Influence of Gas from Long-Flame Coal Spontaneous Combustion on Gas Explosion Limit

Table 4

Gas volume fraction in different stages of coal spontaneous combustion and its lower limit of gas explosion and explosion pressure.

The process of coal spontaneous combustion	Vapor volume fraction (%)							Explosion pressure (MPa)
	CO	CH4	C2H4	C2H6	CO2	O2	N2	CH4 concentration (%)
								5.1%	4.9%	4.6%	4.3%	4.0%
Room temperature stage (with coal temperature 30°C)	0.0005	0.0107	0	0	1.05	19.1	79.7	0.25	NO	NO	NO	NO
Slow oxidation stage (with coal temperature 80°C)	0.0281	0.0287	0.0002	0.0059	2.78	18.8	78.4	0.26	0.21	NO	NO	NO
Rapid oxidation stage (with coal temperature 130°C, which is the change node of C2H6 production)	0.2030	0.0619	0.0011	0.012	2.69	17.7	78.3	0.28	0.26	0.22	NO	NO
Vigorous oxidation stage (with coal temperature 170°C)	0.4350	0.1042	0.0071	0.1018	2.82	15.8	78.7	0.29	0.27	0.24	0.21	NO