Coke -- Determination of coke reactivity index (CRI) and coke strength after reaction (CSR)

ISO 18894:2006 specifies the equipment and techniques used for determining lump-coke (> 20 mm) reactivity in carbon dioxide gas at elevated temperatures and its strength after reaction in carbon dioxide gas by tumbling in a cylindrical chamber.

Coke -- Mesures de l'indice de réactivité du coke (CRI) et de la résistance post-réactionelle du coke (CSR)

General Information

Status
Replaced
Publication Date
19-Apr-2006
Withdrawal Date
19-Apr-2006
Technical Committee
Drafting Committee
Current Stage
6060 - International Standard published
Start Date
20-Mar-2006
Completion Date
20-Apr-2006
Ref Project

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INTERNATIONAL ISO
STANDARD 18894
First edition
2006-04-15
Coke — Determination of coke reactivity
index (CRI) and coke strength after
reaction (CSR)
Coke — Mesures de l'indice de réactivité du coke (CRI) et de la
résistance post-réactionelle du coke (CSR)
Reference number
ISO 18894:2006(E)
ISO 2006
---------------------- Page: 1 ----------------------
ISO 18894:2006(E)
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© ISO 2006

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ii © ISO 2006 – All rights reserved
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ISO 18894:2006(E)
Contents Page

Foreword............................................................................................................................................................ iv

1 Scope ..................................................................................................................................................... 1

2 Normative references ........................................................................................................................... 1

3 Terms and definitions........................................................................................................................... 1

4 Principle................................................................................................................................................. 2

5 Reagents................................................................................................................................................ 3

6 Apparatus .............................................................................................................................................. 3

7 Preparation of test sample................................................................................................................... 4

8 Procedure .............................................................................................................................................. 4

9 Expression of results ........................................................................................................................... 5

10 Precision................................................................................................................................................ 6

11 Test report ............................................................................................................................................. 9

Annex A (normative) Reactivity test apparatus “type A”, single wall ........................................................ 10

Annex B (normative) Reactivity test apparatus “type B”, double wall....................................................... 12

Annex C (normative) Coke-strength-after-reaction tumbler........................................................................ 14

Annex D (informative) Determination of abrasion value .............................................................................. 15

Annex E (informative) Reproducibility critical difference ............................................................................ 16

© ISO 2006 – All rights reserved iii
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ISO 18894:2006(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

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. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. 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.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 18894 was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee SC 3, Coke.

iv © ISO 2006 – All rights reserved
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INTERNATIONAL STANDARD ISO 18894:2006(E)
Coke — Determination of coke reactivity index (CRI) and coke
strength after reaction (CSR)
1 Scope

This International Standard specifies the equipment and techniques used for determining lump-coke

(> 20 mm) reactivity in carbon dioxide gas at elevated temperatures and its strength after reaction in carbon

dioxide gas by tumbling in a cylindrical chamber.
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.
ISO 579, Coke — Determination of total moisture
ISO 3310 (all parts), Test sieves — Technical requirements and testing

ISO 1213–2, Solid mineral fuels — Vocabulary — Part 2: Terms relating to sampling, testing and analysis

ISO 2309, Coke — Sampling

ISO 13909-5, Hard coal and coke — Mechanical sampling — Part 5: Coke — Sampling from moving streams

ISO 13909-6, Hard coal and coke — Mechanical sampling — Part 6: Coke — Preparation of test samples

IEC 60584-1, Thermocouples — Part 1: Reference tables
IEC 60584-2, Thermocouples — Part 2: Tolerances
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 1213-2 and the following apply.

3.1
abrasion value

lack of resistance to abrasion of the coke after reaction with carbon dioxide in the CRI test, measured as the

percentage of a sample passing through a 0,5 mm sieve after tumbling under conditions specified in this

International Standard
NOTE See Annex D.
3.2
coke reactivity index
CRI

percentage weight loss of coke after reaction with carbon dioxide to form carbon monoxide under conditions

specified in this International Standard
© ISO 2006 – All rights reserved 1
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ISO 18894:2006(E)
3.3
coke strength after reaction
CSR

strength of coke after reaction with carbon dioxide in the CRI test, measured as the percentage retained on

either a 10,0 mm or a 9,5 mm sieve after tumbling under conditions specified in this International Standard

4 Principle

A test portion of the dried coke sample having a size range from 19,0 mm to 22,4 mm is heated in a reaction

vessel to 1 100 °C in a nitrogen atmosphere. For the test, the atmosphere is changed to carbon dioxide for

exactly 2 h. After the test, the reaction vessel is allowed to cool down to about 50 °C in a nitrogen atmosphere.

The comparison of the sample weight before and after the reaction determines the coke reactivity index (CRI).

The reacted coke is treated in a specially designed tumbler for 600 revolutions for 30 min. The coke strength

after reaction (CSR) value is determined by sieving and weighing the amount of coke passing through either a

10,0 mm or a 9,5 mm sieve.
An example of the arrangement of the test unit is shown in Figure 1.

NOTE During the development of this International Standard, it was found that 10,0 mm and 9,5 mm sieves are both

commonly used for these types of test. When reacted coke is tumbled, abrasion usually takes place. Particles of about

20 mm lose some edges, but they do not break into pieces. Therefore, it makes almost no difference if the sieving after

tumbling is made with a 10,0 mm or a 9,5 mm sieve, as the size of the coke pieces is either about 20 mm or 0 mm to

5 mm, but not in the range of 10 mm. This has been verified by experiments over a long period of time. It has been shown

that the difference in CSR using both sieve sizes is within the precision range of this International Standard.

Key
1 plotter for recording temperature 7 layer of ceramic balls
2 gas outlet to stack 8 electrically heated furnace
3 gas inlet 9 gas-flow meters
4 thermocouple 10 control valves
5 single or double wall retort with perforated plate as sample holder 11 tumbler
6 test portion
Figure 1 — Example of test unit arrangement
2 © ISO 2006 – All rights reserved
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ISO 18894:2006(E)
5 Reagents

5.1 Nitrogen, having a purity of > 99,9 % by volume, dry and having a maximum oxygen and carbon

dioxide (CO + O ) concentration of 100 mg/kg.
2 2

5.2 Carbon dioxide, having a purity of > 99,5 % by volume, dry and having an oxygen concentration

< 100 mg/kg.
6 Apparatus

6.1 Electric furnace (see Annexes A and B), capable of housing the reaction-vessel assembly containing

the test portion and providing a uniform temperature of (1 100 ± 3) °C in the centre of the test portion. The

uniform temperature zone shall be at least three times longer than the sample height.

It is preferable that the furnace have independently controlled heating in three zones to achieve uniformity of

heating in the reaction vessel.

6.2 Reaction vessel (see Annexes A and B), constructed from heat-resistant steel or nickel alloy to the

dimensions required to fit inside the electric furnace selected for use.

The coke to be tested is placed on a perforated plate in the reaction vessel. Below this perforated plate, a gas

preheater, such as a bed of ceramic Al O balls on a second perforated plate, diffuses the nitrogen and

2 3

carbon dioxide introduced into the vessel up through the coke bed during the course of the test. Both

perforated plates are fixed between two sets of lugs in the reaction vessel. The gas enters through inlets at

the bottom and exits through outlets positioned at the top of the reaction vessel.

The reaction vessel is positioned such that the coke sample contained in the vessel is in the centre of the

uniform temperature zone of the furnace.

6.3 Flowmeters, variable area flowmeter or, preferably, mass flowmeters, used to monitor the nitrogen

and carbon dioxide flow during the test, having an accuracy of gas flow rates of ± 5 % for both nitrogen and

carbon dioxide.
NOTE Fluctuations in the gas flow can cause variability in the test results.

Gas pressures through the flowmeters shall be maintained at the manufacturer’s calibration specification.

6.4 Thermocouple, conforming to the requirements of IEC 60584-1 and IEC 60584-2, used for measuring

and controlling the sample temperature, which shall be designed according to the test conditions [e.g.

platinum–rhodium/platinum (90 % Rh and 10 % Pt, percentage by mass)], enclosed in a heat-resistant steel or

nickel alloy or ceramic protection tube. The protection tube shall be made of gas-tight casing to prevent faulty

measurement caused by a poisoning of the thermocouple by gaseous products. The protection tube is

fastened to the centre of the lid to ensure the positioning of the thermocouple tip in the centre of the coke bed.

6.5 Sieves, square hole conforming to the requirements of ISO 3310, with actual openings of 9,5 mm or

10,0 mm, 19,0 mm and 22,4 mm. A 0,5 mm sieve is also required if the abrasion test (see Annex D) is carried

out.
6.6 Balance, capable of weighing to the nearest 0,1 g.
6.7 Tumbler (see Annex C), with a revolution counter and a time-relay device.
© ISO 2006 – All rights reserved 3
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ISO 18894:2006(E)
7 Preparation of test sample
Sample the coke in accordance with ISO 2309 or ISO 13909-5.

Crush approximately 50 kg of the gross sample with a representative size distribution in a jaw crusher or

rolling crusher. The opening of the crusher shall be set such that the gross sample yields between 10 % and

30 % of the fraction 19,0 mm to 22,4 mm. Divide the crushed sample to obtain a mass of approximately 25 kg

in accordance with ISO 13909-6.
The mass of sample required for the test depends on the following.

a) The minimum mass required for the test is governed by the minimum mass of the 19,0 mm to 22,4 mm

fraction, i.e. 1 000 g.

b) A sample of large coke must be of sufficient size to ensure that it is representative. Therefore, smaller

sample amounts may be used only when it is guaranteed that they are representative. This shall be

indicated in the test report.

Sieve the crushed sample using a 22,4 mm sieve placed on top of a 19,0 mm sieve. Recycle the > 22,4 mm

fraction to the crusher until the oversize is less than 3 % of the crushed sample. Discard the < 19,0 mm and

> 22,4 mm fractions.

Dry the 19,0 mm to 22,4 mm fraction in accordance with ISO 579 to less than 1 % moisture. Sieve the

crushed and dried sample again using 22,4 mm and 19,0 mm sieves to remove adhering breeze. Divide the

crushed and sieved sample to obtain a test sample of approximately 1 000 g.

Alternatively, the sample (fraction 19,0 mm to 22,4 mm) may be divided to approximately 1 000 g before

drying and sieving.

Divide the test sample to get test portions of approximately 200 g each. For each test, prepare a test portion of

200 g ± 2 g and weigh accurately to the nearest 0,1 g. The final mass adjustment can be made by exchanging

a single piece of coke for one slightly lighter or heavier as appropriate.

NOTE Recording the number of pieces in each test portion can be helpful for comparing the test runs.

8 Procedure
8.1 Number of tests
A minimum of two tests shall be carried out.
8.2 Determination of CRI

CAUTION — The waste gas leaving the reaction vessel during the CO gas charging is CO-rich and

therefore hazardous. It should be burnt or led to a ventilated stack. Care should be taken regarding

the hot surface (1 100 °C) of the reaction vessel.

Preheat the furnace to a temperature that will allow the reaction vessel and sample, when placed in the

furnace, to reach (1 100 ± 3) °C within 30 min to 40 min. Before the
...

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