Process Kinetics of the Carbonation of Fly Ashes: A Research Study

Łączny, Marian; Iwaszenko, Sebastian; Smoliński, Adam

doi:10.3390/ma14020253

Cited by 5 publications

(3 citation statements)

References 28 publications

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“…The combustion of pulverized coal after drying goes through two main stages [32]: the combustion (1) of the volatile fraction and (2) of fixed carbon. This is different from the coal that has not been directly dried and burned [33]. Figure 2 shows that TG curves are smooth in the weight-loss phase, indicating that the combustion of the volatile fraction and fixed carbon are closely linked during the combustion process.…”

Section: Thermal Analysis Of Mixed Combustion Of Semicoke and Bitumin...mentioning

confidence: 87%

Enhanced Combustion of Bituminous Coal and Semicoke Mixture by Ferric Oxide with Thermographic and Kinetic Analyses

Kou

et al. 2021

Materials

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We study the specific catalytic effect of the catalyst on the combustion process of pulverized coal of increasing the proportion of semicoke in the mixture of semicoke and bituminous coal, and reducing the cost of blast-furnace coal injection. A combination of thermogravimetric and kinetic analyses were used to study the catalytic effect of Fe2O3 on semicoke and bituminous coal, and to improve the amount of semicoke in the mixed coal powder of bituminous coal and semicoke. Experimental results showed that Fe2O3 had a catalytic effect on both semicoke and bituminous coal, but there were differences in the catalytic stages of the same catalyst for different pulverized coal types. The addition of 2 wt % Fe2O3 to semicoke and bituminous coal each led to the ignition temperature and maximal burning rate temperature of the semicoke decreasing, indicating that the catalyst promoted the precipitation of a volatile fraction from the semicoke. The maximal burning rate temperature and burnout temperature of the bituminous coal decreased, and maximal weight loss rate increased, indicating that the catalyst promoted the combustion of the fixed carbon of bituminous coal. The optimal proportioning amount of semicoke in the mixed coal powder without the addition of a catalyst was 25%. After adding 2 wt % Fe2O3, the proportional amount of semicoke increased by 10%. The addition of the catalyst resulted in even lower activation energy for the same conversion rate. When the conversion rate was in the ranges of 0.1–0.2 and 0.5–0.7, the activation energy decreased by 22% and 26%, respectively, compared with that without a catalyst. Fe2O3 promoted the combustion of bituminous coal and semicoke. This enhanced the combustion performance of the pulverized coal mix and increased the proportion of semicoke in the mix, which has certain guiding significance in reducing the cost of blast-furnace iron making.

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Section: Thermal Analysis Of Mixed Combustion Of Semicoke and Bitumin...mentioning

confidence: 87%

Enhanced Combustion of Bituminous Coal and Semicoke Mixture by Ferric Oxide with Thermographic and Kinetic Analyses

Kou

et al. 2021

Materials

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“…is obtained by burning ground raw materials in a rotary kiln. The five stages which can be distinguished in the clinker production process occur in the following order: (1) the dehydration process (heating and drying of the homogenized raw materials), (2) the calcination process (decomposition of raw materials into calcium oxide and carbon dioxide [33,34], (3) the clinkerization process (formation of clinker phases: tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF) and (4) the clinker cooling process. The cement manufacturing process, along with marked sources of pollutant emissions, is schematically displayed in Figure 2 [32].…”

Section: Cement Manufacturing Processmentioning

confidence: 99%

Conventional and Alternative Sources of Thermal Energy in the Production of Cement—An Impact on CO2 Emission

2021

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The article evaluates the reduction of carbon dioxide emission due to the partial substitution of coal with alternative fuels in clinker manufacture. For this purpose, the calculations were performed for seventy waste-derived samples of alternative fuels with variable calorific value and variable share in the fuel mixture. Based on annual clinker production data of the Polish Cement Association and the laboratory analysis of fuels, it was estimated that the direct net CO2 emissions from fossil fuel combustion alone were 543 Mg of CO2 per hour. By contrast with the full substitution of coal with alternative fuels (including 30% of biomass), the emission ranged from 302 up to 438 Mg of CO2 per hour, depending on fuel properties. A reduction of 70% in the share of fossil fuels resulted in about a 23% decrease in net emissions. It was proved that the increased use of alternative fuels as an additive to the fuel mix is also of economic importance. It was determined that thanks to the combustion of 70% of alternative fuels of calorific value from 15 to 26 MJ/kg, the hourly financial profit gain due to avoided CO2 emission and saved 136 megatons of coal totaled an average of 9718 euros. The results confirmed that the co-incineration of waste in cement kilns can be an effective, long-term way to mitigate carbon emissions and to lower clinker production costs. This paper may constitute a starting point for future research activities and specific case studies in terms of reducing CO2 emissions.

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“…The basics of coal-derived fluidized bed fly ash valorization in the process based on a direct semi-dry carbonation method with the use of 60%vol. carbon dioxide in air at a temperature range of 40–100 °C was tested at a laboratory scale in a thermogravimetric analyzer [ 9 ]. A dynamic model describing the carbonation process was also developed, and fitting of the experimental data to this model was performed with the use of the Levenberg–Marquardt algorithm.…”

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confidence: 99%