Effects of Jincheng coal fine char from fluidized-bed gasifier on ash fusion and CO2 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 CO2 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 (KAlSiO4) and leucite (KAlSi2O6). 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 K2O 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 degrees C and 1000 degrees C, because the destructive effect of high-content K2O on the order degree of JF carbon structure prevailed over the CO2 and heat hindrances of JF on CS char particles at high temperature.

Automated summary

The combined study of ash fusion temperature adjustment and gasification reactivity change provides valuable reference for biomass utilization. Jincheng coal fine char (JF) was found to effectively increase the ash fusion temperatures of peanut hull and cotton stalk through conversion of K-containing minerals. However, JF exerted adverse effects on the gasification reactivity of both biomass, with stronger effects at high JF ratios and low temperatures. The influence of JF on gasification reactivity was lower for cotton stalk due to its higher ash yield and K2O content.