Abstract
Currently, many efforts have been made to improve the approach to build kinetic models. Based on mathematical algorithms, a novel method (named DIM method) of kinetic analysis was introduced in detail. A formula combining differential and integral was deduced and applied to the determination of the mechanism function f(α). Subsequently, multivariable linear regression was conducted to simultaneously obtain the apparent activation energy E, pre-exponential factor A, and oxygen concentration exponent n. In the application of pulverized coal combustion under different oxygen concentrations (3%, 5%, 10%, 15%, and 21%), E, A, and n were calculated as 258,164 J/mol, 6.660 × 1017 s−1, and 3.326, respectively, and the mechanism function f(α) was determined as the Avrami-Erofeev equation. A validation was performed under a 7% oxygen concentration, which shows that the DIM method has a higher accuracy. This work can provide a reference for the study of kinetic analysis.
Highlights
Coal is one of the main fossil fuels [1] and is widely used in industrial boilers, so the efficient use of coal is crucial to the economy
The results showed that the first order kinetic model could fit the combustion process of raw coal and pyrolysis carbocoal well at different heating rates
In consideration of expecting to obtain a reliable kinetic method with a high accuracy, this paper aims at a novel method combining differential and integral, and multivariable linear regression
Summary
Coal is one of the main fossil fuels [1] and is widely used in industrial boilers, so the efficient use of coal is crucial to the economy. Moderate or intense low-oxygen dilution combustion can increase the efficiency and reduce the NOx emission of coal combustion [2,3]. Improving efficiency necessitates better understanding of the mechanisms of the coal combustion process. The kinetic triplet (mechanism function f (α), apparent activation energy E, and pre-exponential factor A) is vital to characterizing the process of coal combustion. The mechanism function was firstly proposed in the 1920s because the reaction order in the homogeneous phase reaction was incapable of characterizing the complex heterogeneous reaction, and it was rapidly developed in the 1930–1940s based on numerous experiments [9]. The exploration of the mechanism function laid a foundation for the kinetic model
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