1. Plant-wide Control Example
Ref.: Sieder et al, Product and Process Design Principles, 2nd Edition, Wiley, 2004, Chapter 20.

2. Plant-wide Control Example: 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

3. Plant-wide Control Example: Vinyl Chloride Production

4. Plant-wide Control Example: Vinyl Chloride Production

5. 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)

6. 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

7. Plant-wide Control Example: Vinyl Chloride Production
Step 4: Set the production rate: V-1

8. 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

9. 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-17, V-15, V-14, V12, V-10.

10. Plant-wide Control Example: Vinyl Chloride Production
Steps 7 & 8: Check component balances and control individual units (V-2)

11. Plant-wide Control Example: Vinyl Chloride Production
Steps 9: Optimize economics and improve dynamic controllability: The setpoints of recycle flow and T-100 feed flow controllers are set in proportional to the feed flow rate.