Answer to Question #215821 in Chemical Engineering for qiqi

Question

A waste gas and theoretical air are entering a furnace at 25°C to produce flue gas at 150°C. If pure O2 rather than air is fed to the furnace, would the flue gas temperature be higher, lower or the same? Provide reasons for the answer.

Answer 1

The flue gas temperature be higher

Because the combustion flue gases inside the flue gas stacks are significantly hotter than the ambient outside air, they are less dense. As a result, the pressure at the bottom of the vertical column of hot flue gas is lower than the pressure at the bottom of a comparable column of outside air.