Question

One means of producing liquid oxygen from atmospheric air is to take advantage of the phase equilibrium properties of oxygen-nitrogen mixtures. This system is illustrated in Fig. P16–121. In this cascaded-reactors system, dry atmospheric air is cooled in the first reactor until liquid is formed. According to the phase-equilibrium properties, this liquid will be richer in oxygen than in the vapor phase. The vapor in the first reactor is discarded while the oxygen enriched liquid leaves the first reactor and is heated in a heat exchanger until it is again a vapor. The vapor mitxure enters the second reactor where it is again cooled until a liquid that is further enriched in oxygen is formed. The vapor from the second reactor is routed back to the first reactor while the liquid is routed to another heat exchanger and another reactor to repeat the process once again. The liquid formed in the third reactor is very rich in oxygen. If all three reactors are operated at 1 atm pressure, select the three temperatures that produce the greatest amount of 99 percent pure oxygen.

16-121 One means of producing liquid oxygen from atmospheric air is to take advantage of the phase-equilib- rium properties of oxygen-nitrogen mixtures. This systenm is illustrated in Fig. P16-121. In this cascaded-reactors sys- tem, dry atmospheric air is cooled in the first reactor until liquid is formed. According to the phase-equilibrium prop erties, this liquid will be richer in oxygen than in the vapor oxygen enriched liquid leaves the first reactor and is heated in a heat exchanger until it is again a vapor. The vapor mix- ture enters the second reactor where it is again cooled until a liquid that is further enriched in oxygen is formed. The vapor from the second reactor is routed back to the first reactor while the liquid is routed to another heat exchanger and another reactor to repeat the process once again. The liquid formed in the third reactor is very rich in oxygen. If all three reactors are operated at1 atm pressure, select the three temperatures that produce the greatest amount of 99 percent pure oxygen. Dry atmospherie air Nitrogen → enriched T. apor Oxygen enriched liquid FIGURE P16-121

Answer 1

First reactor temperature should be -192°C as air gets liquified at this temperature in 1 atm pressure.

Second reactor temperature should be in between -192°C and -183°C.

Third reactor should be in -183°C as at this temperarure oxygen gets liquified.