Comparative Analysis of Models of the Combustion Process of Coal Dust in a Turbulent Flow of a Torch of a Charcoal Boiler

This article provides an overview of existing turbulence models. The scheme of combustion of pulverized coal fuel, the construction of a pulverized coal boiler unit and the process of burning coal in the furnace of a boiler unit BKZ-420-140 are considered. We analyzed the existing turbulence models and selected the most optimal mathematical model to study the combustion process of pulverized coal fuel in order to increase the efficiency of the CHPP.

Ash Evaluation of Indonesian Coal Blending for Pulverized Coal-Fired Boilers

Coal calorific value is one of the main considerations for using coal as a power plant fuel. In addition, the requirements for indications of slagging and fouling are also important to maintain combustion efficiency. However, coal power plants often experience problems in boiler operations due to the use of certain types of coal, even though they have a relatively high calorific value. This research investigates the effect of coal blending on ash fouling and slagging in an experimental investigation using a drop tube furnace with or without additives. Five different types of coal from different locations have been used in this study. Pulverized low-rank coal samples are burned in a drop tube furnace at 1,175°C with probe temperatures of 550°C and 600°C, corresponding to the combustion chamber of 600 MW power plants, including superheater and reheater areas. The ash particles’ characteristics and material composition were also analyzed using scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) and X-ray diffraction (XRD), respectively. All coal mixture combinations demonstrated potential as a fuel for power plants that use pulverized coal-fired boilers. Because of its capacity to reduce slagging and fouling potentials, combining coal blending with the use of chemical additives yielded the greatest results.

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

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.