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Converting Red Liquor, Pulp, and Sludge to Ethanol
Spring 2009 Design Class
Paper Science & Engineering 487
College of Forest Resource
University of Washington11 June 2009
Agenda
Background Red Liquor to Ethanol Production
Process Overview Process Detail Mill Integration Process Economics Environmental and Safety Conclusions and Recommendations
Pulp to Ethanol Production Sludge to Ethanol Production Process Comparison Conclusion
Background
Ethanol – Production Benefits:
Environmental Economical Efficient
Project Objective: Integrate the production of ethanol into the KC Everett mill. Group Objectives:
Production of ethanol from Red Liquor, Pulp, and Sludge
http://i.treehugger.com/files/ch3ch2oh.jpg
Fermentation Options
Three Fermentation MicroorganismsEscherichia coli
Genetically engineered strain KO11 Yield 0.44 g ethanol /g sugar Metabolize 5 and 6 carbon sugars
Zymomonas mobilisGenetically Engineered Strain ZM4:ZB5 More tolerant of acetic acid Yield 0.47g ethanol/g sugar Metabolize 5 and 6 carbon sugars
Saccharomyces cerevisiaStrain 424A(LNH-ST) Yield 0.41 g ethanol/g sugar Metabolize only 6C sugars Proven performance with red liquor
Red Liquor to Ethanol
Chris Ardales, Colynn Boyd,
Sabrina Burkhardt, Danielle Greenwood
Paper Science & Engineering 487
College of Forest Resource
University of Washington
Process Overview
Assumptions Neglect Inhibitors 86% Fermentable Hexoses converted 77% Fermentable Pentoses converted Mill is capable of handling increased steam production
Critical Unit Operations Raise pH with Ammonium Hydroxide prior to fermenting Lower Temperature prior to fermenting Use of Zymomonas mobilis as fermenting agent
Nutrients: corn steep, diammonium phosphate SSL taken from 5th MEE, remaining liquor returns to 1st MEE
Flow Diagram Follows:
Evaporator 5th Stage
Stream 1•Red Liquor•504 GPM•Temp = 149F•pH = 2.6
1
Heat ExchangerTin= 149FTout=106F
Fermenter•5 batch tanks
•1250000 gallon total capacity•pH 5.75 for 1st 24 hrs•pH 6.0 for last 6 hrs•0.47g etOH/g sugar
2Stream 2•504 GPM•Temp = 106F•pH = 2.6
To 1st Stage
3
4
5
Stream 3•NH4OH for pH adjustment•Temp = 106F
Stream 4•NH4OH for pH adjustment•Temp = 106F
Stream 5•Nutrient Addition•Temp = 106F•Corn steep liquor•Diammonium phosphate
6Stream 6•Fermenting Inoculum•Temp = 106F•Z. mobilis
7Stream 7• to storage tanks
CO2 and VOC vent
Evaporator 1st Stage
Stream 8•Water and solids from beer column•504 GPM•Temp = 149F•pH = 2.6
8
RectifierTemp = 212F
Beer Column•Temp = 212F
10
7
Stream 7 (from storage tanks)•Ethanol 15 gpm•Water 418 gpm•Dissolved solids 75 gpm•Temp = 106F9
Stream 9• ethanol 15 gpm, 92.5% •Water 1 gpm, 7.5%
Molecular SieveTemp = 212F
CO2 and VOC vent
Stream 10• ethanol 15 gpm, 95% •Water <1 gpm, 5%
Stream 11• ethanol 15 gpm, 99.5% •Water <0.1 gpm, 0.5%
12
13
11
From evaporator 5th stage
Stream 12•Water to sewer
Stream 13•Water to sewer
Process Detail - WinGEMS
Process Detail - WinGEMS
Process Detail - WinGEMS
Process Detail – Inputs to Process
SSL SW HW
Total Mass Flowrate (klb/hr) 239.59 239.59
Total Dissolved Solids (klb/hr) 56.06 56.06
Total Sugars (klb/hr) 14.63 13.25Fermentable 6 C Sugars (klb/hr) 12.32 9.32Fermentable 5 C Sugars (klb/hr) 1.86 3.59
Other Solids (klb/hr) 4.40 8.94
Lignin Mass Flowrate (klb/hr) 36.59 33.13
Water (klb/hr) 183.53 183.53
Temperature (deg F) 149 149
pH 2.6 2.6
Process Design
Fermenter Outflow to Beer Column
Softwood Hardwood
Ethanol concentration (%) 2.3 2.0
Ethanol (gpm) 14.5 12.6
Total solids (kpph) 40.9 42.1
Water (gpm) 404 413
Process Design
Softwood Hardwood
Dissolved Solids (%) 18.4 19.0
Lignin and extractives (kpph)
35.7 32.3
Sugars (kpph) 0.44 0.33
Water (kpph) 234 234
Beer column outflow to evaporator stage 1
Beer column flow to rectifier and sieve
Process Design
Softwood Hardwood
Ethanol concentration (%) 93.0% 93.0%
Ethanol (gpm) 14.5 12.6
Water (gpm) 195 170
Softwood Hardwood
Ethanol concentration (%) 99.8% 99.8%
Ethanol (gpm) 14.5 12.6
Ethanol (MM gal/yr) 7.3 6.4
Water (gpm) 0.004 0.004
Outflow from rectifier and sieve
Process Detail – Results from WinGEMS
Ethanol Production (WinGEMS Simulation)
Softwood Hardwood
Ethanol (MM gal/yr) 7.6 6.8
Ethanol Production (calculated)
Softwood Hardwood
Ethanol (MM gal/yr) 7.3 6.4
Steam Production from Red Liquor
Without Fermentation
After Fermentation
Wingems Simulation
268 KPPH 127 - 185 KPPH 197 KPPH
31%-53% reduction in steam from red liquorDistillation requires 33 KPPHOther fuels must be burned to makeup the steam requirement Wingems simulation is optimistic
Process Design
Without Fermentation After Fermentation
35.3 28.3
Change in power production from WINGEMS
Process Economics
Capital Costs
Fermentation $ 2,600,000
Distillation $ 5,900,000
Storage $ 800,000
Utilities $ 200,000
Total Installed Equipment Cost $ 9,500,000
Added Costs $ 7,000,000
Total Project Investment $ 16,500,000
Estimated based on NREL corn ethanol process Exclude non-applicable operations 2008$ using ppi Installation factors, cost relationships used by NREL Scaled based on production level
Process Economics
Operating Costs (cents/gal ethanol)
Variable Operating Costs
Chemicals 2.0
Fermentation Nutrients 1.4
Steam 49.5
Fixed Operating Costs 16.9
Total 69.8
Equivalent annual worth values 20 year projection, 20% rate of return
Estimated based on NREL corn ethanol process Chemicals vary from NREL process Fixed costs based on production as in NREL
Process Economics
Steam Use (klb/hr)
Process Demand 33
Steam Production from SSL loss 112
Total 145
Value at $2.2/gal ($/yr) $ (2,800,000)
Cost of Natural Gas Replacement ($/yr) $ (3,400,000)
Natural gas cost: $4/MM Btu
Profitability
20 year projection (pre-tax) Ethanol selling price of $1.50/gal Ethanol production of 7.1 MM gal/yr Desired rate of return at 20%
Net Present Value = $17.3 MM
Break Even Ethanol Price: $1.06/gal
Environmental and Safety
Displacement of Carbon released from gasoline
Calculated using guide lines from The Intergovernmental Panel on Climate Change
Ethanol MM gal/yr
Gasoline replacedMM gal/yr
CO2
released
lbs/gal
Carbon saved MMlbs/yr
Carbonsavedtons/yr
7.1 5 19.5 97 48000
Environmental and Safety
Money in CO2 ?
European Union Results in an
additional earning of 1.6Million dollars/year at $35/ton
Figure 4.4.1. EU-ETS carbon trade: spot and future market volatility 2005-2007 (Point Carbon)
Environmental and Safety
Storage Tank labeling
Materials resistant to ethanol corrosion Unplated and Stainless Steel Black Iron Bronze Nonmetallic Thermoset Reinforced Fiberglass Thermo Plastic Piping Neoprene Rubber Nitrile Teflon
Hazard Rating 4-Extreme 3-Severe 2-Moderate 1-Slight 0-Minimal
Health 2
Flammability 3
Reactivity 0
Environmental and Safety
Odor Control Water Scrubber
Off fermentation and any vents that would contain Ethanol
Majority of the CO2 and 0.2% of the ethanol is vented
Contains 83.7% CO2, 12% ethanol, 4% water
Effluent is fed to the first distillation column Over 99% of the ethanol to scrubber is recovered
Recommendations
Further testing on Z. Mobilis Genetically engineered bacteria my not hold up in
SSL New strains could be more effective
Consider yeast Proven to work well with 6 carbon sugars Will lose the fermentation of 5 carbon sugars Rework analysis for 6 carbon sugars alone
Conclusions
Ethanol production = 7.1 MM gal/yr
Net Present Value = $17.3 MM
Assuming mill can handle increase in steam demand
Z. mobilis yield is accurate and is hardy enough for SSL