Improving the staged gasification of crop straw by choosing a suitable devolatilization temperature

Abstract

A novel biomass staged gasification technology is under development, which includes a medium temperature devolatilization (MTD) stage and a high temperature gasification stage. In this study, the MTD of corn stalk with high K content was conducted at a wide temperature range of 200–550 °C, and the obtained biochar was subjected to steam gasification at 900 °C. The distribution and characteristics of the products from both stages were analyzed in detail. The results demonstrate that owing to the moderate reduction of O/C and the enrichment of fixed carbon and K, a devolatilization temperature exceeding 300 °C, especially at 450 °C, showed a significant promotion effect on the gasification performance. The syngas production, H2 production and H2/CO ratio increased from 62.23 mmol/g, 33.59 mmol/g and 2.13 for corn stalk to 106.15 mmol/g, 72.09 mmol/g and 3.38 for biochar obtained at 450 °C, respectively. This study revealed the correlation between different physicochemical characteristics and gasification performances of MTD-char and the internal mechanism, which is conducive to the high-value utilization of low-quality biomass (i.e., crop straw) via staged gasification.