Environmental Engineering Reference
In-Depth Information
T
ABLE 5.1
Overall Configuration of Technical Arrangements of High Performance
Industrial Furnace Development Project
(I)
Flame characteristics
F
ormation of radicals
1.
High capacity flame (flame with a high flame
capacity); flame with low concentration and
temperature gradients
1.
Green flame generation of CH-component
fuel by C
radical
2
2.
Quantization of C
, CH, OH radicals
2
2.
T
ransparent flame; flame without conspicuous
luminous flame
Lifted flame; stable flame distanced from fuel
nozzle or delayed combustion flame
3.
Reforming to polynuclear aromatic
hydrocarbon (PAH), precursor of soot by
fuel pyrolysis
3.
Flames not conforming to the conventional patterns
classified by combustion technology; new flame and
new combustion
Characteristics of high temperature air
combustion:
Spontaneous ignition
1.
Composite flame and composite combustion
Flame holding mechanism is not required
Flame patterns differ substantially depending
on the method of mixing air and fuel
Instantaneous peak flame temperature is low
Diffusion
Premixed
Turbulent
Laminar
combustion
flow
turbulent diffusion flame with the characteristics
of a premixed flame
Da: Damköhler number
despite using high temperature preheated
air
Temperature variation of the flame is very
2.
Da = reaction rate/transfer rate
small
Diluted combustion or low-oxygen
transfer time/reaction time
Low Damköhler number combustion
Well-stirred reactor; complete mixture system
flame
combustion results from recirculated
burned gas
Reaction zone becomes thick in low oxygen
combustion
3.
(II)
Air
High speed injection
Gas
Fuel dispersion
Dispersed
Diffusion · Suppression of mixing
combustion
Effect of premixing
Multistage
Air dispersion (oxidizing agent)
combustion
Strong recirculation of exhaust gas
Hard mixing, hard diffusion
Balanced combustion
Spontaneous combustion-combustion in low oxygen field higher than autoignition
temperature after-burning, reburning different from spatial position and time axis
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