ASTM D7165-06
(Practice)Standard Practice for Gas Chromatograph Based On-line/At-line Analysis for Sulfur Content of Gaseous Fuels
Standard Practice for Gas Chromatograph Based On-line/At-line Analysis for Sulfur Content of Gaseous Fuels
SCOPE
1.1 This practice is for the determination of volatile sulfur-containing compounds in high methane content gaseous fuels such as natural gas using on-line/at-line instrumentation, and continuous fuel monitors (CFMS). It has been successfully applied to other types of gaseous samples including air, digester, landfill, and refinery fuel gas. The detection range for sulfur compounds, reported as picograms sulfur, based upon the analysis of a 1 cc sample, is one hundred (100) to one million (1,000,000). This is equivalent to 0.1 to 1,000 mg/m3.
1.2 This practice does not purport to measure all sulfur species in a sample. Only volatile compounds that are transported to an instrument under the measurement conditions selected are measured.
1.3 The values stated in SI units are standard. The values stated in inch-pound units are for information only.
1.4 This practice does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this practice to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D7165–06
Standard Practice for
Gas Chromatograph Based On-line/At-line Analysis for
Sulfur Content of Gaseous Fuels
This standard is issued under the fixed designation D7165; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D4084 Test Method for Analysis of Hydrogen Sulfide in
Gaseous Fuels (Lead Acetate Reaction Rate Method)
1.1 This practice is for the determination of volatile
D4468 Test Method for Total Sulfur in Gaseous Fuels by
sulfur-containing compounds in high methane content gaseous
Hydrogenolysis and Rateometric Colorimetry
fuels such as natural gas using on-line/at-line instrumentation,
D4626 Practice for Calculation of Gas Chromatographic
and continuous fuel monitors (CFMS). It has been successfully
Response Factors
applied to other types of gaseous samples including air,
D4810 Test Method for Hydrogen Sulfide in Natural Gas
digester, landfill, and refinery fuel gas. The detection range for
Using Length-of-Stain Detector Tubes
sulfur compounds, reported as picograms sulfur, based upon
D5504 Test Method for Determination of Sulfur Com-
the analysis ofa1cc sample, is one hundred (100) to one
pounds in Natural Gas and Gaseous Fuels by Gas Chro-
million (1,000,000). This is equivalent to 0.1 to 1,000 mg/m3.
matography and Chemiluminescence
1.2 This practice does not purport to measure all sulfur
D6228 Test Method for Determination of Sulfur Com-
species in a sample. Only volatile compounds that are trans-
pounds in Natural Gas and Gaseous Fuels by Gas Chro-
ported to an instrument under the measurement conditions
matography and Flame Photometric Detection
selected are measured.
E594 Practice for Testing Flame Ionization Detectors Used
1.3 The values stated in SI units are standard. The values
in Gas or Supercritical Fluid Chromatography
stated in inch-pound units are for information only.
1.4 This practice does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 Definitions:
responsibility of the user of this practice to establish appro-
3.1.1 direct sampling—Sampling where there is no direct
priate safety and health practices and determine the applica-
connection between the medium to be sampled and the
bility of regulatory limitations prior to use.
analytical unit.
2. Referenced Documents 3.1.2 in-line instrument—Instrument whose active element
2 is installed in the pipeline and measures at pipeline conditions.
2.1 ASTM Standards:
3.1.3 on-line instrument—Automated instrument that
D1072 Test Method for Total Sulfur in Fuel Gases by
samples gas directly from the pipeline, but is installed exter-
Combustion and Barium Chloride Titration
nally.
D1945 Test Method for Analysis of Natural Gas by Gas
3.1.4 at-line instrument—instrument requiring operator in-
Chromatography
teraction to sample gas directly from the pipeline.
D3606 Test Method for Determination of Benzene and
3.1.5 continuous fuel monitor (CFM)—Instrument that
Toluene in Finished Motor and Aviation Gasoline by Gas
samples gas directly from the pipeline on a continuous or
Chromatography
semi-continuous basis.
3.1.6 total reduced sulfur (TRS)—Summation of sulfur
species where the sulfur oxidation number is –2, excluding
This practice is under the jurisdiction of ASTM Committee D03 on Gaseous
sulfurdioxide,sulfones,andotherinorganicsulfurcompounds.
Fuels and is the direct responsibility of Subcommittee D03.12 on On-Line/At-Line
This includes but is not limited to mercaptans, sulfides, and
Analysis of Gaseous Fuels.
disulfides.
Current edition approved Jan. 15, 2006. Published January 2006. DOI: 10.1520/
D7165-06.
3.1.7 near-real time monitoring systems—Monitoring sys-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
temwheremeasurementoccurssoonaftersampleflowthrough
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
the system or soon after sample extraction. The definition of a
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. near real time monitoring system can be application specific.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7165–06
4. Summary of Practice The sampling inlet system is heated as necessary so as to
prevent condensation.All wetted sampling system components
4.1 Arepresentative sample of the gaseous fuel is extracted
must be constructed of inert or passivated materials. Sample
from a process pipe or pipeline and is transferred in a timely
delivered to the inlet system should be in the gas phase free of
manner to an analyzer inlet system. The sample is conditioned
particulate or fluidic matter.
with minimum impact on sulfur content.Aprecisely measured
6.2.1 Carrier and Detector Gas Control—Constant flow
volume of sample is injected into the analyzer. Excess process
control of carrier and detector gases is critical for optimum and
orpipelinesampleisventedorisreturnedtotheprocessstream
consistent analytical performance. Control is achieved by use
dependant upon application and regulatory requirements.
of pressure regulators and fixed flow restrictors. The gas flow
4.2 Sample containing carrier gas is fed to a gas chromato-
is measured by appropriate means and adjusted, as required, to
graph where the components are separated using either a
the desired value. Mass flow controllers, capable of maintain-
packedorcapillarycolumn.Measurementisperformedusinga
ing a gas flow constant to within 6 1 % at the flow rates
suitable sulfur detection system.
necessary for optimal instrument performance can be used.
4.3 Calibration, precision, calibration error, performance
audit tests, maintenance methodology and miscellaneous qual- 6.2.2 Detector—Sulfurcompoundscanbemeasuredusinga
ity assurance procedures are conducted to determine analyzer variety of detectors including but not limited to: sulfur chemi-
performancecharacteristicsandvalidateboththeoperationand
luminescence, flame photometric, electrochemical cell, oxida-
the quality of generated results. tive cell and reductive cells. In selecting a detector, the user
should consider the linearity, sensitivity, and selectivity of
5. Significance and Use particular detection systems prior to installation. The user
should also consider interference from substances in the gas
On-line, at-line, in-line, CFMS, and other near-real time
stream that could result in inaccurate sulfur gas measurement
monitoring systems that measure fuel gas characteristics, such
due to effects such as quenching.
as the sulfur content, are prevalent in the natural gas and fuel
6.3 Columns—Avariety of columns can be used to separate
gas industries. The installation and operation of particular
the sulfur compounds in the sample. Typically, a 60 m 3 0.53
systemsvaryonthespecificobjectives,contractualobligations,
mmIDfusedsilicaopentubularcolumncontaininga5µmfilm
process type, regulatory requirements, and internal perfor-
thickness of bonded methyl silicone liquid phase is used. The
mance requirements needed by the user. This standard is
selected column must provide retention and resolution charac-
intended to provide guidelines for standardized start-up proce-
teristics that satisfy the intended application. The column must
dures,operatingprocedures,andqualityassurancepracticesfor
be inert towards sulfur compounds. The column must also
on-line, at-line, in-line, CFMS, and other near-real time gas
demonstrate a sufficiently low liquid phase bleed at high
chromatographic based sulfur monitoring systems used to
temperature such that a loss of the instrument response is not
determine fuel gas sulfur content. For measurement of gaseous
encountered while operating the column at elevated tempera-
fuel properties using laboratory based methods the user is
tures.
referred to Test Methods D1072, D1945, D4084, D4468,
D4810 and Practices D4626, E594.
6.4 Data Acquisition—Data acquisition and storage can be
accomplished using a number of devices and media. Following
6. Apparatus are some examples.
6.4.1 Recorder—As an example,a0to1mV range record-
6.1 Instrument—Any gas chromatographic based instru-
ingpotentiometerorequivalent,withafull-scaleresponsetime
ment of standard manufacture, with hardware necessary for
of2sor less can be used. A4-20 mA range recorder can also
interfacing to a natural gas or other fuel gas pipeline and
be used.
containingallfeaturesnecessaryfortheintendedapplication(s)
can be used.
6.4.2 Integrator—An electronic integrating device or com-
6.1.1 The chromatographic parameters must be capable of
puter can be used. For GC based systems, it is suggested that
obtaining retention time repeatability of 0.05 min. (3 sec.).
the device and software have the following capabilities:
Instrumentation must meet the performance characteristics for
6.4.2.1 Graphic presentation of chromatograms.
repeatability and precision without encountering unacceptable
6.4.2.2 Digital display of chromatographic peak areas.
interference or bias. The components coming in contact with
6.4.2.3 Identification of peaks by retention time or relative
sample, such as tubing and valving, must be passivated or
retention time, or both.
constructed of inert materials to ensure an accurate sulfur gas
6.4.2.4 Calculation and use of response factors.
measurement.
6.4.2.5 External standard calculation and data presentation.
6.2 Sample Inlet System—Asample inlet system capable of
operating continuously above the maximum column tempera- 6.4.3 Distributed Control Systems (DCS)—Depending on
ture is necessary. A variety of sample inlet configurations can the site requirements, the analytical results are sometimes fed
be used including but not limited to on-column systems and to a distributed control system. The information is then used to
split/splitless injection system capable of splitless operation make the appropriate adjustments to the process. Signal isola-
and split control from 10:1 up to 50:1. An automated gas tion between the analyzer and the distributed control network
sampling valve is required for many applications. The inlet is most often required. Communications protocols with the
system must be constructed of inert material and evaluated DCS will dictate the required signal output requirements for
frequently for compatibility with reactive sulfur compounds. the analyzer.
D7165–06
6.4.4 Data Management Systems—Data management sys- change results in an actual permeation rate that differs from the
tems or other data and data processing repositories are some- certified permeation rate.
times used to collect and process the results from a wide 7.2 Compressed Gas Standards—Alternatively, blended
variety of instrumentation at a single facility. The information gaseous sulfur standards in nitrogen, helium or methane base
is then available for rapid dissemination within the organiza- gas may be used. Care must be exercised in the use of
tion of the operating facility. Communications protocols with compressed gas standards since they can introduce errors in
the data management system will dictate the required signal measurement due to lack of uniformity in their manufacture or
output requirements for the analyzer. instability in their storage and use. Standards should be
blended such that components will not condense under storage
7. Reagents and Materials orwhilethestandardisinuse.Theprotocolforcompressedgas
standards contained in the appendix can be used to ensure
NOTE 1—Warning: Sulfur compounds contained in permeation tubes
uniformity in compressed gas standard manufacture and pro-
or compressed gas cylinders may be flammable and harmful or fatal if
vide for traceability to a NIST or NMi (Nederlands Meetinsti-
ingested or inhaled. Permeation tubes, which emit their contents continu-
ously, and compressed gas standards should only be handled in well tuut) reference material.
ventilated locations away from sparks and flames. Improper handling of
7.2.1 Compressed gas standard regulators must be appro-
compressed gas cylinders containing air, hydrogen, argon, nitrogen or
priate for the delivery of sulfur gases and attached fittings must
helium can result in an explosion or in creating oxygen deficient
be passivated or inert to sulfur gases.
atmospheres. Rapid release of argon, nitrogen or helium can result in
7.2.2 All compressed gas standards must be re-certified as
asphyxiation. Compressed air supports combustion.
recommended by the manufacturer or as needed to insure
7.1 Sulfur Standards—Accurate sulfur standards are re-
accuracy.
quired for the quantitation of the sulfur content of natural gas.
7.3 The following sulfur compounds, including the molecu-
Permeation and compressed gas standards should be stable,
lar formula and the CAS number, are commonly found or are
and of the highest available accuracy and purity.
added to natural gas and related fuel gases and may be useful
7.1.1 Permeation Devices—Sulfur standards can be pro-
as calibrants for on-line and at-line monitors:
duced on demand using permeation tubes, one for each
7.3.1 Hydrogen sulfide (H S) (7783-06-4)
selected sulfur species, gravimetrically calibrated and certified
7.3.2 Methyl mercaptan (CH SH) (74-93-1)
at a convenient operating temperature. With constant tempera-
7.3.3 Ethyl mercaptan (CH CH SH) (75-08-1)
3 2
ture, calibration gases covering a wide range of concentration
7.3.4 1-propanethiol (CH CH CH SH) (107-03-9)
3 2 2
can be generated by varying and accurately measuring the flow
7.3.5 2-propanethiol (CH CHSHCH ) (75-33-2)
3 3
rate of diluent gas passing over the tubes. Permeation devices
7.3.6 Dimethyl sulfide (CH SCH ) (75-18-3)
3 3
delivering calibrant at a known high purity must be used since
7.3.7 Dimethyl disulfide (CH SSCH ) (624-92-0)
3 3
contaminants will adversely impact the calculation of analyte
7.3.8 Tetrahydrothiophene (THT) (110-01-0)
concentration due to error in permeation rate calculated from
7.3.9 t-butyl mercaptan ((CH ) CSH) (75-66-1)
3 3
differential weight measurements of these devices. It is sug-
7.4 Many applications require the periodic preparation of a
gested that certified permeation devices be used whenever
calibration curve or a linearity verification as part of a QA
available.
program. To satisfy this need, three calibration standards can
7.1.1.1 Permeation System Temperature Control—
be used consisting of volatile sulfur species at:
Permeation devices are maintained at the calibration tempera-
7.4.1 10-
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