Moisture, Volatile Matter, Ash, and Fixed Carbon Determination in Coke

Significance of the Topic

Accurate determination of moisture, volatile matter, ash, and fixed carbon in coke is critical for evaluating fuel quality, optimizing combustion efficiency, and ensuring compliance with industry standards. These parameters inform dry-basis calculations, material balances, and purchase specifications for solid fuels.

Objectives and Overview

The study outlines a procedure using a macro thermogravimetric analyzer to measure moisture, volatile matter, ash, and derive fixed carbon in coke samples. It aims to demonstrate method reliability, reproducibility, and compliance with recognized ASTM standards.

Methodology and Instrumentation

The procedure follows ASTM D2013, D346, and D7582 for sample preparation and analysis. Key steps include calibration with reference materials, sequential heating under controlled atmospheres, and stepwise temperature ramps. Used Instrumentation:

• TGA701 macro thermogravimetric analyzer
• Ceramic crucibles (density 3.00 g/cm3) and covers
• Nitrogen flow for moisture and volatile matter steps, oxygen or air for ash determination
• Temperature program: 25→107 °C for moisture, 107→950 °C for volatile matter, 600→950 °C for ash
• Typical sample mass ~1 g

Main Results and Discussion

Analysis of NIST and commercial coke samples yielded moisture contents around 0.3–0.4 %, volatile matter from 1–10.6 %, ash levels between 0.17–7.97 %, and fixed carbon in the 89–93 % range on a dry basis. Standard deviations under repeat conditions were low (<0.1 %), demonstrating method precision. These results align with certified reference values and show robust performance across a broad sample matrix.

Benefits and Practical Applications

• Provides rapid, simultaneous analysis of up to 19 samples for routine QC
• Ensures traceable results via calibration with certified reference materials
• Supports compliance with environmental, industrial boiler, and trading specifications
• Enables dry-basis reporting and precise material balance calculations

Future Trends and Potential Applications

Ongoing developments may include automated sample handling, enhanced data integration for real-time process control, and expanded application to alternative carbonaceous materials. Integration with advanced software analytics could further streamline fuel quality monitoring.

Conclusion

The described gravimetric method using the TGA701 offers a reliable and efficient approach to determine key quality parameters in coke. Its adherence to ASTM protocols and use of reference materials ensure high accuracy and reproducibility, supporting diverse industrial and research applications.

Reference

• ASTM D2013: Standard Practice for Sample Preparation of Coke for Analysis
• ASTM D346: Practice for Sampling and Sample Preparation of Coal and Coke
• ASTM D3176: Ultimate Analysis of Coal and Coke by Difference
• ASTM D7582: Thermogravimetric Analysis of Coke