integrating and piloting lignocellulose biomass conversion … · 2013-09-20 · daniel j. schell...

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Advanced Biofuels Workshop/Fuel Ethanol Workshop

Daniel J. Schell

June 15, 2009

Integrating and Piloting Lignocellulose Biomass Conversion Technology

NREL/PR-510-46125

NREL Process Integration Project Goals

• Investigate bioethanol production technology at the bench and pilot scales using corn stover

• Produce integrated pilot-scale performance data, which when combined with a process design and a cost estimate validates a $1.49 (2007$) per gallon ethanol selling price

National Renewable Energy Laboratory Innovation for Our Energy Future


Key Process Performance Issues

Pretreatment Conditioning

Co-fermentationof C5 & C6Sugars

ProductRecovery Products

By-products

EnzymeProduction

EnzymaticHydrolysis

Residue Processing

HSF

Ethanol YieldsEthanol Concentration

Xylose YieldXylose Degradation

Reactor CostsSolids Loading

Sugar Losses

Glucose Yield

Solids Loading (titer)

Feedstock VariationFeedstock Quality

Enzyme Cost

RateHydrolysate Toxicity

Feedstock Cost

Residual Xylose Yield

Recycle/Waste Streams

Energy RequirementsSeparation EfficienciesImpact on Yields

Process Configurations Investigated


Pretreatment Solid-Liquid Separation

Enzymatic Hydrolysis Fermentation

Conditioning Ethanol

Feed

LiquidAcid

NH4OH or Ca(OH)2

EnzymeWater

30% Total Solids (TS) Loading

Glucose-xylose co-fermenting bacteria, Zymomonas mobilis 8b

15% or 20% Total Solids Loading

Base Case (BC)

Hydrolysis Conditions:• Genencor GC220 at 40

mg protein/g cellulose• 48°C• 4 days

Fermentation Conditions:• Nutrients:10 g/L yeast

extract + 2 g/L KH2PO4• ~1.5 g/L initial cell

density• pH controlled at 5.8

with 2N KOH• 35°C• 3 days

Corn Stover

Process Configurations Investigated


Pretreatment Solid-Liquid Separation

Enzymatic Hydrolysis Fermentation

Conditioning Ethanol

Feed

LiquidAcid

NH4OH or Ca(OH)2

EnzymeWater

30% Total Solids (TS) Loading

Glucose-xylose co-fermenting bacteria, Zymomonas mobilis 8b

15% or 20% Total Solids Loading

Whole Slurry (WS)

Base Case (BC)

Hydrolysis Conditions:• Genencor GC220 at 40

mg protein/g cellulose• 48°C• 4 days

Fermentation Conditions:• Nutrients:10 g/L yeast

extract + 2 g/L KH2PO4• ~1.5 g/L initial cell

density• pH controlled at 5.8

with 2N KOH• 35°C• 3 days

Corn Stover

Pretreatment Conditioning Enzymatic Hydrolysis Fermentation

Ethanol

Feed

Acid

NH4OH or Ca(OH)2

Enzyme

Water

Corn Stover

Conditioning Technologies


Overliming Process (OL)

Ammonium Hydroxide Conditioning (AHC)

Advantages:• Effectively detoxifies dilute acid (DA) hydrolysates• Lime is inexpensiveDisadvantages:• Soluble sugars are lost/degraded• Requires additional filtration step to remove gypsum• Need to dispose of insoluble gypsum• Soluble gypsum remains in solution and can plate

out in downstream equipment

Advantages:• Effectively detoxifies DA hydrolysates• No sugar degradation• Insoluble solids are not producedDisadvantages:• NH4OH is expensive• High ammonia salt concentrations are left

in the treated liquor

Separation

Mixing (30°C, pH 8.5)

Mixing

Pretreated Feedstock

NH4OH

H2SO4

Liquor

Conditioned Liquor

Solids

Separation

Mixing (50°C, pH 10)

Mixing


Ca(OH)2

H2SO4

Liquor

Conditioned Liquor

Solids

Filtration Gypsum

Conditioning Sugar Losses


Best Performance at pH 10

Ammonium Hydroxide Conditioning eliminates sugar losses during conditioning of dilute acid pretreated corn stover hydrolysates

Integrated Performance Results


Pilot scale production of pretreated corn stover

Bench scale conditioning, enzymatic hydrolysis and fermentation

Fermentation Data


0

10

20

30

40

50

60

70

0 24 48 72

Suga

r Con

cent

ratio

n (g

/L)

Time (h)

05

1015202530354045

0 24 48 72

Etha

nol C

once

ntra

tion

(g/L

)

Time (h)

0

10

20

30

40

50

60

70

0 24 48 72

Suga

r Con

cent

ratio

n (g

/L)

Time (h)

05

1015202530354045

0 24 48 72

Etha

nol C

once

ntra

tion

(g/L

)

Time (h)

15% TS, AHC

15% TS, OL

20% TS, AHC

20% TS, OL

LegendBase Case Process

Whole Slurry Process

Solid Lines: Glucose

Dashed Lines: Xylose

Enzymatic Cellulose Hydrolysis


50

60

70

80

90

100

BC 15% AHC

BC 15% OL

BC 20% AHC

BC 20% OL

WS 15% AHC

WS 15% OL

WS 20% AHC

WS 20% OL

Mon

omer

ic G

luco

se Y

ield

(%)

Process Configuration:Total Solids Loading (%):

Conditioning Technology:

Key Results:• Cellulose to monomeric glucose yields improve at lower solids loadings• Yields are independent of conditioning technology• Yields are lower for the whole slurry process

Conversion of Sugars to Ethanol


30

40

50

60

70

80

90

100

BC 15% AHC

BC 15% OL

BC 20% AHC

BC 20% OL

WS 15% AHC

WS 15% OL

WS 20% AHC

WS 20% OL

Xylo

se-t

o-Et

hano

l Yie

ld (%

)



Xylose to Ethanol Yields:• Yields are lower at high solids loadings

• Higher inhibitor concentrations• Higher ethanol concentrations

• Conditioning technology and process configuration have little impact

30

40

50

60

70

80

90

100

BC 15% AHC

BC 15% OL

BC 20% AHC

BC 20% OL

WS 15% AHC

WS 15% OL

WS 20% AHC

WS 20% OL

Ove

rall

Etha

nol Y

ield

(%)



Overall Ethanol Yield:• Base case process configuration outperforms

whole slurry process configuration• Conditioning technology has little impact on

overall conversion yields

*Assumes 90% glucose to ethanol yield

*

Constructing New Pilot Plant Capabilities


• Pilot plant expansion planned for substantial completion by May 2010

• New Equipment: Feedstock milling/handling system, versatile pretreatment systems, high solids enzymatic hydrolysis reactors

• Designed for parallel processing and flexible reconfiguration of unit operations with space for future equipment

Pretreatment


Single Horizontal Screw Reactor

Versatile Pretreatment System• Residence times: minutes to 2 h• Temperatures: 150° to 225°C• Designed for a variety of

pretreatment chemistries

Multi-Tube Reactor SystemFeedstock


Pretreatment Chemicals

High Solids Enzymatic Hydrolysis


High Solids Enzymatic Hydrolysis Reactor• Commercially available batch mixer• No limitations on solids loading• Thoroughly mixes• Chemicals and enzyme added via a distributed

spray system

Integrated Pilot Scale Processing


Main Feed

Hopper

Pretreatment Feed Hopper

Weigh Belt

Pretreatment System

Flash Tank

Scrubber

S/L Separator

Enzymatic Hydrolysis Reactors

Main Fermentor

Train

Seed Fermentor

Train

Conditioning Tank

S/L Separator

Distillation Column

Catalyst and Chemical

Tanks

Enzyme Tank

Nutrient Tanks

S/L Separator

Recycle Water Tanks

Solids Tank

Dryer

Mill Condensers

FeedstockSteam

Catalyst/Solvent

Water

Beer Well Bottoms Tank

SolidsWater

Enzyme Chemical(s)

Feedstock

Nutrients/Chemicals

Nutrients/ Enzyme

Solid Product Feedstock

Concentrated Ethanol

Liquor Tank

Water

Chemical

Inoculum

Pellets

Water

Water

Separator

Pelletizer

Solvent Recovery

Sterilizer

New Equipment

Existing Equipment

New pipingExisting piping

Future Equipment


Acknowledgements

Funding• US DOE EERE Office of the Biomass Program

Contributors • NREL Project Members

• Nancy Dowe Farmer • Bill Bray• Jody Farmer• Wes Hjelm• David Humbird• Deb Hyman• Ed Jennings• Andrew Lowell• Bob Lyons• Gary McMillen• Ali Mohagheghi• Dave Sievers• Millie Zuccarello

• Pilot Plant Designers/Builders

Questions?


integrating and piloting lignocellulose biomass conversion … · 2013-09-20 · daniel j. schell...

Documents