Experimental study on the combustion and NOx emission characteristics of a bituminous coal blended with semi-coke

Hu, Linyong; Yang, Zhilin; Chen, Denggao; Fang, Jugang; Zhang, Man; Wu, Yuxin; Zhang, Hai; Li, Zhenshan; Lyu, Junfu

doi:10.1016/j.applthermaleng.2019.113993

Cited by 47 publications

(15 citation statements)

References 18 publications

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“…The blending ratio of semicoke when cofiring with the bituminous coal was recommended to be lower than 40% based on the burnout data in a DTF. 26 As far as the authors are aware, there are few cocombustion applications of the CGFA in the full-scale boiler. A hypothesis of CGFA cocombustion with coal in a circulating fluidized bed (CFB) boiler 16 is put forward based on the laboratory-scale experimental results.…”

Section: Introductionmentioning

confidence: 99%

“…The cofiring of gasified semicoke and bituminous coal was experimentally studied in a drop-tube furnace, and the effect of oxygen and combustion temperature on the unburned carbon of the semicoke was investigated. The blending ratio of semicoke when cofiring with the bituminous coal was recommended to be lower than 40% based on the burnout data in a DTF . As far as the authors are aware, there are few cocombustion applications of the CGFA in the full-scale boiler.…”

Section: Introductionmentioning

confidence: 99%

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Combustibility and Cofiring of Coal Gasification Fine Ash with High Carbon Content in a Full-scale Pulverized Coal Furnace

et al. 2020

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Coal gasification fine ash (CGFA) having a high carbon content is produced in large quantity as a byproduct from coal gasifiers in China. CGFA is usually disposed of by landfill as a solid waste, which is not only detrimental to environment but also a loss of an enormous energy that renders the process inefficient. Therefore, it is crucial to make use of the high carbon content in the CGFA with an economic and environmentally friendly method. In this study, the ignition and burnout behavior of CGFA were investigated via a thermogravimetric analyzer (TGA), flat-flame burner (FFB), and drop-tube furnace (DTF). Further, the cofiring of CGFA was numerically studied in a tangentially fired pulverized coal boiler burning anthracite with various cofiring ratios (0%, 10%, 20%, and 30%). The TGA results show the similar oxidation reactivity, oxidation kinetics, and ignition behavior of CGFA with the anthracite. In the FFB atmosphere with practical heating rates, the CGFA and anthracite are both heterogeneously ignited with an ignition time of 8.1 and 7.6 ms, respectively. The particle size significantly affected the ignition time of CGFA, as the particle size decreased from 125 to 135 μm to 45−63 μm and the ignition time of CGFA decreased from 10.1 to 5.6 ms. The burnout test in DTF indicates that the promising burnout performance in a pulverized coal furnace required a crucial oxygen concentration >10%, and the CFD simulation results coincided well with the experimental data from DTF. The CFD modeling results of the full-scale furnace show that the cofiring of CGFA is feasible in the pulverized coal furnace burning anthracite. Compared with the mode of pure anthracite combustion, under the cofiring mode with 10−30% CGFA as the energy input, the central maximum temperature of the main combustion zone increases by 50−90 °C, resulting in the slightly improved burnout for both anthracite and CGFA.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Combustibility and Cofiring of Coal Gasification Fine Ash with High Carbon Content in a Full-scale Pulverized Coal Furnace

et al. 2020

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“…Compared with the air combustion, the oxy‐fuel combustion with elevated oxygen content has the advantages of accelerating combustion speed and promoting ignition of coal particle, which has a great adaptability and competitiveness. Previous studies on the combustion of these solid fuels mainly focused on the O 2 /N 2 conditions, while little research, if any, has been focused on oxy‐fuel cases 17,24 . The introduction of oxy‐fuel combustion technology inevitably has an impact, and the influences on the co‐firing performances are still vague.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies on the combustion of these solid fuels mainly focused on the O 2 /N 2 conditions, while little research, if any, has been focused on oxy-fuel cases. 17,24 The introduction of oxy-fuel combustion technology inevitably has an impact, and the influences on the co-firing performances are still vague. Moreover, the interactions and kinetics of oxy-fuel co-firing carbon-based fuels with bituminous coal are still not clear, which are imperative to be discussed and explored.…”

Section: Introductionmentioning

confidence: 99%

Oxy‐fuel co‐combustion performances and kinetics of bituminous coal and ultra‐low volatile carbon‐based fuels

et al. 2020

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Summary The co‐firing of bituminous coal under oxy‐fuel conditions is a feasible measure to improve the ignition and combustion performances of ultra‐low volatile carbon‐based fuels and effectively control pollutants. The present study aimed at the co‐combustion performances and kinetics of bituminous coal and ultra‐low volatile carbon‐based fuels under oxy‐fuel condition by means of thermogravimetric experiments. The results indicate that the volatile content in fuels is likely to affect the ignition temperature and the oxy‐fuel co‐firing of bituminous coal accelerates the ignition and advances combustion of ultra‐low volatile fuels. The combustion behaviors of individual fuel are retained in the co‐firing process to a large extent, and there is a slight synergy at the 350 to 950°C temperature range. Enhancing the oxygen concentration is effective to improve the combustion performances of ultra‐low volatile fuels in oxy‐fuel atmosphere. The apparent activation energy of residual carbon from coal‐water‐slurry gasification in oxy‐fuel atmosphere exceeds that from fluidized bed gasification, which is highly related to gasification technology and raw fuel properties. The apparent activation energy under condition of co‐firing bituminous coal and residual carbon from coal‐water‐slurry varies considerably, changed from 100 to 46 kJ/mol. Therefore, the addition of bituminous coal significantly reduces the activation energy of ultra‐low volatile fuels to improve the co‐firing performances. Based on the present investigation, a better understanding on the oxy‐fuel co‐firing of various carbon‐based solid fuels is obtained, thereby promoting the efficient and clean utilization of solid waste in the coal chemical industry.

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“…The results implied that the ignition and burnout performances improved with the mass fraction of bituminous coal. Hu et al 6 studied the blends of bituminous coal and semi-coke. The results illustrated that the increase of semi-coke deteriorated the combustion behaviors of the blends but barely affected the burnout behavior of blends.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on NO_x Generation Characteristic and Burnout Performance of Co-Combustion of Carbon-Based Solid Fuels under Deep-Staged Combustion

Wang

Jia

et al. 2019

Energy Fuels

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With the development of low-rank coal chemical industry, the production of low-volatile carbon-based solid fuels, such as pyrolyzed and gasified semi-cokes, is ever-increasing. However, it is difficult to use such fuels efficiently because of their poor burnout performance and high NO x generation during the combustion process. Co-combustion of semi-cokes with bituminous coal is a promising approach for large-scale utilization of semi-cokes with ultra-low volatile content. Nevertheless, the NO x generation and burnout characteristics of co-combustion of multiple carbon-based solid fuels are yet to be fully understood. In this paper, the cocombustion characteristics of semicokes and bituminous coal were investigated using a deep-staged co-combustion system. The experimental results indicate that NO x generation displays an increasing trend with the mass fraction of gasified semi-coke. The unburned carbon (UBC) generation in fly ash increases with the proportions of gasified and/or pyrolyzed semi-cokes. The NO x generated from char-N of semi-cokes is reduced by CO and CH i generated from volatile-N of bituminous coal. Compared to air combustion, the increase of oxygen concentration of the O 2 /CO 2 atmosphere is useful for the blended fuels to reduce NO x generation and improve burnout performance because of the prolonged residence time under oxygen enrichment conditions. The conversion of fuel nitrogen to NO x (N-NO x ) and the nitrogen left in ash (N-ash) in O 2 /CO 2 and O 2 /Ar atmospheres decrease with increasing oxygen concentration, with more fuel nitrogen converted into N 2 . When the oxygen concentration of over-fire air varies from 21 to 100%, the NO x generation is increased by 23% and the UBC is decreased by 45%. The present study can offer better understanding on large-scale clean utilization of pyrolyzed and gasified semi-cokes in the utility coal-fired power plants.

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Experimental study on the combustion and NOx emission characteristics of a bituminous coal blended with semi-coke

Cited by 47 publications

References 18 publications

Combustibility and Cofiring of Coal Gasification Fine Ash with High Carbon Content in a Full-scale Pulverized Coal Furnace

Combustibility and Cofiring of Coal Gasification Fine Ash with High Carbon Content in a Full-scale Pulverized Coal Furnace

Oxy‐fuel co‐combustion performances and kinetics of bituminous coal and ultra‐low volatile carbon‐based fuels

Experimental Investigation on NO_x Generation Characteristic and Burnout Performance of Co-Combustion of Carbon-Based Solid Fuels under Deep-Staged Combustion

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Experimental study on the combustion and NOx emission characteristics of a bituminous coal blended with semi-coke

Cited by 47 publications

References 18 publications

Combustibility and Cofiring of Coal Gasification Fine Ash with High Carbon Content in a Full-scale Pulverized Coal Furnace

Combustibility and Cofiring of Coal Gasification Fine Ash with High Carbon Content in a Full-scale Pulverized Coal Furnace

Oxy‐fuel co‐combustion performances and kinetics of bituminous coal and ultra‐low volatile carbon‐based fuels

Experimental Investigation on NOx Generation Characteristic and Burnout Performance of Co-Combustion of Carbon-Based Solid Fuels under Deep-Staged Combustion

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Experimental Investigation on NO_x Generation Characteristic and Burnout Performance of Co-Combustion of Carbon-Based Solid Fuels under Deep-Staged Combustion