ASTM D7551-10

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Designation:D7551 −10
StandardTest Method for
Determination of Total Volatile Sulfur in Gaseous
Hydrocarbons and Liquefied Petroleum Gases and Natural
Gas by Ultraviolet Fluorescence
This standard is issued under the fixed designation D7551; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method covers the determination of total
2.1 ASTM Standards:
volatile sulfur in gaseous hydrocarbons, Liquefied Petroleum D1070Test Methods for Relative Density of Gaseous Fuels
Gases(LPG)andLiquefiedNaturalGas(LNG).Itisapplicable
D1072Test Method for Total Sulfur in Fuel Gases by
toanalysisofnaturalgaseousfuels,processintermediates,final Combustion and Barium Chloride Titration
product hydrocarbons and generic gaseous fuels containing
D1265Practice for Sampling Liquefied Petroleum (LP)
sulfur in the range of 1 to 200 mg/kg. Samples can also be Gases, Manual Method
tested at other total sulfur levels using either pre-concentration
D3588Practice for Calculating Heat Value, Compressibility
methods or sample dilution using a diluent gas. The method-
Factor, and Relative Density of Gaseous Fuels
ology for preconcentration and dilution techniques is not
D3609Practice for Calibration Techniques Using Perme-
covered in this test method. The precision statement does not
ation Tubes
apply if these techniques are used in conjunction with this test
D4150Terminology Relating to Gaseous Fuels
method. The diluent gas, such as UHP nitrogen, zero nitrogen
D4177Practice for Automatic Sampling of Petroleum and
or zero air, shall not have a significant total sulfur concentra-
Petroleum Products
tion.
D4784Specification for LNG Density Calculation Models
D5287Practice for Automatic Sampling of Gaseous Fuels
1.2 This test method may not detect sulfur compounds that
D5503Practice for Natural Gas Sample-Handling and Con-
do not volatilize under the conditions of the test.
ditioning Systems for Pipeline Instrumentation
1.3 This test method covers the laboratory determination
D5504TestMethodforDeterminationofSulfurCompounds
and the at-line/on-line determination of total volatile sulfur in
in Natural Gas and Gaseous Fuels by Gas Chromatogra-
gaseous fuels, LPG, and LNG.
phy and Chemiluminescence
D6228TestMethodforDeterminationofSulfurCompounds
1.4 This test method is applicable for total volatile sulfur
in Natural Gas and Gaseous Fuels by Gas Chromatogra-
determination in gaseous hydrocarbons, LPG, and LNG con-
phy and Flame Photometric Detection
taining less than 0.35 mole% halogen(s).
D6299Practice for Applying Statistical Quality Assurance
1.5 The values stated in SI units are to be regarded as
and Control Charting Techniques to Evaluate Analytical
standard. No other units of measurement are included in this
Measurement System Performance
standard.
D7166Practice forTotal SulfurAnalyzer Based On-line/At-
line for Sulfur Content of Gaseous Fuels
1.6 This standard does not purport to address all of the
E617Specification for Laboratory Weights and Precision
safety concerns, if any, associated with its use. It is the
Mass Standards
responsibility of the user of this standard to establish appro-
E691Practice for Conducting an Interlaboratory Study to
priate safety and health practices and determine the applica-
Determine the Precision of a Test Method
bility of regulatory limitations prior to use. See Sections 4.1,
F307Practice for Sampling Pressurized Gas for GasAnaly-
7.3, 7.4, 11.2, and Section 8.
sis
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous
Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Special Constituents of Gaseous Fuels. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved May 1, 2010. Published June 2010. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D7551–10. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7551−10
2.2 ASTM Manuals: ture combustion tube where the sulfur-containing compounds
ASTM MNL 7 in the sample are oxidized to SO . Water produced during the
2.3 GPA Standards: sample combustion is removed, as required, and the sample
combustiongasesarethenexposedtoasourceofcontinuousor
GPA 2166Obtaining Natural Gas Samples for Analysis by
Gas Chromatography pulsedUVlight.TheSO absorbstheenergyfromtheUVlight
GPA 2174Obtaining Liquid Hydrocarbon Samples for to form SO *. Fluorescence emitted from SO * as it returns to
2 2
Analysis by Gas Chromatography SO ,isdetectedbyaphotomultipliertube.Theresultingsignal
isameasureofthesulfurcontainedinthesample. Warning—
3. Terminology
Exposure to excessive quantities of UV light is injurious to
health. The operator shall avoid exposing any part of their
3.1 Defintions:
person, especially their eyes, not only to direct UV light but
Fordefinitionsof at-line instrumentand on-line instrumentsee
also to secondary or scattered radiation that is present.
Terminology D4150.
3.2 Acronyms:
4.2 Thedesignandinstallationdetailsfortheon-line/at-line
3.2.1 LNG—liquefied natural gas
process analyzer needs to conform to application-specific
requirements including, but not limited to, acceptable design
3.2.2 LPG—liquefied petroleum gas
practices as described in Practice D7166, hazardous area
3.2.3 NIST—NationalInstituteofStandardsandTechnology
classifications, safety practices, and regulatory requirements.
3.2.4 NMi—Nederlands Meetinstituut
Fig. 1 illustrates a general flow diagram applicable for an
3.2.5 NTRM—NIST traceable reference material
on-line/at-line process analyzer. Sample collection and
conditioning, sample introduction and detection system are
3.2.6 QA—quality assurance
depicted.Modificationstomeetsite-specificand/orapplication
3.2.7 QC—quality control
specific requirements may be required.
3.2.8 SO —ground state sulfur dioxide
3.2.9 SO *—excited state sulfur dioxide
5. Significance and Use
3.2.10 SOx—sulfur oxides
5.1 The sulfur content of gaseous hydrocarbons, LPG, and
3.2.11 SRM—standard reference material
LNGusedforfuelpurposescontributestototalSOxemissions
andcanleadtocorrosioninengineandexhaustsystems.Some
3.2.12 UHP—ultra high purity
process catalysts used in petroleum and chemical refining can
3.2.13 UV—ultraviolet
bepoisonedbytraceamountsofsulfur-bearingmaterialsinthe
3.2.14 VSL—Van Swinden Laboratorium
feedstocks.Thistestmethodcanbeusedtodeterminethetotal
volatile sulfur content in process feeds, to control the total
4. Summary of Test Method
volatile sulfur content in finished products and, as applicable,
4.1 Agaseoussampleisinjectedintotheanalyzer,eitherby
to meet regulatory requirements. Practice D1072 has previ-
a sample valve, direct injection at a constant flow rate, or by
ously been used for the measurement of total sulfur in gaseous
syringe.ALPG or LNG sample is vaporized in an appropriate
fuels.
expansion chamber and injected into the analyzer by a sample
valveorasyringeorasamplevalveconnectedtoanexpansion
6. Apparatus
chamber. The gaseous sample then enters into a high tempera-
6.1 Furnace—An electric furnace held at a constant tem-
perature in accordance with the analyzer manufacturer’s rec-
ommendations (nominally 1000 to 1125°C) sufficient to oxi-
MNL7AManual on Presentation of Data and Control Chart Analysis, Seventh
Edition, ASTM International, West Conshohocken. 2002. dize the entire sample to carbon dioxide and water and oxidize
AvailablefromGasProcessorsAssociation(GPA),6526E.60thSt.,Tulsa,OK
the sulfur in the sample to SO .
74145, http://www.gasprocessors.com.
FIG. 1General Flow Diagram—On-Line Analyzer
D7551−10
6.2 Combustion Tube—A quartz tube constructed to allow 7.3 Oxygen—High purity, that is, chromatography or zero
thedirectinjectionofthesampleintotheheatedoxidationzone grade, 99.75% minimum purity, moisture 5 mg/kg maximum,
of the furnace by syringe or sample valve using either oxygen dried over molecular sieves, as required. Warning—Oxygen
or air for the oxidation of the sample. Other tube materials vigorously accelerates combustion.
suitableforuseatthefurnaceoperatingconditionscanbeused
7.4 Air—Use dry, sulfur free air, that is, chromatography
so long as performance is not degraded. The oxidation section
˚
grade or zero grade, –40 C dew point or lower, as required.
shall be large enough to ensure complete conversion of the
Nitrogen/oxygen or helium/oxygen bottled gas blends contain-
sample to carbon dioxide and water and oxidize the sulfur in
ing no more than 30% oxygen can also be used, as required.
the sample to SO .
Warning—Never use pure oxygen as a substitute for air on
6.3 Flow Control—The apparatus shall be equipped with analyzers designed to operate using air as a carrier gas.
flow controllers capable of maintaining a constant volumetric
7.5 Calibration Standards—Certified liquid or gas phase
flowrateofthecarriergasesnecessaryforperformingthetotal
calibration standards from commercial sources or calibration
sulfur analysis.
gases prepared using certified permeation tube devices are
6.4 Drier—The oxidation of the sample produces reaction
required (see Notes 2 and 3).Accurate volatile sulfur contain-
products that include water vapor which, if in excess, must be
ing standards are required for quantization of the volatile total
removed prior to measurement by the detector. This can be
sulfurcontent.Permeationtubesandcompressedgasstandards
accomplished with a membrane drying tube, or a permeation
should be stable, of high purity, and of the highest available
dryer that utilizes a selective capillary action for water re-
accuracy. Use of standards consisting of a sulfur compound
moval.
and matrix similar to samples to be analyzed is recommended.
6.5 UV Fluorescence Detector—A quantitative detector ca-
NOTE 2—Other sulfur sources and diluent materials can be used if
pable of measuring light emitted from the fluorescence of SO
precision and accuracy are not degraded. The use of solvent based
calibrationstandardsthatareliquidatambienttemperaturesandpressures
generated by continuous or pulsed UV light.
is not recommended.
NOTE 1—For an on-line analyzer, detection of uncombusted hydrocar-
NOTE 3—Calibration standards are typically re-mixed and re-certified
bons in the UV Fluorescence Detector can be used to ensure complete
on a regular basis depending upon frequency of use and age. LPG
conversion of the hydrocarbons to carbon dioxide and water and to
calibration standards have a typical useful life of about 6–12 months.
minimize the potential for coke formation in the analytical system.
NOTE 4—Enhanced oxygen containing combustion gasses, such as
6.6 Sample Inlet System—Either of the following two types
30% Oxygen balance Helium, Nitrogen, and/or Argon, can be used if
of sample inlet systems can be used.
precision and accuracy are not degraded.
6.6.1 Sample Valve System—The system provides a gas- NOTE 5—Warning: Compressed gas cylinders as well as sulfur
compoundscontainedinpermeationtubesmaybeflammableandharmful
sampling valve, or an LPG or LNG gas or liquid sampling
or fatal if ingested or inhaled. Permeation tubes and compressed gas
valve with an expansion chamber, or both, with access to the
standards should only be handled in well ventilated locations away from
inlet of the oxidation area. The system is swept by the carrier
sparks and flames. Improper handling of compressed gas cylinders
gas at the manufacturer’s recommended flow rate.
containing air, nitrogen, helium, or other gasses can result in unsafe
6.6.2 Sample Injection—The sample inlet system for gas- conditions that can cause severe damage to equipment and significant
harm, including death, to people. Rapid release of nitrogen or helium can
eous samples shall be capable of allowing the quantitative
result in asphyxiation. Compressed air supports combustion.
delivery of the material to be analyzed into an inlet carrier
7.5.1 Permeation Devices—Standards containing volatile
stream which directs the sample into the oxidation zone at a
sulfurcompoundscanbemadefrompermeationtubes,onefor
controlled and repeatable rate. For a laboratory analysis, a
each selected sulfur species, gravimetrically calibrated and
syringe drive mechanism that discharges the sample from the
certified at a convenient operating temperature. With constant
syringe at a rate of approximately 1 mL/s is required. For at
temperature, calibration gases covering a wide range of con-
line and on-line analysis a constant volumetric flow rate
centration can be generated by varying and accurately measur-
delivery device is used.
ing the flow rate of diluent gas passing over the permeation
6.7 Strip Chart Recorder, equivalent electronic data logger,
tubes. These calibration gases can be used to calibrate the
integrator or, recorder (optional).
analyzer system.
7.5.1.1 Permeation System Temperature Control—
7. Reagents
Permeation devices are maintained at the calibration tempera-
7.1 Purity of Reagents—Reagent grade chemicals shall be
ture within 60.1 °C.
used in tests. Unless otherwise indicated, it is intended that all
7.5.1.2 Permeation System Flow Control—The permeation
reagents shall conform to the specifications of the Committee
flow system measures diluent gas flow over the permeation
on Analytical Reagents of the American Chemical Society,
tubes within an accuracy of 62%.
where such specifications are available. Other grades may be
7.5.1.3 Permeation tubes are inspected and weighed to the
used, provided it is first ascertained that the reagent is of
nearest 0.01 mg on at least a monthly basis using a balance
sufficiently high purity to permit its use without lessening the
calibrated against Specification E617 Class 1 weights or
accuracy of the determination.
equivalent. Analyte concentration is calculated by weight loss
7.2 Inert Gas—Argon or helium only, high purity grade and dilution gas flow rate as per Practice D3609. Permeation
(that is, chromatography or zero grade), 99.998% minimum tubes are replaced when the liquid contents are reduced to less
purity, moisture 5 mg/kg maximum, as required. than10%oftheinitialmassorwhenthepermeationsurfaceis
D7551−10
unusually discolored or otherwise compromised. Permeation 8. Hazards
tube disposal shall be in accordance with all applicable
8.1 Consult current OSHA regulations, supplier
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