Differentiation of thermal effects during low temperature oxidation of coal

✍ Scribed by Boleslav Taraba; Viktor Dobal; Karel Čáp; Milouš Harašta

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 653 KB
• Volume: 67
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(88)90146-9

✦ Synopsis

The heat evolution during the low temperature oxidation of coals ranging from lignite to anthracite was measured by means of four independent methods: adibatic, pulse flow microcalorimetric, differential microcalorimetric, and gas chromatographic. The last one was used to determine the heat evolved during physical adsorption of oxygen on the coal surface. The heat of this sort has been found to represent values from 0.16 to 0.6Jml-' O2 according to coal rank. On the other hand, the chemical reaction releases 11-125 ml-' O2 and is the same for lignite and brown coals at ordinary temperatures as for bituminous coals at elevated temperatures (60-80°C). The heat of chemical interaction varies at a temperature range 30-40°C between 3 and 5 J ml-' 0, for high rank bituminous coals and 7 and 10 J ml-' 0, for bituminous coals with volatile matter greater than 28 wt %. The highest thermal effect (up to 25 Jml-' 0,) is related to existing active sites on the coal surface and therefore is observable only for extremely clean surfaces or at higher initial temperatures of oxidation.