APPARATUS AND METHOD FOR HIGHLY REFINING BIO GAS MUNITY RECYCLING USING CALCIUM HYDROXIDE AND ALKALI COMPOUND

摘要

PURPOSE: A biogas multi-circulating refining apparatus and a method for the same are provided to increase the efficiency of carbon dioxide removal from methane gas by using calcium hydroxide and alkali admixtures. CONSTITUTION: A biogas multi-circulating refining method 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); methane gas without carbon dioxide is supplied to the n-th absorption column to be reacted with the absorption liquid in order to remove carbon dioxide from the methane gas; methane gas is re-supplied to the absorption column according to the concentration of the methane gas(S40); a part or whole of the absorption liquid in the first absorption column is drained according to the pH value of the absorption liquid(S50); and the absorption liquid in the n-th absorption column is supplied to the n-1-th absorption column, and new absorption liquid is supplied to the n-th absorption column to maintain the level of the absorption liquid(S60). [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; (S40) Removing carbon dioxide by re-reacting methane gas if the concentration of the methane gas is lower than the pre-determined value; (S50) 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; (S60) Supplying absorption liquid