7.8 Explosiveness of Mine Gases
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Fourth, calculate the CH 4 ratio:
R =
CH 4 (%)
CH 4 (%) + CO(%) + H 2 (%)
=
1.8
1.8 + 0.94 + 3.3
= 0.3
Although very close to the limit, the diagram indicates that the mixture is
explosive.
(b)
First, calculate the percentage of N 2 excess:
N 2 excess (%) = N 2 sample (%) − N 2 normal (%) = 66.5 − 2.0 · (79.04 ÷ 20.93)
= 58.95
Second, calculate the effective inert gases:
X (%) = N 2 excess (%) + 1.5 CO 2 (%) = 58.95 + 1.5 · 26 = 97.95
Third, calculate the effective combustible gases:
Y (%) = CH 4 (%) + 1.25 H 2 (%) + 6.4 CO (%) = 3 + 1.25 · 1.2 + 0.4 · 1.3 =
5.02
Fourth, calculate the CH 4 ratio:
R =
CH 4
CH 4 + CO + H 2
=
3
3 + 1.3 + 1.2
= 0.55