| 摘要 |
The purpose of the present invention is to further improve the methane concentration in the concentration of a methane gas by PSA. For carrying out a PSA cycle by providing adsorption columns (A1) to (A4) respectively filled with adsorption materials (A11) to (A41) capable of adsorbing a methane gas contained in a coal mine gas, multiple different pressure states are set as intermediate pressure states for the internal pressure of each of the adsorption columns (A1) to (A4), and a first pressure-equalizing (pressure-decreasing) step and a final pressure-equalizing (pressure-decreasing) step are carried out as a pressure-equalizing (pressure-decreasing) step, wherein the first pressure-equalizing (pressure-decreasing) step comprises respectively transporting gases in the adsorption columns (A1) to (A4), each of which is in a high-pressure state, to upper parts of another adsorption columns (A1) to (A4) each of which is in an intermediate pressure state having a lower pressure than that in each of the upper sides of the aforementioned adsorption columns (A1) to (A4) to thereby change the pressure in each of the adsorption columns (A1) to (A4) to a pressure of a high-pressure-side intermediate pressure state, and the final pressure-equalizing (pressure-decreasing) step comprises respectively transporting the gases in the adsorption columns (A1) to (A4), each of which is in a high-pressure-side intermediate pressure state that has a higher pressure than that in the low-pressure state, to another adsorption columns (A1) to (A4) each of which is in a low pressure state to thereby change the pressure in in each of the adsorption columns (A1) to (A4) to a pressure of a low-pressure-side intermediate pressure state. |
