Create a block flow diagram and a process flow diagram (PFD) of an industrial process for the manufacture of propylene glycol. It is not necessary to include instrumentation and control loops on the PFD. Utilities such as the fuel gas header, cooling tower, wastewater treatment plant, etc. should also be excluded. A plant produces propylene glycol (PG) by reacting liquid propylene oxide (PO) with water. Pure liquid PO and water feed streams are combined before entering tubular reactor R-200. The reactions take place in one hundred 1 tubes packed with a solid HCO3- catalyst. The feed streams are supplied to R-200 in a ratio of 11.8 moles of water per mole of propylene oxide. The main reaction is PO + H2O PG but a side reaction also occurs in which some of the propylene glycol product is converted to di-propylene glycol or DPG: PG + PO DPG. Both of these are irreversible and exothermic so it is important to have sufficient heat transfer area and well-designed control systems to prevent thermal run- away. In this design, the outlet temperature of R-200 is regulated by cooling water flowing through the shell side, i.e. between the tubes, in a counter-current direction. The reactor has a per-pass propylene oxide conversion of 100 %, creating 4,900 kilograms of propylene glycol per hour and 300 kilograms of di-propylene glycol per hour. The reactor effluent is first fed to distillation column T-201, which removes unreacted process water as distillate to be pumped to the wastewater treatment plant. The bottoms product is pumped into distillation column T-202. Both fractionators have total cooling- water condensers and medium-pressure steam reboilers and their reflux ratios are less than unity. The T-202 distillate is the propylene glycol product which is pumped through a cooling-water exchanger (E-205) to reduce its temperature to 40 oC before entering its storage tank. Likewise, the DPG-rich bottoms product is pumped through E-206 and on to the tank farm