Interaction between Coal and Biomass during Co-Gasification: A Perspective Based on the Separation of Blended Char

Xiaoming Li,Zongqing Bai,Wen Li,Jin Bai,Mengjie Liu,Jingxia He

doi:10.3390/pr10020286

Abstract

Co-gasification of coal and biomass is an important way to reduce the consumption of fossil fuels and achieve the efficient utilization of biomass resources. Two kinds of biomass containing corn straw (CS) and poplar sawdust (PS) were blended with different coal. Then, the coal char was separated from the blended char after co-pyrolysis based on the difference in particle size. The structural properties, including alkali and alkaline earth metals (AAEMs), microcrystalline structures, and molecular structures of the char samples were analyzed. Gasification reactivity of the char was determined by thermogravimetric analyzer (TGA). Results indicated that K and Mg contents in biomass evaporated easily and deposited on coal char, resulting in the increase in those in coal char during co-pyrolysis, and then the AAEMs contents in coal char were determined by the AAEM species and contents in biomass. Meanwhile, the inhibition effect on the graphitization degree of coal char increased with increasing blend ratio. Likewise, the inhibition effect of CS was higher than that of PS at the same blend ratio. The catalytic activity of inorganic mineral played a much more important role in predicting gasification reactivity than graphitization degree, and then the combination of alkali index and stacking layer number was proposed to better predict the reactivity of coal char.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
The inhibit effect of corn straw (CS) and poplar sawdust (PS) on the graphitization process was promoted with increasing blend ratio, which could be attributed to the fact that with the increase in biomass ratio, the more alkaline earth metals (AAEMs) contents in coal char were transferred from biomass, and the greater inhibition effect on the graphitization degree of coal char was discovered
The effect of biomass type and blend ratio on the structure properties and gasification characteristics of coal char was investigated by using a method that the coal char was separated from blended char based on the difference in particle size, which gave in-depth insights into the interaction mechanism between coal and biomass during co-gasification

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. With the development of economy, consumption of fossil fuels gradually increases. Climate warming caused by greenhouse gas emissions has seriously damaged the human living environment [1]. The characteristics of resource endowment determine that coal is the main source of fossil fuels in China, and two targets, “peak carbon dioxide emissions” and “carbon neutrality”, have been proposed to control the greenhouse gas emissions. Co-gasification of coal and biomass is a promising clean high-efficiency energy technology, which can reduce coal consumption [2]. Considerable reduction in CO2 emission can be expected as a result of the advantage that biomass is a carbon-neutral energy source

Methods

Results

Conclusion