ISO 609:1996

I N T E R NAT I O NA L
IS0
STANDARD
Second edition
1996-02-1 5
Solid mineral fuels - Determination of
carbon and hydrogen - High temperature
combustion method
Combustibles minéraux solides - Dosage du carbone et de
l'hydrogène - Méthode par combustion à haute température
Reference number
IS0 609:1996(E)
IS0 609:1996(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
!nternational Standard IS0 609 was prepared by Technical Committee
ISOflC 27, Solid mineral fuels, Subcommittee SC 5, Methods of
analysis.
This second edition cancels and replaces the first edition (IS0 609:1975),
which has been technically revised.
Annex A of this International Standard is for information only.
0 IS0 1996
All rights reserved Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
inicrofilm, without permission in writing from the publisher
International Organization for Standardization
Case Postale 56 CH-1 21 1 Genève 20 Switzerland
Printed in Switzerland
II
Q IS0
IS0 609:1996(E)
Introduction
An alternative method to that specified in this International Standard is
given in IS0 625: 1996, Solid mineral fuels - Determination of carbon and
hydrogen - Liebig method.
...
Ill
INTERNATIONAL STANDARD 0 IS0
IS0 609:1996(E)
Solid mineral fuels - Determination of carbon and
hydrogen - High temperature combustion method
IS0 1 O1 5:1992, Brown coals and lignites - Determi-
1 Scope
- Direct volumetric
nation of moisture content
method.
This International Standard specifies a method of de-
termining the total carbon and the total hydrogen in
IS0 1170:1977, Coal and coke - Calculation of
hard coal, brown coal and lignite, and coke, by a high
analyses to different bases.
temperature combustion method.
IS0 1988:1975, Hard coal - Sampling.
The results include the carbon in the carbonates and
the hydrogen combined in the moisture and in the
IS0 2309:1980, Coke -- Sampling.
of constitution of silicates. A determination of
water
at the same time, and an ap-
moisture is carried out
IS0 5068:1983, Brown coals and lignites - Determi-
propriate correction is applied to the hydrogen value
nation of moisture content - Indirect gravimetric
obtained by combustion. A determination of carbon
method.
dioxide may also be made and the total carbon value
corrected for the Dresence of mineral carbonates.
IS0 5069-2:1983, Brown coals and lignites - Prin-
- Part 2: Sample preparation for
ciples of sampling
determination of moisture content and for general
analysis.
2 Normative references
3 Principle
The following standards contain provisions which,
A known mass of coal or coke is burnt in a stream of
through reference in this text, constitute provisions
oxygen, at a temperature of 1 350 OC, in a tube
of this International Standard. At the time of publi-
impervious to gases. All the hydrogen is converted to
cation, the editions indicated were valid. All standards
water and all the carbon to carbon dioxide. These
are subject to revision, and parties to agreements
products are absorbed by suitable reagents and de-
based on this International Standard are encouraged
termined gravimetrically. The chlorine and oxides of
to investigate the possibility of applying the most re-
sulfur which are formed are retained by a silver gauze
cent editions of the standards indicated below.
roll at the outlet end of the tube.
Members of IEC and IS0 maintain registers of cur-
rently valid International Standards.
4 Reagents and materials
IS0 331:1983, Coal - Determination of moisture in
WARNING - Care should be exercised when
the analysis sample - Direct gravimetric method.
handling reagents, many of which are toxic and
corrosive.
IS0 687:1974, Coke - Determination of moisture in
the analysis sample.
During the analysis, unless otherwise stated, use only
reagents of recognized analytical grade and only dis-
IS0 925:1980, Solid mineral fuels - Determination
tilled water or water of equivalent purity.
of carbon dioxide content - Gravimetric method.
Q IS0
IS0 609:1996(E)
4.1 Magnesium perchlorate, anhydrous, less than 4.9 Air, compressed.
1,2 mm in size and preferably within the size range
1,2 mm to 0,7 mm.
4.10 Glass wool.
WARNING - Due regard must be taken of local
5 Apparatus
regulations when disposing of exhausted mag-
nesium perchlorate. Regeneration of magnesium
5.1 Analytical balance, capable of weighing to the
perchlorate must not be attempted, owing to the
nearest 0,l mg.
risk of explosion.
5.2 Graduated glassware, conforming to the re-
4.2 Sodium hydroxide on an inert base, preferably
quirements for class A in the International Standards
of a coarse grading, for example 3,O mm to 1,5 mm,
prepared by ISO/TC 48, Laboratory glassware and re-
but not finer than the grading 1,2 mm to 0,7 mm, and
la ted apparat us.
preferably of the self-indicating type.
5.3 Two purification trains, one for absorbing
water vapour and carbon dioxide from the oxygen
4.3 Aluminium oxide (alumina), finely divided, ap-
used for the combustion and the other for similarly
proximately 0,l mm in size.
treating the air used for sweeping out the absorption
train before and after a determination. Assemble each
4.4 Sodium tetraborate, standard volumetric sol-
train using a series of U-tubes or Midvale tubes con-
ution, c(Na2B,0,) = 0,025 mol/l.
taining the following reagents in the order stated, in
the direction of flow:
2 g of sodium tetraborate decahydrate
Dissolve 9,534
in water and dilute to 1 litre. Mix thoroughly.
a) magnesium perchlorate (4.1) for absorbing water;
4.5 Hydrogen peroxide, approximately 30 % (dm).
b) sodium hydroxide on an inert base (4.2) for ab-
sorbing dioxide;
4.6 Pure silver gauze, of mesh approximately
c) magnesium perchlorate for absorbing the water
1 mm, made of wire approximately 0,3 mm in diam-
evolved in the reaction between carbon dioxide
eter.
and sodium hydroxide.
The purification trains shall be large enough to render
4.7 Oxygen, hydrogen-free, preferably prepared
frequent recharging unnecessary, even with continu-
from liquid air and not by electrolysis. Electrolytically
ous use.
prepared oxygen shall be passed over red-hot copper
oxide before use to remove any trace of hydrogen.
NOTE 1 Midvale tubes that have been freshly packed
with absorbent and used in the purification train are thereby
4.8 Mixed indicator solution
conditioned for subsequent use in the absorption train.
5.4 Combustion assembly
4.8.1 Solution A
Dissolve O, 125 g of 2-(4-dimethylaminophenyl-
5.4.1 Heating unit, an electrically heated furnace or
azo)benzoic acid, sodium salt (methyl red) in 100 ml
furnaces, designed to carry a combustion tube (5.4.2)
of water.
and heat it to 1 350 "C over a distance of 125 mm in
the hot zone, and yield a temperature-distribution
profile similar to that shown in figure 1. The heating
4.8.2 Solution B
unit normally requires an auxiliary furnace to ensure
Dissolve 0,083 g of 3,7-bis(dimethylamino)pheno-
that the silver gauze roll (5.9) is maintained at the
thiazine-5-ylium chloride (methylene blue) in 1 O0 ml
correct temperature (approximately 600 "C to
of water. Store in a dark bottle.
800 OC). Suitable furnaces are, for example:
a) molybdenum or tungsten wire wound;
4.8.3 Mixed solution
b) platinum or platinum-rhodium wire wound;
Mix equal volumes of solution A and solution B. Store
in a dark bottle. Discard the mixed solution after
c) heated by silicon carbide rods.
1 week.
Q IS0 IS0 609:1996(E)
Distance from inlet end, mm
?S mm
~
II,I,IIIt,,,
I
I / J
Combustion tube
Silver gauze rolt -1
Heat-resistant mineral fibre
Figure 1 - Typical temperature-distribution curve for furnace
NOTES
deep for brown coal and lignite, capable of with-
a temperature of 1 350 OC.
standing
2 Type cl has the lowest initial cost and has proved satis-
factory in use.
NOTE 4 Combustion boats should not blister, discolour
or change in mass on heating in oxygen at 1 350 OC for
3 Furnaces of the type normally used for the determi-
3 h. A suitable boat lasts for about 10 to 20 determinations
nation of carbon or sulfur in steel are not suitable because
and should then be discarded because of the accumulation
of the absence of the auxiliary section required to maintain
of fused ash. For coals with a high ash content, it may be
the silver gauze roll at the correct temperature.
convenient to line the boat with alumina before adding the
sample, in order to prevent fusion of the ash to the boat.
5.4.2 Combustion tube, of approximately 28 mm
external diameter, 3 mm wall thickness and 650 mm
5.5 Absorption train, for absorbing the water and
length, made of refractory aluminous porcelain which
carbon dioxide evolved by the combustion of the
is impervious to gases up to a temperature of
sample. Midvale tubes (figure 21, which provide a
1 400 OC. The end of the combustion tube shall be
large area of reaction, are used in order to reduce the
lagged with a suitable heat-resistant mineral fibre to
back-pressure in the apparatus, and so obviate the
prevent condensation in the tube.
danger of leakage through the rubber sleeve carrying
the pusher. Assemble the train using the following
5.4.3 Combustion boat, of iron-free, unglazed reagents in the order stated, in the direction of flow:
porcelain, approximately 60 mm long, 12,5 mm wide
a) magnesium perchlorate (4.1) for absorbing the
and 10 mm deep, for hard coal and coke samples and
water evolved during the combustion;
approximately 75 mm long, 15 mm wide and 1 O mm
IS0 609:1996(E)
Q IS0
Dimensions in millimetres
Hollow stopper
0 ext. 33 to 34
---i
Wall thickness 1 to 1.25
r @ ext. 55 to 6
I
--
Li
s
Figure 2 - Midvale tube
water; B and C are the absorbers for carbon dioxide,
b) sodium hydroxide on an inert base (4.2) for ab-
C serving as a control to indicate when the packing in
sorbing carbon dioxide;
B is in need of replacement. Any water released in B
c) magnesium perchlorate for absorbing the water by the reaction between sodium hydroxide and car-
evolved in the reaction between carbon dioxide bon dioxide is absorbed in C.
and sodium hydroxide.
Place glass wool (4.101, previously dried at 105 "C for The inlet of the water-absorption tube shall be in-
serted through the heat-resistant stopper so that it is
1 h, above and below the absorbents to prevent the
flush with the inner end of the stopper. All con-
carry-over of dust by the flow of oxygen, and to pre-
of glass-
vent the cracking of the Midvale tube by the heat of nections between the tubes shall be made
to-glass, using the rubber connecting sleeves merely
reaction. A typical absorption train with details of the
packing is shown in figure3. A is the absorber for as seals.
Q IS0 IS0 609:1996(E)
O
4-
3-
Key
1 Glass wool 3 Magnesium perchlorate, 1,2 mm to 0,7 mm size
2 Sodium hydroxide (see 4.2)
4 Inlet
Figure 3 - Absorption train
5.6 Two flowmeters, both capable of measuring 5.9 Silver gauze roll, for absorbing chlorine and
rates of flow up to 300 ml/min of air. oxides of sulfur. Roll the pure silver gauze (4.6) to
form a plug, 75 mm long and of sufficient diameter to
ensure a close sliding fit in the combustion tube
(5.4.2). A stout, pure silver wire is passed through the
5.7 Heat-resistant stopper (acrylonitrile or
roll to facilitate its removal from the
centre of the
chloroprene) for connecting the absorption train to the
tube.
combustion tube.
5.10 Bubbler, for use when determining the correct
location for the silver gauze roll (see 6.2). It may be a
5.8 Silica or steel pusher, made from rod or sealed
large boiling tube, wide-necked bottle, or Dreschel
tube, approximately 6 mm in diameter and 450 mm
bottle, containing a sintered glass disc of 0,015 mm
long, with a disc end, 12 mm in diameter, for pushing
to 0,040 mm maximum pore size in the gas distri-
the boat into the hot zone of the combustion tube.
bution tube. The diameter of the absorber shaill be
The pusher passes loosely through a glass or metal
a depth of at least
such that the disc is covered to
T-piece, one end of which fits into the stopper which
90 mm by the absorbing solution; a vessel 35 mm in
closes the inlet end of the combustion tube, the other
diameter and 150 mm deep is suitable. A silica
being sealed by a rubber sleeve (see note 61, through
adapter, or the combustion tube fitted with a tubulure,
which the pusher slides. The sleeve prevents the es-
is connected to the bubbler.
cape of oxygen which enters at the stem of the
T-piece. The pusher is usually marked from the disc
To avoid leakage at the rubber sleeve of the inlet end
end, for convenience in ascertaining the position of
due to the resistance of the sintered glass bubbler,
the boat in the combustion tube during pushing.
the bubbler is connected to a suction-pump through
a pressure regulator adjusted to maintain slight
NOTE 5 The rubber sleeve should be changed period-
ically to avoid leakage. suction at the inlet end of the combustion tube.
IS0 609:1996(E)
0 IS0
A convenient assembly of the apparatus for this pur-
oxides of sulfur by the silver gauze roll. Use this exact
pose is illustrated in figure4.
location in all subsequent determinations.
Disconnect the bubbler, pressure regulator (see 5.1 O)
5.1 1 Heat-resistant wire, approximately 2,5 mm
and suction-pump. Using the bent heat-resistant wire
thick and 450 mm long, with a bent end to transfer
(5.111, withdraw the used c
...