posted on 2021-07-14, 17:34authored byFrançoise Defoort, Boris Grangier, Thierry Chataing, Serge Ravel, Gilles Ratel, Sylvie Valin
Hardwood
bark (HW bark) containing a high ash yield (6.5 wt %)
was gasified on a pilot scale in a pressurized entrained flow reactor
(EFR, 250 kWth) in allothermal conditions. Conventional
physical–chemical characterizations were performed on the ash/slag
(ash yield, weight and sieving, inductively coupled plasma, scanning
electron microscopy with energy-dispersive spectroscopy, and X-ray
diffractometry) and water (pH and ionic chromatography) both collected
at the bottom of the EFR. Simulations were performed to predict the
phase speciation (solid + liquid + gas) at equilibrium with FactSage
7.3 and its databases and to predict the viscosity with the FactSage “melt”
and Thomas models above and below the liquidus temperature, respectively.
Results showed that the inorganic matter collected could be characterized
with a well closed overall and elemental mass balance. Slight pollution
by the alumina wall of the reactor was observed. A very small amount
(<4%) of fly ash was noticed. The quench water was acidic as a
result of the oxidation of injected N2 (and not as a result
of N biomass). A good consistency was observed between experimental
results of the main condensed phases and the prediction either from
a simple phase diagram or with global calculations but for only 1/4 of the collected ashes. The remaining ashes,
i.e., 3/4, contained unpredicted phases, such
as SiO2 (from soil contaminant) and CaCO3 (from
raw HW bark), that did not react together. The viscosity was predicted
to be between 1 and 10 Pa s in the 1300–1400 °C temperature
range. This viscosity is below the 25 Pa s criteria to have a slag
flowing adequately along the EFR wall.