Measurement of GCV in different basis
- The variables are measured in weight percent (wt. %) and are calculated in several basis, they are
- AR (as-received) basis is the most widely used basis in industrial applications. AR basis puts all variables into consideration and uses the total weight as the basis of measurement.
- AS RECEIVED BASIS (AR) = TM+IM+ASH+VM+FC+S (Includes all moistures)
- AD (air-dried) basis is to neglect the presence of moistures other than inherent moisture while DB (dry-basis) leaves out all moistures, including surface moisture, inherent moisture, and other moistures.
- AS DRIED BASIS (AD) = 0+IM+ASH+VM+FC+S (Includes Inherent moisture)
- DAF (dry, ash free) basis is to neglect all moisture and ash constituent in coal
- AS DRY ASH FREE (DAF) = 0+0+0+VM+FC+0 (Excludes all moisture & Ash)
- DMMF (dry, mineral-matter-free) basis leaves out the presence of moisture and mineral matters in coal, for example: quartz, pyrite, calcite, etc. Mineral matter is not directly measured but may be obtained by one of a number of empirical formula based on the ultimate and proximate analysis.
- AS DRY BASIS (DB) = 0+0+ASH+VM+FC+S (Excludes all moisture)
(TM=Total Moisture, IM=Inherent Moisture, VM=Volatile Matter, FM=Fixed Carbon, S=Sulphur)