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

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.

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Numerical Simulation of Premixed Propane/Air Flame Propagation Using a Dynamically Thickened Flame Approach

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.444-445.1574 ◽

2013 ◽

Vol 444-445 ◽

pp. 1574-1578 ◽

Cited By ~ 1

Author(s):

Hua Hua Xiao ◽

Zhan Li Mao ◽

Wei Guang An ◽

Qing Song Wang ◽

Jin Hua Sun

Keyword(s):

Numerical Simulation ◽

Flame Propagation ◽

Numerical Study ◽

Vortex Motion ◽

Combustion Process ◽

Single Step ◽

Premixed Combustion ◽

Premixed Flame ◽

Flame Surface ◽

Arrhenius Kinetics

A numerical study of premixed propane/air flame propagation in a closed duct is presented. A dynamically thickened flame (TF) method is applied to model the premixed combustion. The reaction of propane in air is taken into account using a single-step global Arrhenius kinetics. It is shown that the premixed flame undergoes four stages of dynamics in the propagation. The formation of tulip flame phenomenon is observed. The pressure during the combustion process grows exponentially at the finger-shape flame stage and then slows down until the formation of tulip shape. After tulip formation the pressure increases quickly again with the increase of the flame surface area. The vortex motion behind the flame front advects the flame into tulip shape. The study indicates that the TF model is quite reliable for the investigation of premixed propane/air flame propagation.

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Numerical Simulation on Moisture Influence to MSW Combustion

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1006-1007.181 ◽

2014 ◽

Vol 1006-1007 ◽

pp. 181-184

Author(s):

Zhu Sen Yang ◽

Xing Hua Liu ◽

Shu Chen

Keyword(s):

Numerical Simulation ◽

Moisture Content ◽

Flue Gas ◽

Combustion Process ◽

Average Temperature ◽

Excess Air ◽

Heat Value ◽

Moisture Influence ◽

Excess Air Coefficient ◽

Combustible Gases

The combustion process of municipal solid waste (MSW) in a operating 750t/d grate furnace in Guangzhou was researched by means of numerical simulation. The influence of MSW moisture content on burning effect was discussed. The results show that: with the moisture content dropped from 50% to 30%, the heat value could be evaluated from 13.72% to 54.91% and the average temperature in the furnace could be promoted 90-248°C. However, the combustible gases and particle in the flue gas of outlet would take up a high proportion since lacking of oxygen would lead to an incomplete combustion. The excess air coefficient should be increased to 2.043~2.593 in order to ensure the flue gas residence time more than 2s and temperature in the furnace higher to 800°C.

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