Homework #11.18 Nitrogen gas can be injected into oil wells to increasethe recovery of crude oil (enhanced oil recovery). Usually,natural gas is produced with the oil and it is desirable torecover the nitrogen from the gas for reinjection into thewell. Furthermore, the natural gas must not contain morethan 3 mol% nitrogen if the natural gas is to be put into apípeline. A total of 170,000 SCFH (based on 60°F and 14.7psia) of natural gas containing 18% N2, 75% CH4, and 7%C2Hs at 100°F and 800 psia is to be processed for N2 removal.A two-step separation process has been proposed consistingof (1) membrane, separation with a nonporous glassy polyimide membrane, followed by (2) pressure-swing adsorptionusing molecular sieves to which the permeate gas is fed. Themembrane separator is highly selective for N2 (SPn,,cH16) and completely impermeable to ethane. The pressure-swing adsorption step selectively adsorbs methane, giving97% pure methane product in the adsorbate, with an 85%recovery of CH4 fed to the adsorber. The nonpermeate (retentate) gas from the membrane step and adsorbate fromthe pressure-swing adsorption step are combined to give amethane stream that contains 3.0% N2. The pressure dropacross the membrane is 760 psia. The permeate at 20°F iscompressed in two stages to 275 psia and cooled to 100°Fbefore entering the adsorption step. The adsorbate gas,which exits the adsorber during regeneration at 100°F and15 psia, is compressed in three stages to 800 psia and cooledto 100°F before being combined with nonpermeate gas togive the final pipeline natural gas(a) Draw a process flow diagram of the separation processusing appropriate symbols from Tables 1.2 and 1.3. Includethe gas compressors and heat exchangers. Label the diagramwith all of the data given above, and number all processstreams.(b) Compute by material balances, using' the data above,the component flow rates of N2, CH4, and C2Hs in Ibmol/hfor all process streams entering and exiting the two separation operations. Place the results in a material balance tablesimilar to Table 1.521 시 4