Work

Experimental study on the vaporization and condensation of alkali metal chlorides in biomass ash under pressurized conditions

Year: 2026

Type: article

Abstract: The aim of this work was to understand the vaporization and condensation of alkali chlorides in biomass ash under elevated pressure, a series of experiments have been conducted on a horizontal high-pressure tube furnace. Stainless steel sheets were located in the tube furnace to condense inorganic species. Scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD), X-ray fluorescence (XRF), and ImageJ software were employed to characterize and analyze the condensates and solid refractory residues. The results demonstrated that at 4.0 MPa, the relative change rates( λ ) of K 2 O and Cl in the solid residues reached 20.89% and 726.44%, respectively. Elevated pressure inhibited the vaporization of alkali metal chlorides in biomass ash, and high pressure further promoted the formation of mullite (Al 2.4 Si 0.6 O 4.8 ) and potassium calcium phosphate (KCaPO 4 ) in the solid residues. The condensates formed under different pressures were mainly white, square or spherical KCl and NaCl particles; when the pressure increased from 0.1 MPa to 2.0 MPa, the particle size of the condensates decreased to 18.8% of the initial value. In conclusion, pressure exerted a crucial regulatory effect on the vaporization and condensation processes of gaseous chlorides throughout the entire thermal conversion process. • Increasing reaction pressure inhibited the vaporization of alkali chlorides in corn straw ash. • Mullite (Al 2.4 Si 0.6 O 4.8 ) diffraction peaks detected in solid residue under pressure (2 MPa and 4 MPa). • The average size of condensates reduced from 3.733 μm at 0.1 MPa to 0.723 μm at 4.0 MPa. • The condensate was mainly white, spherical and square KCl and NaCl particles.

Source: Fuel Processing Technology

DOI: 10.1016/j.fuproc.2026.108403