BIOCHAR PRODUCTION BY PYROLYSIS OF LIGNOCELLULOSIC BIOMASS IN A CONICAL SPOUTED BED REACTOR

1. eman ta zabal zazu Universidaddel País Vasco Euskal Herriko Unibertsitatea BIOCHAR PRODUCTION BY PYROLYSIS OF LIGNOCELLULOSIC BIOMASS IN A CONICAL SPOUTED BED REACTOR Maider Amutio, Gartzen Lopez, Maite Artetxe, Astrid Barona, Martin Olazar Chemical Engineering Department, University of the Basque Country UPV/EHU PO Box 644 – 48080 Bilbao. Spain. martin.olazar@ehu.es

2. Introduction • Biomass • Alternative to fossil fuels → the only renewable source of fixed carbon. • Biomass → Liquid, solid and gaseous fuels + heat and power. • Pyrolysis • One of the technologies with the best industrial perspectives. • Bio-oil as biorefinery feedstock (decouple bio-oil production). • Biomass flash pyrolysis • Maximum liquid production: • Products: Bio-oil = 60-80 wt%. Alternative fuel or source of chemicals Gas = 10-20 wt%. Supply energy to the pyrolysis plant Char = 15-25 wt%. Fuel, activated carbon or soil amendment. T ~ 500 ºC Very high heating rates Short gas residence time Rapid char removal Minimize secondary cracking reactions Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

3. Introduction • Vacuum pyrolysis • Improvement of the operational capacity of this technology: • Reduction of the mass flow-rate of the inert gas→ reduction in the energy requirement to heat the gas to the reaction temperature. • Simplification of the bio-oil condensation and collection section. • Advantages: • Reduction of secondary cracking reactions: rapid desorption and extraction of the volatile products from the reaction environment. • Improvement in char quality. • Reactors • Biomass flash pyrolysis: Fluidized bed reactors. • Biomass vacuum pyrolysis: Vacuum moving bed. Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

4. Introduction • Conical spouted bed reactor (CSBR) Advantages: • Simple design • Less pressure drop than fluid beds • Different particle diameters and irregular materials • Great versatility in gas flow (low residence time) • Good heat and mass transfer • Allows continuous extraction of char Fountain Spout Annulus Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

5. Conical spouted bed reactor (CSBR) Introduction Advantages: • Simple design • Less pressure drop than fluid beds • Different particle diameters and irregular materials • Great versatility in gas flow (low residence time) • Good heat and mass transfer • Allows continuous extraction of char Annulus Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

6. Experimental • Pyrolysis bench scale plant Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

7. Experimental • Raw material: Pinewood (pinus insignis) sawdust • Experimental conditions • Temperature: 400 and 500 ºC • Pressure: 0.25 and 1 atm • Biomass: 0.1-2 mm, 25 kg/min • Bed: 20 kg sand (1-2 mm) • Inert gas flow rate (liters/s) • On line product analysis: GC, µGC and GC/MS Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

8. Experimental Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

9. Experimental Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

10. Results: product yields • Fractions: gas, bio-oil and char. Yields in wet basis 400 ºC 500 ºC • High liquid yields: 77 % wt at 500 ºC and 0.25 atm • P ↓ → bio-oil ↑, char ↓ (reduction of secondary reactions) • P ↓ → Desorption and diffusion of the volatiles in the biomass particle ↑ • Residence time of volatiles in the particle ↓ Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

11. Results: gas composition • Mainly made up of CO2 and CO • P ↓ → CO2 ↑, T ↑→ CO2 ↓ Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

12. Results: bio-oil composition • Water is the main compound ~ 25 %wt • Phenols: guaiacols (methoxy phenols), catechols (benzenediols) and alkyl-phenols. • Saccharides: levoglucosan yield increases at lower pressures. • Pressure has different influence at 400 ºC and 500 ºC • P ↓→ Bio-oil is composed of heavier compounds Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

13. Results: bio-oil properties • P ↓→ Carbon content increases slightly (less water and more heavier and less oxygenated compounds) → Calorific value ↑ • Operating at subatmospheric pressure slightly improves bio-oil’s valorization prospects as fuel. However, its calorific value is low, so it has to be subjected to treatments. Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

14. Results: char characterization • T ↑→ Carbon content and calorific value ↑ • P ↓ → Carbon content and calorific value ↑ at 400 ºC but ↓ at 500 ºC. • Carbon content > 75 % . Low ash content • LHV higher than the ones of soft coal (29 MJ/kg) and lignite (20 MJ/kg) Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

15. Results: char characterization • P ↓ → BET surface area ↑, pore diameter ↓ • 500 ºC, 0.25 atm → mesopores of 100 Å and micropores of 19 Å are formed • Devolatilization and diffusion of volatiles through the biomass particle ↑ Blocking of the pores due to carbonaceous material deposits ↓ 500 ºC, 0.25 atm 500 ºC, 1atm Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

16. Conclusions • Conical spouted bed reactor: suitable technology to perform vacuum biomass flash pyrolysis. • High bio-oil yields: 77 wt% at 500 ºC and 0.25 atm. • Vacuum influence on product yields and properties: • Low influence on fraction yields, but bio-oil yield slightly increases. • Bio-oil: heavier compounds (phenols, levoglucosan, etc.), less water. Calorific value ↑ • Char: Improvement of surface characteristics. • Vacuum increases process viability: Inert gas flow rate is lower → Less energy is required to heat the carrier gas and the condensation of the product stream is easier. Chemical Engineering Department. University of the Basque Country PO Box 644 – 48080 Bilbao. www.ehu.es/cpwv

17. eman ta zabal zazu Universidaddel País Vasco Euskal Herriko Unibertsitatea BIOCHAR PRODUCTION BY PYROLYSIS OF LIGNOCELLULOSIC BIOMASS IN A CONICAL SPOUTED BED REACTOR Maider Amutio, Gartzen Lopez, Maite Artetxe, Astrid Barona, Martin Olazar Chemical Engineering Department, University of the Basque Country UPV/EHU PO Box 644 – 48080 Bilbao. Spain. martin.olazar@ehu.es