Consider the benzene purification column, T-101, in Figure 1.5 for the toluene hydrodealkylation process. The column feed contains noncondensables, mainly methane and a small amount of hydrogen, that must be vented from the system. The vent is taken off the top of the reflux drum, V-104. Sketch a control system in which the valve on this vent line is used to control the pressure of the column. Explain what happens when

1. The column pressure begins to drop

2. The amount of noncondensables fed to the column suddenly increases

Figure 1.5

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V-101 Toluene Feed Drum Toluene KEY Temperature (°C) Pressure (bar) Mass Flow (1000 kg/h) Hydrogen 3 10.0 25 1.9 P-101A/B Toluene Feed Pumps 0.82 25 25.5 E-101 Feed Preheater LV-101 P-101A/B H-101 Heater R-101 Reactor 225 25.2 hps E-101 4 Air C-101A/B Recycle Gas Compressor Combustion Products 5 600 25 fg H-101 6 654 24 E-102 Reactor Effluent Cooler R-101 V-102 High-Pres. Phase Sep. /25.5 C-101A/B 9 V-103 High-Pres. Phas e Sep. E-102 <8) 380 239 V-102 E-10 3 Feed Preheater Reboiler V-103 E-106 T-101 E-104 Benzene Benzene Benzene Column Condenser 18 E-103 Ips mps E-106 T-101 E-104 3.3 CW 112 V-104 P-102A/B V-104 Reflux Drum 7 P-102A/B Reflux Pump CW E-105 E-105 Product Cooler Date Date Date Revision +0 Fuel Gas Benzene TBWS Designs - Toluene HDA Process Drawn by Checked by Approved by Drawing No.