Question

Nitric oxide (NO) can be produced by partially oxidizing ammonia (NH3) with oxygen via the following reaction:

2NH3 + 2.5O2 = 2NO + 3H2O (1)

Air 750°C Products 920°C NH3 25°C H2o H20 ) 25°C 105°C

Ammonia can also react with oxygen via the following reactions:

2NH3 + 1.5O2 = N2 + 3H2O (2)

2NH3 + 3.5O2 = 2NO2 + 3H2O (3)

Ammonia is fed to a reactor at 25 °C and 500 kg/h. Dry air (21 mol % O2, 79 mol % N2) enters at 8000 kg/h. Eighty percent (80%) of the NH3 entered the reactor is consumed. Of the NH3 reacted, 60 % reacted via reaction (1), 15 % reacted via reaction (2), and 25 % reacted via reaction (3). The products exit the reactor at 920 °C, and the heat generated is used to convert liquid H2O into steam. Liquid H2O enters at 25 °C and steam exits at 105 °C.

Question: how many kilograms of steam is produced every hour?

For 25°C at 1 atm:

dHf, NH3, gas = -67.20 kJ/mol

dHf, H2O, gas = -241.83 kJ/mol

dHf, NO, gas = 90.374 kJ/mol

dHf, H2O, liquid = -285.84 kJ/mol

dHf, NO2, gas = 33.85 kJ/mol

dHv, H2O, @0°C = 2500 kJ/kg

Cp for all gases and vapors: 30 J/mol.K

Answer 1