ISO 647:2017

Brown coals and lignites - Determination of the yields of tar, water, gas and coke residue by low temperature distillation

ISO 647:2017 specifies a method for the determination of the yields of tar, water, gas and coke residue obtained from brown coal and lignite by distillation to a final temperature of 520 °C.

Charbons bruns et lignites — Détermination des rendements en goudron, en eau, en gaz et en résidu de coke par distillation à basse température

General Information

• Status: Published
• Publication Date: 18-Jul-2017
• ICS: 73.040 - Coals
• Technical Committee: ISO/TC 27/SC 5 - Methods of analysis
• Drafting Committee: ISO/TC 27/SC 5/WG 7 - Brown coals and lignites
• Current Stage: 9093 - International Standard confirmed
• Start Date: 29-Mar-2023
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 647:1974 - Brown coals and lignites - Determination of the yields of tar, water, gas and coke residue by low temperature distillation
• Effective Date: 20-Feb-2016

Overview

ISO 647:2017 - Brown coals and lignites: Determination of the yields of tar, water, gas and coke residue by low temperature distillation - specifies a laboratory method to quantify tar yield, total water (moisture + decomposition water), gas and coke residue from brown coal and lignite. The test uses a low‑temperature distillation sequence to 520 °C (80 min total heating) with product condensation and gravimetric determination. Results are reported on the as‑analysed and dry bases and are used as a basis for classification and quality assessment for low temperature carbonization.

Key topics and technical requirements

• Scope: Determination of yields of tar, water, gas and coke residue from brown coals and lignites by distillation to 520 °C.
• Principle: Heat a ~50 g sample in an aluminium retort; condense tar and water in a water‑cooled receiver; weigh coke residue; determine water by entrainment with toluene or xylene; calculate tar by difference and gas by subtraction.
• Apparatus and reagents: Aluminium retort (≈170 ml ±10 ml), brass outlet tube, 750 ml round‑bottom receiver, cooling bath (10–15 °C), calibrated thermocouple or mercury thermometer (to 550 °C), toluene/xylene for entrainment, graphite paste for sealing.
• Heating schedule: Controlled temperature ramp to 520 °C over 80 minutes (specified intermediate points, hold 520 °C at end).
• Sample preparation: Crush to pass 1 mm sieve (≥90 %), moisture between 10–20 % recommended; determine moisture separately per ISO 5068-2.
• Results and reporting: Report means of duplicate determinations to 0.1 %; tar may also be expressed on a dry ash‑free basis; include any deviations and test conditions in the test report.
• Precision: Repeatability and reproducibility (dry basis) limits are specified:
  • Tar: r = 0.5 % abs, R = 0.7 % abs
  • Decomposition water: r = 0.4 % abs, R = 0.8 % abs
  • Coke residue: r = 0.7 % abs, R = 1.0 % abs

Applications

• Classification of brown coal and lignite for low temperature carbonization and tar production.
• Quality control and product specification in coal processing laboratories.
• Research into coal devolatilization and char (coke) formation.
• Regulatory and commercial testing where tar and gas yields are contractually relevant.

Who uses this standard

• Coal testing laboratories and quality control teams
• Coal producers and processors involved in low temperature carbonization
• Utilities, chemical manufacturers and research institutions studying coal pyrolysis
• Accreditation bodies and conformity assessment labs performing standardized fuel analyses

Related standards

• ISO 5068-2 - Determination of moisture content (indirect gravimetric method) - referenced for moisture correction.
• ISO 1170 - Calculation of analyses to different bases (used for converting to dry/dry ash‑free bases).

Keywords: ISO 647:2017, brown coals, lignites, low temperature distillation, tar yield, coke residue, decomposition water, gas yield, retort, receiver, toluene entrainment, coal analysis.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 647
Second edition
2017-07
Brown coals and lignites —
Determination of the yields of tar,
water, gas and coke residue by low
temperature distillation
Charbons bruns et lignites — Détermination des rendements en
goudron, en eau, en gaz et en résidu de coke par distillation à basse
température
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Preparation of test sample . 5
8 Procedure. 5
9 Expression of result . 7
10 Precision . 7
10.1 Repeatability limit . 7
10.2 Reproducibility limit . 8
11 Test report . 8
Foreword
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This document was prepared by Technical Committee ISO/TC 27, Solid minerals fuels, Subcommittee
SC 5, Methods of analysis.
This second edition cancels and replaces the first edition (ISO 647:1974), of which it constitutes a minor
revision. The changes compared to previous edition are as follows: dated references and other minor
items have been changed.
iv © ISO 2017 – All rights reserved

Introduction
The yield of distillation products by low temperature distillation, especially the yield of tar, forms the
basis for the classification of brown coal and lignite for use in low temperature carbonization.
INTERNATIONAL STANDARD ISO 647:2017(E)
Brown coals and lignites — Determination of the yields
of tar, water, gas and coke residue by low temperature
distillation
1 Scope
This document specifies a method for the determination of the yields of tar, water, gas and coke residue
obtained from brown coal and lignite by distillation to a final temperature of 520 °C.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 5068-2, Brown coals and lignites — Determination of moisture content — Part 2: Indirect gravimetric
method for moisture in the analysis sample
ISO 1170, Coal and coke — Calculation of analyses to different bases
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
4 Principle
The sample is heated in an aluminium retort to a temperature of 520 °C during a period of 80 min.
The products of decomposition pass into a water-cooled receiver. The tar and water are condensed
while gaseous products pass to atmosphere. The coke residue remaining in the retort is weighed. The
receiver and its contents are also weighed and the mass of the water in it determined by entrainment
with toluene or xylene. The mass of tar is obtained by difference.
The total water in the receiver includes the moisture in the coal as well as that from the decomposition
of the coal. A separate determination of moisture in the coal is made so that the decomposition water
can be calculated.
The percentage of gas (plus errors) is obtained by subtracting from 100 the sum of the percentages of coke
residue, tar and total water. The results are reported on the “as analysed” basis and on the “dry” basis.
5 Reagents
5.1 Graphite paste.
Ground dry and made into suitable paste with water or thick lubricating oil.
...