We wish to absorb n-butane and n-pentane from a gas stream that is at (25.0^{circ} mathrm{C}) and

Question:

We wish to absorb n-butane and n-pentane from a gas stream that is at \(25.0^{\circ} \mathrm{C}\) and \(1.0 \mathrm{~atm}\) and has a flow rate of \(100.0 \mathrm{kmol} / \mathrm{h}\). Feed is \(90.0 \mathrm{~mol} \%\) methane, \(4.0 \mathrm{~mol} \% \mathrm{n}\)-butane, and \(6.0 \mathrm{~mol} \% \mathrm{n}\)-pentane. Two liquid streams are available as solvent. Liquid stream \(\mathrm{A}\) is at \(30.0^{\circ} \mathrm{C}\) and \(1.0 \mathrm{~atm}\) and has a flow rate of 75.0 \(\mathrm{kmol} / \mathrm{h}\). Stream A is \(96.0 \mathrm{~mol} \% \mathrm{n}-\) nonane ( 9.0 carbons), \(1.0 \mathrm{~mol} \% \mathrm{n}\)-butane, and \(3.0 \mathrm{~mol} \% \mathrm{n}\)-pentane. All of stream A will be used. Liquid stream B is pure n-nonane. This stream is at \(1.0 \mathrm{~atm}\) and \(20.0^{\circ} \mathrm{C}\). The flow rate of stream \(\mathrm{B}\) can be adjusted to any desired value. Absorber operates at a pressure of \(1.0 \mathrm{~atm}\) and has seven stages. Gas should be fed on stage 7. The two liquid streams can be fed above any of the stages. Outlet gas stream should be between 99.0 and \(99.1 \mathrm{~mol} \%\) methane. Use the Peng-Robinson VLE package.

Determine the minimum flow rate of stream B and the optimum feed stages for streams A and B required to just achieve the desired methane purity of the outlet gas stream. Report the following:

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