BioSep™: A New Ethanol Recovery Technology for Small Scale Rural Production of Ethanol from Biomass Yu (Ivy) Huang, Ph.D. Membrane Technology & Research, Inc. 1360 Willow Road, Suite 103 Menlo Park, California
& Leland M. Vane, Ph.D. Office of Research and Development U.S. Environmental Protection Agency Cincinnati, Ohio
AICHE San Francisco, California November 2006 1
Ethanol production is growing globally Brazil
> 50% sugar cane crop
40% non-diesel fuel
USA
currently, 15% corn crop 2% non-diesel fuel > 1/3 oil displacement by 2025
EU
6% biofuel by 2010 20 - 30% replacement of oil by 2030
China
Launched a program to use ethanol as a fuel
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How much ethanol can we produce? Current: ¾Oil consumption: 873 MM gal/day, 58% import ¾Ethanol production: 12 MM gal/day
Forecast for 2025: ¾Oil consumption from import: 870 MM gal/day ¾The President’s goal: replace 75% import from Mideast − 100 MM gal/day 40,000 35,000 30,000 Total annual ethanol production (MM gal/y)
25,000 20,000 15,000 10,000 5,000 0 1970
1980
1990
2000
2010
2020
2030
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Conventional Bioethanol Process
MOL SIEVE
Ethanol
Biomaterial FERMENTATION
DISTILLATION COLUMN
Water
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Ethanol from Biomass Two competing driving forces: ¾ Ethanol concentration/purification by distillation/molecular sieve is only economical at > 40-50 MM gal/year Æ driver for central production ¾ Transport of biomass over long distances is costly and energy inefficient Æ driver for distributed production in rural areas (with added benefits for rural economies) Can this problem be solved? The solution is membranes (of course). 5
MTR BioSep Process MOL SIEVE
Biomass
Ethanol
DISTILLATION
FERMENTATION
Water Water PERVAPORATION (dehydration)
Ethanol
FERMENTATION PERVAPORATION (ethanol concentration)
DEPHLEGMATION
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Applications of BioSep Process ¾ Small biomass waste streams generated in the production of -- beer, wine, and juice -- cane and beet sugar -- potatoes, yams, and other root crops -- cheese, soft drinks, confectionery and packaged foods
¾ Replace molecular sieve in conventional corn to ethanol plant
¾ Replace distillation in conventional corn to ethanol plant
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What is pervaporation? Pervaporation = Permeation + Evaporation To vacuum system permeate
βmem βevap feed
Separation factor
Saturated vapor Liquid feed
β = β evap ⋅ β mem
residue
y1 /(1 − y1 ) = x1 /(1 − x1 )
Not limited by thermodynamic vapor-liquid equilibrium (VLE) 8
Pervaporation Applications
¾ Dehydration of organic solvents
Primarily dehydration of ethanol and iso-propanol First commercial plant in the world was put into operation in Brazil in 1984. Commercial application of inorganic membranes Needs improvements to be competitive with molecular sieves in large scale applications
¾ Removal and recovery of organic solvents from water
Commercially successful applications are hard to find 9
Pervaporation using Ethanol-Permeable and Water-Permeable Membranes Ethanol removal from 5-10 wt% ethanol/water mixture
Water removal from 90 wt% ethanol/water mixture
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Fractional condensation (dephlegmation) improves separation
Vapor enters at the bottom Vapor is partially condensed at the top Condensate trickles down, creates a counter-current effect Achieves 4 to 6 theoretical stages of separation
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Significant increase in separation performance ….
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MTR BioSep Process 2
0.5 wt% ethanol to recycle or waste 4
Ethanolpermeable pervaporation membrane
1 Filtered biomass feed (10 wt% ethanol)
90 - 95 wt% ethanol
30-40 wt% 3 ethanol vapor
7
Waterpermeable pervaporation membrane 6
99+ wt% ethanol
Dephlegmator 20 wt% 5 ethanol vapor
5 wt% ethanol recycle
Pervaporation-dephlegmation
Dehydration
13
Ethanol Permeable Membranes 5 MM gal/year plant, feed ethanol concentration = 10wt% 30
15
25
20
10
Energy consumption for distillation
Total membrane area
15
2
(Thousand m ) 5
Total energy consumption (million Btu/hr)
10
5
0
0
10
20
30
40
50
0
EtOH/H O separation factor, β 2
Solution: zeolite mixed-matrix membrane 14
Mixed-matrix Membranes
Effects of zeolite loadings 5
30
4 20 3
Ethanol/water separation factor, β
Ethanol/water selectivity, β 2
mem
10 1
0
0
20
40
60
80
0 100
Zeolite loading (wt%)
15
Ethanol Dehydration Membranes
100
MTR-2 Celfa
80
60
Permeate water concentration (wt%)
40
MTR-2 20 o
Temperature = 100 C 0
0
20
40
60
80
100
Feed water concentration (wt%)
16
Package membranes into spiral-wound modules
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Conclusions • Pervaporation offers alternative to distillation for ethanol recovery Higher selectivity membranes will yield energy savings Membranes scale down better than distillation • Pervaporation offers alternative to molecular sieves for water removal Chemical and thermal stable membranes developed Systems commercially available • Synergies achievable through use of pervaporation for both ethanol recovery and dehydration Combined with dephlegmation condensation
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Acknowledgments
• • • •
U.S. Department of Energy U.S. Department of Agriculture Jennifer Ly, Tiem Aldajani, Karl Amo of MTR Vasudevan Namboodiri, Travis Bowen of EPA
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Questions?
2020 Liquid Separation Group
MTR Confidential