Solid Carbon Conversion (Biomass & MSW) via CO 2

Transcription

1 Solid Carbon Conversion (Biomass & MSW) via CO 2 Marco J. Castaldi Department of Earth & Environmental Engineering Henry Krumb School of Mines, Columbia University Need refs and atom economy Workshop on lignocellulosic biofuels using thermochemical conversion June Auburn University

2 Energy Two-fold increase in energy consumption (demand) From 472 exajoules to over next 40 years The world is sensitive to energy supply (new paradigm) Security, Procurement supply chain disruptions CO 2 atmospheric concentrations are rising (environment) Prevent carbon dioxide emissions sequester, create value

3 The Need Carbon neutral energy production Clean chemical production (e.g. H 2 ) Reduce the dependence on single feedstock Indigenous source of fuel, distributed sources Power and chemicals produced must be economically attractive compared to current sources.

4 Working the Atom Economy Energy conversion & Efficiency C x H y Biomass MSW Coal Fuel (e.g. C 2 H 5 OH) Biomass + H 2 O CO + H 2 atom =100% Biomass + CO 2 CO + H 2 atom =100% Energy and water savings 20% of 2008 total transportation energy demand incorporates CO 2 Remove 308 million vehicles from the road Eliminate CO 2 emissions from MW coal-fired power plants.

5 What is the Problem? Energy sector is inefficient ~60% of energy is wasted! World Energy Consumption 5x10 20 J (2008) Remaining Fossil Fuel 0.4x10 24 J (800x) Fossil + hydrate 2x10 24 J (4000x)

6 Conversion Problem 100 Heating Rate = 10 o C min -1 Residual Mass (%) Determining and Understanding Reaction Mechanisms allows design of more efficient and selective processes and technologies Unprocessed residual Completely processed to desired outcome Reactor Temperature ( o C)

7 CO Mole Fraction Enhanced Gasification 100 Heating Rate = 10 o C min Residual Mass (%) % 40% 30% 20% Reactor Temperature ( o C) % CO 2 injected 10% % % Furnace Temperature ( o C ) Enhanced CO production with CO 2 Production begins to level off above 20% CO 2 Butterman, H. C.; Castaldi, M. J., Environmental Engineering Science 2009, 26, (4),

8 Value: CO 2 Enhanced Char Burnout Walnut Shells: 0% CO 2 Walnut Shells: 30% CO 2 Identical time on stream, reaction temperature profile, total flow rate Physical evidence of more efficient gasification with CO 2 Douglas Fir: 0% CO 2 ~20% biomass remaining Douglas Fir: 30% CO 2 <2% remaining as inorganic ash Observed for all samples tested Butterman, H. C.; Castaldi, M.J, Environ. Sci. Technol., 2009, 43 (23), pp

9 Residual Mass (%) } Actual Biomass Steam vs CO 1 o C min Heating Rate = 10 o C min Poplar steam gasification CO 2 gasification }Dominant Process Cellulose H 2 /CO Blue Fir Needles steam gasification CO 2 gasification Dominant Process Lignin + CO 2 CO low temperature pyrolysis behavior is similar for CO 2 & H 2 O Blue Fir Needles, higher lignin begins pyrolytic degradation earlier (200 o C) slower rate of decay Poplar wood, higher cellulose begins pyrolytic degradation later (250 o C) faster decomposition rate Greatest difference between H 2 O and CO 2 gasification after 900 o C < 2% ash remains using CO 2 Reactor Temperature ( o C) Figure 3B. Real Feedstock Decomposition Curve

10 Lignin Decomposition H 2 H 2 Lignin CH 4 Vinyl Ionic Phenoxy CH 4 Methane producing species 2-Furaldehyde Decarboxylation Methylation and Dehydrogenation Of Lattice Structure CO Continued Carbon enrichment HC HO CH C CH 2 O CH 2 CH HC CH 2 HO O C CH CH HC Lignin Char Large CO 2 influence CH O CH 2 C CH 2

11 Cellulose Decomposition Levoglucosan Trehalose Dehydroxylation Polymerization (Methanol soluble Oligosaccharides) Amylose (Water soluble Polysaccharides and Furans and Carbonyls) Cellobiose Furfural undergoes decarbonylation Devolatilization Carbonized Cellulose Char O No Char formation O Large CO C 2 O CH 2 influence Low MW Volatiles CH C CH O CH CH CO,CO 2,CH 4,H 2

12 Major Gasification Reactions Low Temperature Water Gas Shift CO + H 2 O CO 2 + H 2 Methanation C + 2H 2 CH 4 High Temperature Steam Gasification C + H 2 O H 2 + CO Boudouard C + CO 2 2CO 2CO + 2H 2 CH 4 + CO 2 CO + 3H 2 CH 4 + H 2 O Steam Gasification C + H 2 O H 2 + CO Char Burnout: O (Biomass/Steam) C + ½O 2 CO Reverse Water Gas Shift CO 2 + H 2 CO + H 2 O

13 Representative Representative Kinetic Parameters Kinetic COParameters 2 Pyrolysis CO ( Pyrolysis o C) (11 Representative Kinetic Parameters CO 2 Pyrolysis ( o C) Sample Heating Sample Rate Heating A o Rate A o E ave n E ave Sample Heating ( o C min Rate -1 ) (sec ( o C A -1 min K -½-1 ) (sec (kj -1 Kmole -½ ) -1 ) (kj mole o E ave n Lignin (CO 2 ) Lignin 5 (CO 2 ) ( o C min -1 ) (sec -1 K -½ ) (kj mole -1 ) Lignin (N 2 /H 2 O) Lignin 1 (N 2 /H 2 O) Lignin (CO 2 ) Cellulose Cellulose 1.40xE xE Lignin (N 2 Poplar {/H 2 O) Poplar xE xE Cellulose xE Douglas Cellulose Fir Douglas 10 Fir 3.82xE xE Poplar xE Pine Pine xE xE Douglas Fir xE Maple Maple xE xE Pine xE Oak Oak xE xE Maple xE Spruce Spruce xE xE Oak xE A. Beachgrass A. Beachgrass xE xE Spruce { xE Maple Bark Maple 10 Bark xE xE A. Beachgrass xE Alfalfa Alfalfa xE xE Maple Lignin Bark xE Blue Fir Needles Blue 10 Fir Needles xE xE Alfalfa xE Green Pine Needles Green 10 Pine Needles Blue Fir Needles xE Green Pine Needles

14 CO Comparison Butterman and Castaldi, Indus. & Eng, Chem. Res, (2007) 47,

15 H 2 Comparison Butterman and Castaldi, Indus. & Eng, Chem. Res, (2007) 47,

16 CH 4 Comparison Butterman and Castaldi, Indus. & Eng, Chem. Res, (2007) 47,

17 So What is happening? Why is CO 2 better? Char Pore Development- Enhanced Char Burnout With CO 2 Lignin 0% CO 2 -H 2 O/N 2 1 o C/min, o C Lignin 100% CO 2 1 o C/min o C Lignin 100% CO 2 1 o C/min, o C R Ae E RT act i C i Where; A = f (SA, V pore, etc) Butterman, H.C.; Castaldi, M.J.,Env. Eng. Sci., 2010, 27(7):

18 Physical Changes in Biomass during Gasification Removed - publication in preparation

19 Achieving high surface area: Why is sintering avoided with CO 2? Removed - publication in preparation

20 CO 2 impact on gasification products CO Mole Fraction (10-1 ) CO 2 Variation 0% 5% 10% 15% 20% 30% 40% 50% Increasing CO 2 H 2 Mole Fraction (10-1 ) CO 2 Variation 0% 5% 10% 15% 20% 40% 50% Increasing CO Reactor Temperature ( o C) Reactor Temperature ( o C) Figure 1. CO Enhancement with CO 2 gasification Figure 1. H 2 depression with CO 2 gasification CO increases with CO 2 H 2 decreases with CO 2

21 H 2 /CO produced in gasifier Fuels Chemicals Combustion Fuel cells H 2 /CO (Syngas) Tuning SOFC operation Gas Turbine Combustion Low NO x operation/good stability Fisher Tropsch diesel fuels Fisher Tropsch Fe & Co-based Catalyst processes specialty chemicals 0 0% 10% 20% 30% 40% 50% % CO 2 added to gasification influent

22 Lignin & Cellulose w/ CO 1 & 100 o C min -1 Residual Mass (%) Cellulose 1 min min -1 CO 2 Gasification Lignin 1 min min Thermally process the cellulosic at low temperature Treat remaining lignin thermally and chemically via CO 2 Steam: ~40% of the lignin still unprocessed to volatiles by 930 o C CO 2 : 100% conversion by 930 o C Can optimize the percent of lignin in the pyrolytic char Thermal processing heating rate for steam gasification Auburn/NSF/biomass Figure 3A. Lignin & 6/14/12 Cellulose CO 2 gasification Reactor Temperature ( o C) Butterman, H.C.; Castaldi, M.J.,Env. Eng. Sci., 2010, 27(7):

23 Oil Synthesis: Aromatic Adjustment Removed - publication in preparation Kwon, E., and Castaldi, M.J. (2008). NAWTEC17,Chantilly, VA, United States, May 18-20, 2009.

24 Ballistic ~100 o C min -1 Mass Loss and Temperature continuously measured t for test (~70 seconds) Temperature (centigrade) achieved for test

25 Chemical Species with Ballistic ~700 o C min -1 Chemical Species Concentration (%) Major Species Temperature ( o C) Chemical Species Concentration (%) Online gas analysis capability H 2 : MW = 2 g gmol -1 C 4 s HC: MW = 58 g gmol -1 Minor Species Collection T(*C) vs N2 Collection T(*C) vs O2 Collection T(*C) vs CO Collection T(*C) vs CO Collection T(*C) vs H2 Collection T(*C) vs CH4 Collection T(*C) vs Ethylene Collection T(*C) vs Ethane Collection T(*C) vs Acetylene Collection T(*C) vs Propylene Collection T(*C) vs Propane Collection T(*C) vs Butane Temperature ( o C)

26 Higher Order Hydrocarbon Results Removed - publication in preparation Trend toward dehydrogenation as temperature increases Commensurate H 2 increase

27 MSW DATA 100 Mass % vs Temp for Varius Amounts of CO 2 80 Area 1: water volatiliz ation Area 2: biomas s degradation Mass % % CO2 10% CO2 5% CO2 2.5% CO2 Inert 1% CO2 Area 3: petrochemical degradation Area 4: boudouard reaction (C O 2 + C 2C O ) Temperature ( o C) Kwon, E., and Castaldi, M.J. (2008). NAWTEC17,Chantilly, VA, United States, May 18-20, Kwon, Eilhann; Castaldi, Marco J. Environ. Sci. Technol. 2009, 43(15),

28 CO 2 Impact on Coal Decrease in H 2 production with CO 2 Increase in CO production with CO 2

29 Conclusions H 2/CO produced in gasifier Biomass, waste, coal solid carbon fuels can be efficiently converted using CO 2 instead of steam CO 2 helps in thermal separation of lignin and cellulose CO 2 enhances CO production, suppresses H 2 Improved char burnout Modeling matches data % 10% 20% 30% 40% 50% % CO 2 added to gasification influent Residual Mass (%) CO 2 Gasification Lignin 1 min min -1 Cellulose 1 min min Reactor Temperature ( o C) Kinetic parameter estimation suggests reaction order 1.0 for cellulose and 3.0 for lignin Adjustment of aromatic content in liquid portion

30 Acknowledgments Dr. Eilhann Kwon Dr. Heidi Butterman Professor John Dooher (Adelphi University) Kelly Westby You, the audience for listening