERSONNEL REQUIREMENTS
This procedure requires one technician trained on this ROP. It is recommended that this
technician be experienced in the sampling of gaseous emissions from combustion sources.
2.2 FACILITIES
This procedure requires a laboratory setup for the assembly of the two-cartridge solid-sorbent
system, the space to include a fume hood, a source of deionized (Ol) water, and chemical storage.
2.3 SAFETY PRECAUTIONS
The cartridge assembly procedure uses calcium hydroxide [Ca(OH)2] and phosphorous
pentoxide (P2O$)- Both substances are known to be hazardous if inhaled or swallowed. P2O5 and H2O
produce a mild exothermic reaction. The sample container conditioning procedure uses methanol
(MeOH). There are known hazards of fire and of poisoning due to ingestion. This procedure should be
performed in a well-ventilated area. Personnel protection should include safety glasses, laboratory
coats, and latex gloves.
2.4 APPARATUS
Sample Container:
• 600 cc stainless steel sample cylinder equipped with: Teflon® - coated inner surface, septum
port, 1/4-in.* female nominal pipe thread (NPT) end connections
For readers more familiar with the metric system, 1 in. - 2.54 cm.
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• Toggle valves (2), stainless steel, 1/4-in. male NPT x 1/4-in. compression fitting, Whitey Co.,
(Cat. No. SS-92M4-S4) or equivalent
• Gas chromatograph septa, 3/8-in. outside diameter (OD), Alltech Associates Inc., (Cat. No.
6514) or equivalent
• Stainless steel washer, 8/32-in. OD
• 1/4-in. stainless steel compression fitting nut (1) and end caps (2), Swagetock Co., (Cat. Nos.
SS-402-1, SS-400-P, respectively) or equivalent
• Methanol, Burdick and Jackson, pesticide grade or equivalent
• Drying oven capable of 100 ±5 °C
• Nitrogen, zero grade
• 1/4-in. Teflon® tape
SO2 Sorbent Cartridge:
• 120 cc refutable traps, gastight, Baxter Scientific, (Cat. No. MT120U-ATU) or equivalent
• Stainless steel O-ring-sealed straight-thread male connectors with 1/4-in. compression fittings
(2), Swagetok Co., (Cat. No. SS-400-1-OR) or equivalent
• Teflon® tubing, 1/4-in. OD
• 1/4-in. stainless steel compression fitting nut (4), Swagetock Co., (Cat. No. SS-402-1) or
equivalent
• 1/4-in. stainless steel compression fitting ferrules (2 sets), Swagetock Co., (Cat. No. SS-400-
SETS) or equivalent
• 1/4-in. ceramic-filled Teflon® compression fitting ferrules, Supelco, (Cat. No. 2-2086M) or
equivalent
• Calcium hydroxide, 98+ percent, ACS reagent grade, Aldrich Chemical Co. (Cat. No. 23,
923-2) or equivalent
• 18-20 mesh (0.85-1.00 mm particle diameter) sand, Unimin Co. or equivalent
• Large metal pan (e.g., 13-in. baking pan)
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• Play sand (optional)
• U.S. Standard testing sieve -18 mesh (1.00 mm particle diameter), Fisher Scientific (Cat.
No. 04-881 L) or equivalent (optional)
• U.S. Standard testing sieve - 20 mesh (0.85 mm particle diameter), Fisher Scientific (Cat.
No. 04-881M) or equivalent (optional)
• Sieve shaker, Fisher Scientific (Cat. No. 04-909-4) or equivalent (optional)
H2O Sorbent Cartridge:
• 120 cc refutable traps, see SO2 sorbent cartridge apparatus
• Stainless steel O-ring-sealed straight-thread connectors, see SO2 sorbent cartridge
apparatus
• Phosphorous pentoxide, indicating, Mallinckrodt Inc., (Aquasorb - Cat. No. 6063) or
equivalent
• Glass wool, Fisher Scientific (Cat. No. 11-390) or equivalent
Sampling Equipment:
• Vacuum sample pump, air pumping rate of 8-12 L/min, Thomas Industries Inc., (Model No.
107CA14TFEL-A) or equivalent
[NOTE: The sample pumps used during development of this
procedure nominally delivered flow rates of 8-12 L/min under no-load
conditions. However, during actual sampling, the pressure drop
across the sorbent cartridges restricted sample flow rates to 4-10
Umin. tt was under this flow rate range that the method was
evaluated. The sample pump flow rate requirement of £ 8 Umin was
Identified as the minimum flow rate required to ensure adequate flow
during sampling.]
• Ftowmeter, 1-10 L/min range, Dwyer Instruments Inc., (Model RMA-21)
• Teflon® tubing, 1/4-in. OD
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SECTION 3
PREPARATION OF SAMPLING MATERIALS AND EQUIPMENT
3.1 SAMPLE CONTAINER
3.1.1 Sample Container Assembly
Samples are collected in 600 cc stainless steel sample containers with their inner surface
Teflon® coated. The Teflon® coating provides a less reactant surface and eases sample container
cleanup. The sample containers are equipped with toggle valves compatible with 1/4-in. compression
fittings on both ends and a septum port for syringe sample extraction (Figure 3-1). If the sample
container is not equipped with an injection port, a 1/4-in. male connector compression fitting can be
welded to the sample container. A 1/4-in. stainless steel compression fitting nut, containing an 8/32-in.
washer, and a 3/8-in. OD gas chromatograph (GC) septum seal the port. This port allows direct
extraction of the sample gas with a gaslight syringe from the sample container for injection onto a GC
without contaminating the sample with room air. For record keeping purposes, each sample container
should be engraved or stamped with its own unique identification number.
3.1.2 Sample Container Conditioning
The sample containers must be conditioned prior to use. The sample containers used for
sampling must be dean and dry. Any residual moisture within the sample container may cause N2O
generation in excess of the limits of this procedure. The sample containers are conditioned as follows:
1. Remove nut, washer, and septum from side port.
2. Remove end caps from toggle valves and open toggle valves.
3. Soak sample containers in hot, soapy water for about 2 hours.
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4. Rinse three times with deionized (Dl) water and drain.
5. Rinse once with methanol.
6. Allow to dry.
[CAUTION: K oven temperature goes over 130 °C, the Teflon* coating
and toggle valves may be damaged.]
7. Place sample containers in a hot oven (105 °C) for about 8 hours.
8. Replace washer and septum in the 1/4-in. nut.
9. Remove sample containers from oven, close toggle valves, replace end caps, and replace
nuts and septa.
10. Allow sample containers to cool.
11. To purge and pressurize the sample containers, connect an H2O sorbent cartridge
(Section 3.3) to the nitrogen tank regulator. Attach a short piece of 1/4-in. OD Teflon®
tubing to the cartridge, then affix a toggle valve to the free end of the tubing. Next attach
another piece of the Teflon® tubing to the free end of the valve.
12. Remove end caps from a sample container and attach container to the Teflon® tubing.
13. Open the nitrogen cylinder (10 psi)*; then open the toggle valve after the H2O sorbent
cartridge.
14. Open the toggle valve on the sample container so the container fills with nitrogen.
15. Open the outlet valve on the sample container and remove the nut and septum from the
injection port.
16. Allow the sample container to purge for 1-2 minutes (at least 7 volume exchanges).
17. Replace nut and septum.
18. Close the outlet valve and then the inlet valve of the sample container. The sample
containers are now pressurized. The pressure within the sample containers will serve as a
For readers more familiar with the metric system, 1 psi - 6.9 kPa.
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quality control leak check prior to sampling use (see Section 4.2).
19. Close toggle valve located after the H20 sorbent cartridge.
20. Disconnect sample container and replace end caps.
The sample containers are now clean, pressurized (~10 psi), and ready for sampling.
3.2 SO2 SORBENT CARTRIDGE
3.2.1 Sorbent Cartridge Preparation
The sorbent cartridges used for SO2 removal are 120 cc refutable traps. The SO2 sorbent
cartridge has the addition of two dispersion tubes to increase the reactive surface area. The cartridges
are fitted with stainless steel O-ring-sealed straight-thread connectors. The fittings for the SO2 sorbent
cartridge are drilled out to allow 1/4-in. tubing to slide through them (17/64-in. drill bit). (See Figure 3-
2A.)
The cleaning procedure for the SO2 sorbent cartridges is: rinse with water and use a soft bristle
brush to remove grit, especially around the threads. Rinse the cartridges with Dl water and dry.
3.2.2 Dispersion Tubes
To prevent channeling in the SO2 sorbent cartridge and to increase the reactive surface area,
dispersion tubes are used. The dispersion tubes are designed to spray the flue gas through the solid
sorbent thus maximizing the contact between the gas and sorbent. Dispersion tubes are made from
1/4-in. Teflon® tubing, 6 in. long. One end of the tubing is sealed with a 1/4-in. stainless steel
compression fitting nut, ferrules, and cap (Figure 3-2B). About 70 0.0225-in. holes (No. 74 drill bit) are
drilled in a 2-in. section behind the nut and cap. The collective area of the 70 holes is greater than the
annular area of the Teflon® tubing to minimize flow restrictions. These tubes are used at both the inlet
and the outlet of the SO2 sorbent cartridge. The dispersion tubes slide through the drilled out O-ring-
sealed straight-thread connectors.
The dispersion tubes are secured in the cartridges using 1/4-in. ceramic-filled Teflon® ferrules.
These ferrules do not become permanently compressed to the Teflon® tubing and allow for removal of
the dispersion tubes for easy breakdown and refilling of sorbent cartridges.
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3.2.3 SOg Sorbent Preparation
The SO2 sorbent is a 10:1 ratio dry mixture of sand to Ca(OH)2. This procedure requires the
sand particles to be 18-20 mesh (particle diameter = 0.85-1.00 mm) in size. This size range was found
to maximize surface area with minimal pressure drop across the sorbent cartridge. To prepare the SO2
sorbent, weigh the desired amount of sand (e.g., 500 g) in a large pan, then weigh one-tenth of the
sand amount of Ca(OH)2 (e.g., 50 g) and add to pan. Mix the sand and sorbent by hand for -15 min.
Store the mixture in a desiccator.
[NOTE: If the 18-20 mesh sand Is not purchased, the following procedure
may be used (generic play sand Is suitable for this alternate procedure). This
procedure requires an 18-mesh sieve, a 20-mesh sieve, and a sieve shaker.
Put the larger, 18-mesh sieve on top of the 20-mesh sieve. Pour the play
sand Into the 18-mesh sieve. Place both sieves on the shaker. Turn on
shaker and let It run until sand is completely sifted. Collect the sand that
goes through the 18-mesh sieve but does not go through the 20-mesh sieve.
Discard the larger and smaller particle-size sand fractions.]
3.2.4 Filling SOg Sorbent Cartridge
Before filling the sorbent cartridges, make sure the cartridges are clean and dry. Fill the
sorbent cartridges by packing the sand/Ca(OH)2 mixture around the dispersion tubes located within the
sorbent cartridge (Figure 3-2C). The dispersion tubes extend into the sorbent cartridge approximately
3.5 in. from each end. The dispersion tubes are held in place by the end caps of the sorbent cartridge.
The dispersion tubes are secured to the end caps using a 1/4-in. compression fining nut and ceramic-
filled Teflon® ferrule, tightened to the O-ring seal connector compression fitting (Figures 3-2A and 3-
2B).
The following procedure details the filling/assembly of the SO2 sorbent cartridges:
1. Insert a dispersion tube into one of the sorbent cartridge end caps and attach with the
ceramic-filled Teflon® ferrule.
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2. Attach the body of the sorbent cartridge to the end cap (a gaslight seal is made against the
O-ring located within the end cap). Adjust the dispersion tube so that ft extends into the
sorbent cartridge approximately 3.5 in.
3. Holding the sorbent cartridge assembly vertically, add the sand/Ca(OH)2 mixture to the
cartridge, filling ft to approximately 3.5 in. from the top. During the filling process, tap the
cartridge occasionally to accelerate sorbent settling.
4. While holding the remaining dispersion tube upright inside the sorbent cartridge (the
compression fitting on the dispersion tube should rest on the sorbent already within the
cartridge), pack additional sorbent around the tube and fill the sorbent cartridge to the top.
Again, tap the sorbent cartridge occasionally while filling.
5. Slide the remaining end cap over the open end of the dispersion tube, and attach it to the
sorbent cartridge. Make sure that surface of the sorbent cartridge contacting the O-ring
seal in the end cap is smooth and free from sorbent mixture.
6. Secure the dispersion tube to the end cap with a ceramic-filled Teflon® ferrule and 1/4-in.
compression fitting nut.
The SO2 sorbent cartridge is attached to the pump and H2O sorbent cartridge by a 1/4-in.
compression fitting nut and ceramic-filled Teflon® ferrule.
3.3 H2O SORBENT CARTRIDGE
3.3.1 Cartridge Preparation
The sorbent cartridges used for H2O removal are also the 120 cc refillable traps. Dispersion
tubes are not used in the H2O sorbent cartridge. Stainless steel, O-ring seal, straight-thread male
connectors with 1/4-in. compression fittings are used for attaching the H2O sorbent cartridge to the
associated sampling equipment.
The cleaning procedure for the sorbent cartridges is: rinse with water and use a soft bristle
brush to remove grit, especially around the threads. Rinse the cartridges with Dl water and dry.
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3.3.2 H2O Sorbent Preparation
The H2O is removed using commercial indicating P2O5. No sorbent preparation is needed.
3.3.3 Filling H2O Sorbent Cartridge
The H2O sorbent cartridges are filled with the indicating P2O5. The desiccant is held in place
with glass wool plugs at each end of the sorbent cartridge. To fill the sorbent cartridges, attach an end
cap to the cartridge body, hold it vertically, insert a glass wool plug in the capped end, and fill with -50
g of P2O5. Fill the remainder of sorbent tube with glass wool and attach the remaining end cap. Make
sure that the surface of the sorbent cartridge contacting the O-ring seal in the end cap is smooth and
free from sorbent particles.
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1/4-in. stainless steel nut
stainless steel
toggle valve
600 cc sample container
with septum port
8/32-in. washer
«*
3/8-in. OD septum
1/4-in. NPT 1/4-in. NPT
(female) (male)
1/4-in. compression fitting
Figure 3-1. Sample container schematic.
JO «- 3J
$ § « S?
0 g <. 2
^ *
oo ro -^ co
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CO
do
1/4-in. ceramic-filled Teflon ferrule
120ccrefillabletrap
1/4-in. nu
m\>
1/4-in. compression fitting
7/16-20-in.
straight
thread
stainless steel
O-ring seal connector
1/4-in. ceramic-filled
Teflon ferrule
Figure 3-2A. SQ sorbent cartridge components. end caP
dispersion tube (w/0.0225-in. holes) 1/4.jn_ stain|ess stee| ferrules
O-ring seal HHi end cap (O-ring inside end cap)
Rgure 3-2B. Dispersion tube hardware.
Figure 3-2C. Complete SOj sorbent cartridge.
Figure 3-2. SO2 sorbent cartridge assembly.
O) ^ Tl
<5 c to V)
oo ro _»
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SECTION 4
SAMPLING PROCEDURE
4.1 SUMMARY OF PROCEDURE
This procedure is used to collect gaseous grab samples from combustion sources for
subsequent analysis of N2O. This procedure is designed so that it can be used compatibly with
continuous emission monitoring (CEM) flue gas sample delivery/conditioning systems or as a stand
alone procedure. When samples are obtained from a CEM flue gas delivery system, the N2O grab
sample must be collected upstream of any moisture removing device(s); e.g., refrigeration and ice bath
condensers or desiccants (Figure 4-1 A).
The sampling system consists of a vacuum sample pump, a SO2 sorbent cartridge, a H2O
sorbent cartridge, and a grab sample container. Important - Do not reverse order. The SO2
cartridge requires a wet sample. Prepare the associated apparatus according to the procedures in
Section 3. In summary, a flue gas sample from a post-combustion process stream is drawn, under
vacuum, by the sample pump. The sample pump, under positive pressure, forces the flue gas sample
through the SO2 sorbent cartridge, H2O sorbent cartridge, and sample container consecutively (Figure
4-1B). Three separate, consecutive, grab samples can be taken per two-cartridge, solkj-sorbent,
sample conditioning system. The three consecutive grab samples should be collected from the same
sample location on each unit. The sample containers are sealed and can be stored for up to 2 weeks
at room temperature. The containers may be analyzed at any point during the 2-week holding period.
As stated previously, this procedure was developed to characterize the N2O emissions from
different combustion sources. To aid in this characterization of the combustion systems, certain
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operating parameters of the combustion source need to be recorded. Figure 4-2, the N2O Field Data
Form, is an example of the information needed to characterize a combustion source. Complete this
form during or immediately after the grab samples are collected.
Also provide sample custody documentation (Figure 4-3). The Sample Custody Sheet will aid
in the tracking of samples from the sampling location to the laboratory for the subsequent N2O analysis.
4.2 SAMPLING PROCEDURE
To collect N2O grab samples:
1. Tee sample pump into a sample line with the inlet side of the sample pump connected to
the tee (Figure 4-1A). Locate the pump before any CEM flue gas sample moisture
conditioning systems.
2. Connect SO2 sorbent cartridge in series to outlet of sample pump (Figure 4-1B). Connect
H2O sorbent cartridge in series to the SO2 sorbent cartridge.
3. Remove 1/4-inch end caps from sample container.
4. Connect sample container in series to H2O sorbent cartridge (Figure 4-1 B).
5. Attach flow meter to exit of sample container.
6. Leak check the sample container by opening the outlet valve of the sample container. If
the sample container is still pressurized (passing the teak check), the flow meter will
momentarily indicate flow. If no flow is observed, replace the sample container.
7. Turn on sample pump.
8. Open the sample inlet valve of the sample container.
9. Verify that sample flow exiting the sample container is between 4 and 10 L/min.
10. Purge the sample container for sufficient time (2-3 min) to allow at least 7 volume
exchanges to pass through the sample container.
11. Simultaneously close the sample outlet valve and sample inlet valve of the sample
container.
12. Turn off sample pump.
4-2
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Section 4
Revision 1
June 1992
Page 3 of 6
13. Disconnect and remove sample container.
14. Replace both 1/4-in. end caps and tighten securely.
15. Repeat steps 3-14 for the two remaining sample containers.
16. Complete N2O Field Data Form (Figure 4-2). Identification numbers are stamped on the
ends of the sample containers.
17. Complete Sample Custody Sheet (Figure 4-3). Transfer samples to laboratory for
subsequent N2O analysis.
4-3
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stack
flow
To CEMs, dryart, ate
sample
pump
Figure 4-1A. Location of sampling system.
from stack
sample pump
Inlet
HjOsorbent
Rgure 4-1B. Sorbent/sample container schematic.
Rgure 4-1. N^O Sampling system configuration.
outlet
sample container
flow
meter
o> ro -* *>.
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Section 4
Revision 1
June 1992
Page 5 of 6
EPA/AEERL N2O FIELD DATA FORM
1. Sampler Identification - 2. Untt Identification
Sampler's Name:
Company Name:
Company Address:
Phone:
Date Samples Taken:
Date Samples Sent: _
3. Fuel Characterization
Type of Fuel:
Fuel Analysis:
Proximate Analysis (wt%)
Volatile Matter:
Fixed Carbon:
Moisture:
Ash:
Ultimate Analysis (dry wt%)
Carbon:
Hydrogen:
Nitrogen:
Oxygen:
Sulfur:
Ash:
Heating Value (HHV):.
Btu/lb
5. Other Stack Emissions
Oxygen (O2):
Moisture
Carbon Dioxide (CO2):
N2O Cone.
Sulfur Dioxide (SO2):
Nitric Oxide (NO):
Nitrogen Oxides (NOX):
Carbon Monoxide (CO):
_ppm
_ppm
jppm
_ppm
Figure 4-2.
Manufacturer of Unit:.
Type of Unit:
Thermal Rating:
Unit Name*:
Btu/hr
MW
Unit Location*:
'Optional (please include alphanumeric code if desired)
4. Operating Conditions •
Unit Load: Btu/lb
Stoichiometric Ratio:
Excess Air
Type of Burners:
NOX Control Used:.
Flue Gas Cleaning Used:
Operating Notes:.
6. N,O Analysis -
Date Samples Received:.
Date Analyses Performed:
Container f
Analysis Performed By:
field data form.
MW
4-5
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N20 SAMPLE CUSTODY SHEET
Section 4
Revision 1
June 1992
Page 6 of 6
Samples collected by
Signature of collector
Samples shipped by _
Signature of transferor.
For Laboratory Use
Samples received by _
Signature of transferee
Date
Date
Date
Sample ID
Sample Contents \ Comments
Date Collected
AMf -. w>sX XvCwv$?W*<
FerLabifeg"
Date Analyzed;;
" tm%£\
V,
f • ' .''*$&
Comments \ Suggestions:
Sample custody sheet.
4-6
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Sections
Revision 1
June 1992
Page 1 of 1
SECTION 5
REFERENCES
1. Ford, J.S., "Recommended Operating Procedure No. 45: Analysis of Nitrous Oxide from
Combustion Sources," 1990. EPA-600/8-90-053 (NTIS PB90-238502).
2. Weiss, R.F., The Temporal and Spatial Distribution of Tropospheric Nitrous Oxide," Journal of
Geophysical Research, 86, 7185-7195, 1981.
3. Muzio, L.J., and Kramlich, J.C., "An Artifact in the Measurement of N2O from Combustion
Sources," Geophysical Research Letters, 15:1369,1988.
4. Linak, W.P., McSorley, J.A., Hall, R.E., Ryan, J.V., Srivastava, R.K., Wendt, J.O.L., and Mereb,
J.B., "Nitrous Oxide Emissions from Fossil Fuel Combustion," Journal of Geophysical Research,
95(D6), 7533-7541, 1990.
5. Ryan, J.V., and Srivastava, R.K., "EPA/IFP European Workshop on the Emission of Nitrous
Oxide from Fossil Fuel Combustion," 1989. EPA-600/9-89-089 (NTIS PB90-126038).
5-1
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/R-92-141
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Recommended Operating Procedure No. 56: Collection
of Gaseous Grab Samples from Combustion Sources
for Nitrous Oxide Measurement
5. REPORT DATE
July 1992
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Jeffrey V. Ryan and Shawn A. Karns
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Acurex Environmental
P. O. Box 13109
Research Triangle Park, North Carolina 27709
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-DO-0141, Task 92-066
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air and Energy Engineering Research Laboratory
Research Triangle Park, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task final; 1-12/91
14. SPONSORING AGENCY CODE
EPA/600/13
15.SUPPLEMENTARY NOTES AEERL project officer is William P. Linak, Mail Drop 65, 919/
541-5792.
16. ABSTRACT Tne Document is a recommended operating procedure (ROP), prepared for
use in research activities conducted by EPA's Air and Energy Engineering Research
Laboratory (AEERL). The procedure applies to the collection of gaseous grab sam-
ples from fossil fuel combustion sources for subsequent analysis of nitrous oxide.
The procedure details only the grab sampling methodology and associated equipment.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. cos AT I Field/Group
Pollution
Sampling
Nitrogen Oxide (N2O)
Analyzing
Fossil Fuels
Combustion
Pollution Control
Stationary Sources
Operating Procedures
13 B
14B
07B
21D
21B
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
27
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
5-2
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