Ammonia is being absorbed in a column packed with 1-in. metal Fleximax by pure water at 25 C and 1.0 atm pressure. The entering gas contains 2.4 mol% of ammonia in the air, with a flow rate of 4,800 lb/h. The process design specifies a liquid-to-gas mass flow rate ratio (L/G) of 2.2. If the pressure drop of the packing column is 0.5 in. H2O/ft of packing, please determine the internal diameter of the absorption column. (Assuming both gas phase and liquid phase are ideal)