Pyrolysis and Char Oxidation of Biomass and Coal Blends: Kinetic Study Using Thermogravimetric Analysis

Hoang Anh Tran,Laurent Van De Steene,Duc Dung Le

doi:10.1088/1755-1315/159/1/012035

Abstract

Vietnam as an agricultural country has a high potential in biomass, especially agricultural and forestry wastes. This resource offers a promising way to develop co – combustion technology of biomass and coal in Vietnam and thus tackle the environmental issues. A fundamental research was established to study combustion of Vietnamese rice straw and coal. Blends was made by mixing manually 50% wt. of rice straw and 50% wt. of coal. Pyrolysis in inert gas, char oxidation in oxidizing gases (10 % O2 in N2) and combustion process in oxidizing gases (10 % O2 in N2) were implemented. A particular attention was paid to the behaviour of rice straw/coal blends during thermochemical transformation. Concerning pyrolysis process, the char yield of the mixture is equivalent to weighted sum of the char yield of two solid fuels. During the combustion of the blends, we observed a coupling between pyrolysis and char oxidation. The exothermic oxidation reactions could overheat the sample itself and accelerate the pyrolysis and char oxidation kinetics.

Highlights

In Vietnam an abundant fossil fuel, coal is used mostly as a principal energy resource to produce heat and electricity
The objective of this work is to study the kinetic of rice straw/coal mixture and to understand the coupling effect occurred in the pyrolysis, char oxidation and the overall combustion process
These results show that there is a coupling between pyrolysis and char oxidation when mixing two solid fuels

Summary

Introduction

In Vietnam an abundant fossil fuel, coal is used mostly as a principal energy resource to produce heat and electricity. In 2015, electricity production coming from coal fire power accounted for 33.5% and was classified in the second position after hydropower at 38% [1]. The latest “National Power Development Plan” indicated that Vietnam will continue developing coal as the main energy source for electricity production. Biomass is a promising source of energy to be exploited in order to support national energy security and reduce the dependency to fossil fuels. The largest biomass sources for energy production in Vietnam are crop residues and wood. Despite of the low heating value of biomass compared to coal, it remains a promising resource because of its large quantity available [3]

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