ASTM D4891-13(2018)
(Test Method)Standard Test Method for Heating Value of Gases in Natural Gas and Flare Gases Range by Stoichiometric Combustion
Standard Test Method for Heating Value of Gases in Natural Gas and Flare Gases Range by Stoichiometric Combustion
SIGNIFICANCE AND USE
5.1 This test method provides an accurate and reliable procedure to measure the total heating value of a fuel gas, on a continuous basis, which is used for regulatory compliance, custody transfer, and process control.
5.2 Some instruments which conform to the requirements set forth in this test method can have response times on the order of 1 min or less and can be used for on-line measurement and control.
5.3 The method is sensitive to the presence of oxygen and nonparaffin fuels. For components not listed and composition ranges that fall outside those in Table 1 and Table 2, modifications in the method and changes to the calibration gas or gasses being used may be required to obtain correct results.
SCOPE
1.1 This test method covers the determination of the heating value of natural gases and similar gaseous mixtures within the range of composition shown in Table 1, and Table 2 that covers flare components but is not intended to limit the components to be measured in flare gases.
1.2 This standard 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 standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D4891 − 13 (Reapproved 2018)
Standard Test Method for
Heating Value of Gases in Natural Gas and Flare Gases
Range by Stoichiometric Combustion
This standard is issued under the fixed designation D4891; 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 3.2 Definitions of Terms Specific to This Standard:
3.2.1 combustion ratio, n—the ratio of combustion air to
1.1 Thistestmethodcoversthedeterminationoftheheating
gaseous fuel.
value of natural gases and similar gaseous mixtures within the
3.2.2 burned gas parameter, n—apropertyoftheburnedgas
rangeofcompositionshowninTable1,andTable2thatcovers
after combustion which is a function of the combustion ratio.
flarecomponentsbutisnotintendedtolimitthecomponentsto
be measured in flare gases.
3.2.3 criticalcombustionratio,n—foraspecificburnedgas
parameter, the combustion ratio at which a plot of burned gas
1.2 This standard does not purport to address all of the
parameter versus combustion ratio has either maximum value
safety concerns, if any, associated with its use. It is the
or maximum slope.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
3.2.4 combustion air requirement index (CARI), n—is the
mine the applicability of regulatory limitations prior to use.
amount of air required for complete combustion of the gas
1.3 This international standard was developed in accor-
being measured and can be used to index against other
dance with internationally recognized principles on standard-
measured values such as the Wobbe Index or Heating Value.
ization established in the Decision on Principles for the
3.2.5 stoichiometricratio,n—thecombustionratiowhenthe
Development of International Standards, Guides and Recom-
quantity of combustion air is just sufficient to convert all of the
mendations issued by the World Trade Organization Technical
combustibles in the fuel to water and carbon dioxide.
Barriers to Trade (TBT) Committee.
4. Summary of Test Method
2. Referenced Documents
2 4.1 Air is mixed with the gaseous fuel to be tested. The
2.1 ASTM Standards:
mixture is burned and the air-fuel ratio is adjusted so that
D1826TestMethodforCalorific(Heating)ValueofGasesin
essentially a stoichiometric proportion of air is present. More
Natural Gas Range by Continuous Recording Calorimeter
exactly, the adjustment is made so that the air-fuel ratio is in a
E691Practice for Conducting an Interlaboratory Study to
constant proportion to the stoichiometric ratio that is a relative
Determine the Precision of a Test Method
3 measure of the heating value. To set this ratio, a characteristic
2.2 EPA Standard:
property of the burned gas is measured, such as temperature or
EPA-600/2-85-106EvaluationoftheEfficiencyofIndustrial
oxygen concentration.
Flares: Flare Head Design and Gas Composition
5. Significance and Use
3. Terminology
5.1 This test method provides an accurate and reliable
3.1 All of the terms defined in Test Method D1826 are
procedure to measure the total heating value of a fuel gas, on
included by reference.
a continuous basis, which is used for regulatory compliance,
custody transfer, and process control.
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous
Fuels and is the direct responsibility of Subcommittee D03.03 on Determination of
5.2 Some instruments which conform to the requirements
Heating Value and Relative Density of Gaseous Fuels.
set forth in this test method can have response times on the
Current edition approved Sept. 1, 2018. Published September 2018. Originally
orderof1minorlessandcanbeusedforon-linemeasurement
approved in 1989. Last previous edition approved in 2013 as D4891–13. DOI:
10.1520/D4891-13R18.
and control.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.3 The method is sensitive to the presence of oxygen and
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
nonparaffin fuels. For components not listed and composition
the ASTM website.
ranges that fall outside those in Table 1 and Table 2, modifi-
Available from United States Environmental Protection Agency (EPA), Ariel
cations in the method and changes to the calibration gas or
Rios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20004, http://
www.epa.gov. gasses being used may be required to obtain correct results.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4891 − 13 (2018)
TABLE 1 Natural Gas Components and Range of Composition TABLE 2 Natural Gas Components and Range of Composition
A
Covered Covered
Compound CAS Number
Compound Concentration Range, mole, %
Volatile Analytes
Helium 0.01 to 5
Acetone 67-64-1
Nitrogen 0.01 to 20
Acetonitrile 75-05-8
Carbon dioxide 0.01 to 10
Acrolein 107-05-8
Methane 50 to 100
Acrylonitrile 107-13-1
Ethane 0.01 to 20
Benzene 71-43-2 2
Propane 0.01 to 20
1,3-Butadiene 106-99-0
n-butane 0.01 to 10
Carbon disulfide 75-15-0
isobutane 0.01 to 10
Chlorobenzene 108-90-7
n-pentane 0.01 to 2
Cumene 98-82-8
Isopentane 0.01 to 2
(isopropylbenzene)
Hexanes and heavier 0.01 to 2
1,2-Dibromoethane 106-93-4
Ethylbenzene 100-41-4 2,2,4
Hexane 110-54-3
Methanol 67-56-1
6. Apparatus
Methyl isobutyl ketone 108-10-1
Methyl t-butyl ether 1634-04-4
6.1 A suitable apparatus for carrying out the stoichiometric
Methylene chloride 75-09-2
combustion method will have at least the following four
Nitrobenzene 98-95-3
components: flow meter or regulator, or both; combustion Nitropropane 79-46-9
Pentane2 109-66-0
chamber; burned gas sensor; and electronics. The requirement
Styrene 100-42-5
for each of these components is discussed below. The detailed
Tetrachloroethene 127-18-4
design of each of these components can vary. Three different Toluene 108-88-3
Trichloroethene 79-01-6
apparatus are shown in Fig. 1, Fig. 2 and Fig. 3. In each figure
Trimethylpentane 2 540-84-1
the equivalent of the four necessary components are enclosed
Xylenes (mixed isomers) 1330-20-7
Trimethylpentane 2 540-84-1
in dashed lines.
Xylenes (mixed isomers) 1330-20-7
6.2 Overview—Airandfuelentertheapparatusandtheflow
Semi-volatile Analytes
of each is measured. Alternatively, only one gas flow need be
Acenaphthene 83-32-9
measured if the flow of the other is kept the same during
Acenaphthylene 208-96-8
measurement and calibration.This is illustrated in Fig. 2. Next
Aniline 62-53-3
Anthracene 120-12-7
there is a combustion chamber in which the air and fuel are
Benzidine1 92-87-5
mixedandburned.Thiscanbeassimpleasabunsenormeeker
Benz[a]anthracene 56-55-3
burner, but precautions should be taken that subsequent mea-
Benzo[b]fluoranthene 205-99-2
Benzo[k]fluoranthene 207-08-9
surements of burned gas characteristics are not influenced by
Benzo[g,h,i]perylene 191-24-2
ambient conditions. Finally, there is a sensor in the burned gas
Benzo[a]pyrene 50-32-8
which measures a property of this gas that is sensitive to the Benzo[e]pyrene2 192-97-2
Biphenyl2, 92-52-4
combustion ratio and has a unique feature at the stoichiometric
Cresol (mixed isomers) 1319-77-3
ratio. Two such properties are temperature and oxygen
Chrysene 218-01-9
concentrations, and either can be measured. Dibenz[a,h]anthracene 53-70-3
Dibenzofuran 132-64-9
6.3 Flow Meter or Regulator, or both—The flow measure-
Dibenzo(a,e)pyrene 192-65-4
3,3’- Dimethoxybenzidine 119-90-4
ment part of the apparatus should have an accuracy and
Dimethylaminobenzene 60-11-7
precision of the order of 0.1%. Likewise, if the flow is to be
7,12- 57-97-6
kept constant, the flow regulator should maintain this constant
Dimethylbenz(a)anthracene
3,3’- Dimethylbenzidine 119-93-7
valuewithin0.1%.Themeterorregulatorfornaturalgasmust
á,á- 122-09-8
maintain this precision and accuracy over the density and
Dimethylphenethylamine
viscosityrangesconsistentwiththecompositionrangeinTable
2,4-Dimethylphenol 105-67-9
Fluoranthene 206-44-0
1 or Table 2.
Fluorene 86-73-7
6.4 Combustion Chamber: Indeno(1,2,3-cd)pyrene 193-39-5
Isophorone 78-59-1
6.4.1 There are two different types of combustion chambers
3-Methylcholanthrene 56-49-5
thatmaybeused.Inthefirsttypetheairandfuelaremixedand
2-Methylnaphthalene 91-57-6
burned in a single burner. The apparatus shown in Fig. 1 has Naphthalene 91-20-3
Perylene2 198-55-0
this type of combustion chamber.
Phenanthrene 85-01-8
6.4.2 In the second type of combustion chamber, the air and
Phenol 108-95-2
fuel are each divided into two streams, and combustion takes 1,4-Phenylenediamine 106-50-3
Pyrene 129-00-0
place simultaneously in two burners. The division of air flow
o-Toluidine 95-53-4
must be such that the proportion of air going to each burner
Aldehydes
always remains the same. Likewise the division of fuel flow
Methanol 67-56-1
must always remain the same even through fuel composition
Formaldehyde 50-00-0
changes.Anotherrequirementisthattheflowdivisionsbesuch
Acetaldehyde 75-07-0
thatoneburnerhasamixturewithaslightlyhighercombustion
D4891 − 13 (2018)
TABLE 2 Continued
Compound CAS Number
Propanal 123-38-6
C1 to C5 Hydrocarbons
Description Compound CAS Number
C1 Alkanes Methane 74-82-8
C2 Alkanes Ethane 74-84-0
C3 Alkanes Propane 74-98-6
n-Butane 106-97-8
C4 Alkanes
Isobutane 75-28-5
n-Pentane 109-66-0
C5 Alkanes 2-Methylbutane 78-78-4
Cyclopentane 287-92-3
C2 Olefins Ethylene 74-85-1
C2 Alkanes Acetylene 74-86-2
C3 Olefins Propylene 115-07-1
C4 Olefins 1-Butene 106-98-9
2-Butene 107-01-7
Isobutene 115-11-7
C5 Olefins 1-Pentene 109-67-1
FIG. 2 Stoichiometric Combustion Apparatus
Cis-2-pentene 627-20-3
Trans-2-pentene 646-04-8
2-Methyl-1-butene 563-46-2
ratiothantheother.TheapparatusshowninFig.2hasthistype
3-Methyl-1-butene 563-45-1
of combustion chamber.
2-Methyl-2-butene 513-35-9
Cylcopentene 142-29-0
6.4.3 A third type utilizes a combustion oven operating in
C3 Alkadienes Propadiene 463-49-0
excess of 800°C (1472°F) to assure the combustion of gases
C4 Alkadienes 1,2-Butadiene 590-19-2
1,3-Butadiene 106-99-0 withinthenaturalorflaregascompositionsbeingcombustedas
C5 Alkadienes 1,2-Pentadiene 591-95-7
shown in Fig. 3.
1-cis-3-Pentadiene 1574-41-0
1-trans-3- Pentadiene 2004-70-8 6.5 Burned Gas Sensor:
1,4-Pentadiene 591-93-5
6.5.1 The burned or combusted gas sensor must measure a
2,3-Pentadiene 591-96-8
characteristic of the burned gas which is a function of the
3-Methyl-1,2- butadiene 598-25-4
2-Methyl-1,3- butadiene 78-79-5
combustion ratio and for which there is a critical combustion
Cyclopentadiene 542-92-7
ratio related to the stoichiometric ratio.Acombustion chamber
Heating Value Range
of the first type (Fig. 1) would have one sensor in the burned
Unit Lower Upper
Btu/ft 83 2350
gas and its output signal would constitute the desired measure-
A
Flare Gas Heating Value range defined in Table 2 is derived from the Evaluation ment. In a combustion chamber of the second type (Fig. 2)
of the Efficiency of Industrial Flares: Flare Head Design and Gas Composition
there would be a sensor in the burned gas from each burner.
EPA-600 /2-85-106 September 1985 Table 1-1. Agency Information Collection
Thedifferencebetweenthetwooutputsignalswouldconstitute
Activities OMB Responses EPA ICR Number 2411.01; NSPS and NESHAP for
Petroleum Refineries Sector Residual Risk and Technology; OMB Number thedesiredmeasurement.Inthethirdtype(Fig.3),theresidual
2060-0657.
oxygen is measured and the resulting oxygen value is corre-
lated to the CARI and Wobbe Index.
6.5.2 There are several properties of the burned gas which
are related uniquely to the combustion ratio. A burned gas
sensormaybeselectedwhichprovidesameasureofanyoneof
these, for example, either temperature or oxygen partial pres-
sure.
6.6 Electronics—Electronics are used to receive the signals
from the components described above to control the flow of
gases into the combustion chamber in response to the signal
from the burned gas sensor and to provide a digital or analog
output signal, or both, which is proportional to the heating
value of the gaseous fuel.
6.7 Temperature Stability and Operating Environment—The
method is capable of operating over a range of temperatures
limited only by the specific apparatus used to realize the
FIG. 1 Gas Btu Transmitter (Functional Overview)
method. It is desirable to equilibrate the air and fuel tempera-
tures before the gases are measured. The electronics should
D4891 − 13 (2018)
FIG. 3 Residual Oxygen Stoichiometric Combustion Apparatus
D4891 − 13 (2018)
also be stabilized against temperature changes and the burned 6. If the apparatus has two flow meters, the combustion ratio is
gas sensor should be insensitive to changes in the ambient the ratio of the output of the air flow meter divided by the
conditions. outputofthefuelflowmeter.Iftheapparatushasonlyoneflow
meter, then the combustion ratio is set numerically equal to
7. Reagents and Materials
either the output of the air flow meter or the reciprocal of the
output of the fuel flow meter. The burned gas parameter is a
7.1 Physical Contamination—The air and gas must be free
function of the combustion ratio and is measured at different
of dust, liquid, water, liquid hydrocarbons, and other entrained
combustion ratios. The critical combustion ratio, R, is taken as
solids. Foreign materials should be removed by a sample line
that point where this function has a maximum value, minimum
filter. To avoid any problems in the line from any liquid
value, or maximum rate of change. The heating value, C,is
accumulation, pitch the line to a low point and provide a drip
calculated from the equation
leg.
C 5 F·R1B, (1)
7.2 Chemical Contamination—The air must be free of
combustible compounds. The oxygen content and the absolute
where the constants B and F are determined as described in
humidity of the air should be the same during measurement as
8.1 and 8.2.
during calibration.
9.1.2 This procedure may be automated, for example, by
using a microprocessor in the electronics.
8. Calibration and Standardization
9.2 For making laboratory measurements of highest
8.1 The calibration factor, F, and the constant, B,inthe
precision, use the following procedure:
equation, C=F·R+B, are determined through a
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