Release of P from Pyrolysis, Combustion, and Gasification of Biomass - A Model Compound Study
Artikel i vetenskaplig tidskrift, 2021

Phosphorus-rich biomass can cause operational problems in combustion units. Na-phytate, a model compound used to simulate phosphorus in biomass, was studied in a laboratory-scale reactor under temperature and gas atmosphere conditions relevant for pyrolysis, combustion, and gasification in fixed bed or fluidized bed reactors to understand the P and Na release behavior. Solid residues from Na-phytate thermal conversion were analyzed using ICP with optical emission spectrometry in order to quantify the P and Na release. The release mechanism was evaluated based on FTIR spectroscopy analysis of the residues, measurement of the flue gas CO/CO2 concentration, characterization of flue gas particles using SEM with EDS, and thermodynamic equilibrium calculations. Na-phytate decomposed in several steps under a nitrogen atmosphere, starting with condensation of the phosphate OH groups, followed by carbonization in the temperature range 300-420 °C. In the carbonization process, the phosphate units detached from the carbon structure and formed cyclic NaPO3. Above 800 °C, the C in the char reacted with the melted NaPO3 to form CO and gaseous elemental P. When the char produced from flash pyrolysis of Na-phytate at 800 °C for 10 min was exposed to 1% O2, 10% CO2, or 10% H2O (in N2), the release of Na and P to the gas phase in the temperature range 800-1000 °C was around 0-7%. However, the release of P in an inert atmosphere, with a holding time of 2 h or until full char conversion had been achieved, increased from around 4% at 800 °C to almost 30% at 1000 °C. The results indicated that carbothermic reduction reaction is responsible for the release of P and that NaPO3 vaporization is not the dominating mechanism for P and Na release at temperatures below 1000 °C. A small amount of P was released in the O2, CO2, and H2O containing gases because these gas species consumed the char and thereby inhibited the release of P.


Emil O. Lidman Olsson

Danmarks Tekniske Universitet (DTU)

Sino-Danish Center for Education and Research China

Chinese Academy of Sciences

Peter Glarborg

Danmarks Tekniske Universitet (DTU)

Henrik Leion

Chalmers, Kemi och kemiteknik, Energi och material

Kim Dam-Johansen

Danmarks Tekniske Universitet (DTU)

Hao Wu

Danmarks Tekniske Universitet (DTU)

Energy & Fuels

0887-0624 (ISSN) 1520-5029 (eISSN)

Vol. 35 19 15817-15830


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