
152 Oxygen-Enhanced Combustion
water contents decrease from 42% to 5% with coal ranks
(from lignite to anthracite).
The chemical composition of a coal usually is
expressed by either an ultimate or proximate analysis or
both. Ultimate analysis refers to an analysis routine that
includes moisture, combined water, carbon, hydrogen,
sulfur, nitrogen, and ash.
The proximate analysis is to measure water content, vola-
tile matter, xed carbon and ash. The procedures include
the following steps: (1) Heat the sample up to between 104°C
and 110°C (219°F and 230°F) for 1h; the weight loss is due to
moisture. (2) Ignite in a covered crucible for 7min at ...