Chapter 9, Problem 9.63P

Methanol vapor is burned with excess air in a catalytic combustion chamber. Liquid methanol initially at 25°C is vaporized at 1.1 atm and heated to 100°C; the vapor is mixed with air that has been preheated to 100°C, and the combined stream is fed to the reactor at 100°C and 1 atm. The reactor effluent emerges at 300°C and 1 atm. Analysis of the product gas yields a dry-basis composition of 4.8% CO₂, 14.3% O₂, and 80.9% N₂.

1. Calculate the percentage excess air supplied and the dew point of the product gas.

Taking a basis of 1 g-mole of methanol burned, calculate the heat (kJ) needed to vaporize and heat the methanol feed, and the heat (kJ) that must be transferred from the reactor.

Suggest how the energy economy of this process could be improved. Then suggest why the company might choose not to implement your redesign.