Simulation results demonstrate that absolute sorption (expressed as a mass basis) divided by bulk gas density has negligible temperature effect on CH4, C2H6, and CO2 sorption on dry coal when pressure is over 6 MPa.
This research was aimed at testing a hypothesis, that at elevated CO2 pressure coal can soften at temperatures well below those obtained in the presence of other gases.
This research was initially aimed at validating earlier literature results obtained on a similar device, which showed that at elevated CO2 pressure coal can soften at temperatures well below those obtained in the presence of other gases (Khan and Jenkins 1985).
Using dual-energy X-ray computed tomography (X-ray CT), (Karacan 2003) has observed that certain microlithotypes of confined Pittsburgh seam coal, at pressures 1.7 4.4 MPa, showed a decreasing trend in the bulk density for ~ 40 h, after which there was a period of slight density increase at each pressure step.
(3) Unprotected range increases with the increase of coal pillar width, pressure relief angle is 49° 60°, pressure relief angle of both sides is negative correlation with mined out areas.
Taking advantage of this mining approach, the adjacent coal seams experience pressure relief and the permeability will increase significantly, thereby providing efficient drainage conditions for pressure-relief gas, eliminating the outburst risk of adjacent seams, achieving effective coal exploitation, and realizing the safe and efficient extraction of coal and gas.
Other technologies, like using pulverised coal injection, top pressure recovery turbines and blast furnace control systems, can reduce direct energy use by 10% and electricity by 35%.
But with falling oil prices, continued supplies of cheap coal and EU pressure to increase cost-competitive renewable power generation, the shale gas industry needs positive results fast, and less controversy.
Numerous process concepts are under development worldwide that convert coal at elevated pressure.
