Combustion kinetics of Chinese Shenhua raw coal and its pyrolysis carbocoal

Wang, Yunfei; Song, Yinmin; Zhi, Keduan; Li, Yang; Teng, Yan; He, Rong; Liu, Quansheng

doi:10.1016/j.joei.2016.04.011

Cited by 33 publications

(16 citation statements)

References 47 publications

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“…The temperature at this part is relatively low (see Figure 5), which would slow the char ignition and fuel-N release. 26 In comparison to bituminous coal, the semi-coke is more difficult to combust at low temperature, 7 thus the NO x generation from semi-coke is slower at the bottom half part of burner zone. Then, with the burnout of semi-coke and the injection of bituminous coal, the amount of NO gets significantly increased at higher position.…”

Section: Influence Of Injection Height Of Semi-cokementioning

confidence: 99%

Computational fluid dynamics investigation on the effect of co-firing semi-coke and bituminous coal in a 300 MW tangentially fired boiler

Wang

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part A:

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In this paper, the effect of co-firing semi-coke in a 300 MW tangentially fired boiler was numerically investigated. The results indicate that the incomplete combustion heat loss and NO x emission both increase with semi-coke co-fired ratio. Semi-coke may be injected into the furnace at a different height, which can lead to different thermal efficiency and NO x emission. It is suggested that semi-coke should not be fed from the top or bottom layer burners, since this could give rise to high carbon content respectively in fly ash and bottom slag. In addition, injecting semi-coke from the top burners could significantly increase the NO x emission. Under 1/2 co-firing ratio, the optimal fuel allocation is that feeding semi-coke from the B, D, and E layer burners. The growth in semi-coke particle size could increase the unburned carbon loss and NO x emission. It is highly recommended to reduce the unburned carbon loss under semi-coke co-fired condition by increasing the stoichiometric ratio of primary air for semi-coke. As it is increased from 0.25 to 0.3, the combustion efficiency of the co-fired condition is 99.47%, the same as when only firing bituminous coal, and the NO x emission is about 30% higher.

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Section: Influence Of Injection Height Of Semi-cokementioning

confidence: 99%

Computational fluid dynamics investigation on the effect of co-firing semi-coke and bituminous coal in a 300 MW tangentially fired boiler

Wang

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part A:

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show abstract

“…The reaction process with changing O 2 concentration is taken as an example. The apparent kinetic model for different O 2 concentrations is assumed as: (14) in which, n and f o 2 denote the O 2 concentration exponent and O 2 concentration, respectively. After the replacement with f (α), logarithm is made at both sides of Equation 14:…”

Section: Rtmentioning

confidence: 99%

“…A, E, n, R = 8.314 J/(mol•K) and f (α) are used to substitute the corresponding values in Equation (14). After rearrangement, the consequently apparent kinetic model of coal based on this experiment data is described as Equation (36).…”

Section: Numbermentioning

confidence: 99%

“…The experiment of coal combustion with a 7% O 2 concentration was conducted in the same conditions as the experiment aforementioned in Section 2.2. In addition, the Achar differential method [36], Coats-Redfern integral method, and the method developed by Wang et al [14] (called the Wang method below in this paper) were respectively applied and the comparisons were provided for the prediction effect with the DIM method.…”

Section: Validationmentioning

confidence: 99%

“…For a long period of time, many scholars have been trying to explore the reaction mechanisms and the kinetic analysis methods to reproduce the basic characteristics of coal combustion. Wang et al [14] performed a kinetic analysis of raw coal and pyrolysis carbocoal using TG data. 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.…”

Section: Introductionmentioning

confidence: 99%

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A Novel Method of Kinetic Analysis and Its Application to Pulverized Coal Combustion under Different Oxygen Concentrations

et al. 2018

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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 × 10 17 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.

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The effect of soaking in increasingly alkaline aqueous solutions on the spontaneous combustion characteristics of bituminous coal

et al. 2021

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Summary The spontaneous combustion characteristics of residual air‐dried coal change after soaking, which can pose a threat to coal mining safety. To study the effects of increasing alkalinity, pH values (7–11), on the spontaneous combustion characteristics of coal, we conducted a number of experiments using thermogravimetry (TG) and Fourier‐transform infrared spectroscopy (FTIR). TG was used to investigate parameters including the ignition index ()Di, combustion characteristic index (S), combustion intensity index (Hf), and activation energy (E) to show any variations in oxidative exothermic characteristics of coal. The results showed that the values of Di and S of the coal samples after alkaline treatment, increased with the increasing pH values. However, the values of Hf and E followed the opposite trend. To further explain the reason behind these variations, we investigated functional groups of coal using FTIR. These results indicated that the active functional groups, including oxygen‐containing functional groups, methyl and methylene groups, of the coal, increased after alkaline treatment, which showed microscopically that the coal was more active after soaking. These parameter variations together illustrate that the oxidation activity of the coal was enhanced after the alkaline treatment, and that it is more prone to spontaneous combustion.

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Combustion kinetics of Chinese Shenhua raw coal and its pyrolysis carbocoal

Cited by 33 publications

References 47 publications

Computational fluid dynamics investigation on the effect of co-firing semi-coke and bituminous coal in a 300 MW tangentially fired boiler

Computational fluid dynamics investigation on the effect of co-firing semi-coke and bituminous coal in a 300 MW tangentially fired boiler

A Novel Method of Kinetic Analysis and Its Application to Pulverized Coal Combustion under Different Oxygen Concentrations

The effect of soaking in increasingly alkaline aqueous solutions on the spontaneous combustion characteristics of bituminous coal

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