Co-Combustion Studies of Low-Rank Coal and Refuse-Derived Fuel: Performance and Reaction Kinetics

Mudassar Azam,Sajjad Miran,Asma Ashraf,Saman Setoodeh Jahromy,Franz Winter,Nadeem Raza,Christian Jordan,Florian Wesenauer,Michael Harasek

doi:10.3390/en14133796

Abstract

In connection to present energy demand and waste management crisis in Pakistan, refuse-derived fuel (RDF) is gaining importance as a potential co-fuel for existing coal fired power plants. This research focuses on the co-combustion of low-quality local coal with RDF as a mean to reduce environmental issues in terms of waste management strategy. The combustion characteristics and kinetics of coal, RDF, and their blends were experimentally investigated in a micro-thermal gravimetric analyzer at four heating rates of 10, 20, 30, and 40 °C/min to ramp the temperature from 25 °C to 1000 °C. The mass percentages of RDF in the coal blends were 10%, 20%, 30%, and 40%, respectively. The results show that as the RDF in blends increases, the reactivity of the blends increases, resulting in lower ignition temperatures and a shift in peak and burnout temperatures to a lower temperature zone. This indicates that there was certain interaction during the combustion process of coal and RDF. The activation energies of the samples were calculated using kinetic analysis based on Kissinger–Akahira–Sunnose (KAS) and Flynn–Wall–Ozawa (FWO), isoconversional methods. Both of the methods have produced closer results with average activation energy between 95–121 kJ/mol. With a 30% refuse-derived fuel proportion, the average activation energy of blends hit a minimum value of 95 kJ/mol by KAS method and 103 kJ/mol by FWO method.

Highlights

Global warming and anthropogenic emission of CO2 are crucial issues and have achieved great attention due to their critical impact on human society and ecosystem [1]
This study emphasizes the co-firing of low-rank local coal and refusederived fuel (RDF) as a resource to reduce the amount of solid wastes to landfill, by utilizing it under the waste to energy strategy
The obtained TG (% weight loss) and DTG thermograms for low-rank coal, RDF, and coal/RDF blends (10%, 20%, 30%, and 40% of RDF in coal) at a heating rate 10 ◦C/min under air atmosphere are illustrated in Figures 1 and 2

Summary

Introduction

Global warming and anthropogenic emission of CO2 are crucial issues and have achieved great attention due to their critical impact on human society and ecosystem [1]. This alteration of MSW into RDF may show significant improvement in: (a) recovery of materials such as glass and metal which may be reused or recycled, (b) reduction in materials which can contribute to pollution and maintenance issues, and c) enhanced consistency of RDF may help to transport and market it as a commodity to solid fuel consumers [12] Due to aspects such as the abundance of availability of coal and the long life of coal fired power plants, the usage of coal for power generation has been increased in developing countries. This study emphasizes the co-firing of low-rank local coal and RDF as a resource to reduce the amount of solid wastes to landfill, by utilizing it under the waste to energy strategy

Materials and Methods

Kinetic Modelling

Thermal Decomposition

Effect of Blending of Coal with RDF

Kinetic Analyses