Thermodynamics, Design, Simulation and Benchmarking of Biofuel Processes Mauro Torli Philip Loldrup Fosbøl Georgios Kontogeorgis
SYNFERON project work packages Commercial syngas fermentation technologies: Coskata: 2006 Using technology licensed by Oklahoma State University and University of Oklahoma INEOS Bio: (1990) J.L. Gaddy Bioengineering Resources Inc, 2008 INEOS technology acquisition LanzaTech: 2005 S. Simpson New Zealand 2 DTU Kemiteknik, Danmarks Tekniske Universitet
Syngas fermentation to liquid biofuels James L. Gaddy. US patent: 6,136,577. Filed Jul. 1, 1996 Syngas composition Vol% on anhydrous 5 basis H 2 20-45 CO 20-45 CO 2 11-18 CH 4 0-15 N 2 0.5-10 3 DTU Kemiteknik, Danmarks Tekniske Universitet
Patent screening US patent 2009/0215153 2015/0031099 A1 4 DTU Kemiteknik, Danmarks Tekniske Universitet
Syngas fermentation Doesn t require a fixed H 2 :CO ratio Ethanol 6CCCC + 3HH 2 OO CCCC 3 CCCC 2 OOOO + 4CCCC 2 2CCCC 2 + 6HH 2 CCCC 3 CCCC 2 OOOO + 3HH 2 OO rr GG 0 = 224 kkkk/mmmmmm rr GG 0 = 104 kkkk mmmmmm Acetic acid 4CCCC + 2HH 2 OO CCCC 3 CCCCCCCC + 2CCCC 2 2CCCC 2 + 4HH 2 CCCC 3 CCCCCCCC + 2HH 2 OO rr GG 0 = 175 kkkk/mmmmmm rr GG 0 = 95 kkkk mmmmmm 5 DTU Kemiteknik, Danmarks Tekniske Universitet
Wood-Ljungdahl Pathway Main fermentation products 6 DTU Kemiteknik, Danmarks Tekniske Universitet
UNIQUAC Highly non-ideal and strongly associated mixtures and moderate pressures γγ φφ approach Binary mixtures Water Ethanol Acetic acid ln γγ ii (TT, nn) = ln γγ ii CC (nn) + ln γγ ii RR (TT, nn) Ethanol X UU iiii TT = AA iiii TT + BB iiii + CC iiii TT lllltt + Acetic Acid X X DD iiii TT 2 Butanol X X X 7 DTU Kemiteknik, Danmarks Tekniske Universitet
Hayden-O Connell method for Virial coefficient Association and dimerization of acetic acid molecules in the vapor phase BB tttttttttt iiii = BB ffffffff iiii + BB mmmmmmmmmmmmmmmmmmmm iiii + BB bbbbbbbbbb ccccccc iiii + BB iiii Van der Waals forces Interactions contribution deriving from charge-transfer complexing such as hydrogen bonding Chemical interactions contribution deriving from the molecular associations When a compound with strong association is present, the entire mixture is treated according to the chemical theory of dimerization BB iiii ffffffff = BB iiii nnnnnnnnnnnnnnnn + BB iiii pppppppppp BB iiii mmmmmmmmmmmmmmmmmmmm + BB iiii bbbbbbbbbb ccccccc BB iiii BB mmmmmmmmmmmmmmmmmmmm iiii + BB bbbbbbbbbb iiii + BB ccccccc iiii = KK iiii RRRR KK iiii equilibrium constant for dimerization reaction 8 DTU Kemiteknik, Danmarks Tekniske Universitet
Water-Acetic acid Ethanol-Acetic acid O'Connel method "Redlich Kwong" 160 120 150 140 2.7 bar 110 Temperature, C 130 120 110 1.0 bar Temperature, C 100 90 1.0 bar 80 100 0.5 bar 90 0.5 bar 70 80 0 0.2 0.4 0.6 0.8 1 Acetic acid molefrac 60 0 0.2 0.4 0.6 0.8 1 Acetic acid molefrac 9 DTU Kemiteknik, Danmarks Tekniske Universitet
Water-Butanol VLE Newly regressed binary parameters: solid lines 210 190 170 10 bar Temperature, C 150 130 5.0 bar 110 2.0 bar 90 1.0 bar 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Butanol molefrac 10 DTU Kemiteknik, Danmarks Tekniske Universitet
Water-Butanol LLE Newly regressed binary parameters: solid lines 105 95 85 Temperature, C 75 65 55 45 35 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Butanol mole fraction 11 DTU Kemiteknik, Danmarks Tekniske Universitet
Single regression over the two pieces of line ΔU ij (T)=A ij T+B ij +C ij Tln(T)+D ij T 2 Solid Curves 10 bar 5.0 bar 2.0 bar 1.0 bar 12 DTU Kemiteknik, Danmarks Tekniske Universitet
Prediction of Quaternary System Ethanol-Acetic acid-ethyl Acetate-Water VLE Ethanol-Acetic acid is a reactive system. Phase equilibrium overlaps chemical equilibrium 115 110 105 CCCC 3 CCCC 2 OOOO + CCHH 3 CCCCCCCC CCCC 3 CCOOOOCCCC 2 CCCC 3 + HH 2 OO KK eeee = aa CCCC3CCOOOOCCCC2CCCC3 aa CCCC 3CCCC2OOOO aa HH2OO aa CCHH 3CCCCCCCC Calculated temperature, C 100 95 90 85 80 boiling_points dew_points RMSD=1.58 C 75 70 70 75 80 85 90 95 100 105 110 115 Experimental temperature, C 13 DTU Kemiteknik, Danmarks Tekniske Universitet
Substrate solubility Syngas fermentation processes are known to be greatly limited by gas-liquid diffusion Knowing the Henry constants is fundamental to estimate the dissolved concentration in the fermentation broth It is required for any rate base model for the fermenter 14 DTU Kemiteknik, Danmarks Tekniske Universitet
Supercritical Components The ionic strengths in the fermentation broth is assumed so small to not affect gas solubility ln HH ii TT, PP, nn kk =ln HH ii TT, PP ssssss ssssss, nn kk + 1 RRRR PP PP ssssss ssssss vv ii TT, PP, nn kk dddd ln HH ii TT, PP ssssss ssssss, nn kk =AA ii,nnkk + BB ii,nn kk + CC TT ii,nn kk ln TT + DD ii,nnkk TT ff iill TT, PP, nn =xx ii γγ ii (TT, PP, nn)hh ii TT, PP, nn kk Parametrization was carried out using the minimum number of coefficients for the temperature dependence at witch the model satisfactory explain the measured solubility. Two parameters were adequate for most systems; CO-Water and H 2 required three Water Ethanol Acetic Acid Butanol CO2 CO H2 CH4 X X X X X X X X X X X X X X X X 15 DTU Kemiteknik, Danmarks Tekniske Universitet
Ethanol-Hydrogen solubility data points Aspen Plus default Henry constant * and regressed ones 0.07 0.06 18 C REGRESSION 1 Estimated H2 x molefrac 0.05 0.04 0.03 0.02 26-100 C REGRESSION 1 120-200 C REGRESSION 1 18 C APV86 HENRY-AP 26-100 C APV86 HENRY-AP 120-200 C APV86 HENRY-AP [A i, B i, C i, D i ] 0.01 0 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 Experimental H2 x molefrac 16 DTU Kemiteknik, Danmarks Tekniske Universitet
Preliminary simulation of the recovery section Some preliminary process simulations to outline the heat requirement for distillation, were recently studied 1. A column with feed preheating using the stream leaving the bottom of the column 2. A column with feed preheating and a vapor compression stage 17 DTU Kemiteknik, Danmarks Tekniske Universitet
Ethanol Distillation: Base Case Feed specification Composition [wt%] Ethanol 1.0-5.0 Acetic acid 0.5 Water 98.5-94.5 Flow [kg/hr] 1000 Temperature fermenter [C] 40 Temperature at the column inlet 90 Pressure [kpa] 120 Column specification Number of trays 42 Feed tray 24 Overall tray efficiency E OG 0.65 Energy consumption, MJ/kg-ethanol 50 45 40 35 30 25 20 15 10 0,99 ethanol recovery 0,98 ethanol recovery 0,96 ethanol recovery 0,93 ethanol recovery Heat of combustion Condenser pressure [kpa] 100 5 Ethanol recovery [%] 93-99 Distillate purity [wt%] 93 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 Ethanol concentration in feed, wt% 18 DTU Kemiteknik, Danmarks Tekniske Universitet
Vapor Compression Vapor compression specification Inlet pressure [kpa] 100 Inlet temperature [C] 78 Outlet pressure [kpa] 350 Outlet temperature [C] 152 Dew temperature [C] 113 Isentropic efficiency 0.72 19 DTU Kemiteknik, Danmarks Tekniske Universitet
Energy Saving Comparison: Electric to heat equivalent 1:3.5 SEAI. Commercial/Industrial Fuels: Comparison of Energy Costs. 2017 50 100 Energy consumption, MJ/kg-ethanol 45 40 35 30 25 20 15 10 0,99 ethanol recovery 0,98 ethanol recovery 0,96 ethanol recovery 0,93 ethanol recovery 0,99 ethanol recovery 0,98 ethanol recovery 0,96 ethanol recovery 0,93 ethanol recovery Vapor compression (reboiler duty+3.5 x compressor power) Vapor compression, energy saving % 90 80 70 60 50 40 30 20 0,99 ethanol recovery 0,98 ethanol recovery 0,96 ethanol recovery 5 10 0,93 ethanol recovery 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 Ethanol concentration in feed, wt% 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 Ethanol concentration in feed, wt% 20 DTU Kemiteknik, Danmarks Tekniske Universitet
Acetic Acid Recycling or Separation Patents deposited by Coskata and INEOS Bio, usually consider the recycle of the bottom product of the ethanol column directly to the fermenter, without any acetic acid removal step LanzaTech patents suggest that the bottom product of the ethanol column is passed on an activated charcoal bed selectively adsorbing acetic acid. Successive elution with ethanol allows the acetic acid recovery 21 DTU Kemiteknik, Danmarks Tekniske Universitet
Water-Butyl Acetate VLLE Newly regressed binary parameters: Solid lines 140 120 100 1.0 bar Temperature, C 80 60 40 0.1 bar 20 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Butyl acetate molefrac 22 DTU Kemiteknik, Danmarks Tekniske Universitet
Conclusions and next steps A thermodynamic consistency study was conducted in order to verify the reliability of UNIQUAC combined with O Connell method for in representing equilibrium condition for the most probable products from syngas fermentation. The prediction capabilities were tested using a quaternary system: Ethanol-Acetic Acid-Ethyl Acetate-Water Gas solubility data for CO 2, CO, H 2 and CH 4 in the different solvents were regressed in order to obtain the Henry constants needed for the process simulation of the reactor, and any other stage that involve degassing of the fermentation media. Salt concentration is sufficiently low that any effect on solubility can be neglected Preliminary process simulations for the distillation section were analyzed from an energetic point of view. Additional layout such as pervaporation will be considered The reliability of the thermodynamic package was verified for binary mixtures with butyl-acetate: simulation of extraction followed by azeotropic distillation for acetic acid recovery is currently ongoing 23 DTU Kemiteknik, Danmarks Tekniske Universitet
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