7.3 Toluene hydrodealkylation process-separation section. As dis. cussed in Example 6.7, the following stream at 100F and 484 psia is to be separated by two distillation columns into the Products 1-3 in the following table. Figure 7.32 Toluene hydrodealkylation process-Distillation section. Ibmol/hr Species Feed Product 1 Product 2 Product 3 H CH, CH, (benzene) C,H, (toluene) C2H, biphenyl) 0.1 1.5 19.3 262.8 84.7 5.1 1.5 19.2 1.3 258.1 0.1 3.1 84.6 5.1 Two different distillation sequences are to be examined as shown in Figure 7.32. In the first sequence, H, and CH, are removed in the first column. If using ASPEN PLUS, the DSTWU module is used to estimate the reflux ratio and theoretical tray requirements for both sequences. In addi- tion, the RK-SOAVE option is used. Specify a reflux ratio equal to 1.3 times the minimum. Use design specifications to adjust the isobaric col. umn pressures so as to obtain distillate temperatures of 130F, however, no column pressure should be less than 20 psia. Also, specify total con densers but note that a partial condenser is used when H, and CH, are taken overhead, Species Flow Rates (Ibmol/hr) CH Feed 0 0 0 274.2 0 Recycle Gas Recycle 0 2,045.9 0 3,020.8 3.4 42.8 82.5 5.3 1.0 0 CH. (benzene) CH, (toluene) CH. (biphenyl) Feed 75F, 569 psia Vapor Product Gas Recycle 121F 569 psia Recycle 250F. 569 psia U = 50 AP= 5 psi 100F FLASH DRUM U= 60 AP= 5psi 120F CW 90F 1.200F 1,000F Junts FURNACE AP = 70 psi 1.150F 1.268F REACTOR OUENCH Liquid = 0 psi PUMP Product Figure 7.31 Reactor section of the toluene hydrodealkylation process