Question

(25) Reactor/Recycle Specification Before performing energy balances on the fire heater and the reactor, you must specify the reacting system. Again, the competing reactions occurring in this process are: C3H6 + C&H. → CH12 or P+BIB C3H + CH12 + C12H18 or P+IB → DB Below is a simplified version of the flow sheet dealing with just the recycle loop of the process. Fresh benzene (B) is mixed with a recycle stream that contains only B and propylene (P). The resulting mixed stream is joined with fresh P to form the reactor feed. The reactor product stream contains unreacted reactants and both isopropyl benzene (IB) and diisopropyl benzene (DB). This mixture is sent into the flash condenser/ benzene distillation column sequence, which we treat here as one large unit. Three streams leave this combined unit: a vapor stream containing 7.42 mol B/h, 6.75 mol P/h, and 0.72 mol 1B/h; a process stream containing 0.80 mol B/h, 93.6 mol IB/h, and 2.80 mol DB/h; and a recycle stream containing 92.4% of the B that was fed to the flash condenser and 30.1% of the P that was fed to flash condenser. Determine the volumetric flow rate of the vapor stream (in SCMH), the overall conversion of benzene for this process, the single pass conversion of benzene in the reactor, and benzene recycle ratio (mol B in recycle/mol fresh B feed).

Answer 1

RB Process strear 0.80 mal B/hr 91.6 mol lolhe 2.80 mi Dolar R Bip 1 FI P Reacted Blb vap strear 7.42 mol 6.75 mol Play md Blar 072 volo flow rate of vop. stream: V = 7,42 +6.75 +0.72 3 14.89 mollima flow. at STP 14-89 X 22.4 l/mor + 333.336 L ne = 0.333 sm /or Benzene fed to Reactor Fz +R2 propylene fed to Reactor: fit R(1-21) Bennene consumed a (IB + DB ) formed 93.6 +2-80.+0.72 ogrufi 97.12 mallny Raya 0-9244f7+**) 070-76-RX do Benzene to flash condenser (Fz+Q261) – 97,12 Ra, 0.924 (F₂ + R2,) - 31.12 0.924 62 -0.076 R to, = 89.74 propylene consumed - (IB+DB) formed + (DB) feened 97.12 +228 - 99.92 mol/mo 80 propane to flash condenser : fit R(1-xy) – 99.92 R(1-21) - 0.301 [F, +R 11 =1) – 99.92] → 0.301 F, 0.699 R11-20) 20.076.0 overall benzene Balance. Fatra 97.12 + R2 + 0.8 + 7.42 o fz > 105.34 moll no overall propylene Balance. fi + R (1-x2) 99.92 + R60-1) + 6.75 fi = 106.67 rollur 89.74 - 0.924X 105.14 99.92 mol RL from eq" 0 -0.076 overall conversion of Ba Benzere conermed Benzen in fresh feed 97,12 100% - 92.20"/ 108.14 single pass Conv. of B Beureve consumed Total Benzere to reach 97.12 47,5%. x 100% 105.34 +99-42 0.94857 Bensene in Recycle Renene in fresh feed 99.92 103:24