What is the advantage to quenching the hydrocarbon gas with a liquid rather than with another (cooler) gas? Explain.

A stream of hydrocarbon gas at 500°C is cooled by continuously combining it with

a stream of light oil in an adiabatic tower. The light oil enters as a liquid at 25°C;

the combined stream leaves as a gas at 200°C.

(a) Draw a carefully labeled flow diagram for the process.

(b) Let F and D denote respectively the molar flow rates of hot hydrocarbon gas and

light oil. Use data given below to determine a numerical value for the oil-to-gas

ratio D/F. Explain your analysis.

(c) What is the advantage to quenching the hydrocarbon gas with a liquid rather than

with another (cooler) gas? Explain.

Data: CP

v (ave) = 150 J⋅mol−1⋅K−1 for the hydrocarbon gas.

CP

v (ave) = 200 J⋅mol−1⋅K−1 for the oil vapor.

ΔHlv (oil) = 35,000 J⋅mol−1 at 25°C.