$6\mathrm{.}23.$ Production of $95\%$ H$2$ by absorption of HCs from a refinery gas.

Fuel cell automotive systems are being considered that will require hydrogen of $95\%$ purity. A refinery stream of $800,000$ scfm $($at $32$F$,1$ atm$),$ containing $72\mathrm{.}5\%$ H$2,25\%$ CH$4,$ and $2\mathrm{.}5\%$ C$2$H$6,$ is available. To convert this gas to the required purity, oil absorption$,$ activated charcoal adsorption, and membrane separation are being considered. For oil absorption$,$ an available n$-$octane stream can be used as the absorbent$.$ Because the $95\%$ H$2$ must be delivered at not less than $375$ psia, the absorber will operate at $400$ psia and $100$F$.$ If at least $80\%$ of the hydrogen fed to the absorber is to leave in the exit gas, determine the following: $($a$)$ the minimum absorbent rate in gpm; $($b$)$ the absorbent rate if $1\mathrm{.}5$ times the minimum amount is used; $($c$)$ the number of theoretical stages; $($d$)$ the stage efficiency for each of the three species in the feed gas, using the O$$Connell correlation; $($e$)$ the number of trays actually required; and $($f$)$ the exit gas composition, accounting for octane stripping. For part $($g$)$ of the exercise, if the lost octane in part $(6\mathrm{.}23.$ Production of $95\%H2by$ absorption of HCs from a refinery gas.

Fuel cell automotive systems are being considered that will require hydrogen of $95\%$ purity. A refinery

stream of $800,000scfm($at $32$@$F,1$atm $),$ containing $72\mathrm{.}5\%H2,25\%CH4,$ and $2\mathrm{.}5\%C2H6,$ is available.

To convert this gas to the required purity, oil absorption$,$ activated charcoal adsorption, and membrane

separation are being considered. For oil absorption$,$ an available $n-$octane stream can be used as the

absorbent$.$ Because the $95\%H2$ must be delivered at not less than $375a,$ the absorber will operate at $400$

psia and $100$@$F.$ If at least $80\%$ of the hydrogen fed to the absorber is to leave in the exit gas, determine the

following: $($a$)$ the minimum absorbent rate in gpm; $($b$)$ the absorbent rate if $1\mathrm{.}5$ times the minimum amount

is used; $($c$)$ the number of theoretical stages; $($d$)$ the stage efficiency for each of the three species in the feed

gas, using the O'Connell correlation; $($e$)$ the number of trays actually required; and $($f$)$ the exit gas

composition, accounting for octane stripping. For part $($g$)$ of the exercise, if the lost octane in part $($f$)$ is not

recovered, estimate its value if the process operates $7,900\frac{h}{?}$ year and the octane is valued at $$1\mathrm{.}00$gal.

Would the use of octane preclude use of this hydrogen in fuel cells? Obtain the necessary properties from

a process simulator.