Methane is usually found with nitrogen. It is necessary to concentrate methane to at least $98\%$ for final application. Separation of Methane$-$Nitrogen is known to be one of the toughest separations. Figure below shows the shows the process flow diagram for methane recovery. As you can see this separation is very utility intensive. Use your engineering skills and optimize this process.

A$)$ If the $\backslash$Delta Tmin$=10\backslash$deg F$,$ calculate the minimum energy requirement for this process.

B$)$ Design a heat exchanger network with minimum energy requirement and minimum number of your design should utilize only one cold utility and one hot utility $($if any needed$).$