Hierarchy of Decisions

1. Hierarchy of Decisions

2. LEVEL 3 : purge reactor separator products feeds Liquid ? Liquid / Vapor ? Vapor ?

3. LEVEL 4 : 1 ) Liquid LEVEL 3 reactor liquid separation system liquid products feeds Liquid recycle

4. purge LEVEL 4 : 2 ) Liquid / Vapor Vapor Recovery system vapor gas recycle vapor 35C Phase Split liq. liq. reactor liquid separation system liquid products feeds Liq. recycle LEVEL 3

5. purge LEVEL 4 : 3 ) Vapor Vapor Recovery system vapor gas recycle 35C Phase Split liquid liquid vapor reactor liquid separation system products feeds Liquid recycle LEVEL 3

6. LOCATIONS OF VAPOR RECOVERY SYSTEM Gas Recycle Purge 2 1 3 vapor from phase split 1 ) The purge stream 2 ) The gas-recycle stream 3) The flash vapor stream 4 ) None

7. RULES FOR PLACING THE VAPOR RECOVERY SYSTEM 1 ) Place the vapor recovery system on the purge stream if significant amounts of valuable materials are being lost in the purge. 2 ) Place the vapor recovery system on the gas-recycle stream if materials that are deleterious to the reactor operation (catalyst poisoning, etc.) are present in this stream or if recycling of some components degrades the product distribution. 3 ) Place the vapor recovery system on the flash vapor stream if both 1 ) and 2 ) are valid. 4 ) Do not use a vapor recovery system if neither 1 ) nor 2 ) are important.

8. TYPE OF VAPOR RECOVERY SYSTEM 1 ) Condensation - low. T and/or high P 2 ) Absorption 3 ) Adsorption 4 ) Membrane separation 5 ) Reaction ADJUST MATERIAL BALANCE ?

9. DECISION IN SYNTHESIZING LIQUID SEPARATION SYSTEM 1. How should light ends be removed, if they might contaminate the product ? 2. What should be the destination of light end ? 3. Do we recycle components that from azeotropes with reactants, or do we split the azeotropes ? 4. What separations can be made by distillation ? 5. What sequence of columns do we use ? 6. How should we accomplish separations if distillation is not feasible ?

10. 1 ) ALTERNATIVES FOR LIGHT-ENDS REMOVAL  Phase Splitter — T and/or P Partial Condenser on Product Column   Pasteurization Section on Product Column   a Stabilizer Column before the Product Column  Lower cost Higher cost lights    lights lights product product product

11. 2 ) DESTINATION OF LIGHT ENDS a ) vent or flare stacks - if light ends have very little value. b ) fuel - if light ends are flammable. c ) vapor recovery system - if light ends are valuable. 3 ) AZEOTROPES WITH REACTANTS 4 ) APPLICABILITY OF DISTILLATION 5 ) SEQUENCING OF SIMPLE COLUMNS 6 ) COMPLEX COLUMNS

12. Purge Compressor H2, CH4 Reactor Flash Toluene Benzene H2, CH4 Recycle Product Stablizer Diphenyl

13. Process Simulation Run ChemCAD to obtain M&E balance data !

14. ECONOMIC POTENTIAL AT LEVEL 4 EP4 = EP3 - annual purge loss - annualized distillation costs - annualized vapor recovery costs 2106 1106 $/yr 0 -1106 -2106 -3106 0.2 0.4 0.6 0.1 0.3 0.5 0.7

15. 2 ) DESTINATION OF LIGHT ENDS a ) vent or flare stacks - if light ends have very little value. b ) fuel - if light ends are flammable. c ) vapor recovery system - if light ends are valuable. 3 ) AZEOTROPES WITH REACTANTS 4 ) APPLICABILITY OF DISTILLATION 5 ) SEQUENCING OF SIMPLE COLUMNS 6 ) COMPLEX COLUMNS

16. A B C Design 1 : Direct Sequence

17. A C B Design 2 : Indirect Sequence

18. A B C Design 3 : Side-stream rectifier

19. A B C Design 4 : Side-stream Stripper

20. A A , B B B , C C Design 5 Prefractionator arrangement

21. A A B B C C Design 6Design 7 side stream