RECOVERY AND PURIFICATION OF IMPURE ARGON

Abstract

PROBLEM TO BE SOLVED: To provide a method for recovering and purifying impure argon, capable of efficiently recovering and purifying the argon discharged from a silicon growth oven at a low cost by executing processes for removing oxygen, water, CO 2 and residual impurities from the impure argon. SOLUTION: This method for recovering and purifying impure argon comprises compressing an argon outflow gas containing nitrogen, oxygen, water, hydrogen, CO 2 , CO, hydrocarbons, a dopant, etc., discharged from a silicon crystal growth oven 18, cooling the compressed gas with a heat exchanger 27, allowing the cooled gas to pass through a liquid scrubber 33 to remove the dopant and particulate impurities, heating the left impure argon 35 with a heat exchanger 37, charging the heated impure argon into a deoxo catalyst device 43 to react the impure argon with hydrogen to remove oxygen, removing O 2 and water in the flow 50 with zeolite adsorption beds 55a, 55b, mixing the left argon with argon 70 charged from a low temperature distillation tower, dividing the flow 120 into a raw material 140 and a flow 150 with a two tower type distillation tower 125, and removing nitrogen, hydrogen, CO and hydrocarbons with a lower or upper distillation tower 128. Thus, both the cryogenic distillation technique and the cryogenic adsorption technique are used to recover and purify the argon.