METHOD OF PURIFYING GAS, APPARATUS THEREFOR, AND ACID-GAS-ABSORBING LIQUID FOR USE IN THE PURIFICATION

摘要

An acid gas is efficiently separated and recovered from a gas mixture at a low cost. The amount of an acid gas to be absorbed per unit volume of an absorbing liquid is increased and the amount of the absorbing liquid to be circulated is reduced to save the circulatory energy. An absorbing liquid comprising an ionic liquid as the main ingredient is supplied to an upper part of an absorption column (13) kept at a given temperature and a given pressure, while a gas mixture comprising an acid gas and a nonacid gas is supplied to a lower part of the absorption column (13) to bring the gas mixture into contact with the absorbing liquid. Thus, the acid gas is absorbed in the absorbing liquid and the nonacid gas is separated from the acid gas and recovered from the absorption column (13). The absorbing liquid containing the acid gas absorbed therein is supplied to an upper part of a regeneration column (16) kept at a temperature which is equal to or higher than the temperature of the inside of the absorption column (13) and at a pressure lower than the pressure of the absorption column (13). The acid gas is thus released from the absorbing liquid and recovered from the regeneration column (16) simultaneously with the regeneration of the absorbing liquid. The absorbing liquid regenerated is supplied to the upper part of the absorption column (13).