Recovery of Dilute Organics Using Liquid-Liquid Extraction Dr. Robert C. Schucker Bart Carpenter Clostridium 11 October 6, 2010 Engineering Architecture Design-Build Surveying GeoSpatial Solutions
Merrick s Experience Bioprocessing Biofuels / Biochemicals MillerCoors ethanol recovery plant NREL Integrated Biorefinery Research Facility Range Fuels thermochemical cellulosic ethanol facility Solix Biofuels Coyote Gulch demonstration facility OPXBio commercial-scale bioacrylic acid plant Cobalt Technologies biobutanol pilot plant Enertech biosolids-to-fuel plant assessment Valero Renewable Energy ethanol pant process safety Slide 2
Biofuels Background EISA 2007 mandated 36 BGPY Renewable Fuel Standard (2022) 21 BGPY of that from non-corn (i.e. sugar or cellulosic feeds) 100 MGPY target for 2010 Biobutanol not currently produced commercially in the U.S. Butamax Advanced Biofuels LLC Commercial Target - 2012 Gevo 2011 (retrofit corn plant) Difficult to meet the EISA 2007 mandate Mandated Supply (Billions of Gallons) 40 35 30 25 20 15 10 Cellulosic Biofuels Other Non - Corn Biofuels Conventional Corn - Based Biofuels 5 2008 2010 2012 2014 2016 2018 2020 2022 YEAR Slide 3
Challenges in Biobutanol Production ABE Fermentation produces dilute mixtures of organics in water (max of ~ 26 g/l) Acetone: Butanol: Ethanol: 8 g/l 16 g/l 2 g/l All products have value (need to recover) Recovery by traditional distillation consumes significant amounts of energy Need to heat significant quantities of water Two azeotropes (water/ethanol and water/butanol) Slide 4
Cases Studies Case 1: Conventional Distillation Case 2: Liquid-Liquid Extraction Assumptions Only n-butanol in feed at 1.56 wt% Butanol plant capacity ~ 20 MM GPY Feed temperature = 35 C (95 F) Feed pressure = 15 psig Biomass has been removed All simulations done using DESIGN II (WinSim) Slide 5
Case 1: Conventional Distillation FEED D-1 2 M 4 5 PS Stream Flow Rate Butanol Water (lb/hr) (wt %) (wt%) Feed 1,055,688 1.56% 98.44% 2 29,924 54.80% 44.09% 3 1,025,754 0.01% 99.99% 8 13,434 0.00% 100.00% 9 16,490 99.42% 0.58% 3 6 7 D-2 D-3 Unit BTU/hr D-1 78,748,070 D-2 4,397,140 D-3 7,173,332 Total 90,318,542 8 9 Slide 6
Liquid-Liquid Extraction A Viable Option Solvent immiscible with feed contacted in such a way as to efficiently transfer solute from the feed phase to the solvent Emulsion Choice of solvent critical Minimize emulsions Minimum solvent dissolution into feed (eliminate raffinate still) Minimum water dissolution (for aqueous feeds) into extraction solvent (easier downstream separation) No Emulsion Slide 7
Hansen 3-D Solubility Parameters* Solubility Parameter: Measure of molecular cohesive energy density d t 2 = d d 2 + d h 2 + d p 2 Where: d t = total solubility parameter (MPa) 1/2 d d = contribution of dispersion forces (MPa) 1/2 d h = contribution of hydrogen bonding forces (MPa) 1/2 d p = contribution of polar forces (MPa) 1/2 Original theory described a sphere Like dissolves like However, effects of dispersion forces are less important Therefore, result is projection onto two dimensional plane with x axis (d h ) and y axis (d p ) *Expansion of Hildebrand Solubility Parameter (1936) Slide 8
Hansen Plot for ABE Products d p (MPa) 1/2 Slide 9 18 16 14 12 10 8 6 4 2 0 acetone ethanol n-butanol 0 10 20 30 40 50 d h (MPa) 1/2 water water ethanol 3-butoxybutano butoxyethoxypr 2-butyl octanol cyclohexanol 2-decanol acetic acid acetone oleic acid castor oil glycerine ethylene glycol dibenzyl ether n-butanol tetralin methyl oleate silicone oil DC 1-octene toluene p-xylene Methanol Dimethyl carbon N-Pentane
Fast Equilibration is Important Slide 10 Concentration of Ethanol in Extract (wt %) 0.012 0.010 0.008 0.006 0.004 0.002 0.000 Approach to Equilibrium for Extraction of Ethanol with 33% Dodecanol in Isopar E 0 1 2 3 4 5 6 Time (min)
Distribution Curves for n-butanol Extract Composition (gm ethanol/gm solvent) 0.014 0.012 0.010 40 C 22 C 1.150 0.720 0.008 0.006 0.004 0.002 Preferred Solvent 0.000 0.000 0.002 0.004 0.006 0.008 0.010 0.012 0.014 0.016 Raffinate Composition (gm ethanol/gm water) Slide 11
Case 2: Liquid-Liquid Extraction Process 9 4 S-2 6 S-4 10 11 Unit BTU/hr E-1 9,428,617 S-2 900,916 S-4 5,632,855 Total 15,962,388 FEED 1 2 SOLVENT 3 E-1 5 7 8 Stream Flow Rate Solvent Butanol Water (lb/hr) (wt%) (wt %) (wt%) Feed 1,055,688 0.00% 1.56% 98.44% 3 1,219,628 100.00% 0.00% 0.00% 4 1,236,615 98.61% 1.32% 0.07% 5 1,038,701 0.02% 0.01% 99.97% 6 1,235,892 98.67% 1.33% 0.00% 8 835 0.00% 0.00% 100.00% 9 1,219,403 100.00% 0.00% 0.00% 11 16,377 0.00% 100.00% 0.00% Slide 12
Choice of LLE Contactor is Critical Oldshue-Rushton Column Karr Column York Scheibel Column Podbielniak Extractor Plot from: Glatz, D. and W. Parker; Enriching Liquid-Liquid Extraction, Chemical Engineering, November 2004, 44-48. Slide 13
Case Comparisons Conventional Distillation Number Material Energy Estimated Vessel Req'd Diameter Height of Consumed Capital Cost (ft) (ft) Construction (BTU/hr) ($) Stripping Column 1 13 31 Stainless steel 78,748,070 Water Column 1 2 61 Stainless steel 4,397,140 Butanol Column 1 5 61 Stainless steel 7,173,332 Total Energy Consumed (BTU/hr) or Cost ($) 90,318,542 3,330,000 Liquid-Liquid Extraction LLE (Packed) 2 9 47 Carbon steel 9,428,617 Dehydration 2 4 35 Carbon steel 900,916 Butanol Recovery 2 12 60 Carbon Steel 5,632,855 Total Energy Consumed (BTU/hr) or Cost ($) 15,962,388 Reduction in Energy Consumption and Capital Cost vs Distillation 82% 2,330,000 30% Capital cost estimated at equipment x 3.5; does not include impact on balance of plant Slide 14
LLE Advantages Operating Cost Conventional Distillation consumes 90 MMBTU/hr versus only 16 MMBTU/hr for LLE system Reduces operating cost by $2.9 MM per year based on $4.00/MMBTU for natural gas, 95% stream factor and 85% boiler efficiency Capital Cost Conventional Distillation system estimated to cost $3.33 MM versus $2.33MM for LLE system LLE equipment can be carbon steel LLE option will also dramatically reduce the size of the boiler Total benefit (NPV @ 8%) = $35.8MM = 3 cpg biobutanol advantage Slide 15
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