The research on gas diffusion through the coal ash layer during the coal combustion process

2002 ◽  
Vol 174 (10) ◽  
pp. 55-73 ◽  
Author(s):  
Hongtao Zhang ◽  
Jianhua Yan ◽  
Mingjiang Ni ◽  
Kefa Cen
Keyword(s):  
Coal Combustion ◽  
Combustion Process ◽  
Coal Ash ◽  
Gas Diffusion ◽  
Ash Layer

scholarly journals Simulation of Thermal Effects on the Flow Field in a Pilot-Scale Kiln

2021 ◽  
Author(s):  
I. A. Sofia Larsson ◽  
Anna-Lena Ljung ◽  
B. Daniel Marjavaara
Keyword(s):  
Flow Field ◽  
Coal Combustion ◽  
Thermal Effects ◽  
Iron Ore ◽  
Combustion Process ◽  
Pilot Scale ◽  
Mixing Properties ◽  
Process Gas ◽  
Mixing Rates ◽  
Computational Fluid Dynamics Cfd

AbstractThe flow field and coal combustion process in a pilot-scale iron ore pelletizing kiln is simulated using a computational fluid dynamics (CFD) model. The objective of the work is to investigate how the thermal effects from the flame affect the flow field. As expected, the combustion process with the resulting temperature rise and volume expansion leads to an increase of the velocity in the kiln. Apart from that, the overall flow field looks similar regardless of whether combustion is present or not. The flow field though affects the combustion process by controlling the mixing rates of fuel and air, governing the flame propagation. This shows the importance of correctly predicting the flow field in this type of kiln, with a large amount of process gas circulating, in order to optimize the combustion process. The results also justify the use of down-scaled, geometrically similar, water models to investigate kiln aerodynamics in general and mixing properties in particular. Even if the heat release from the flame is neglected, valuable conclusions regarding the flow field can still be drawn.

NOx process inhibition and energy efficiency improvement in new swirl modification device for steel slag based on coal combustion

2018 ◽  
Vol 16 (7) ◽  
Author(s):  
Junxiang Guo ◽  
Lingling Zhang ◽  
Daqiang Cang ◽  
Liying Qi ◽  
Wenbin Dai ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Flue Gas ◽  
Coal Combustion ◽  
Steel Slag ◽  
Coal Ash ◽  
Combustion Efficiency ◽  
Gas Temperature ◽  
Staged Combustion ◽  
Energy Efficiency Improvement ◽  
Swirl Combustion

Abstract In this study, a novel swirl combustion modified device for steel slag was designed and enhanced with the objective of achieving highly efficient and clean coal combustion and also for achieving the whole elements utilization of coal. Coal ash and steel slag were melted in the combustion chamber and subsequently entered the slag chamber. The detrimental substances solidified and formed crystals, which allowed for the comprehensive utilization of the ash and slag. Our experiments mainly aimed to mitigate the formation of NOx, while using the heat and slag simultaneously during the coal combustion without a combustion efficiency penalty. The increase in the device’s energy efficiency and reduction in the NOx emissions are important requirements for industrialization. The experiments were carried out in an optimized swirling combustion device, which had a different structure and various coal feeding conditions in comparison to previously reported devices. The fuel-staged and non-staged combustion experiments were compared under different coal ratios (bitumite:anthracite). For the fuel-staged combustion experiments, the NOx concentration in the flue gas was observed to decrease significantly when the coal ratio of 1:1, an excess air coefficient of 1.2, and a fuel-staged ratio of 15:85 were used. Under these conditions, the flue gas temperature was as high as 1,620°C, while the NOx concentration was as low as 320 mg/m3 at 6 % O2. The air-surrounding-fuel structure that formed in the furnace was very beneficial in reducing the formation of NOx. In comparison to other types of coal burners, the experimental combustion device designed in this study achieved a significant reduction of NOx emissions (approximately 80 %).

Mass Absorption Corrected X-ray Diffraction Analysis of Entrained-Flow Reactor Coal Combustion Products

1990 ◽  
Vol 34 ◽  
pp. 429-435
Author(s):  
Leo W. Collins ◽  
David L. Wertz
Keyword(s):  
Coal Combustion ◽  
Initial Phase ◽  
Flow Reactor ◽  
Combustion Process ◽  
Combustion Products ◽  
X Ray Diffraction ◽  
Coal Combustion Products ◽  
X Ray ◽  
Entrained Flow ◽  
Entrained Flow Reactor

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.

scholarly journals Biogeocenosis development during initial revegetation of a coal combustion ash dump

2018 ◽  
Vol 11 ◽  
pp. 00038 ◽  
Author(s):  
Natalia Sheremet ◽  
Ivan Belanov ◽  
Vladimir Doronkin ◽  
Tatiana Lamanova ◽  
Natalia Naumova
Keyword(s):  
Moisture Content ◽  
Plant Communities ◽  
Coal Combustion ◽  
Soil Cover ◽  
Thermal Power ◽  
Coal Ash ◽  
Soil Formation ◽  
Plant Species Composition ◽  
Initial Stage ◽  
Substrate Moisture

The initial stage of biogeocenoses development on the coal ash dump produced by the thermal power staton in Novosibirsk (55.000, 83.068), Russia, were studied after 9 years of spontaneous revegetation. Soil properties, soil cover and plant communities were examined in detail. The predominating types of embryozems and transition from open to succession plant communities were described. Soil substrate moisture content was found to determine changes in plant species composition, projective cover and abundance, altogether causing asynchronicity of soil formation in different sites.

Numerical simulation of the coal combustion process initiated by a plasma source

2014 ◽  
Vol 21 (6) ◽  
pp. 747-754 ◽  
Author(s):  
A. S. Askarova ◽  
V. E. Messerle ◽  
A. B. Ustimenko ◽  
S. A. Bolegenova ◽  
V. Yu. Maksimov
Keyword(s):  
Numerical Simulation ◽  
Coal Combustion ◽  
Combustion Process ◽  
Plasma Source

The Effect of Calcium-Bearing Mineral on Ash Melting Behavior During Zhundong Coal Combustion

2017 ◽  
Author(s):  
Ma Haidong ◽  
Wang Yungang ◽  
Zhao Qinxin
Keyword(s):  
Calcium Oxide ◽  
Coal Combustion ◽  
Coal Ash ◽  
Melting Behavior ◽  
Sintering Behavior ◽  
Efficient Operation ◽  
Transition Mechanism ◽  
Ash Melting ◽  
Zhundong Coal ◽  
Ash Melting Behavior

Two typical pulverized Zhundong coal with different calcium oxide contents in ash were selected to use in this work. The liquid nitrogen was used to cool ash rapidly at different temperatures, in order to avoid changes in mineral condition. The ash melting behavior and mineral transition mechanism, especially calcium-bearing minerals was studied by ash melting point test platform, XRD, XRF, SEM and EDS. The results showed that the different states of calcium are the dominant reasons for different sintering behaviors of coal ash. The calcium-bearing minerals in ash, such as calcium oxide (CaO), calcium silicate (CaSiO3), gehlenite (2CaO·Al2O3·SiO2), and anorthite (CaO·Al2O3·2SiO2), etc., are the most important factors influencing the initial sintering behavior of coal ash in the temperature range from 1373K to 1473K under oxidizing atmosphere during coal combustion. That is the reason why ash starts to melt at relatively high temperature during ash melting behavior in laboratory, but has severe slagging and contamination characteristic at low temperature during coal combustion in boilers. The research achievments have important guiding significance for the design of partially or completely burning Zhundong coal boiler as well as its long-term safe and efficient operation. (CSPE)

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