Integrated Steam Pyrolysis and MILD Oxidation System for Biochar and Energy Production (Abstract/Poster in atti di convegno)

Type
Label
  • Integrated Steam Pyrolysis and MILD Oxidation System for Biochar and Energy Production (Abstract/Poster in atti di convegno) (literal)
Anno
  • 2012-01-01T00:00:00+01:00 (literal)
Alternative label
  • P. Giudicianni, P. Sabia, M. de Joannon, R. Ragucci (2012)
    Integrated Steam Pyrolysis and MILD Oxidation System for Biochar and Energy Production
    in 20th European Biomass Conference and Exhibition (20th EU BC&E), Milan, Italy, 18-22, June, 2012
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • P. Giudicianni, P. Sabia, M. de Joannon, R. Ragucci (literal)
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  • abstract/poster (literal)
Note
  • Poster (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Istituto di Ricerche sulla Combustione - C.N.R., Naples, Italy Istituto di Ricerche sulla Combustione - C.N.R., Naples, Italy Istituto di Ricerche sulla Combustione - C.N.R., Naples, Italy Istituto di Ricerche sulla Combustione - C.N.R., Naples, Italy (literal)
Titolo
  • Integrated Steam Pyrolysis and MILD Oxidation System for Biochar and Energy Production (literal)
Abstract
  • , with a high surface area higher) but poses the problem of a condensable fraction of the products, which represent a potentially combustible materials dispersed in a steam flow. MILD combustion represents a very profitable way of burning those combustibles, thus recovering part of the energy required by the pyrolysis process without the need of a steam removal stage. As matter of facts, MILD oxidation that uses steam as major diluent species has been demonstrated to be feasible and presents the advantage of being usable also for low calorific value fuels like those produced in the vegetable steam pyrolysis process. In the first part of this paper effects of pressure, heating rate and final temperature on the yields and on the chemical and physical properties of gaseous and solid products of a biomass steam pyrolysis process are presented and discussed. This study characterizes single species pyrolysis, cellulose, hemicellulose (xylan), lignin at selected operating conditions (P=5×105 Pa, HR=5 K/min, Tf=703, 873 K) in terms of products yield, char elemental analysis and BET surface, vapor phase heating value and gas phase composition. Results obtained suggest a major role of cellulose in determining final biochar porosity. Elemental analysis of the water soluble fraction of pyrolysis liquids show that O/C ratio of water soluble condensable species produced by steam pyrolysis of lignin is lower than those obtained processing cellulose and xylan accounting for the higher calorific value measured in the former case. As concerns gas phase it has been observed that CO, CO2 and CH4 are the main constituents of gas phase resulting from the pyrolysis of the three biomass components. Only small amounts of H2, C2H4 and C2H6 are observed. Xylan is the main responsible of gas phase release, even though gas produced by lignin is characterized by the highest HHV due to the highest content of CH4. In the second part oxidation process under MILD operative conditions of a reference gas whose composition was chosen on the basis of experimental results obtained in the biomass steam pyrolysis facility was studied in a lab scale tubular flow reactor. Mixture ignition delay times as a function of mixture extensive parameters (mixture composition, dilution level, diluent nature, pre-heating temperature) were evaluated for N2 dilutions. Simultaneously gas-chromatographic analyses were performed to characterize the evolution of the combustion process and the reference gas conversion. Finally, maps of combustion regimes were drawn up to identify the operative conditions in which industrial systems should be exercised. Results confirm that MILD combustion is a reliable process to efficiently burn low BTU gases and that characteristic kinetic times are compatible with industrial systems. Such aspect is crucial for designing and dimensioning industrial facilities. The results shown in this paper support the thesis that the integration of a biomass steam pyrolysis system with a MILD combustion process would be a feasible and rational strategy to valorize biomasses as energy source. (literal)
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