In a simple turboexpander plant, similar to that shown in Figure 12.15, the bottom and side reboiler are heated by exchange with inlet gas. The total inlet gas flow rate is 10,000 lb-mol/h (4,536...

In a simple turboexpander plant, similar to that shown in Figure 12.15, the bottom and side reboiler are heated by exchange with inlet gas. The total inlet gas flow rate is 10,000 lb-mol/h (4,536 kg-mol/h). The inlet gas, which is at 104°F (40°C), splits into two streams. One portion is cooled by cold residue gas. The other portion is cooled first in the reboiler and then the side reboiler. The liquid from the demethanizer to the side reboiler is at 0°F (–18°C). The side reboiler duty is 2.866 MMBtu/h (3.024 GJ/h) and the reboiler duty is 2.397 MMBtu/h (2.529 GJ/h). If the inlet gas has a molar heat capacity of 11.20 Btu/ lb-mol (26.05 kJ/kg-mol) over the temperature range being considered and the minimum exchanger approach temperature7 is 10°F (5.6°C), what fraction of the inlet gas is needed to provide the required demethanizer heating?