|
IS0
I N TE RN AT1 O N AL O R GAN I Z AT1 O N F O R S TAN DAR D I ZATI O N
IS0 RECOMMEN DATION
R 609
DETERMINATION OF CARBON AND HYDROGEN
IN COAL AND COKE
BY THE HIGH TEMPERATURE COMBUSTION METHOD
1st EDITION
June 1967
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
---------------------- Page: 1 ----------------------
BRIEF HISTORY
The IS0 Recommendation R 609, Determination of Carbon and Hydrogen in Coal and Coke
by the High Temperature Combustion Method, was drawn up by Technical Committee ISO/TC 27,
Solid Mineral Fuels, the Secretariat of which is held by the British Standards Institution (BSI).
Work on this question by the Technical Committee began in 1950 and led, in 1961, to the
adoption of a Draft IS0 Recommendation.
In October 1963, this Draft IS0 Recommendation (No. 605) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature,
by the following Member Bodies:
Argentina Denmark Portugal
Australia Germany Republic of South Africa
Austria
India Romania
Belgium Italy Spain
Bulgaria Japan Switzerland
Canada Netherlands U.A.R.
Chile
New Zealand United Kingdom
Czechoslovakia
Poland U.S.A.
Three Member Bodies opposed the approval of the Draft:
France
Turkey
U.S.S.R.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in June 1967, to accept it as an IS0 RECOMMENDATION.
-3-
---------------------- Page: 2 ----------------------
ISOlR 609 - 1967(E)
IS0 Recommendation R 609 June 1967
DETERMINATION OF CARBON AND HYDROGEN
IN COAL AND COKE
BY THE HIGH TEMPERATURE COMBUSTION METHOD
1. SCOPE
This IS0 Recommendation describes the high temperature combustion method of determining
the total carbon and the total hydrogen in hard coal, brown coal and lignite, and coke; the results
include the carbon in the carbonates and the hydrogen combined in the moisture and in the water
of hydration of silicates. A determination of moisture is carried out at the same time, and an
appropriate correction is applied to the hydrogen value obtained by combustion. A determination
of carbon dioxide may also be made and the total carbon value corrected for the presence of
mineral carbonates.
2. PRINCIPLE
The sample is burned in a rapid current of oxygen at a high temperature in an impervious tube;
all the hydrogen is converted to water and all the carbon to carbon dioxide. These products are
absorbed by suitable reagents and determined gravimetrically. Oxides of sulphur and chlorine
are retained by a silver gauze roll at the outlet end of the tube.
3. REAGENTS
All reagents should be of analytical reagent quality. Distilled water should be used throughout.
3.1 Magnesium perchlorate, anhydrous (anhydrone), less than 1.2 mm in size and preferably
within the size range 1.2 to 0.7 mm.
NOTE. -Regeneration of the magnesium perchlorate should not be attempted, owing to the risk of explosion.
When exhausted, the magnesium perchlorate should be washed down the sink with a current of water.
3.2 Soda asbestos, preferably of coarse grading, e.g. 3.0 to 1.5 mm, and not finer than the grading
1.2 to 0.7 mm, and preferably of self-indicating type.
3.3 Alumina, finely divided, approximately 0.1 mm in size.
3.4 Sodium borate solution, 0.05 N.
3.5 Hydrogen peroxide, 1 % neutral solution.
3.6 Pure silver gauze, approximately 10 meshes per centimetre, made of wire approximately
0.3 mm in diameter.
3.7 Oxygen, hydrogen-free. The oxygen should preferably be prepared from liquid air and not
by electrolysis. Electrolytically prepared oxygen should be passed over red-hot copper oxide
before use, to remove any trace of hydrogen.
4. APPARATUS
4.1 Two Purification trains, one for absorbing water vapour and carbon dioxide from the oxygen
used for the combustion and the other for similarly treating the air used for sweeping out
the absorption train before and after a determination. Assemble each train using the following
reagents in the order stated:
(1) Magnesium perchlorate (3.1) for absorbing water,
(2) Soda asbestos (3.2) for absorbing carbon dioxide,
(3) Magnesium perchlorate (3.1) for absorbing the water evolved in the reaction between
carbon dioxide and soda asbestos.
The purification trains should be large enough to render frequent recharging unnecessary
even with continuous use.
-5-
---------------------- Page: 3 ----------------------
ISOlR 609 - 1967 (E)
4.2 Combustion device
4.2.1 A furnace, capable of carrying a tube approximately 25 mm outside diameter and heating
it over a length of approximately 12.5 cm to over 1250 OC and up to a maximum of 1350 OC.
A temperature-distribution curve for a typical furnace is shown in Figure 1. Suitable
furnaces are, for example,
(a) molybdenum or tungsten wire wound,
(b) platinum or platinum-rhodium wire wound,
(c) heated by silicon carbide rods.
Type (c) has the lowest initial cost and has proved satisfactory in use.
NOTE. - Furnaces of the type normally used for the determination of carbon or sulphur in steel are not
suitable because of the absence of the auxiliary section to maintain the silver gauze roll at the correct
temperature.
4.2.2 A combustion tube, approximately 20 mm internal diameter and approximately 70 cm
long, made of refractory aluminous porcelain which is not permeable to gases at 1400 OC.
4.2.3 A combustion boat of iron-free unglazed porcelain, approximately 6 cm long and 12.5 min
wide and 10 mm deep, capable of withstanding a temperature of 1350 OC.
NOTE. - Boats should not blister, discolour or change in mass on heating in oxygen at 1350 "C for
3 hours. A suitable boat lasts for about 10 to 20 determinations and should then be discarded because of
the accumulation of fused ash. For high ash coals, it may be convenient to line the boat with alumina
before adding the sample, in order to prevent fusion of the ash to the boat.
4.3 An absorption train, for absorbing the water and carbon dioxide evolved by the combustion
of the sample. Midvale tubes (Fig. 2), which provide a large area of reaction, are used in
order to reduce the back-pressure in the apparatus and so obviate the danger of leakage
through the rubber sleeve carrying the pusher. Assemble the train using the following reagents
in the order stated:
(1) Magnesium perchlorate (3.1) for absorbing the water evolved during the combustion,
(2) Soda asbestos (3.2) for absorbing carbon dioxide,
(3) Magnesium perchlorate (3.1) for absorbing the water evolved in the reaction between
carbon dioxide and soda asbestos.
Cotton wool is placed above and below the absorbents to prevent carryover of dust by the
rapid flow of oxygen and the cracking of the soda asbestos tube by the heat of reaction.
A typical absorption train with details of the packing is shown in Figure 3, page 12. A is
the absorber for water; B and C are the absorbers for carbon dioxide, C serving as a control
to indicate when the packing in B is in need of replacement. Any water released in B by
the reaction between soda asbestos and carbon dioxide is absorbed in C.
4.4 Two flowmeters, one capable of measuring rates of flow up to 300 ml per minute and the
other to 250 mi per minute.
4.5 A U-gauge to measure the resistance of the system
NOTE. - The normal back-pressure on the system is 50 to 70 mmH2O.
4.6 A heat-resisting stopper (acrylonitrile or chloroprene) for connecting the absorption train to
the combustion tube.
4.7 A silica pusher with a disk end 12 mm in diameter for pushing the boat into the furnace.
It is about 45 cm long, made from 6 mm diameter silica rod flattened at one end, or from a
6 mm diameter silica tube sealed and flattened similarly.
-6-
---------------------- Page: 4 ----------------------
ISO/R 609 - 1967 (E)
The pusher passes loosely through a glass T-piece, one end of which fits into the rubber
stopper which closes the inlet end of the combustion tube, the other being sealed with a
rubber sleeve", through which the pusher slides. Oxygen is admitted through the limb of
the T-piece. The pusher is marked from the disk end for convenience in ascertaining the
position of the boat in the combustion tube during pushing.
4.8 Balance sensitivc to 0.1 mg.
5. PREPARATION OF AP
...