In this study, an extraction method and environmental scanning electron microscopy (SEM) are employed to reveal the changes in the occurrence mode of fluorine in a coal-fired power plant in Inner Mongolia, China. The different occurrence states of fluorine during coal combustion and emission show that fluorine in coal mainly assumes insoluble inorganic mineral forms. The results illustrate that the three typical occurrence modes in coal are CaF2, MgF2 and AlF3. The fluorine in fly ash can be captured by an electrostatic precipitator (EPS) or a bag filter. In contrast, the gaseous fluorine content in flue gas is only in the range of several parts per million; thus, it cannot be used in this study. The occurrence mode of fluorine in bottom ash and slag is inorganic villiaumite (e.g., soluble NaF, KF and insoluble CaF2) which is difficult to break down even at high temperatures. The occurrence mode of fluorine with the highest content in fly ash is physically adsorbed fluorine along the direction of the flue gas flow. The insoluble inorganic mineral fluoride content in fly ash is also high, but the gradually increasing fluorine content in fly ash is mainly caused by physical adsorption. Fluorine in the coal-fired power plant discharges mostly as solid products; however, very little fluorine emitted into the environment as gas products (HF, SiF4) cannot be captured. The parameters used in this study may provide useful references in developing a monitoring and control system for fluorine in coal-fired power plants.

The radiation emission of CO 2 plays an important role in the radiative heat transfer of high-temperature furnace and gas turbine, it is essential to estimate the radiative heat transfer of CO 2 accurately with an appropriate spectral database. Based on the two versions of high-resolution transmission molecular absorption databases (HITRAN 2008 and HITRAN 2016), the latest version of high-temperature molecular spectroscopic database (HITEMP 2010) and the high-temperature version of carbon dioxide spectroscopic databank (CDSD-4000), the statistical narrow band (SNB) model was employed to study the radiative heat transfer of CO 2 in a one-dimensional planar enclosure. The effects of four different spectral databases on accuracy of radiation calculation results of CO 2 were discussed. The results calculated with CDSD-4000 database were in good agreement with the benchmark, and the maximum average relative error was 6%. Moreover, the absolute values of the radiative heat source calculated with CDSD-4000 in all cases were larger than the benchmark, because there were more spectral lines involved in CDSD-4000 database. However, due to the lack of hot lines in HITRAN databases, significant deviation could be observed, especially for the high temperature cases with 39% maximum average relative error. Finally, the Planck mean absorption coefficients of CO 2 were calculated by the LBL method with CDSD-4000 database.

The combustion of a biomass with coal may be one of the most effective methods to improve energy utilisation efficiency. This study aims to investigate the combustion characteristics of distillers' grains with bituminous coal using a thermogravimetric analyser. The results demonstrate that increasing the proportion of distillers' grains in coal results in a reduced ignition temperature (T i) and burnout temperature (T b), and activation energy (E) in the combustion stage. Therefore, the comprehensive combustion index (CCI) improves. In an O 2 /CO 2 atmosphere, T i increased by ∼15°C, while T b did not change much. However, E and CCI declined relative to an O 2 /N 2 atmosphere. Under the O 2 /CO 2 atmosphere, with an increase in O 2 concentration from 10 to 40%, T i changed over a small range, but T b declined from 745.8 to 641.4°C, while E and CCI improved. As the heating rate rose from 10 to 30°C/min, the values of T i decreased (from 281.4 to 244.9°C), but the values of T b increased significantly (from 662.8 to 745.8°C); the value of E reduced, and CCI also improved. This research could provide useful information as a practical reference for heat and power production.

With the energy consumption increasing, the coal supply in China has been becoming tight, which has made it difficult for thermal power generation in Yunnan Province. Making full use of local inferior coal and biomass resources in Yunnan can remedy the lack of fuel in power plants. In this paper, an oxygen-rich atmosphere thermogravimetric experiment was performed for a blended sample of Xiaolongtan lignite, Yiliang tobacco rod, and Fuyuan bituminous coal. The combustion characteristics of the mixed fuel under several key operating parameters (i.e., mass ratios, oxygen concentration, and heating rates) were studied. The response surface methodology was used to determine the optimal blending ratio of the three fuels. The results show that the ignition and burnout temperature of coal decrease and the combustion time diminishes with the enrichment of oxygen. The optimal oxygen concentration in the practical application is around 30%. The activation energy and preexponential factor increase with the enlargement of oxygen concentration. Such complex evaluation and optimization approach ensure the stable operation of thermal power plant production.

The environmental pollution and high energy consumption caused by the coal-dominated energy structure in China have been the focus of attention for a long time. The co-firing of biomass with coal can save coal resources and realize effective utilization of biomass. In this paper, brewery wastewater sludge (SD) and bituminous coal (BC) were blended for an experimental study which aimed to provide basic experimental data and operational guidance as a reference for practical application in power plants. The co-firing characteristics of sludge and bituminous coal were studied. The results show that the burnout temperature and ignition temperature decrease with an increase in the sludge blending ratio. The Comprehensive Combustion Index (CCI) first rises, then decreases, reaching a maximum at about 15%. Compared with the atmosphere with 79% N2/21% O2, under the 79% CO2/21% O2 atmosphere, ignition is delayed and the burnout temperature is higher. Under an O2/CO2 atmosphere, as the O2 concentration improves, the thermo-gravimetric (TG) curve shifts to the low-temperature region, the burnout temperature drops significantly, and the comprehensive combustion characteristics are improved. With an increment of the heating rate, the curve of TG analysis shifts to the high-temperature region and the CCI increases. This study could provide helpful information on practical blending in coal-fired power plants for energy savings and emission reductions.