ISO 20336:2017 pdf download

ISO 20336:2017 pdf download.Solid mineral fuels — Determination of total sulfur by Coulomb titration method
1 Scope
This document specifies an alternative method of determining the total sulfur content of coal and coke by high-temperature combustion — Coulomb titration.
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 687, Solid mineral fuels — Coke — Determination of moisture in the general analysis test sample
ISO 5068-2, Brown coals and lignites — Determination of moisture content — Part 2: Indirect gravimetric method for moisture in the analysis sample
ISO 11722, Solid mineral fuels — Hard coal — Determination of moisture in the general analysis test sample by drying in nitrogen
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:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
4 Principle
In the presence of the catalyst, a weighed sample is combusted at 1 150 °C in a stream of purified air.The sulfur oxides are formed and dissolved in the electrolytic solution. The sulfur dioxides are titrated by the iodine and bromine librated from the electrolysis of the potassium iodide and potassium bromide solution. The quantity of the electricity consumed by electrolysis is integrated and used to calculate the content of sulfur dioxides. The instrument is calibrated with certified reference materials.The percentage of total sulfur in the sample is calculated according to the sulfur dioxides content and the prior calibration.
5 Reagent and materials
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity.
5.1 Potassium iodide.
5.2 Potassium bromide.
5.3 Glacial acetic acid.
8 Procedure
8.1 Preparation of test
8.1.1 Raise the temperature of the furnace to 1 150 °C. Measure the position and length of high temperature zone of (1 150 ± 10) °C and the position of preliminary decomposition zone of 500 °C in combustion tube using a calibrated pyrometer with Pt-Rh—Pt thermocouple.
8.1.2 Adjust the program controller so the combustion boat moves into the preliminary decomposition zone of 500 °C and then to the combustion zone of 1 150 °C automatically.
8.1.3 Pack the exit end of the combustion tube with the clear and dry glass wool (5.7). Pack the place of (80 to 100) mm from the exit end with (3 to 5) mm thickness of aluminosilicate wool (5.8). 8.1.4 Assemble tube resistance furnace (6.2) with a combustion tube (6.2), electrolytic cell (6.3), magnetic stirrer (6.3), coulomb integrator (6.4), the program controller (6.5), purified air stream supply system (6.6). The combustion tube, stopcock and electrolytic cell should be connected in glass to glass closely and seal them with the silicone rubber sleeves.