Gas content: gravimetric method
As the gas contained in the bomb during the saturation
stage consisted of gases absorbed in the coal and the gas filled the space
surrounding the coal sample, it is necessary to determine the amount of
the gas contained in coal per unit of coal mass. Accordingly, the procedure
used for calculating gas contained in coal is determined using the following
relationship (Lama and Bodziony, 1996)
Qp=(1 / w2 – w1)
* [ (w3 – w2)/pg – V1/V0 *
(V0 – (w2 – w1) / pC]
Where Qp = gas absorbed at given equilibrium pressure p,
m3/t;
w1 = mass of evacuated (empty) bomb, g;
w2 = mass of bomb with coal sample, g;
w3 = mass of coal and bomb at equilibrium pressure p, g;
V0 = free volume of the bomb when empty at NTP, cm3;
V1 = volume of gas at NTP contained in bomb at equilibrium pressure
p, cm3;
pg = density of gas, g/cm3;
pc = density of coal, g/cm3;
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