Estimativa da composição elementar do carvão mineral de Candiota (RS) a partir da análise imediata

Abstract

The composition of the coal can be evaluated in relation to its proximate analysis and ultimate analysis. Proximate analysis is simple and inexpensive to perform, while ultimate analysis is more complex and expensive because it requires special equipment. A useful resource for the evaluation of coal is to obtain its elementary analysis from its immediate analysis. For this work we aim to obtain linear and non linear correlations from data from the immediate analysis of ash, volatile matter and fixed carbon and elementary analysis to estimate the carbon, hydrogen, oxygen and nitrogen content of Candiota coal. To estimate their respective elementary compositions, a set of 20 experimental analyzes of the literature was used to obtain correlations of 1st, 2nd and 3rd orders, they were evaluated using the following statistical parameters: average relative error, average standard deviation and coefficient of determination. The parameter estimation was obtained using the LibreOffice Calc software version 7.1.0.3 (x64) solver tool using the determination coefficient maximization criterion. The correlations obtained for carbon showed coefficients of determination from 0.52 to 0.86, for hydrogen from 0.77 to 0.83, for oxygen from 0.77 to 0.94 and for nitrogen from 0.39 to 0.64. The best results were achieved for the 3rd order correlations as they obtained the highest determination coefficients. The average relative errors obtained for the 3rd order correlations were 4.66%, 5.42%, 7.26% and 7.71% for carbon, hydrogen, oxygen and nitrogen, respectively. The 3rd order correlations, obtained in this work, were significant when compared to other authors’ correlations. LibreOffice Calc proved to be an efficient tool for finding correlations, in addition to being free and easy to operate. Finally, we emphasize that the correlations are important resources for application in studies of modeling and process simulation.