Indian Institute of Petroleum (Council of Scientific & Industrial Research ) Dehradun

1. INNOVATIVE EXTRACTION PROCESSES FOR CHALLENGING FEED-STOCKS Indian Institute of Petroleum (Council of Scientific & Industrial Research )Dehradun SYMPOSIUM ON SOLVENT EXTRACTION REVISITED FEBRUARY 5TH – 6th , 2010 IIChE (NRC) Auditorium NEW DELHI-INDIA

2. Aromatic Extraction • Extraction Step Removal of Aromatics Recovery of Aromatics Capacity Selectivity Pure BTX Production FGH/SK/ATF/LOBS Production Innovations Required • Solvent Recovery Step : Distillation • Limitations of conventional scheme • Overlapping of boiling point of feed-stock • & solvent • High level of impurities in feed stock

3. Examples • De-aromatization of Middle distillate by using re-extraction • Pure BTX from Straight Run Naphtha

4. Middle Distillate De-aromatization • Trend towards increasing use of hydroprocessing • Not attractive for small refineries as requires high capital & operating expense • Loss of valuable aromatics • Search for alternative to hydrotreatment • Solvent extraction already established for naphtha fraction and Lube fraction • Extended to Middle Distillates

5. Kerosene De-aromatization using Sulfolane Based Extraction Sulfolane Technology developed jointly with EIL and HPCL Demo was given to IOCL on ATF pilot plant at HPCL, mumbai Process Package along with EIL was submitted to IOC Digboi

6. Limitations of Sulpholane Based Extraction Technology Utilities required were high due to use of distillation step for the solvent recovery Further work was initiated at IIP to improve the solvent recovery process • RE-EXTRACTION • A novel approach for solvent recovery

7. Re-extraction Technology Replacement of energy intensive distillation step by using reverse extraction High capacity solvent like NMP can be used in spite of boiling point overlap with feedstock – No distillation Re-Extraction Solvent Low Boiling Hydrocarbon Stream– Low energy required for separation from aromatics

8. Capacity And Selectivity Of Solvents For NMP Water Blend NMP + Water Water NMP

9. Like DissolvesLike Aromatics in Feed LPS + Aromatics Saturate in feed Extraction solvent Re-Extraction Solvent Re-extractor Extract Phase LPS Lean Solvent

10. FLOW SHEET WITH RE-EXTRACTION AROMATIC EXTRACT TOP PHASE LEAN SOLVENT WATER RE-EXT COL. EXTN. COL. SEC. SOLV. REC. EXT- WASH COL. FEED WATER + NMP EXT PHASE SEC-SOLVENT FURNACE FUEL DEAROM. RAFFINATE RE-EXT COL BOTTOM WATER SOLV REC COL. WATER RAFF WASH COL. LEAN SOLVENT RAFFINATE PHASE WATER + NMP

11. De-aromatization of Heavy Naphtha, Kerosene and Gas Oil KTU REVAMP at IOC GUWAHATI

12. Feed-stocks for De-aromatization 194.0

13. VALUE ADDITION

14. Challenges with Given feed-stocks Three different feed-stocks of different boiling range Conventional scheme with single solvent not feasible – Boiling point overlap Re-extraction with NMP using blocked out mode operation is an alternative

15. De-aromatization in block out mode Solvent EXTRACTION UNIT Heavy Naphtha De-aromatized Heavy Naphtha De-aromatized Kero-fractiom Kero De-aromatized Gas Oil Gas Oil

16. Experimental studies • Detailed experimental studies have been carried out with feedstock provided by Guwahati Refinery • Feed stocks analysis • Single stage LLE data • - Extraction • - Re-extraction • Continuous column studies for extraction and re-extraction steps • Total number of data point generated = 175

17. Typical Experimental Results Raffinate and extract produced met the desired specifications

18. Simulation And Modeling • Feed Characterization (Model Hydrocarbons) GC & GC MS Hydrocarbon type analysis • Prediction of LLE Based on UNIFAC • Development and Simulation of Process Flow sheet Using ASPEN PLUS • Optimization of Heat Integration and Operating Parameters to Minimize Utility Requirements

19. Hydrocarbon Rep. Model Structural Mol. B.P. Type Hydrocarbons Formula Formula oC CH3(CH2)4CH3 C16H34 287 C20H40 351 C12H22 239 C14H22 264 C16H14 306 C13H14 274 C14H14 274 C13H10 297 C15H30 C2H5 Model Hydrocarbons Representing Gas Oil C8H17 Paraffins n-Hexadecane Non Condensed n-Pentadecyl Cycloparaffins Cyclopentane Condensed Bicyclohexyl Cycloparaffins Alkyl Benzenes n-Octyl Benzene Indanes & 1-n-Hexyl 1,2,3,4 Tetralins Tetrahydro Naphthalene Diaromatics 1-n-Propyl Naphthalene Bi-phenyls 1,1-Diphenylethane Fluorenes Fluorene C6H13 C3H7 C2H5

20. Experimental And Simulated Aromatics Concentration On Solvent Free Basis

21. Summary: De-aromatization of Middle Distillate • Re-extraction Technology is available for de-aromatization of petroleum fractions of different boiling ranges • Process package for similar application is already completed

22. Pure BTX from Straight Run Naphtha

23. Background • Huntsman Petrochemicals Ltd., approached IIP for revamp of their NMP unit • Revamp involved changing the feed from Reformate to Straight Run Naphtha to produce pure BTX and de-aromatized Naphtha as cracker feed • To increase feed-product differential costs • To increase the Naphtha cracker capacity and performance

24. Improvement in Naphtha Cracker Performance Conventional Naphtha Cracking Dearomatized Naphtha Cracking C2/C3 Olefins Paraffinic Naphtha ~10% aromatics CRACKER C2/C3 Olefins Cracker Paraffinic Naphtha ~10% aromatics ARU Pure B T & X • ~10% capacity addition can be obtained in the Cracker • Off spec cracker naphtha feeds can be used • Improvement in economic due to production of pure BTX

25. Possible Feed-stocks for BTX production Conventional Challenging

26. Challenges to produce pure BTX from SR Naphtha • Technologies for production of pure BTX from high aromatics feed stocks already established • Conventional feed stocks are rich in aromatics and low in naphthenes • Proposed feed stock : Naphtha • Aromatics content low (~10 wt.%) • Ratio of aromatic to naphthenes less than 1 (Higher Naphthenes) Difficult to produce pure aromatics without innovations

27. SIMPLIFIED PROCESS FLOW SHEET FOR THE PRODUCTION OF PURE AROMATICS SOLVENT RECOVERY RAFFINATE WASH STRIPPER EXTRACTOR RAFFINATE EXTRACT BENZENE FEED SOLVENT REGENERATOR

28. Effect of carbon number and HC type on separation with solvent Relative solubility Relative volatility Separation of naphthlenes is comparatively difficult by distillation Stripper is limiting

29. Innovations for Removal of Naphthenes

30. Extract Purity Improvement For achieving targeted purities of aromatics various combinations of the operating variables were tried: • Different S/F in the extractor • Use of different backwash streams along with existing backwash stream • Use of water as antisolvent • Use of secondary solvent

31. Continuous column extraction runs with straight run naphtha at 40 °C • Back wash : Benzene Rich C6 cut • S/F : 3.0 w/w • Feed : S R Naphtha with 10% aromatics • Solvent : NMP with water

32. Processing of Straight Run Naphtha Composition, wt.% P-65.83 N-31.60 A-2.57 Raffinate Water P-63.4 N-25.7 A-10.9 Solvent Naphtha EXTRACTOR BW + recycle P-16.5 N-2.2 A-81.3 Pentane Extract

33. Simulation And Modeling Of BTX Unit • Required modified interaction parameters for naphthenes and solvent • Large Number of LLE data with naphthenes ( Model HC) and solvent were generated which were not required for conventional system, for simulation studies • Simulation of Process Flow sheet Using ASPEN PLUS

34. Plant simulation Diagram Closed loops Simulation: Results gives us the confidence that data are correct and well fitted for real plant operation

35. BTX Quality Achieved • Solvent contamination : 1ppm • Non-aromatic content (based on normal boiling point) • bp<110 °C : 700 ppm wt/wt in benzene fraction • 110 °C<bp<136 °C : 2000 ppm wt/wt in toluene fraction • 136 °C<bp<138 °C : 3000 ppm wt/wt • in ethyl benzene fraction • 145 °C<bp : 5000 ppm wt/wt in remaining fraction

36. Process Economics • The concept & economics of integrating Cracker with Straight Run Naphtha dearomatization was published in April 2007 issue of Hydrocarbon processing much after our work • The author studied two types of off spec. Naphtha for integrating dearomatization and cracking on a cracker • The payout period was found to be ~0.8 year

37. IIP Technology for pure BTX from S R Naphtha Outcome Technology successfully developed and demonstrated on lab scale Plan for retrofitting the above in the existing unit was also provided to the client in UK

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