To burn one pound of natural gas, approximately how many pounds of air are required?

The correct choice emphasizes the stoichiometric relationship between natural gas and air necessary for combustion. For one pound of natural gas (which primarily consists of methane, CH4), around 14.7 pounds of air are ideally needed to ensure complete combustion. This ratio accounts for the required amount of oxygen from the air to fully oxidize the hydrocarbons present in natural gas.

In practical terms, the air needed for combustion consists of about 21% oxygen and 79% nitrogen by volume. The 14.7 pounds of air to one pound of natural gas ensures that there is enough oxygen available for the chemical reaction that produces carbon dioxide and water vapor, minimizing unburned fuel and enhancing efficiency in the combustion process. This understanding is critical for operations and maintenance teams to optimize energy consumption and emissions controls in facilities that utilize natural gas.

The other choices reflect incorrect stoichiometric relationships. For example, 1 pound is far too low to support combustion, while 5.5 and 144 pounds overestimate or misrepresent the required air-fuel ratio in combustion processes.