Enter the crucible weighings from the moisture, ash and volatile matter tests to get fixed carbon by difference on every basis, or the loss on ignition of a mineral, with an estimated heating value.
Pre-sizing and estimating tool: results do not replace design, calculations or reports signed by a licensed professional, nor verification against the applicable codes and standards.
Moisture, ash, volatile matter and fixed carbon, adding to 100% on each basis.
Conversions per ASTM D3180: the tests measure on the as-determined basis.
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It splits a solid fuel into four parts: moisture, ash, volatile matter and fixed carbon. The first three are measured by mass loss or residue in an oven and muffle furnace; fixed carbon is what is left to reach 100%. It is used to compare coals, cokes and biomass, control carbonization and buy fuel on quality.
The example coal has 2.50% moisture in the analysis sample and, on a dry basis, 10.09% ash, 34.36% volatile matter and 55.54% fixed carbon. Its fuel ratio (FC/VM) is 1.62. As received, at 8% total moisture, fixed carbon drops to 51.10%.
As received includes all the lot moisture, dry excludes water, and dry ash-free excludes ash as well. The same material shows different numbers on each basis, so a report without the basis cannot be compared. To compare lots and suppliers, use the dry basis.
Because it is what remains after water and volatiles leave, less ash, and there is no simple direct test for it. So any error in the other three measurements goes straight into fixed carbon. Weighing to 0.1 mg and cooling crucibles in a desiccator are essential.
Moisture at 104–110 °C (219–230 °F). Ash at 700–750 °C for coal (ASTM D3174), 550 °C for biomass (ISO 18122) and 750 °C for wood charcoal (ASTM D1762). Volatile matter in a covered crucible for 7 minutes at 950 °C (ASTM D3175) or 900 °C (ISO 562). Always record the standard on the report.
It can estimate it. The calculator uses the Parikh correlation, which for the example coal gives about 24.9 MJ/kg (about 10,700 Btu/lb) dry, with a typical error of 3% to 4%. For contracts, purchasing or energy balances, measure it in a bomb calorimeter (ASTM D5865).
Letting crucibles cool outside the desiccator (they pick up moisture), opening the furnace during the volatile test (air burns carbon and raises the loss), using poorly ground or mixed samples and combining results from different standards. In loss on ignition of iron-bearing ores, oxidation can even increase the mass.
Important notice: Indus Metrics tools produce estimates and pre-sizing results from the data you enter and from published engineering methods. They do not replace design, calculations or reports signed by a licensed professional engineer (PE), nor verification against the applicable codes, standards and regulations, such as OSHA rules and the ASME codes. Material and fuel properties vary: check manufacturer data or your own process analyses before deciding. By using this site you agree to the Terms of Use.
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