Used Tires as Fuel in Clinker Production: Economic and Environmental Implications

Antonio Vega Y De La Fuente,Marc Bascompta,Lluís Sanmiquel,Fernando Gómez-Fernández,Víctor Contreras,Ana María Castañón

doi:10.3390/su131810455

Abstract

This work analyzes how gases emitted during the manufacture of clinker vary in a cement plant using two types of fuel: petroleum coke and unusable tires (UTs). This study is based on a case study using real time data on more than 40 process variables. Gases are analyzed from two points of the production process: from the sintering kiln, where the main focus of emissions to the atmosphere is by chimney, and from the preheater. The variation of CO and NOx depending on the oxygen and fuel type is studied. The SO2 levels are also analyzed and a decrease was observed when using the UTs. The quality of the clinker is compared according to the fuel type. The results are analyzed, on the one hand, by the quality of the clinker, determined by the content of the majority (C3S, alite) and minority (free CaO) phases, and, on the other hand, by the kiln sintering temperature, the most influential parameter in the productive process. It is verified that the clinker quality is maintained regardless of the type of fuel used. Therefore, the use of UTs as fuel could generate important economic and environmental benefits for cement companies.

Highlights

The goals of this study are: (a) compare how the gases emitted during the clinker manufacture vary in a cement plant using two types of fuel: petroleum coke and unusable tires (UTs), and (b) evaluate the introduction of UTs into the system from economic and environmental points of view
Of alite and free calcium oxide (CaO)); and (c) the concentration of O2, carbon monoxide (CO), nitrogen oxides (NOx), and SO2 emitted in the furnace, preheater, and stack
The results obtained provide an interesting insight into the usage and comparison between petroleum coke and alternative fuels from a real case study analyzing the emissions generated, the technical operability, and the economic implications of both fuel options

Summary

Introduction

Over the last thirty years, the scientific community has been reporting that the main source of greenhouse gases and global warming is the massive use of fossil fuels, such as coal, oil, and natural gas [1,2]. Various proposals have been put forward to mitigate their effects [3], prominent among which is the use of alternative fuels to reduce emissions [4]. In the case of cement factories, the substitution of traditional fossil fuels reduces emissions, CO2 , and provides a use for wastes such as sludge, municipal solid waste, and tires, yielding energy savings and environmental benefits [5,6,7,8], with several particular case studies analyzed in this regard [9]

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