BioSep : A New Ethanol Recovery Technology for Small Scale Rural Production of Ethanol from Biomass

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Elfreda Tate
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1 BioSep : A New Ethanol Recovery Technology for Small Scale Rural Production of Ethanol from Biomass Yu (Ivy) Huang, Ph.D. Membrane Technology & Research, Inc 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

2 Ethanol production is growing globally Brazil USA > 50% sugar cane crop 40% non-diesel fuel currently, 15% corn crop 2% non-diesel fuel > 1/3 oil displacement by 2025 EU 6% biofuel by % replacement of oil by 2030 China Launched a program to use ethanol as a fuel 2

3 How much ethanol can we produce? Current: Oil consumption: 873 MM gal/day, 58% import Ethanol production: 12 MM gal/day Forecast for 2025: Oil consumption from import: 870 MM gal/day The 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,

4 Conventional Bioethanol Process MOL SIEVE Ethanol Biomaterial FERMENTATION DISTILLATION COLUMN Water 4

5 Ethanol from Biomass Two competing driving forces: Ethanol concentration/purification by distillation/molecular sieve is only economical at > MM gal/year driver for central production Transport of biomass over long distances is costly and energy inefficient 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

6 MTR BioSep Process Biomass MOL SIEVE Ethanol FERMENTATION DISTILLATION Water FERMENTATION Water PERVAPORATION (dehydration) Ethanol PERVAPORATION (ethanol concentration) DEPHLEGMATION 6

7 Applications of BioSep Process 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 Replace molecular sieve in conventional corn to ethanol plant Replace distillation in conventional corn to ethanol plant 7

8 What is pervaporation? Pervaporation = Permeation + Evaporation To vacuum system permeate β mem β evap Saturated vapor feed Separation factor Liquid feed β = β β evap mem = residue y x 1 1 /(1 /(1 y x 1 1 ) ) Not limited by thermodynamic vapor-liquid equilibrium (VLE) 8

9 Pervaporation Applications Dehydration of organic solvents Primarily dehydration of ethanol and iso-propanol First commercial plant in the world was put into operation in Brazil in Commercial application of inorganic membranes Needs improvements to be competitive with molecular sieves in large scale applications Removal and recovery of organic solvents from water Commercially successful applications are hard to find 9

10 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 10

11 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 11

12 Significant increase in separation performance. 12

13 MTR BioSep Process wt% ethanol to recycle or waste 1 Filtered biomass feed (10 wt% ethanol) Ethanolpermeable pervaporation membrane wt% ethanol Waterpermeable pervaporation membrane wt% ethanol wt% ethanol vapor Dephlegmator 5 20 wt% ethanol vapor 7 5 wt% ethanol recycle Pervaporation-dephlegmation Dehydration 13

14 Ethanol Permeable Membranes 5 MM gal/year plant, feed ethanol concentration = 10wt% Total membrane area (Thousand m 2 ) Energy consumption for distillation 15 Total energy consumption (million Btu/hr) EtOH/H 2 O separation factor, β Solution: zeolite mixed-matrix membrane 14

Mixed-matrix Membranes Effects of zeolite loadings 30 5 4 Ethanol/water separation factor,

15 Mixed-matrix Membranes Effects of zeolite loadings Ethanol/water separation factor, β Ethanol/water selectivity, β mem Zeolite loading (wt%) 15

16 Ethanol Dehydration Membranes Celfa MTR-2 60 Permeate water concentration (wt%) 40 MTR-2 20 Temperature = 100 o C Feed water concentration (wt%) 16

17 Package membranes into spiral-wound modules 17

18 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 18

19 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 19

20 Questions? Liquid Separation Group MTR Confidential

Abstract Process Economics Program Report 190C ADVANCES IN MEMBRANE TECHNOLOGY FOR CHEMICAL SEPARATION APPLICATIONS (June 2001)

Abstract Process Economics Program Report 190C ADVANCES IN MEMBRANE TECHNOLOGY FOR CHEMICAL SEPARATION APPLICATIONS (June 2001) Membrane separation process technology has an enormous variety of applications.