Chapter 4, Problem 4.43P

A gas consisting only of CO and N₂ is made by passing a mixture of flue gas and air through a bed of incandescent coke (assume pure carbon). The two reactions that occur both go to completion:

$C{O}_2+C\to 2CO$ and $2C+O_2\to 2CO$

The flue gas composition is 12.8 mol-% CO, 3.7 mol-% CO₂, 5.4 mol-% O₂, and 78.1 mol-% N₂. The flue gas/air mixture is so proportioned that the heals of the two reactions cancel, and the temperature of the coke bed is therefore constant. If this temperature is 875 °C. if the feed stream is preheated to 875°C. and if the process is adiabatic, what ratio of moles of flue gas to moles of air is required, and what is the composition of the gas produced?