1. OPTIMISATION OF ETHYLENE CRACKER HEMENDRA KHAKHAR

2. PROJECT SUMMARY REQUIREMENT OF SIMULATOR: PREDICTION OF CONVERSION AND YIELD OF PRODUCTS WITH CHANGE IN OPERATING CONDITIONS SUNDARAM AND FROMENT MODEL: MOLECULAR REACTION SCHEME ( 8 REACTIONS ) CONCERNS OF OPTIMISATION: DOWNSTREAM PLANT CAPACITIES PLANT FEED CAPACITY PRICE OF CRUDE OIL CYCLIC FLUCTUATION IN PETROCHEMICAL PRICES AVAILABLE REACTOR TIME

3. INTRODUCTION FEED STOCKS FOR THERMAL CRACKING: ETHANE, PROPANE, LPG, NAPHTHA,GAS OIL, CRUDE OIL, ETC. MAIN PRODUCTS: ETHYLENE, PROPYLENE BY PRODUCTS: BUTENE, HYDROGEN, GAS OIL, FUEL OIL OPERATING VARIABLEAS: TEMPERATURE PARTIAL PRESSURE OF H/C RESIDENCE TIME

4. ETHANE CRACKING FURNACE

5. PROBLEM DESCRIPTION FEED: ETHANE/PROPANE/LPG CAPACITY : 200000 lb/hr. MAIN PRODUCTS : ETHYLENE: 100000 lb/hr. PROPYLENE:20000 lb/hr. DOWNSTREAM PLANTS: ETHYLENE GLYCOL POLYVINYL CHLORIDE HIGH DENSITY POLYETHYLENE POLYPROPYLENE

6. ISSUES FOR OPTIMISATION LARGE NO. OF FEED & PRODUCT STREAMS NECESSITATING CAREFUL CHOICE OF FEEDS AND CONDITIONS INCREASING FLEXIBILITIES OF THE REACTORS CLAIMED BOTH FOR FEEDSTOCK UTILISATION AND EFFLUENT DISTRIBUTION RECYCLING STREAMS RUNLENGTH OF REACTORS RELIABLE PREDICTION OF EFFLUENT DISTRIBUTION REVAMPING OF UNITS

7. OPTIMISATION MODEL THREE WAYS FOR SCALING UP : DIRECT EXPERIMENTAL SIMULATION EQUIVALENT TIME AS A DESIGN PARAMETER MATHEMATICAL MODELLING AVAILABLE MODELS: EMPIRICAL MODEL MOLECULAR ( STOICHIOMETRIC ) MODEL MECHANISTIC MODEL

8. ADOPTED MODEL DIFFICULTIES ENCOUNTERED; 1. STIFFNESS OF DIFFERENTIAL EQUATIONS 2. UNKNOWN INITIAL VALUES OF DEQ STOICHIOMETRIC MODEL: SUNDARAM & FROMENT MOLECULAR MODEL MATERIAL BALANCE: dF i /dz = -  (S i r i ) * d t 2 /4 ENERGY BALANCE: dT/dz = 1/  F i cp i { Q(Z)* d t + d t 2 /4*r i *(-  Hi)

9. REACTION SCHEME

11. FORMULATION OF OBJECTIVE FUNCTION OBJECTIVE FUNCTION, PROFIT, f = PRODUCT COST - FEED COST - ENERGY COST INEQUALITY CONSTRAINTS: CRACKER CAPACITY : 200000 lb/hr. ETHYLENE PROCESSING CAPACITY : 100000 lb/hr. PROPYLENE PROCESSING CAPACITY : 20000 lb/hr. EQUALITY CONSTRAINTS: ETHANE RECYCLE BALANCE PROPANE RECYLCE BALANCE ENERGY BALANCE

12. RESULTS OF ACTUAL RUN

13. SENSITIVITY ANALYSIS:RUN IV

14. SENSITIVITY ANALYSIS:RUN II

15. SENSITIVITY ANALYSIS:RUN III

16. SUGGESTION FOR FUTURE WORK RADICAL REACTION MODEL: ETHANE CRACKING: 49 REACTIONS,11 MOLECULAR SPECIES, 9 RADICAL SPECIES PROPANE CRACKING: 80 REACTIONS,11 MOLECULAR SPECIES, 11 RADICAL SPECIES DEVELOPMENT OF GEAR ALGORITHM TO SOLVE STIFF DEQ REGOROUS ENERGY BALANCE(BOTH COMBUSTION AND PROCESS SIDE ) AND MOMENTUM BALANCE REQUIRES COMPUTATIONAL FLUID DYNAMICS