Experimental Study on Methane Desorption from Lumpy Coal under the Action of Hydraulic and Thermal
Table 2
Raw data of the two coal samples at gas adsorption pressure around 0.25 MPa.
Experimental stage
Sample number
ΔP (MPa)
P1 (MPa)
V1 (L)
P2 (MPa)
m1 (g)
m2 (g)
ω (%)
V2 (L)
V3 (L)
V4 (L)
dV5 (mL/g)
ηmax
Natural desorption
1
0.11
0.295
1702
—
1101
—
0
93.62
272.63
4110.87
3.73
0.3477
2
0.11
0.241
1782.03
—
1074
—
0
102.02
242.73
4140.77
3.65
0.3717
1 time of adsorption pressure (about 0.25 MPa)
1
0.1
0.215
630
0.222
1101
—
1.455
93.86
199.21
3785.79
3.43
0.114
12
0.1
0.215
2400.68
0.222
1101
1117.02
1.455
93.86
199.21
3785.79
3.43
0.5815
2
0.11
0.230
1116.07
0.230
1074
1090.93
1.576
113.15
256.9
4126.6
3.84
0.2082
2.5 times of adsorption pressure (about 0.625 MPa)
1
0.1
0.195
401.57
0.508
1101
—
1.144
94.52
181.96
3803.04
3.45
0.0577
12
0.1
0.195
1269
0.508
1101
1112.66
1.144
94.52
181.96
3803.04
3.45
0.2858
2
0.105
0.182
441.14
0.458
1074
1089.24
1.41
101.95
183.18
4001.07
3.72
0.0644
6.25 times of adsorption pressure (about 1.56 MPa)
1
0.1
0.225
365.29
1.25
1101
—
1.57
93.81
208.38
3776.62
3.42
0.0415
12
0.1
0.225
1343
1.25
1101
1118.35
1.57
93.81
208.38
3776.62
3.42
0.3004
2
0.11
0.196
311.4
1.295
1074
1090.13
1.502
102.02
197.41
4186.09
3.89
0.0272
16 times of adsorption pressure (about 4.00 MPa)
1
0.1
0.215
269.02
3.212
1101
—
1.251
93.861
199.21
3785.79
3.43
0.0192
12
0.1
0.215
1018
3.212
1101
1114.77
1.251
93.861
199.21
3785.79
3.43
0.2162
2
0.11
0.195
211.36
3.223
1074
1091.24
1.605
102.02
196.40
4187.1
3.89
0.0271
Note. ΔP is the D value between initial and final gas pressures of the gas storage tank, which the content of 3.8 L; P1 is the gas adsorption pressure at final stage; V1 is the desorption volume of the coal sample at each stage; P2 is the water injection pressure; it depends on final gas adsorption pressure; V2 is the free content after coal into the sample container; it is measured by helium; m1 is the mass of the dry coal sample; m2 is the mass of the wet coal sample after water injection and desorption; ω is the moisture content of the coal sample appending on dry coal after water injection and desorption; V3 and V4 are the free gas volume and adsorption gas volume, respectively; dV5 means adsorption gas volume per unit mass of coal; ηmax is accumulative desorption rate after 48 h desorption. All data are converted to the value at standard status (273.15 K, 1 atm).
