1. Steam Cracker Furnace Energy Improvements Tim Gandler Energy Coordinator Baytown Olefins Plant, Baytown Tx 2010 Industrial Energy Technology Conference May, 2010

2. Page 2 Baytown Complex Steam Cracking to Olefins Furnace overview & challenges in steam cracking Energy efficiency improvements Overview Baytown Olefins Plant

3. Page 3 Baytown Complex One of world’s largest integrated, most technologically advanced petroleum/petrochemical complexes ~3,400 acres along Houston Ship Channel, ~ 25 mi. east of Houston Includes 4 manufacturing sites, 2 technology/engineering offices Significant community involvement Baytown Refinery

4. Page 4 Steam Cracking to Olefins Process 60+ years old; ExxonMobil one of pioneers Endothermic, non-catalytic process to produce light olefins/diolefins –Ethylene, propylene, butylenes, butadiene Molecules “crack”, large → small –C 2 H 6 → C 2 H 4 +H 2 –C 3 H 8 → C 2 H 4 +CH 4 –C 3 H 8 → C 3 H 6 +H 2 –Many others…… Must heat feed to very high temperature to adequately “crack” –The lighter the feed the higher the temperature Very energy intensive process; furnace fuel accounts for ~60% of plants energy use

5. Page 5 Furnace Overview 1.Convection Section –Preheats and vaporizes the feed by absorbing excess heat –Combines the hydrocarbon with dilution steam 2.Radiant –Cracks the feed into products at short residence times –Contains the burners –1500+ °F 3.Heat Recovery –Arrests the cracking reaction by cooling the effluent –High pressure steam generated

6. Page 6 Challenges in Steam Cracking – Dilution Steam Reduces partial pressure of hydrocarbon, resulting in higher C2= yields Helps keep free radicals from recombining into undesirable compounds, e.g. coke, methane, hydrogen Requires additional firing

7. Page 7 Challenges in Steam Cracking - Coke Formation Coke is a undesirable byproduct of steam cracking formed from complete dehydrogenation of hydrocarbon molecules Thickness of coke layer increases with run length –Reduces heat transfer to process stream After a period of being online furnaces “Decoke” with steam+air due to –High pressure drop –High tube wall temperatures Furnace tube hydrocarbon + steam

8. Page 8 Steam Cracker Furnace Energy Efficiency Overall energy efficiency of furnace depends on –Run length or % of time furnace is online (more decokes lead to lower efficiency) –Amount of dilution steam (more steam leads to lower efficiency) –Furnace design –Furnace condition Very challenging to balance energy efficiency and production down online time Furnace status

9. Page 9 Energy Efficiency Improvement - How did we do it? Multi-disciplinary team identified monitoring, procedural and maintenance improvements –Team met weekly to review performance and create run-plan –Improved procedures resulted in greater attention to details –Maintenance improvements executed as planned Gaps closed over 1-2 year period No capital spending required Review Performance Create Run-plan Execute Run-plan

10. Page 10 BOP Furnace Energy Efficiency Improvements Overall energy efficiency improvement of 2.4% –Significant improvements in run length –Significant improvements in S/HC Energy Savings of 660,000 MBTU/yr or more than 38,000 T/CO 2 per year Site remains dedicated to further improvements in energy efficiency