Supercritcal water gasification of biomass residues

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1 Supercritcal water gasification of biomass residues Christina Ceccarelli, Andrea Kruse, Nikolaos Boukis? Forschungszentrum Karlsruhe, Institute for Technical Chemistry 1

2 Use of Biomass Why? The loss and increase in the price as well as a heavy, uncertain access to fossil resources. CO 2 -neutral; United Nations Kyoto Protocol for the reduction CO 2 -emissions. Potential: 2/3 of the unused biomass in Germany is wet 5-10 %* (> 50 %, often % water content) %** of the primary energy consumption *FZK; **Climate Change 1995, Watson et al 2

3 Outline: Process development What is supercritical water gasification of biomass? Advantages Basic investigations Influence of -salts, -proteins. Bench scale plant Summary and conclusion Main challenges 3

4 The process Wet (green) biomass is heated up to 600 C and 30 MPa. Because of thermodynamic reasons No coke at optimized conditions Nearly complete gasification to H 2, CO 2 and lower amounts of CH 4 4

5 Advanges No drying of wet biomass necessary Very low amounts of tar and (no) coke High H 2 -yield, low CO content H 2 under pressure Easy CO 2 -separation under pressure High space-time-yield Inorganic ingredients are not volatile 5

6 Role of water Water is reactant: -H 2 and CO 2 is formed instead of Syngas Very low CO content (C 6 H 12 O 6 ) + 6H 2 O 6 CO H 2 - Fast hydrolysis of Cellulose Homogenous reaction Water is solvent: Intermediates are dissolved Less polymerization reactions Less tar and coke 6

7 Disadvantage? Heating up of a large amount of water is a disadvantage? Heat exchange is necessary and very efficient (no evaporation in the heat exchanger) 7

8 Wet biomass Industrial application Hydrogen Process engineering Bench scale plant Kinetics Reaction pathways Optimization Lab.-scale plant Thermodynamics 8

9 Goals of basic research Investigation of the influence of - process parameters (T, p, c, reactor type) - biomass ingredients (salts, proteins, lignin) dc 1 /dt=-k 1 *c 1 dc 2 /dt=k 1 *c 2 +k 2 *c Identification of optimized reaction conditions for a large variety of biomass feedstock. Kinetic model of the reaction. 9

10 Lab-scale plants Tumbling batch reactor 500 C, 50 MPa, 1 L Tubular reactor 600 C, 30 MPa, 20 ml, 6 m long. Continuous stirred tank reactor (CSTR) 600 C, 100 MPa, 190 ml 10

11 Model Systems CH 2 OH OH O OH OH OH + Salts + Amino acids... Phytomass: carrots, potatoes Zoomass: chicken, rice 11

12 Influence of Salts Gas yield/ ml 6 4 Glucose + KHCO3 Glucose τ / s CO 2 H 2 H C, 25 MPa 2 % (g/g) Glucose 0.2 % (g/g) KHCO 3 CO 2 CH 4 CO 12

13 Alkali salts catalysis of the water-gas shift reaction CO + H 2 O CO 2 + H 2 Formation of active hydrogen D. C. Elliott, L. J. Sealock, Ind. Eng. Chem. Prod. Res. Develop. 22, 1983,

14 Cellulose Glucose Fructose Different short Intermediates O Furfurales Phenols Coke Gases: H 2, CO 2, CH 4, CO 14

15 K 2 CO 3 KHCO 3 KOH Cellulose Glucose Fructose Different short Intermediates O Furfurales Phenols Coke Gases: H 2, CO 2, CH 4, CO 15

16 Biomass: Gas yield and gas composition Gas yield / (mol/kg) Phytomass Glucose / K 2 CO MPa; 6 τ / min A. Kruse et al., Ind. Eng. Chem. Res. 44, 2005, CH 4 CO 2 15% 0.17% CO 45% 47% H 2 40% H 2 CH 4 CO 2 15% 0% CO 38% Ca. 5% DM, 500 C, % (g/g) K 2 CO 3 16

17 Influence of proteins Gas yield and gas composition 17 Gas yield / (mol/kg) Glucose / K 2 CO 3 Zoomass τ / min A. Kruse et al., Ind. Eng. Chem. Res. 44, 2005, % H 2 CO 2 38% 41% 44% H 2 CO 2 CH 4 CH 4 0% 15% 0.3% Ca. 5 % DM, 500 C, 30 MPa; 0,5 % (g/g) K 2 CO 3 14% CO CO

18 Formation of free-radical scavengers Maillard-Reaction HC NR CHOH CHOH Z Aldolsplitting HC NHR CHOH Amadori H 2 C CHO NHR R N N R HC NR CH 2 OH RNH 2 + Aldose R N Z = Sugar residue N R 18

19 Compensation of the protein influence Gas yield / (mol/kg) τ / min A. Kruse et al., Ind. Eng. Chem. Res. 44, 2005, K 2 CO 3 1 % DM, 500 C, 30 MPa; 0,5 % (g/g) K 2 CO 3 19

20 Wet biomass Industrial application Hydrogen Process engineering Bench scale plant Kinetics Reaction pathways Optimization Lab.-scale plant Thermodynamics 20

21 Pilot plant VERENA 700 C 32 MPa 100 kg/h Feeding Reaction Separation 21

22 Pilot plant VERENA 22

23 100 kg/h, 5-20 % DM 35 L, 600 C, 30 MPa 23

24 Experiments in the VERENA-Plant Materials tested : maize silage, greens, residues from wineries and breweries, such from bioethanol and biogas-production, but also biocrude oil, glycerol from biodiesel production 24

25 Summary / Conclusion Gas yield/ ml 6 4 Different short Intermediates O Wet biomass Cellulose Glucose Fructose Glucose + KHCO3 Glucose 2 5 Gases: H 2, CO 2, CH 4, CO τ / s Furfurales CO 2 H 2 H 2 Coke CO Phenols CO Hydrogen C, 25 MPa 2 %(g/g) Glucose 0.2 %(g/g) KHCO 3 CH 4 Process engineering Industrial application Pilot plant Kinetics Reaction pathways Optimization Thermodynamics 25

26 Main Challenge Salt separation to close the nutrition cycle Transformation of research results to a plant in technical scale. Very suitable for biomass residues from other biomass conversion processes (biochemical, biological, chemical or thermochemical conversions) Part of a biorefinery 26

27 Thanks! 27