Natural gas $left(mathrm{CH}_{4} ight)$ is transported through a $6 mathrm{in}$. ID pipeline at a rate of $10,000 mathrm{scfm}$. The compressor stations are 150 miles apart,

Natural gas $\left(\mathrm{CH}_{4}\right)$ is transported through a $6 \mathrm{in}$. ID pipeline at a rate of $10,000 \mathrm{scfm}$. The compressor stations are 150 miles apart, and the compressor suction pressure is maintained at 10 psig above that at which choked flow would occur in the pipeline. The compressors are each two-stage, operate adiabatically with interstage cooling to $70^{\circ} \mathrm{F}$, and have an efficiency of $60 %$. If the pipeline temperature is $70^{\circ} \mathrm{F}$, calculate

(a) The discharge pressure, interstage pressure, and compression ratio for the compressor stations

(b) The horsepower required at each compressor station