Ethylene oxide (C 2 H 4 O) is a high volume chemical intermediate that is used to produce glycol and polyethylene glycol. Ethylene oxide is produced by the partial oxidation of ethylene (C 2 H 4 )...

Ethylene oxide (C₂H₄O) is a high volume chemical intermediate that is used to produce glycol and polyethylene glycol.  Ethylene oxide is produced by the partial oxidation of ethylene (C₂H₄) using a solid catalyst in a fixed bed reactor:

                                    2C₂H₄
+ O2 è 2C₂H₄O                                                   (1)

      Unfortunately, a portion of the ethylene reacts completely to CO₂
and H₂O:

                                    C₂H₄
+ 3O₂
è 2CO₂
+ 2H₂O                                           (2)

      The product gas leaving a fixed bed ethylene oxide reactor has the following water free composition:  20.5% C₂H₄O, 72.7 % N₂, 2.3 % O₂, and 4.5% CO₂.  Determine the percent excess air used in the reactor, based on the desired reaction (1) and the mass of ethylene feed (in lbs/hr) required to produce 100,000 tons/year of ethylene oxide.