| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method where ammonia of high purity can be recovered from exhaust gas from a treatment stage related to a semiconductor including gallium nitride or the like, and to provide a device therefor. <P>SOLUTION: The method for recovering gaseous ammonia comprises: a dissolution stage where gaseous ammonia in exhaust gas derived from a treatment stage is dissolved into water; a distillation stage where aqueous ammonia with ammonia dissolved is distilled, so as to separate water and gaseous ammonia; and a liquefaction stage where the separated gaseous ammonia is liquefied. Impure components are adsorbed away from the exhaust gas derived from the treatment stage, and the exhaust gas after the impure components are adsorbed away is fed to the dissolution stage. In the dissolution stage, the dissolution step is repeated, so as to increase the concentration of ammonia, and the aqueous ammonia with a prescribed concentration is stored in an aqueous ammonia tank. The gaseous ammonia derived from the distillation stage is dehumidified, and is thereafter liquefied. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
