SELECTIVE MULTIPHASE ABSORPTION DEVICE AND METHOD FOR HIGHLY REFINING BIO GAS

摘要

PURPOSE: A selective multi-leveled absorption apparatus for refining biogas and a method for the same are provided to obtain methane gas of high concentration by continuously introducing biogas. CONSTITUTION: A selective multi-leveled absorption apparatus for refining biogas includes the following steps: biogas is supplied to a first absorption column to be reacted with absorption liquid containing calcium hydroxide and an alkali admixture in order to remove carbon dioxide from the biogas(S10); the methane gas without the carbon dioxide is supplied to a second absorption column to be reacted with the absorption liquid in order to remove carbon dioxide from the methane gas(S20); the methane gas is circulated to a subsequent absorption column to be reacted with the absorption liquid according to the concentration of the methane gas(S30); the absorption liquid is drained according to the pH value of the absorption liquid(S40); and the level of the absorption liquid is maintained by supplying new absorption liquid to a third absorption column after the absorption liquid is drained from the first absorption column(S50). [Reference numerals] (AA) Start; (BB) End; (S10) Removing carbon dioxide by primarily reacting biogas; (S20) Removing carbon dioxide by secondarily reacting methane gas; (S30) Removing carbon dioxide by thirdly reacting methane gas if the concentration of the methane gas is lower than the pre-determined value; (S40) Draining the absorption liquid of a first absorption column if the pH value of the absorption liquid is lower than the pre-determined pH value; (S50) Supplying absorption liquid