비구형 산화철을 위한 중간모델

목차

1. 서 론

2. 입자형상의 영향을 고려한 중간모델
2.1 비구형 입자를 위한 Thiele 수의 가정
2.2 총괄반응속도식
2.3 속도파라메터의 결정법

3. 고 찰
3.2 입자형상의 변화에 의한 반응속도 변화의 메카니즘
3.3 반응속도에 미치는 광석 형상의 영향

4.결 론

본문내용

hrough product layer included in
the intermediate model, (cm2/s)
Dso : Effective intraparticle diffusivity through reactant layer included in
the intermediate model, (cm2/s)
Ef, Ef': Effectiveness factor, (-)
F : Fractional reduction, (-)
kf : Mass transportation coefficient through gas film, (cm/s)
kv : Volume-based chemical reaction rate constant of Ishida-Wen's model, (s-1)
Lm : Non-spherical radius of reactant shell, (cm)
Lo : Non-spherical radius of pellet, (cm)
rm : Radius of reactant shell, (cm)
ro : Radius of pellet, (cm)
t : Reaction time, (s)
Greek letters
gamma_A
: Chemical reaction rate, (mol/cm3·s)
PHI , PHI '
: Thiele's modulus for non-spherical particle, (-)
phi_L
: Leva's shape coefficient, (the surface area of the sphere which has the same volume as a non-spherical particle)/(the surface area of the non-spherical particle), (-)
xi_m
: Dimensionless non-spherical radius of reactant shell,
xi_m
= Lm/Lo, (-)
θv: Dimensionless reaction time, (-)
θvc: Dimensionless reaction time of the 1st stage of the intermediate model, (-)
6. 참고문헌
(1) Y. Ono and T. Murayama : J. Jpn. Inst. Met, 25 (1986) 973
(2) H. W. Kang, W. S. Chung and T. Murayama : ISIJ Int., 38 (1998) 109
(3) H. W. Kang, W. S. Chung., T. Murayama and Y. Ono : ISIJ Int., 38 (1998), 324
(4) H. Y. Sohn and J. Szekely : Chem. Eng. Sci., 27 (1972) 763
(5) M. Ishida and C. Y. Wen : AIChE. J. 14 (1968) 311
(6) M. Leva : Chem. Eng. Prog., 48 (1947) 549
(7) T. Murayama and Y. Ono : Tetsu-To-Hagane 73 (1988) 1323
(8) W. E. Ranz and W. R. Marshall : Chem. Eng. Progr. 48 (1952) 1415
(9) H. W. St., Clair : Trans. Met. Soc. AIME 233 (1965) 1145
(10) H. W. Kang, U. C. Chung, W. S. Chung. I. O. Lee and Y. Ono : J. the Korean Inst. of Met. & Mater, 35(1997), 326.
CAPTION
Table 1. Characteristics of samples.
Table 2. Kinetic parameters obtained from the intermediate model considering particle shape effect.
Table 3. Condition for the calculation of the reaction curves shown in Figs. 7, 8 and 9.
Fig. 1. Conceptual diagram of Thiele's modulus for a non-spherical particle.
Fig. 2. Reduction curves for the reduction step of hematite to
magnetite with 10%CO-90%CO2 gas mixture. a) sample P2 at 900 ℃.
b) sample P5 at 900 ℃.
- Comparision of the measured reduction data with values calculated from
the intermediate model considering particle shape effect.
Fig. 3. Relation between modified Thiele's modulus
PHI
and
non-spherical radius
phi_L cdot r_o
.
Fig. 4. Relation between effectiveness factor Ef and
non-spherical radius
phi_L cdot r_o
.
Fig. 5. Relation between volume-based chemical reaction rate constant kv
and non-spherical radius
phi_L cdot r_o
.
Fig. 6. Relation between effective diffusivities through product layer Ds and in reactant zone Dso and non-spherical radius
phi_L cdot r_o
.
Fig. 7. Theoretical reduction curves for Φ values of 100 and 200.
Fig. 8. Theoretical reduction curves for Φ values of 10 and 20.
Fig. 9. Theoretical reduction curves for Φ values of 0.5, 1 and 2.

키워드

비구형 산화철,   중간모델,   속도파라메터의 결정법,   총괄반응속도식,   반응속도에 미치는 광석 형상의 영향,   입자형상의 영향을 고려한 중간모델