It is possible to upgrade a natural gas stream by using membranes. Refer to Figure 13.2 and modify the schematic as follows: • Add a third membrane unit at the end of the two-membrane train. • The...

It is possible to upgrade a natural gas stream by using membranes. Refer to Figure 13.2 and modify the schematic as follows: • Add a third membrane unit at the end of the two-membrane train. • The permeate from the third unit is compressor fuel and the residue goes to the flare. Replace all values in Figure 13.2 as follows: • The feed is 10 MMscfd (2.68 × 105 Nm3/day), 15% N2, 85% CH4 • The product gas is 4% N2, 7.6 MMscfd (2.04 × 105 Nm3/day) • The recycle stream is 8.7% N2 • The compressor fuel (third membrane unit) is 26% N2, 0.9 MMscfd (24 × 103 Nm3/day) • The flare is 65% N2 a. What percent of the CH4 is lost in the flare gas? b. What is the total Btu (kJ) recovery in the product stream?