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1
Mohd Samsuri, Muhamad Shazarizul Haziq, Hasril Hasini, Noor Akma Watie Mohd Noor e Meor Mohd Faisal Meor Zulkifli. "Temperature Profile Assessment of Sub-Bituminous Coal by Using a Single Burner Combustion Test Facility". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 78, n. 1 (1 dicembre 2020): 1–10. http://dx.doi.org/10.37934/arfmts.78.1.110.
Testo completoAbstract (sommario):
This paper presents a thermogravimetric analysis and combustion test for different coals used in a coal-fired power plant in Malaysia. The main objective is to investigate the suitability of adopting a newly-introduced sub-bituminuous coal in an existing boiler furnace commonly firing standard design coals. In order to ensure that the new coal will not give an adverse effect to the boiler, detail analytical and thermal performance of the new coal is investigated, together with design and other limiting coals. The combustion test was performed in a scaled down, 150kW, single swirl burner combustion test facility available in TNB Research Sdn. Bhd. In the study, combustion gas temperature at different sectors downstream of burner region is measured to determine the peak temperature for all tested coals. Based on the investigation, it was noted that coal with the highest fixed carbon content gives the highest temperature measure at all sectors. Similarly, coal with the lowest fixed carbon gives the lowest temperature. The temperature profile for the newly tested coal was found to be comparable to the design and limiting value coals. Even though it was observed that the temperature given by the new coal is the highest slightly downstream of the burner, the temperature was observed to be decreases as combustion gas flow downstream of the combustor rig. Based on the observation it can be said that the new coal is suitable to be used by the existing boiler furnace.
2
Ran, Jing Yu, Li Juan Liu, Chai Zuo Li e Li Zhang. "Numerical Study on Optimum Designing of the Air Distribution Structure of a New Cyclone Combustor". Advanced Materials Research 347-353 (ottobre 2011): 3005–14. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.3005.
Testo completoAbstract (sommario):
A new type of cyclone combustor is designed based on the traditional pulverized coal liquid slag combustor in this paper. According to the characteristics of swirl combustion and flow, numerical simulation of pulverized coal combustion in a new cyclone combustor has carried out using Realizable k-ε equation model with swirl modified to gas phase and stochastic trajectory model under Lagrange coordinate system to particle phase. Flows and combustion characteristics under different working conditions are mainly studied by changing the angles of primary and secondary air inlets, and then structural characteristics of the combustor are analyzed. Results show that structural characteristics of the primary and secondary air have great influence on internal flow and combustion characteristics of the combustor. When the pitch angle, the rotation angle of the secondary air and the expansion angle of the primary air respectively are 20°, 51° and 60°, the combustion efficiency of the combustor can reach up to 98.1% and it is conducive to high-temperature liquid slagging. It is also helpful to prevented pulverized coal depositing and accumulating near the wall and then plugging the combusting channel during the starting stage in low temperature region.
3
Aich, Subhajit, Dibyajyoti Behera, Barun Kumar Nandi e Sumantra Bhattacharya. "Relationship between proximate analysis parameters and combustion behaviour of high ash Indian coal". International Journal of Coal Science & Technology 7, n. 4 (27 marzo 2020): 766–77. http://dx.doi.org/10.1007/s40789-020-00312-5.
Testo completoAbstract (sommario):
AbstractThis work presents the analysis of combustion characteristics of high ash Indian coal (28%–40%) collected from different mines of Singaurali coalfield, India. All the coal samples were characterized by proximate and gross calorific value analysis. Combustion performance of the coals were characterised using thermo-gravimetric analysis to identify the burning profile of individual coals. Various combustion kinetic parameters such as ignition temperature, peak temperature and burnout temperature, ignition index and burnout index, combustion performance index plus rate and intensity index of combustion process, activation energy were determined to analyse the combustion behaviour of coal. Further all these combustion properties were compared with the volatile matter, ash, fixed carbon and fuel ratio of each coal. Theoretical analysis shows that with increase in ash content, combustion performance initially increases and later descends. Further, coal with (25 ± 1.75)% volatile matter, 20%–35% ash and fuel ratio 1.4–1.5 were found to be optimum for coal combustion.
4
Yang, Shuang Ping, Jie Dong e Miao Wang. "Experiment on Combustion-Supporting Agent on PCI for Combustibility of Coal Powder". Materials Science Forum 658 (luglio 2010): 248–51. http://dx.doi.org/10.4028/www.scientific.net/msf.658.248.
Testo completoAbstract (sommario):
In order to improve the combustion effects of pulverized coal and replacement ratio of coals, the combustion- supporting mechanism, development and applications are analyzed and industry experiment are carried out based on the research of combustion- supporting agent without alkalis on coals combustion with TG- DTG- DSC ways. The results show that there is an optimum addition percent for coals combustion with combustion- supporting agent. The coal ratio and coke ratio are improved obviously with 1.7%combustion- supporting agent in LongGang.
5
Murko, V. I., V. V. Bukhmirov, E. N. Bushuev, A. K. Dzhundubaev, M. S. Sultanaliev e E. N. Temlyantseva. "Technological assessment of processes of water-coal fuel combustion of brown coal of Kara-Keche deposit of Kyrgyz Republic". Vestnik IGEU, n. 5 (31 ottobre 2022): 12–17. http://dx.doi.org/10.17588/2072-2672.2022.5.012-017.
Testo completoAbstract (sommario):
Brown coals are valuable natural resource. Brown coals of the Kara-Keche deposit are most of all ready for industrial development in the Kyrgyz Republic. To solve the problems of effective development of brown coal of this deposit, it is necessary to study the issues of direct combustion of water-coal fuel (WCF) without thermal stabilization of the flame with additional sources of heat release. Experimental studies of WCF combustion have been conducted at the experimental industrial technological stand of Siberian State Industrial University, Novokuznetsk city. Structural-rheological and thermal characteristics of a pilot batch of brown coal of the Kara-Keche deposit, as well as data on the organization of efficient combustion of WCF, have been obtained. Brown coal of the Kara-Keche deposit meets the requirements of pipeline transportation and direct combustion in the furnaces of boilers of thermal power plants and boiler houses. The resulted water-coal fuel of brown coal is effectively burned in a vortex adiabatic furnace and the combustion process is like the combustion of WCF of hard coals of “G” type.
6
Kazagic, Anes, Izet Smajevic e Neven Duic. "Selection of sustainable technologies for combustion of Bosnian coals". Thermal Science 14, n. 3 (2010): 715–27. http://dx.doi.org/10.2298/tsci1003715k.
Testo completoAbstract (sommario):
This paper deals with optimization of coal combustion conditions to support selection a sustainable combustion technology and an optimal furnace and boiler design. A methodology for optimization of coal combustion conditions is proposed and demonstrated on the example of Bosnian coals. The properties of Bosnian coals vary widely from one coal basin to the next, even between coal mines within the same basin. Very high percentage of ash (particularly in Bosnian brown coal) makes clear certain differences between Bosnian coal types and other world coal types, providing a strong argument for investigating specific problems related to the combustion of Bosnian coals, as well as ways to improve their combustion behavior. In this work, options of the referent energy system (boiler) with different process temperatures, corresponding to the different combustion technologies; pulverised fuel combustion (slag tap or dry bottom furnace) and fluidized bed combustion, are under consideration for the coals tested. Sustainability assessment, based on calculation economic and environment indicators, in combination with common low cost planning method, is used for the optimization. The total costs in the lifetime are presented by General index of total costs, calculated on the base of agglomeration of basic economic indicators and the economic indicators derived from environmental indicators. So, proposed methodology is based on identification of those combustion technologies and combustion conditions for coals tested for which the total costs in lifetime of the system under consideration are lowest, provided that all environmental issues of the energy system is fulfilled during the lifetime. Inputs for calculation of the sustainability indicators are provided by the measurements on an experimental furnace with possibility of infinite variation of process temperature, supported by good praxis from the power plants which use the fuels tested and by thermal calculations of the different options (different temperature in the boiler furnace) of the referent energy system.
7
Bee´r, J. M., e R. V. Garland. "A Coal-Fueled Combustion Turbine Cogeneration System With Topping Combustion". Journal of Engineering for Gas Turbines and Power 119, n. 1 (1 gennaio 1997): 84–92. http://dx.doi.org/10.1115/1.2815567.
Testo completoAbstract (sommario):
Cogeneration systems fired with coal or other solid fuels and containing conventional extracting-condensing or back pressure steam turbines can be found throughout the world. A potentially more economical plant of higher output per unit thermal energy is presented that employs a pressurized fluidized bed (PFB) and coal carbonizer. The carbonizer produces a char that is fed to the PFB and a low heating value fuel gas that is utilized in a topping combustion system. The topping combustor provides the means for achieving state-of-the-art turbine inlet temperatures and is the main contributor to enhancing the plant performance. An alternative to this fully coal-fired system is the partially coal, partially natural gas-fired air heater topping combustion cycle. In this cycle compressed air is preheated in an atmospheric pressure coal-fired boiler and its temperature raised further by burning natural gas in a topping gas turbine combustor. The coal fired boiler also generates steam for use in a cogeneration combined cycle. The conceptual design of the combustion turbine is presented with special emphasis on the low-emissions multiannular swirl burner topping combustion system and its special requirements and features.
8
Dudzińska, Agnieszka. "The Effect of Pore Volume of Hard Coals on Their Susceptibility to Spontaneous Combustion". Journal of Chemistry 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/393819.
Testo completoAbstract (sommario):
In this paper the results of the experimental studies on a relationship between pore volume of hard coals and their tendency to spontaneous combustion are presented. Pore volumes were determined by the gas adsorption method and spontaneous combustion tendencies of coals were evaluated by determination of the spontaneous combustion indexesSzaandSza′on the basis of the current Polish standards. An increase in the spontaneous combustion susceptibility of coal occurs in the case of the rise both in micropore volumes and in macropore surfaces. Porosity of coal strongly affects the possibility of oxygen diffusion into the micropores of coal located inside its porous structure. The volume of coal micropores determined on the basis of the carbon dioxide adsorption isotherms can serve as an indicator of a susceptibility of coal to spontaneous combustion.
9
Mohd Noor, Noor Akma Watie, Hasril Hasini, Muhamad Shazarizul Haziq Mohd Samsuri e Meor Mohd Faisal Meor Zulkifli. "CFD Analysis on the Effects of Different Coal on Combustion Characteristics in Coal-fired Boiler". CFD Letters 12, n. 10 (1 novembre 2020): 128–38. http://dx.doi.org/10.37934/cfdl.12.10.128138.
Testo completoAbstract (sommario):
Coal quality is essential for the optimum functioning of coal-fired power plants. One of the issues associated with coal quality deterioration is poor combustion behaviour which could result in ash deposition and environmental issues. This paper presents a CFD investigation of flow and combustion process in a full-scale furnace. Three different sub-bituminous coals with different properties were tested namely Coal A, B and C. The aim is to predict the combustion performance of these coals by observing its flow, temperature and species concentration inside the furnace. The exact boiler furnace geometry obtained from boiler operator was translated into CFD model with very little modification made for optimizing mesh. Grid dependency test carried out prior to the work shows the current mesh scheme is sufficient to accurately resolve the flow field. The results of the study show that combustion temperature for Coal B is the highest at approximately 1400°C. Coal C is predicted to give the highest velocity peak at certain regions of the furnace and interestingly enough, the same coal shows the shortest flame length and thus requiring additional flow to achieve the same penetration compared to other coals. Tracing of oxygen concentration inside the furnace show minimum oxygen left in the rear pass given by Coal A, indicating optimum combustion.
10
Tulepov, Marat I., Larissa R. Sassykova, Dauren A. Baiseitov, Bibigul U. Rakhimova, Fedosya Y. Abdrakova, Galiya A. Spanova, Sestager Kh Aknazarov e Zhansaya Beksultan. "Synthesis and optimization of combustion of briquettes based on substandard brown coals of Kazakhstan deposits with multipolymer binders". Mediterranean Journal of Chemistry 10, n. 3 (27 marzo 2020): 302–9. http://dx.doi.org/10.13171/mjc02003271253ls.
Testo completoAbstract (sommario):
The work aimed to study the process of burning coal briquettes with polymers. As the object of the research, the coals of Kazakhstan deposits were applied. The methodology of the study included theoretical and computational studies on the applied significance of coal processing, analysis by physicochemical research methods, pressing, drying and briquetting of coal with binders. It is shown that the briquettes combustion takes place stepwise and is characterized by a stationary regime. This is due to the mutual influence of the stages of pyrolysis of polyolefins and combustion of coke residue of substandard coal. In the combustion zone, the temperature did not depend on the content of polyethylene and was 400–500ºC in the coal burnout zone. The optimal compositions of briquettes supporting the combustion temperature of 1300°С were determined: coal-40 %, clay-20 %, polyethylene-40 %. Adding up to 20% clay to the polymer and coal mixture led to the formation of a combustion wave structure with symmetric temperature profiles. Thermogravimetric analysis shows that polyethylene plays the role of the initiator of combustion, burning at 500ºC, and in the future does not affect the maintenance of the combustion temperature of the briquette. The perspective of the results obtained is the possibility of utilization of low-demand coals of various brands of Kazakhstan deposits, which are waste of coal mining and coal enrichment with further production of coal briquettes of the required quality. Coal briquettes made from substandard coals with a multi-polymer binder, from chemical production waste have a higher calorific value, are mechanically robust during prolonged storage, do not crumble in the furnace until complete combustion, and are waterproof. These advantages determine their use for the population, as well as for various purposes of industrial economy, metallurgy and chemical industry.
11
Qiu, Shuxing, Ramana G. Reddy, Xianyou Huang, Chen Yin e Shengfu Zhang. "Relationships between Combustion Behavior in Air and the Chemical Structure of Bituminous Coal during Combustion Processes". Energies 15, n. 14 (15 luglio 2022): 5154. http://dx.doi.org/10.3390/en15145154.
Testo completoAbstract (sommario):
The structural parameters of five bituminous coals were analyzed by using X-ray diffraction and attenuated total reflection–Fourier transform infrared spectroscopy. The combustion behavior of coal was investigated by using a thermogravimetric analyzer under air conditions. Furthermore, the relationships between combustion parameters and the coal structure were established. The results show that bituminous coals contain crystalline and amorphous carbon. The aromaticity, interlayer spacing, average stacking height, aliphatic chain length, and the hydrocarbon-generating potential varied with the different bituminous coals. The coal samples exhibited similar weight changes during the combustion process, and the combustion parameters increased with increments in heating rate. The maximum combustion rate and activation energy increased with declining interlayer spacing and hydrocarbon-generating potential and increasing aromaticity, average stacking height, and aliphatic chain length. The bituminous coal for the utilization of combustion should have high aromaticity, a degree of graphitization, crystalline, long aliphatic chain length, and weak hydrocarbon-generating potential.
12
Fan, Jiuyuan, Gang Wang e Jiuling Zhang. "Study on Spontaneous Combustion Tendency of Coals with Different Metamorphic Grade at Low Moisture Content Based on TPO-DSC". Energies 12, n. 20 (15 ottobre 2019): 3890. http://dx.doi.org/10.3390/en12203890.
Testo completoAbstract (sommario):
In the environments of various open coal storage sites, mining-affected coalbeds, and goafs, etc., some coal bodies are often affected by external environmental factors. They are highly prone to spontaneous combustion in low moisture content (≤8%). In order to examine the effect of low moisture content on the spontaneous combustion tendency of coals with different metamorphic grade, we conducted a temperature programmed oxidation (TPO) experiment and differential scanning calorimetry (DSC) experiment to study the spontaneous combustion characteristics of coals with different metamorphic grade at four different low moisture contents. The change laws of the characteristic parameters of four different metamorphic grade coals at four different low moisture contents were comparatively analyzed. The experimental results indicate that: (1) Compared other low moisture content, anthracite and fat coal at a low moisture content of 1.2 % show a stronger tendency for spontaneous combustion, and long flame coal and lignite at a low moisture content of 3.4% and 5.6% are more prone to spontaneous combustion. (2) Four different metamorphic grade coals at a low moisture content of 7.8% are less prone to spontaneous combustion.
13
Cui, Wei, Qingjun Meng, Wenbo Li e Qiyan Feng. "Enrichment and Chemical Speciation of Vanadium and Cobalt in Stone Coal Combustion Products in Ankang, Shanxi Province, China". International Journal of Environmental Research and Public Health 19, n. 15 (27 luglio 2022): 9161. http://dx.doi.org/10.3390/ijerph19159161.
Testo completoAbstract (sommario):
Stone coal enriches more elements compared to other coals, especially Vanadium (V). The content of Co is relatively low, while its environmental risk is relatively high. This study collected the stone-coal samples to investigate the enrichment characteristics and the chemical speciation in the combustion products of V and Co in stone coal at an open-pit coal mine in Ankang City, Shanxi Province, China. A simulation combustion experiment and sequential chemical extraction were conducted. Mineral composition was analyzed for raw-stone coal and its combustion products. The results showed that most of V and Co are mainly enriched in combustion products during the combustion process, the enrichment capacity of Co is higher than V. With the increase in the combustion temperature, the bioavailable chemical speciation of V in stone coal combustion products increased, while Co decreased. If the combustion products are stored without effective treatment, the surrounding environment will be polluted, and then human health might be endangered.
14
Som, S. K., S. S. Mondal e S. K. Dash. "Energy and Exergy Balance in the Process of Pulverized Coal Combustion in a Tubular Combustor". Journal of Heat Transfer 127, n. 12 (25 luglio 2005): 1322–33. http://dx.doi.org/10.1115/1.2101860.
Testo completoAbstract (sommario):
A theoretical model of exergy balance, based on availability transfer and flow availability, in the process of pulverized coal combustion in a tubular air-coal combustor has been developed to evaluate the total thermodynamic irreversibility and second law efficiency of the process at various operating conditions. The velocity, temperature, and concentration fields required for the evaluation of flow availability have been computed numerically from a two-phase separated flow model on a Eulerian-Lagrangian frame in the process of combustion of pulverized coal particles in air. The total thermodynamic irreversibility in the process has been determined from the difference in the flow availability at the inlet and outlet of the combustor. A comparative picture of the variations of combustion efficiency and second law efficiency at different operating conditions, such as inlet pressure and temperature of air, total air flow rate and inlet air swirl, initial mean particle diameter, and length of the combustor, has been provided to shed light on the trade-off between the effectiveness of combustion and the lost work in the process of pulverized coal combustion in a tubular combustor.
15
Mohammad Nurizat Rahman. "Optimisation of Solid Fuel In-furnace Blending for an Opposed-firing Utility Boiler: A Numerical Analysis". CFD Letters 14, n. 9 (30 settembre 2022): 89–107. http://dx.doi.org/10.37934/cfdl.14.9.89107.
Testo completoAbstract (sommario):
Continuous research on the clean and effective use of coal is still necessary as coal will continue to play a key role in global energy supply for the foreseeable future. Hence, in the current study, the optimisation of in-furnace coal blending for one of Malaysia's opposed-firing utility boilers was numerically executed on the basis of hydrodynamics and combustion characteristics. The predicted FEGT from the numerical model was validated against the actual FEGT from the coal-fired power plant, revealing a difference of less than 10 %. Four (4) coal blended cases were tested, which included both bituminous (bit) and sub-bituminous (sub-bit) coals. The findings demonstrate that due to the difference in density between bit and sub-bit coals, the hydrodynamic performance is predicted to significantly improve when sub-bit coal is injected at the bottom burner as opposed to the upper burner. In terms of kinetics, the higher volatile matter (VM) of sub-bit coal in contrast to bit coal has been postulated to release a substantial amount of volatiles and improve the combustibility of bit coal. Furthermore, enhanced oxygen release from sub-bit coal volatiles can aggravate the gas-solid heterogeneous reaction during bit coal char combustion. As a result of the bottom burner's high temperature, it has been discovered that introducing sub-bit coals into those burners speeds up VM release and char combustion, which increases the rate of combustion. Thus, when combustibility rises, the peak temperature position moves downward, reducing the likelihood of delayed combustion and, consequently, the risk of heat exchanger pendant failure and ash deposition. In a furnace with a relatively long coal residence time, a considerable fraction (>20 %) of high gross calorific value (GCV) sub-bit coal (>5800 kcal/kg) is predicted to produce two peak flame temperatures exceeding 1600°C owing to the likelihood of enhanced char which created delayed combustion. Therefore, a furnace condition with a comparatively shorter coal residence time may aid in the rapid evacuation of residual char from the combustion/burner zone and minimise the potential for delayed combustion. Nonetheless, residual char escape may exacerbate the emission problem by releasing considerable unburned carbon. Overall, the current numerical model has the potential to be a reliable and cost-effective tool for investigating the combustion characteristics of coal blends in a power plant boiler.
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Pełka, Piotr, Grzegorz Golański e Paweł Wieczorek. "Evolution of the Structure and Mechanical Strength of a Coal Particle During Combustion in the Atmosphere of Air and the Mixture of Oxygen and Carbon Dioxide / Ewolucja Struktury Oraz Wytrzymałości Mechanicznej Ziarna Węgla Podczas Spalania W Atmosferze Powietrza Oraz Mieszaninie Tlenu I Dwutlenku Węgla". Archives of Mining Sciences 58, n. 3 (1 settembre 2013): 673–90. http://dx.doi.org/10.2478/amsc-2013-0047.
Testo completoAbstract (sommario):
Abstract The research was conducted on the basis of four different types of hard coal and one type of brown coal. There are typical coals commonly used as fuel in Polish CFB boilers. The combustion process was conducted at a temperature of 850°C and the atmosphere of ambient air as well as in the mixture of oxygen and carbon dioxide in different proportions. The research was carried out using specially prepared cubical coal particles with measurements of 15×15mm and also 10×10 mm. The change of the mechanical properties was analyzed based on three parameters, i.e. compression strength, Vickers hardness and fracture toughness. The analysis was supplemented by microscopic images of the surface of the particles using an atomic force microscope. The results obtained clearly indicated the mechanical changes of the coal during its combustion, particularly at the moment of ignition of the char. Moreover, the results correlate very well with the processes of coal comminution that have been described by other authors (Basu, 1999; Chirone et al., 1991) during combustion in the circulating fluidized bed and also explain the sudden change of susceptibility to erosion in the conditions with and without combustion. The measured values can be used as strength parameters in the modelling of the mass loss of coal particles in conditions of circulating fluidized bed combustor that are hard to describe.
17
Zhuikov, A. V., D. A. Loginov, G. R. Mongush, S. V. Chicherin e N. A. Zemlyansky. "Thermogravimetric analysis of the combustion of Tuva coals before and after their carbonization". iPolytech Journal 26, n. 2 (5 luglio 2022): 270–83. http://dx.doi.org/10.21285/1814-3520-2022-2-270-283.
Testo completoAbstract (sommario):
The process of combusting Tuva coals before and after their carbonization was studied using the methods of thermogravimetric analysis and electron microscopy. Coal samples were subjected to thermomechanical and elemental analysis, which revealed a higher content of volatile substances in Kaa-Khem coal (47.5 %) compared to Chadan coal (10 %). Following carbonization, a decrease in volatile substances to 11.5 % and 9.3 %, respectively, was observed. The conducted thermogravimetric analysis showed the ignition temperature of the coke residue of the Kaa-Khem and Chadan coal samples to increase by 76 °C and 90 °C, respectively, after carbonization. The burnup temperature of the coke residue after carbonizing (723 °C) Kaa-Khem coal samples remained effectively the same, while the Chadan coal showed an increase from 704 °C to 727 °C. The carbonization of coals was established to decrease the maximum reaction rate from 19 % per min to 10% per min for Kaa-Khem coal and from 26 % per min to 11 % per min for Chadan coal. The process of combusting the coke residue after coal carbonization was found to shift into the region of higher temperatures: from 448–723°C to 524–724°C for Kaa-Khem coal and from 436–704 °C to 526–727 °C for Chadan coal. A morphological analysis of the surface of coal particles after carbonization showed the appearance of larger-size pores and cracks on the surface of carbonates compared to coal before carbonization. The conclusion is made that the content of volatile substances, rather than the developed pore structure, comprises the main factor in improving the combustion characteristics of Tuva coals under the conditions of non-isothermal heating before and after their carbonization.
18
Hainley, D. C., M. Z. Haji-Sulaiman, S. Yavuzkurt e A. W. Scaroni. "Operating Experience With a Fluidized Bed Test Combustor". Journal of Energy Resources Technology 109, n. 2 (1 giugno 1987): 58–65. http://dx.doi.org/10.1115/1.3231325.
Testo completoAbstract (sommario):
This paper presents operating experience with a fluidized bed combustor burning various coals. The primary focus is on the effect of relevant coal properties on combustor performance. Tests were carried out using anthracite, HVB and HVC bituminous and sub-bituminous A coals, and petroleum coke. Comparisons of the performance of the combustion on the various fuels are made. A two-stage fluidized bed combustor operating in a single-stage mode without recycle was employed. Experimental measurements included temperature, fuel feed rate, fluidization velocity and bed height. For some of the coals, bed agglomeration was found to occur. The results indicate that coal properties have an important effect upon the operation of the fluidized bed combustor.
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Ghetti, Paolo, Ubaldo De Robertis, Salvatore D'Antone, Marco Villani e Emo Chiellini. "Coal combustion". Fuel 64, n. 7 (luglio 1985): 950–55. http://dx.doi.org/10.1016/0016-2361(85)90150-4.
Testo completo
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Umar, Datin, Suganal Suganal, Ika Monika, Gandhi Hudaya e Dahlia Diniyati. "The influence of steam drying process on combustion behavior of Indonesian low-rank coals". Indonesian Mining Journal 23, n. 2 (novembre 2020): 105–15. http://dx.doi.org/10.30556/imj.vol23.no2.2020.1105.
Testo completoAbstract (sommario):
Steam drying process of the Low Rank Coals (LRCs) has been conducted to produce coal which is comparable with the High Rank Coal (HRC). Characterization of the raw and dried coals was carried out through proximate, ultimate, calorific value, Fourier Transform Infrared (FTIR) spectroscopy and Thermo Gravimetry-Differential Thermal Analysis (TG-DTA) to study the combustion behavior of the coals. This study used Indonesian low rank coals coming from Tabang (TKK coal) and Samurangau (SP coal), East Kalimantan. The results indicate that the calorific value of the dried coals increases significantly due to the decrease in moisture content of the coal. The FTIR spectrums show that the methylene-ethylene (RCH3/CH2) and aromaticity-aliphaticity ratios (Rar/al) of the dried coals increased while the ratio of RCO/ar decreased which reflect that the rank of the coals increased equivalent to the high rank coal (bituminous). Meanwhile, the TG-DTA indicates that the ignition temperature (Tig) and combustion rate (Rmax) of the dried coals increased. This analysis expresses that the dried coals produced by steam drying process have better combustion behavior due to the higher calorific value than those of the raw coals.
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Teng, Ying Yue, Yu Zhe Liu, Quan Sheng Liu e Chang Qing Li. "Macerals of Shengli Lignite in Inner Mongolia of China and Their Combustion Reactivity". Journal of Chemistry 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/2513275.
Testo completoAbstract (sommario):
The macerals, including fusinitic coal containing 72.20% inertinite and xyloid coal containing 91.43% huminite, were separated from Shengli lignite using an optical microscope, and their combustion reactivity was examined by thermogravimetric analysis. Several combustion parameters, including ignition and burnout indices, were analyzed, and the combustion kinetics of the samples were calculated by regression. Fusinitic coal presented a porous structure, while xyloid coal presented a compact structure. The specific surface area of fusinitic coal was 2.5 times larger than that of xyloid coal, and the light-off temperature of the former was higher than that of the latter. However, the overall combustion reactivity of fusinitic coal was better than that of xyloid coal. The combustion processes of fusinitic and xyloid coals can be accurately described by both the homogeneous model and the shrinking core model. The features of xyloid coal agree with the shrinking core model when its conversion rate is 10%–90%. The activation energy of fusinitic coal during combustion can be divided into three phases, with the middle phase featuring the highest energy. The activation energy of xyloid coal is lower than that of fusinitic coal in the light-off phase, which may explain the low light-off temperature of this coal.
22
Ejesieme, Vitus O., Nicole Vorster, Juan Riaza, Gary Dugmore e Ben Zeelie. "Reclamation of ultra-fine coal with scenedesmus microalgae and comprehensive combustion property of the Coalgae® composite". Journal of Energy in Southern Africa 31, n. 1 (28 febbraio 2020): 14–27. http://dx.doi.org/10.17159/2413-3051/2020/v31i1a6430.
Testo completoAbstract (sommario):
Combustion of South African discard ultra-fine coal (i.e. coal dust), charcoal, microalgae biomass, and composites of the three under air were studied. The study involves to find out the effect of Scenedesmus microalgae biomass on the comprehensive combustion characteristics of the ultra-fines. Coal dust is considered as waste material, but it could be modified and combusted for energy. The composites were designed with Design Expert, and unlike blending with the dry microalgae biomass, fresh slurry was blended with the ultra-fine coal and charcoal. Non-isothermal combustion was carried out at heating rate of 15 C/min from 40 – 900 ºC and at flow rate of 20 ml/min, O2/CO2 air. Combustion properties of composites were deduced from TG-DTGA and analysed using multiple regression. On combustion, the interaction of coal-charcoal-microalgae was antagonistic (b = - 1069.49), while coal-microalgae (b = 39.17), and coal-charcoal (b = 80.37), was synergistic (p = 0.0061). The coal-microalgae (Coalgae®) indicated first order reaction mechanism unlike, coal, and the charcoal. Comprehensive combustion characteristics index of Coalgae®, (S-value = 4.52E8) was superior relative to ultra-fine (S-value = 3.16E8), which indicated high quality fuel. This approach to combusting ultra-fine coal with microalgae biomass is partly renewable, and it would advance the production of heat and electricity.
Key words: coal-dust, combustion, s-value, Coalgae®, renewable.
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Cowell, L. H., R. T. LeCren e C. E. Tenbrook. "Two-Stage Slagging Combustor Design for a Coal-Fueled Industrial Gas Turbine". Journal of Engineering for Gas Turbines and Power 114, n. 2 (1 aprile 1992): 359–66. http://dx.doi.org/10.1115/1.2906599.
Testo completoAbstract (sommario):
A full-size combustor for a coal-fueled industrial gas turbine engine has been designed and fabricated. The design is based on extensive work completed through one-tenth scale combustion tests. Testing of the combustion hardware will be completed with a high pressure air supply in a combustion test facility before the components are integrated with the gas turbine engine. The combustor is a two-staged, rich-lean design. Fuel and air are introduced in the primary combustion zone where the combustion process is initiated. The primary zone operates in a slagging mode inertially removing coal ash from the gas stream. Four injectors designed for coal water mixture (CWM) atomization are used to introduce the fuel and primary air. In the secondary combustion zone, additional air is injected to complete the combustion process at fuel lean conditions. The secondary zone also serves to reduce the gas temperatures exiting the combustor. Between the primary and secondary zones is a Particulate Rejection Impact Separator (PRIS). In this device much of the coal ash that passes from the primary zone is inertially separated from the gas stream. The two-staged combustor along with the PRIS have been designated as the combustor island. All of the combustor island components are refractory-lined to minimize heat loss. Fabrication of the combustor has been completed. The PRIS is still under construction. The combustor hardware is being installed at the Caterpillar Technical Center for high pressure test evaluation. The design, test installation, and test plan of the full-size combustor island are discussed.
24
Chai, Yi-fan, Jian-liang Zhang, Qiu-jun Shao, Xiao-jun Ning e Kai-di Wang. "Experiment Research on Pulverized Coal Combustion in the Tuyere of Oxygen Blast Furnace". High Temperature Materials and Processes 38, n. 2019 (25 febbraio 2019): 42–49. http://dx.doi.org/10.1515/htmp-2017-0141.
Testo completoAbstract (sommario):
AbstractThe actual combustion rate of pulverized coal in the blast furnace tuyere is hard to be measured. In this research, the combustion rate of pulverized coal injected into oxygen blast furnace was obtained by a new equipment. This equipment can simulate the actual blast furnace well, and the relationship between pulverized coal injection (PCI) ratio and AO/C was established by mathematical deduction. The experimental results show that the best combustibility of the four pulverized coals is C, and when the coal injection ratio is 350 kg/tHM, the combustion rate can be reached 79%, while the combustion rate of B in the same case is only 45.6%. With the increase of AO/C, the relative amount of oxygen to coal increases, the combustion conditions become better, and combustion rate of the pulverized coal increases. In addition, under the condition of high temperature and rapid combustion, with the increase of coal’s volatile, the combustion rate increases and the corresponding PCI ratio is also increased. By using the new equipment, the unburned coal under the oxygen blast furnace conditions can be collected for further study.
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HARADA, Eiichi, e Kenichi FUJII. "Coal partial combustor for low-NOx coal combustion system." Journal of the Fuel Society of Japan 69, n. 2 (1990): 112–17. http://dx.doi.org/10.3775/jie.69.112.
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Zhuikov, A. V., A. I. Matyushenko, V. A. Kulagin e D. A. Loginov. "Research of combustion of solid fuel mixture based on coals of different degrees of metamorphism in the regions of Yenisei Siberia". Power engineering: research, equipment, technology 24, n. 5 (9 dicembre 2022): 136–46. http://dx.doi.org/10.30724/1998-9903-2022-24-5-136-146.
Testo completoAbstract (sommario):
THE PURPOSE. Consider the combustion process of two coals of different degrees of metamorphism and their mixtures using thermogravimetric analysis based on the change in mass and the rate of change in mass during the heating of fuels. Determine the main characteristics of fuels and the combustion process (temperature of ignition and burnout of the coke residue). Determine the tendency to slagging of coal mixtures. METHODS. When solving the tasks, the thermogravimetric method (TGA). RESULTS. The article provides a brief overview of the combustion of non-design fuels at thermal power plants. The results of technical and elemental analysis of Chernogorsk bituminous coal and Balakhta brown coal are presented. A technique for determining the ignition temperature and burnout of the coke residue is described. The thermograms of the combustion process of two coals of different degrees of metamorphism and their mixtures are presented. The main characteristics of their combustion have been determined. A qualitative analysis of the surface of fuel particles for the presence of pores and cracks is shown. The calculation of the tendency to slagging of coal mixtures has been carried out. CONCLUSION. Thermogravimetric analysis showed an earlier ignition of the Balakhta brown coal in comparison with the Montenegrin bituminous coal. With an increase in the proportion of Balakhta coal in the coal mixture, the profile of the combustion curves shifts to the region of lower temperatures. The addition of 25% Balakhta coal reduces the ignition temperature of Chernogorsk coal by 16%, with an increase in the proportion of Balakhta coal in the mixture, the ignition temperature does not change. Balakhta coal has a high tendency to slagging furnace walls, in contrast to Chernogorsk coal, therefore, an increase in its mass fraction in the coal mixture increases the tendency to slagging furnace screens.
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Rowan, Steven L., Ismail B. Celik, Albio D. Gutierrez e Jose Escobar Vargas. "A Reduced Order Model for the Design of Oxy-Coal Combustion Systems". Journal of Combustion 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/943568.
Testo completoAbstract (sommario):
Oxy-coal combustion is one of the more promising technologies currently under development for addressing the issues associated with greenhouse gas emissions from coal-fired power plants. Oxy-coal combustion involves combusting the coal fuel in mixtures of pure oxygen and recycled flue gas (RFG) consisting of mainly carbon dioxide (CO2). As a consequence, many researchers and power plant designers have turned to CFD simulations for the study and design of new oxy-coal combustion power plants, as well as refitting existing air-coal combustion facilities to oxy-coal combustion operations. While CFD is a powerful tool that can provide a vast amount of information, the simulations themselves can be quite expensive in terms of computational resources and time investment. As a remedy, a reduced order model (ROM) for oxy-coal combustion has been developed to supplement the CFD simulations. With this model, it is possible to quickly estimate the average outlet temperature of combustion flue gases given a known set of mass flow rates of fuel and oxidant entering the power plant boiler as well as determine the required reactor inlet mass flow rates for a desired outlet temperature. Several cases have been examined with this model. The results compare quite favorably to full CFD simulation results.
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Israilov, M., T. Akbarov e Y. Nurboboyev. "SELF-HEATING AND SPONTANEOUS COMBUSTION ANGREN BROWN COAL". Technical science and innovation 2020, n. 3 (30 settembre 2020): 90–95. http://dx.doi.org/10.51346/tstu-01.20.3-77-0085.
Testo completoAbstract (sommario):
The article presents the issues of prevention and prevention of processes related to ensuring safe and comfortable working conditions in the development of coal deposits, namely the study of spontaneous combustion of coal Angren deposit. Chemical activity of coals at low temperatures contributing to spontaneous combustion is emphasized, as well as the influence of hot climate in the region on the increase in chemical activity of coals. In this connection, climatic conditions of the region have been studied, i.e., increased temperature (from +250 to +500C) gives a sharp increase in the chemical activity of Angren coal. The main parameter that characterizes reservoir properties and filtration coefficient, showing the ability of the reservoir to let fluid through under the influence of the applied pressure gradient, is determined. The causes of spontaneous combustion are studied, depending on the rate of oxygen sorption by coal, reducing its pre-injection of water into the coal bed before excavation, the method of calculation of determining the incubation period of spontaneous combustion of coal is given
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Sorokin, Anatoly, e Oleg Ageev. "The technology of gold-containing concentrates recovery from the coal combustion products of the Yerkovetskoye brown coal deposit (the Amur Region, Russia)". E3S Web of Conferences 56 (2018): 03003. http://dx.doi.org/10.1051/e3sconf/20185603003.
Testo completoAbstract (sommario):
The results of experimental research of the native gold distribution in the coal combustion products (CCP) obtained out of the brown coals of the Yerkovetskoye deposit combustion material in the experimental technological complex “Amur” (ETС “Amur”) are described in the article. The technology of the formation of slag, fly ash and products of wet cleaning of flue gases in the process of various combustion modes of coal combustion is examined. The possibility of the obtaining of enriched gold-containing concentrate by gravity and magnetic methods from the brown coal combustion products and extraction of native gold out of the concentrate is shown.
30
Demirbaş, Ayhan. "Biomass Co-Firing for Coal-Fired Boilers". Energy Exploration & Exploitation 21, n. 3 (giugno 2003): 269–78. http://dx.doi.org/10.1260/014459803769520070.
Testo completoAbstract (sommario):
In this study ground biomass and pulverized coal were used for co-firing test. The tests of co-firing of coal and biomass were carried out in a bench-scale bubbling fluidized bed combustor. Biomass is an attractive and sustainable renewable fuel to supplement coal combustion in utility boilers. Coal co-firing was successful with up to a 20% biomass mix boilers. Coal and biomass fuels are quite different in composition. Ash composition for the biomass is fundamentally different from ash composition for the coal. Chlorine in the biomass may affect operation by corrosion. Ash deposits reduce heat transfer and may also result in severe corrosion at high temperatures. Biomass and coal blend combustion is a promising combustion technology; however, significant development work is required before large-scale implementation can be realized. Issues related to successful implementation of coal biomass blend combustion are identified. Co-firing of coal and biomass is an effective method of control NOx. Formation of NOx decreases with the increase of biomass fraction.
31
Collins, Leo W., e David L. Wertz. "Mass Absorption Corrected X-ray Diffraction Analysis of Entrained-Flow Reactor Coal Combustion Products". Advances in X-ray Analysis 34 (1990): 429–35. http://dx.doi.org/10.1154/s0376030800014749.
Testo completoAbstract (sommario):
AbstractThe analysis of coal and the understanding of the combustion process is complex, due to the heterogeneous nature of the material and the myriad of high-temperature reactions inherent in this fossil fuel. The research presented below utilizes recently-developed x-ray diffraction methods to analyze the coal combustion products generated from a laboratory-scale entrained-flow reactor. The reactor was designed, constructed, and tested, as planned for the initial phase of a long-term project to evaluate the coals located in Mississippi. In this initial phase a well-characterized coal was used, supplied by The Pennsylvania State University. The proximate, ultimate, and sulfur analyses of the coal, PSOC 1368p, are outlined in the Appendix. X-ray diffraction techniques have been used In the past to characterize coals. An analysis of the mineral transformation during coal combustion has also been performed using x-ray diffraction instrumentation. The semi-quantitative results of the pyrite (FeS2) phase transformation at variable temperatures and the percent combustion of the coal, as determined by x-ray methods are reported below.
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KONG, Dejuan, Yong WANG, Qulan ZHOU, Na LI, Yuhua LI, Tongmo XU e Shien HUI. "B210 COMPARATIVE STUDY ON COMBUSTION PERFORMANCE OF PETROLEUM COKE, HEJIN COAL AND SHENMU COAL(Combustion-6)". Proceedings of the International Conference on Power Engineering (ICOPE) 2009.2 (2009): _2–135_—_2–139_. http://dx.doi.org/10.1299/jsmeicope.2009.2._2-135_.
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Shvydkii, V. S., S. P. Kudelin, I. A. Gurin e V. Yu Noskov. "Development of information modeling system of coal-dust fuel injection into tuyeres of blast furnace". Izvestiya. Ferrous Metallurgy 62, n. 12 (15 gennaio 2020): 979–86. http://dx.doi.org/10.17073/0368-0797-2019-12-979-986.
Testo completoAbstract (sommario):
The article considers a mathematical model of combustion zone of blast furnace working with the use of injection of coal-dust fuel. In this model, two subsystems were identified: 1) subsystem of heating the particles of coal dust and volatiles release in the combustion zone; 2) subsystem of heat exchange and combustion processes in the tuyere. A two-dimensional velocity field of gas in the combustion zone was investigated. The combustion processes are considered as a set of simultaneously developing phenomena of coke burning in a layer, single pieces of coke and particles of coal dust. The model includes following equations: total gas mass balance, gas component mass balance, gas heat balance, movement of coal dust particles and heat balance of coal dust particles. The model calculates maximum burning temperature in combustion zone; the distance from the cut of the tuyere to the focus of combustion; the length of the oxygen combustion zone; gas temperature; the content of gas phase components and the degree of carbon burnout of pulverized coal at the outlet of the tuyere combustion zone. Information-modeling system has been developed. It allows investigation of influence of combined blast characteristics, the properties of coke and coal-dust fuel, the geometric dimensions of tuyeres and other factors on temperature fields and concentrations of components of gas phase in combustion zone. The model also helps to select a rational mode of pulverized coal that will ensure completeness of its combustion in the tuyere combustion zone. Main functions of the program are as follows: representation of results of calculation in form of tables and diagrams, storage of options of basic data in a database and export of results of calculation to Microsoft Excel. Conclusions were made on reduction of combustion temperature in combustion zone and the approach of focus of combustion to the tuyere when pulverized coal was injected. The authors also have established the need to use coals with certain quality characteristics and place where coal dust was introduced into the blast stream.
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Hou, Shuhn-Shyurng, Chiao-Yu Chiang e Ta-Hui Lin. "Oxy-Fuel Combustion Characteristics of Pulverized Coal under O2/Recirculated Flue Gas Atmospheres". Applied Sciences 10, n. 4 (17 febbraio 2020): 1362. http://dx.doi.org/10.3390/app10041362.
Testo completoAbstract (sommario):
Oxy-fuel combustion is an effective technology for carbon capture and storage (CCS). Oxy-combustion for coal-fired power stations is a promising technology by which to diminish CO2 emissions. Unfortunately, little attention has been paid to the oxy-combustion characteristics affected by the combustion atmosphere. This paper is aimed at investigating the oxy-fuel combustion characteristics of Australian coal in a 0.3 MWth furnace. In particular, the influences of various oxygen flow rates and recirculated flue gas (RFG) on heating performance and pollutant emissions are examined in O2/RFG environments. The results show that with increases in the secondary RFG flow rate, the temperatures in the radiative and convective sections decrease and increase, respectively. At a lower oxygen flow rate, burning Australian coal emits lower residual oxygen and NO concentrations. In the flue gas, a high CO2 concentration of up to 94.8% can be achieved. Compared to air combustion, NO emissions are dramatically reduced up to 74% for Australian coal under oxy-combustion. Note that the high CO2 concentrations in the flue gas under oxy-coal combustions suggest great potential for reducing CO2 emissions through carbon capture and storage.
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Smajevic, Izet, Nihad Hodzic e Anes Kazagic. "Lab-scale investigation of Middle-Bosnia coals to achieve high-efficient and clean combustion technology". Thermal Science 18, n. 3 (2014): 875–88. http://dx.doi.org/10.2298/tsci1403875s.
Testo completoAbstract (sommario):
This paper describes full lab-scale investigation of Middle-Bosnia coals launched to support selection an appropriate combustion technology and to support optimization of the boiler design. Tested mix of Middle-Bosnia brown coals is projected coal for new co-generation power plant Kakanj Unit 8 (300-450 MWe), EP B&H electricity utility. The basic coal blend consisting of the coals Kakanj: Breza: Zenica at approximate mass ratio of 70:20:10 is low grade brown coal with very high percentage of ash - over 40%. Testing that coal in circulated fluidized bed combustion technique, performed at Ruhr-University Bohum and Doosan Lentjes GmbH, has shown its inconveniency for fluidized bed combustion technology, primarily due to the agglomeration problems. Tests of these coals in PFC (pulverized fuel combustion) technology have been performed in referent laboratory at Faculty of Mechanical Engineering of Sarajevo University, on a lab-scale PFC furnace, to provide reliable data for further analysis. The PFC tests results are fitted well with previously obtained results of the burning similar Bosnian coal blends in the PFC dry bottom furnace technique. Combination of the coals shares, the process temperature and the air combustion distribution for the lowest NOx and SO2 emissions was found in this work, provided that combustion efficiency and CO emissions are within very strict criteria, considering specific settlement of lab-scale furnace. Sustainability assessment based on calculation economic and environmental indicators, in combination with Low Cost Planning method, is used for optimization the power plant design. The results of the full lab-scale investigation will help in selection optimal Boiler design, to achieve sustainable energy system with high-efficient and clean combustion technology applied for given coals.
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Shin, Jeong-Seon, Dowon Shun, Churl-Hee Cho e Dal-Hee Bae. "A Study on the Co-Combustion Characteristics of Coal and Bio-SRF in CFBC". Energies 16, n. 4 (16 febbraio 2023): 1981. http://dx.doi.org/10.3390/en16041981.
Testo completoAbstract (sommario):
Bio-SRF based on livestock waste has low heating value and high moisture content. The concentration of toxic gases such as SOx, NOx, and HCl in the flue gas is changed according to the composition of fuel, and it has been reported. Therefore, the study of fuel combustion characteristics is necessary. In this study, we investigated combustion characteristics on the blended firing of coal and Bio-SRF (bio-solid refused fuel) made from livestock waste fuel in CFBC (circulating fluidized bed combustor). The raw materials for manufacturing Bio-SRF include agricultural waste, herbaceous plants, waste wood, and vegetable residues. Bio-SRF, which is formed from organic sludge, has a low heating value and a high moisture content. Bio-SRF of livestock waste fuel is blended with different ratios of coal based on heating values when coal is completely combusted in CFBC. In the result of experiment, the combustor efficiency of calculated unburned carbon concentration in the fly ash shows 98.87%, 99.04%, 99.64%, and 99.71% when the multi co-combustion ratio of livestock waste fuel increased from 100/0 (coal/livestock waste) to 70/30 (coal/livestock waste). In addition, the boiler efficiency is shown to be 86.23%, 86.30%, 87.24% and 87.27%. Through the experimental results, we have identified that co-combustion of livestock waste fuel does not affect boiler efficiency. We have systematically investigated and discussed the temperature changes of the internal combustor, compositions of flue gases, solid ash characteristics, and the efficiency of combustion and of the boiler during co-combustion of coal and Bio-SRF.
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WATANABE, Hiroaki, Kenji TANNO, Yuya BABA, Ryoichi KUROSE e Satoru KOMORI. "B201 LARGE-EDDY SIMULATION OF COAL COMBUSTION ON A PULVERIZED COAL COMBUSTION TEST FURNACE WITH A PRACTICAL SWIRL BURNER(Combustion-4)". Proceedings of the International Conference on Power Engineering (ICOPE) 2009.2 (2009): _2–83_—_2–88_. http://dx.doi.org/10.1299/jsmeicope.2009.2._2-83_.
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Novack, M., G. Roffe e G. Miller. "Combustion of Coal/Water Mixtures With Thermal Preconditioning". Journal of Engineering for Gas Turbines and Power 109, n. 3 (1 luglio 1987): 313–18. http://dx.doi.org/10.1115/1.3240041.
Testo completoAbstract (sommario):
Thermal preconditioning is a process in which coal/water mixtures are vaporized to produce coal/steam suspensions, and then superheated to allow the coal to devolatilize producing suspensions of char particles in hydrocarbon gases and steam. This final product of the process can be injected without atomization, and burned directly in a gas turbine combustor. This paper reports on the results of an experimental program in which thermally preconditioned coal/water mixture was successfully burned with a stable flame in a gas turbine combustor test rig. Tests were performed at a mixture flowrate of 300 lb/hr and combustor pressure of 8 atm. The coal/water mixture was thermally preconditioned and injected into the combustor over a temperature range from 350°F to 600°F, and combustion air was supplied at between 600°F to 725°F. Test durations varied between 10 and 20 min. Major results of the combustion testing were that: A stable flame was maintained over a wide equivalence ratio range, between φ = 2.2 (rich) and 0.2 (lean); and combustion efficiency of over 99 percent was achieved when the mixture was preconditioned to 600°F and the combustion air preheated to 725°F. Measurements of ash particulates, captured in the exhaust sampling probe located 20 in. from the injector face, show typical sizes collected to be about 1 μm, with agglomerates of these particulates to be not more than 8 μm. The original mean coal particle size for these tests, prior to preconditioning, was 25 μm. Results of additional tests showed that one third of the sulfur contained in the solids of a coal/water mixture with 3 percent sulfur was evolved in gaseous form (under mild thermolized conditions) mainly as H2S with the remainder as light mercaptans.
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Nakata, T., M. Sato, T. Ninomiya e T. Hasegawa. "A Study on Low NOx Combustion in LBG-Fueled 1500°C-Class Gas Turbine". Journal of Engineering for Gas Turbines and Power 118, n. 3 (1 luglio 1996): 534–40. http://dx.doi.org/10.1115/1.2816680.
Testo completoAbstract (sommario):
Developing integrated coal gasification combined-cycle systems ensures cost-effective and environmentally sound options for supplying future power generation needs. The reduction of NOx emissions and increasing the inlet temperature of gas turbines are the most significant issues in gas turbine development in Integrated Coal Gasification Combined Cycle (IGCC) power generation systems. The coal gasified fuel, which is produced in a coal gasifier of an air-blown entrained-flow type has a calorific value as low as 1/10 of natural gas. Furthermore, the fuel gas contains ammonia when a gas cleaning system is a hot type, and ammonia will be converted to nitrogen oxides in the combustion process of a gas turbine. This study is performed in a 1500°C-class gas turbine combustor firing low-Btu coal-gasified fuel in IGCC systems. An advanced rich-lean combustor of 150-MW class gas turbine was designed to hold stable combustion burning low-Btu gas and to reduce fuel NOx emissions from the ammonia in the fuel. The main fuel and the combustion air are supplied into a fuel-rich combustion chamber with strong swirl flow and make fuel-rich flame to decompose ammonia into intermediate reactants such as NHi and HCN. The secondary air is mixed with primary combustion gas dilatorily to suppress the oxidization of ammonia reactants in fuel-lean combustion chamber and to promote a reducing process to nitrogen. By testing under atmospheric pressure conditions, the authors have obtained a very significant result through investigating the effect of combustor exit gas temperature on combustion characteristics. Since we have ascertained the excellent performance of the tested combustor through our extensive investigation, we wish to report on the results.
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Chemezov, E., e K. Fedorov. "SPONTANEOUS COMBUSTION OF COALS IN PERMAFROST CONDITIONS". TRANSBAIKAL STATE UNIVERSITY JOURNAL 28, n. 2 (2022): 29–35. http://dx.doi.org/10.21209/2227-9245-2022-28-2-29-35.
Testo completoAbstract (sommario):
Taking into account the prospects for the growth of coal production in the conditions of the North-East, the countries require further development of research to more reliably justify measures to prevent endogenous fires in the permafrost zone, which cause serious economic damage and worsen the environmental situation due to the release of large amounts of toxic gases. The authors have studied the chemical activity and tendency to spontaneous combustion of coals in the permafrost zone. The effect of ambient temperature on the dynamics of oxidative processes in coal accumulations is shown. These studies have identified the main factor in preventing the endogenous fire hazard of coal deposits in the North-East of the country, which consists in maintaining negative or low air temperatures to prevent the intensification of oxidative processes in the coals of the permafrost zone. In laboratory conditions, the influence of physical and chemical factors on the process of spontaneous combustion of frozen coals was studied. Field experiments were carried out on many coal mines in the permafrost area. A system analysis and generalization of domestic and foreign methods of prevention of spontaneous combustion of coals has been carried out. Antipyrogenic compositions have been proposed to reduce the oxidizing ability of coals
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Wang, Yong Zheng, Xiu Juan Li, Su Le Tian e Chun Mei Lu. "Experimental Study on the Pollutants Release Characteristics During Combustion of Lean Coal with Different Coal Rank". Advanced Materials Research 518-523 (maggio 2012): 2143–46. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.2143.
Testo completoAbstract (sommario):
In this paper, the characteristics of SO2 and NO release during combustion of lean coal with different coal rank were experimentally studied in the one-dimensional furnace for pulverized coal combustion. The results showed: The coal property and proportion of the component coals have great influence on the characteristics of SO2 and NO release. The releasing concentration of SO2 and NO distributing along the furnace height is generally between that of component coals, and the releasing characteristics of SO2 and NO would be more near to that of the larger proportion coal. The measuring value of the formation concentration of SO2 and NO are different from the calculating value based on the weighted means of the component coals to a certain extent. While the different coal are added to lean coal, the time corresponding with peak value releasing concentration of SO2 and NO is different.
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Kim, Gyeong-Min, Jae Hyung Choi, Chung-Hwan Jeon e Dong-Ha Lim. "Effects of Cofiring Coal and Biomass Fuel on the Pulverized Coal Injection Combustion Zone in Blast Furnaces". Energies 15, n. 2 (17 gennaio 2022): 655. http://dx.doi.org/10.3390/en15020655.
Testo completoAbstract (sommario):
CO2 emissions are a major contributor to global warming. Biomass combustion is one approach to tackling this issue. Biomass is used with coal combustion in thermal power plants or with blast furnaces (BFs) because it is a carbon-neutral fuel; therefore, biomass provides the advantage of reduced CO2 emissions. To examine the effect of co-firing on pulverized coal injection (PCI) in BFs, two coals of different ranks were blended with the biomass in different proportions, and then their combustion behaviors were examined using a laminar flow reactor (LFR). The PCI combustion primarily functions as a source of heat and CO to supply the upper part of the BF. To create a similar PCI combustion environment, the LFR burner forms a diffusion flat flame with an oxygen concentration of 26% with a flame temperature of ~2000–2250 K at a heating rate of 105 K/s. The combustion characteristics, such as the flame structure, burning coal particle temperature, unburned carbon (UBC), and CO and CO2 emissions were measured to evaluate their effect on PCI combustion. With the increase in the biomass blending ratio, the brightness of the volatile cloud significantly increased, and the particle temperature tended to decrease. The fragmentation phenomenon, which was observed for certain coal samples, decreased with the increase in the biomass blending ratio. In particular, with an increase in the biomass blending ratio, the optimum combustion point occurred, caused by the fragmentation of coal and volatile gas combustion of biomass.
43
Wu, Yuguo, Yulong Zhang, Jie Wang, Xiaoyu Zhang, Junfeng Wang e Chunshan Zhou. "Study on the Effect of Extraneous Moisture on the Spontaneous Combustion of Coal and Its Mechanism of Action". Energies 13, n. 8 (16 aprile 2020): 1969. http://dx.doi.org/10.3390/en13081969.
Testo completoAbstract (sommario):
It is imperative to have an in-depth understanding of the effect of extraneous moisture on the spontaneous combustion of coal not only for the control and prevention of coal spontaneous combustion in the coal mining industry, but also for the optimization design and application of the technological process. In this study, the type of moisture in a coal body has been redefined for the first time from the perspective of disaster prevention and control, i.e., original occurrence of moisture in the coal matrix and the extraneous moisture from the technological process. A suit of coal bodies with different extraneous moisture was prepared by soaking long-flame coal with a low water content. Using a temperature-programmed oxidation test, the effects of extraneous moisture on the temperature increase rate of coal bodies and the emission characteristics of gaseous products during coal spontaneous combustion were studied. Moreover, combined with the characterization of thermal analysis and of pore structure test, the action the mechanism of extraneous moisture on the coal spontaneous combustion process was also explored. The experimental results indicated that the effect of the extraneous moisture content varied with the development of coal spontaneous combustion. In the slow oxidation stage, extraneous moisture played a physical inhibition role in the coal oxidation. In the accelerated oxidation stage, extraneous moisture exhibited a catalytic effect on the coal–oxygen reaction or directly participated in the reaction. After entering the rapid oxidation stage, a delayed effect appeared. When the coal temperature exceeded 180 °C, the spontaneous combustion characteristics of coals with different initial moisture contents gradually tended to achieved balance.
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Hussain, Ahmad, Faraz Junejo, Muhammad Nauman Qureshi e Afzal Haque. "Hydrodynamic and combustion behavior of low grade coals in the riser of a circulating fluidized bed combustor". NUST Journal of Engineering Sciences 11, n. 1 (10 marzo 2019): 1–11. http://dx.doi.org/10.24949/njes.v11i1.436.
Testo completoAbstract (sommario):
This study is conducted for understanding the fluidization behavior in a CFB combustor for low ranked coals. A lab-scale cold CFB test rig was built at the NFCIET Multan for understanding the fluidization behaviour. Influence of fluidizing air on the fluidization behavior was observed. It was found that voidage along the riser height is affected by riser geometry. The combustion behavior of low grade coals from Thar coal was also explored in a CFB Combustor. The influence of the fluidizing air on the combustion erformance was examined and their effect on emissions was established. The temperature in the riser of the CFB rose quickly to around 900°C. This rise in temperature has caused an increase in the amount of exhaust gasses which has their influence on the suspension density. From this study, a firsthand experience of combustion behavior of low grade Pakistani coals was documented.
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Wu, Jian Qun, Dun Xi Yu, Lan Lan He, Jun Chen, Meng Ting Si, Wei Zhi Lv e Ming Hou Xu. "Partitioning of Harmful Elements in PM10 from Air-and Oxy-Coal Combustion: Iron and Sulfur". Advanced Materials Research 726-731 (agosto 2013): 963–66. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.963.
Testo completoAbstract (sommario):
Adverse health effects of Fe and S in airborne particulate matter (PM) have been reported. However, little work has been done to characterize Fe and S in PM10 from coal combustion. In this study, a sub-bituminous coal (coal A) and a bituminous coal (coal B) were subjected to combustion in a drop tube furnace under air-and oxy-firing conditions. Size distribution and elemental composition of PM10 (PM with aerodynamic diameter 10 μm) were obtained by low pressure impactor and X-ray fluorescence techniques, respectively. The partitioning characteristics of Fe and S in PM10 were investigated. Data shows that particles of ~0.1μm contains the highest concentration of Fe for both coals under different combustion conditions. The concentration of Fe in the ultrafine particle mode decreases when switching from air combustion to oxy-fuel combustion with 21% O2. It increases when the oxygen concentration increases from 21% to 32% O2 during oxy-fuel combustion. Changing combustion conditions has little effects on Fe partitioning in particles >0.3μm. The concentration of S in PM10 increases with decreasing particle size, but changing combustion conditions have inconclusive influence. Fe and S are dominant elements in ultrafine particles, indicating a greater threat to human health.
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Taborda Acevedo, Esteban Alberto, William Jose Jurado Valencia e Farid B. Cortés. "Glycerol effect on the inhibition of spontaneous combustion of subbituminous coal". Boletín de Ciencias de la Tierra, n. 40 (1 luglio 2016): 64–74. http://dx.doi.org/10.15446/rbct.n40.55999.
Testo completoAbstract (sommario):
Factors favoring the phenomenon of spontaneous combustion in coal mainly depend on the intrinsic properties such as coal particle size, moisture content, among others; the medium in which it is located and how it is stored. Consistent with this, the objective of this work is to evaluate the effect of glycerol on the inhibition of self-combustion as water re-adsorption reducer through the addition of glycerol in different amounts (4, 8, 18 and 28% wt). The coal sample was extracted from the Córdoba department, Colombia. Incipient impregnation method was used to perform the addition of glycerol to the desired quantities. Characterizing the coal samples was performed by: TGA-DTG, nitrogen adsorption at -196 °C, C-H-N-O, FTIR, and SEM. The TGA of the coals evaluated in an air atmosphere, show changes in combustion properties of each sample. Di ignition index is reduced as the coal is impregnated with glycerol, obtaining its lowest value for 8wt% of glycerol. The effect of glycerol in inhibiting the spontaneous combustion of coal is exposed in the adsorption equilibrium; the sample with 8wt% glycerol shows the highest reduction of water adsorption in coal validating the proposed technology as inhibitor agent spontaneous combustion phenomenon found in Colombian coal.
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Kijo-Kleczkowska, Agnieszka. "Research on coal-water fuel combustion in a circulating fluidized bed / Badanie spalania zawiesinowych paliw węglowo-wodnych w cyrkulacyjnej warstwie fluidalnej". Archives of Mining Sciences 57, n. 1 (29 ottobre 2012): 79–92. http://dx.doi.org/10.2478/v10267-012-0006-5.
Testo completoAbstract (sommario):
In the paper the problem of heavily-watered fuel combustion has been undertaken as the requirements of qualitative coals combusted in power stations have been growing. Coal mines that want to fulfill expectations of power engineers have been forced to extend and modernize the coal enrichment plants. This causes growing quantity of waste materials that arise during the process of wet coal enrichment containing smaller and smaller under-grains. In this situation the idea of combustion of transported waste materials, for example in a hydraulic way to the nearby power stations appears attractive because of a possible elimination of the necessary deep dehydration and drying as well as because of elimination of the finest coal fraction loss arising during discharging of silted water from coal wet cleaning plants. The paper presents experimental research results, analyzing the process of combustion of coal-water suspension depending on the process conditions. Combustion of coal-water suspensions in fluidized beds meets very well the difficult conditions, which should be obtained to use the examined fuel efficiently and ecologically. The suitable construction of the research stand enables recognition of the mechanism of coal-water suspension contact with the inert material, that affects the fluidized bed. The form of this contact determines conditions of heat and mass exchange, which influence the course of a combustion process. The specificity of coal-water fuel combustion in a fluidized bed changes mechanism and kinetics of the process.
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Cai, Ping, Li Jun Zhao, Kun Wang e Song Tao Kong. "Experiment Study on Mixed Combustion of Biomass and Coal". Advanced Materials Research 978 (giugno 2014): 3–6. http://dx.doi.org/10.4028/www.scientific.net/amr.978.3.
Testo completoAbstract (sommario):
Mixed combustion of biomass and coal is a new combustion way of comprehensive utilization biomass and coal energy resources. Biomass is more volatile, lower combustion temperature, combustion is mainly concentrated in front, low calorific value and the use of value is limited. Coal is less volatile, high combustion temperature, combustion exothermic are mainly concentrated in coke combustion, and exothermic is high. Studying on the combustion process and the combustion characteristics of mixed combustion of biomass and coal is development technologies based of mixed combustion of biomass and coal. Choose two biomass sample Sawdust, confetti and a coal, analyze combustion characteristics to mixing sample of different ratio, to obtain combustion process of mixed sample, combustion performance impact of biomass to coal and calorific influence of coal to biomass.
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Qi, Juan, Jianjun Wu e Lei Zhang. "Influence of Molding Technology on Thermal Efficiencies and Pollutant Emissions from Household Solid Fuel Combustion during Cooking Activities in Chinese Rural Areas". Symmetry 13, n. 11 (21 novembre 2021): 2223. http://dx.doi.org/10.3390/sym13112223.
Testo completoAbstract (sommario):
Resident combustion of solid fuel has been widely acknowledged as a high potential for pollutant reduction. However, there is a marked asymmetry between more pollutant emission and less burned volatiles of biomass and coal in the combustion process. To study the solid fuel optimum combustion form in a household stove, both the pollution reduction and energy efficient utilization of crop straws and coals were investigated. Taking the molding pressure and clay addition ratio as variable process conditions, the research of bio-coal briquette (made from the mixture of anthracite and biomass) was implemented in the range of 15~35 MP and 5~15%, respectively. Biomass and coal work complementarily for each other’s combustion property development. In particular, the pyrolysis gas produced by biomass low-temperature devolatilization is featured with low ignition point and is distributed in the bio-coal briquette. Its own combustion provides energy for anthracite particle combustion. Consequently, a positive effect was identified when bio-coal briquettes were used as residential fuel, and further improvement manifested in reducing more than 90% of particle matter (PM) and achieving about twice the thermal efficiencies (TEs) compared with the mass-weighted average values of coal briquettes and biomass briquettes. 88.8 ± 11.8%, 136.7 ± 13.7% and 81.4 ± 17.7% more TEs were provided by wheat straw–coal briquettes, rice straw–coal briquettes and maize straw–coal briquettes. 93.3 ± 3.1% (wheat straw–coal), 97.6 ± 0.2% (rice straw–coal) and 90.4 ± 2.2% (maize straw–coal) in terms of PM2.5 emission factors (EFs) was reduced. For bio-coal briquette, a 25 MPa and 10% addition were determined as the optimum molding pressure and clay addition ratio. Bio-coal briquettes with higher TEs and lower PM EFs will bring about substantial benefits for air quality promotion, human health and energy saving.
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Robertson, A., e D. Bonk. "Effect of Pressure on Second-Generation Pressurized Fluidized Bed Combustion Plants". Journal of Engineering for Gas Turbines and Power 116, n. 2 (1 aprile 1994): 345–51. http://dx.doi.org/10.1115/1.2906826.
Testo completoAbstract (sommario):
In the search for a more efficient, less costly, and more environmentally responsible method for generating electrical power from coal, research and development has turned to advanced pressurized fluidized bed combustion (PFBC) and coal gasification technologies. A logical extension of this work is the second-generation PFBC plant, which incorporates key components of each of these technologies. In this new type of plant, coal is devolatilized/carbonized before it is injected into the PFB combustor bed, and the low-Btu fuel gas produced by this process is burned in a gas turbine topping combustor. By integrating coal carbonization with PFB coal/char combustion, gas turbine inlet temperatures higher than 1149°C (2100°F) can be achieved. The carbonizer, PFB combustor, and particulate-capturing hot gas cleanup systems operate at 871°C (1600°F), permitting sulfur capture by time-based sorbents and minimizing the release of coal contaminants to the gases. This paper presents the performance and economics of this new type of plant and provides a brief overview of the pilot plant test programs being conducted to support its development.