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Plant-wide Control Example. Ref.: Sieder et al, Product and Process Design Principles, 2 nd Edition, Wiley, 2004. . Plant-wide Control Example: Vinyl Chloride Production. First Reaction: Chlorination of Ethylene At 90 o C , 1.5 atm and about 100% conversion
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Plant-wide ControlExample Ref.: Sieder et al, Product and Process Design Principles, 2ndEdition, Wiley, 2004.
Plant-wide ControlExample: Vinyl Chloride Production First Reaction: Chlorination of Ethylene At 90oC , 1.5 atm and about 100% conversion Second Reaction: Thermal cracking of Dichloroethane At 500oC , 26 atm and about 60% conversion of DCE Products specifications: Main product: VC(Liquid) with more than 99% purity By product: HCl (Gas) with more that 99% purity After preliminary design, the PFD and Mass & Energy balance Table are as follows
Plant-wide Control Example: Vinyl Chloride Production Step 1: Design a control system to produced 100,000 lb/hr VCM with more than 99% purity Step 2: Twenty control valves have been positioned in the PFD (DOF determination)
Plant-wide Control Example: Vinyl Chloride Production Step 3: Establish the energy-management system: V-3, V-6, V-5, V-7, V-8, V-20
Plant-wide Control Example: Vinyl Chloride Production Step 4: Set the production rate: V-1
Plant-wide Control Example: Vinyl Chloride Production Step 5: Control product quality (V-11, V-16, V-13, V-18), and safety, environmental, and operational constraints
Plant-wide Control Example: Vinyl Chloride Production Step 6: Fix recycle flow rates (V-4) and vapor and liquid inventories (R-100, V-19, V-10, V-12, V-14, V17, V-15.
Plant-wide Control Example: Vinyl Chloride Production Steps 7 & 8: Check component balances and control individual units (V-2)
Plant-wide Control Example: Vinyl Chloride Production Steps 9: Optimize economics and improve dynamic controllability: The setpoint of recycle flow controller is set in proportional to the feed flow rate.