||Air-Dried Basis. In coal sample analysis, ADB neglects
the presence of moisture other than inherent moisture while DB (dry-basis)
leaves out all moisture, including surface moisture, inherent moisture, and
||As-Received Basis. In coal sample analysis, ARB puts all
variables into consideration and uses the total weight as the basis of
measurement. ARB is the most widely used basis in industrial applications..
||Ash content is the non-combustible
residue that remains after coal is burnt. Ash reduces handling and burning
capacity, affects combustion efficiency and boiler efficiency and therefore
increases handling costs.
||American Society for Testing and Materials
||Gross As Received. Thermal coal is quoted on a GAR
basis, except for Europe/ARA, Richards Bay 6,000 kcal/kg, and Japan and Korea
West CIF, which are quoted on a NAR (Net As Received) basis.
||Fixed carbon is the solid combustible
residue that remains in the furnace after volatile matter is distilled off,
comprised mostly of carbon but also containing some hydrogen, oxygen, sulphur
and nitrogen not driven off with the gases. It provides a rough estimate of the
heating value of coal.
||The relative ease with which coal can be pulverized depends on the strength of the coal and is measured by the Hard grove Grind ability Index (HGI). This empirical test indicates how difficult it would
be to grind a specific coal to the particle size necessary for effective
combustion in a pulverized coal fired boiler
(or bed moisture) means moisture that exists as an integral part of the coal
seam in its natural state, including water in pores, but excluding that present
in microscopically visible fractures.
||Sulphur content in coal presents problems with
utilization and resultant pollution, as it causes corrosion and fouling of
boiler tubes, and atmospheric pollution when released in flue gases.
||Total moisture in coal is represented
by measuring weight loss from aggressive drying in an air atmosphere under
rigidly controlled conditions of temperature, time and air flow. The presence
of moisture is an important factor in both the storage and the utilization of
coal, as it adds unnecessary weight during transportation, reduces the
calorific value, and poses some handling problems.
||Volatile matter is the material that
is driven off when coal is heated to 950 �C in the absence of air under
specified conditions. It consists of a mixture of gases, low-boiling-point
organic compounds that condense into oils upon cooling, and tars. In general,
coals with high volatile-matter content ignite easily and are highly reactive
in combustion applications.
|NAR (Net As Receive):
||NAR is an Abbreviation form use for USA Non-Cooking Steam Coal by ASTM (American
Society for Testing and Materials). In this method, we calculate Coal NCV without TM (Total
Moisture) & Inherent Moisture. We can also say NCV = Net Calorific Value.