Effects of Jincheng coal fine char from fluidized-bed gasifier on ash fusion and CO gasification behaviors of biomass

The combined study of ash fusion temperature (AFT) adjustment and gasification reactivity change provides a valuable reference for biomass utilization. The effects of Jincheng coal fine char (JF) on the AFT and CO gasification reactivity of biomass [peanut hull (PH) and cotton stalk (CS)] were investigated by ash fusion tester and thermogravimetry analyzer, respectively. Furthermore, the AFT change mechanism was explored by X-ray diffraction analysis, and the influences of JF mass ratio and temperature on gasification reactivity were studied. As JF mass ratio varied from 5 to 25%, the JF addition could increase the AFTs of PH and CS effectively; however, the change trends were different due to their different ash yields and ash compositions. The AFT increase was ascribed to the conversions of low melting point (MP) K-containing minerals into high MP kalsilite (KAlSiO) and leucite (KAlSiO). JF exerted adverse effects on the gasification reactivity of PH and CS, and the effects strengthened at high JF ratio and low temperature. JF had less effect on the gasification reactivity of CS because its ash yield and KO content were higher than those of PH. Inhibition effect did not exist during the gasification process of CS/JF mixture with relatively low JF ratio at 950 °C and 1000 °C, because the destructive effect of high-content KO on the order degree of JF carbon structure prevailed over the CO and heat hindrances of JF on CS char particles at high temperature. Graphical abstract: [Figure not available: see fulltext.].