ISIJ International, Vol. 54 (2014), No. 1, pp. 43–48
Influence of Operation Parameters on Dome Temperature of COREX Melter Gasifier Jing SUN,* Shengli WU, Mingyin KOU, Wei SHEN and Kaiping DU School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083 China. (Received on May 13, 2013; accepted on September 22, 2013)
Statistical analysis and theoretical calculation have been carried out to study the parameters affecting dome temperature of COREX melter gasifier by using actual plant data. The relationship between parameters and dome temperature has been realized qualitatively and quantitatively. It is found that the dome temperature is influenced significantly by metallization, fuel rate, coal rate, coke rate, and oxygen volume. High volatile matter and low moisture coal are beneficial to maintaining dome temperature. Regression analysis was carried out and equations have been developed to predict and regulate dome temperature. KEY WORDS: COREX melter gasifier; dome temperature; metallization; fuel rate; regression analysis.
In the present paper, various factors on the dome temperature were researched based on 2010–2011 actual plant data of a steel enterprise COREX. Correlation analysis and regression analysis by means of statistical analysis software were used to analyze the qualitative and quantitative relationships between operation parameters and dome temperature. Furthermore, dome temperature model was developed on the basis of material and heat balance to calculate dome temperature in order to verify the statistical results.
1. Introduction COREX is the world’s first commercially established and industrially proven smelting-reduction process. It consists of two separate reactors: the pre-reduction shaft furnace and the melter gasifier. The dome of melter gasifier is a vital part of COREX process in which multiphase reactions taken place continuously. The hot DRI along with partially calcined fluxes from the pre-reduction shaft furnace is charged into the melter gasifier through downpipes. In addition, noncoking coal and a small amount of coke are continuously fed by lock hopper system. The dome temperature should be maintained at about 1 050°C to meet the thermal demand of endothermic reaction and to ensure the cracking of coal.1) The fluctuation of dome temperature is undesirable for stable operation. If the dome temperature is too low, the quality of reduction gas goes down due to the incomplete cracking of volatiles from coal and the gas pipes are clogged due to the formation of tar.2) However, if the dome temperature is too high, reduction gas takes more heat away which leads to a high energy loss of the dome and damage of refractory materials. Hence, the dome temperature of melter gasifier should be within a certain range to keep the operation stable. P. P. Kumar et al.3,4) studied the influence of coal size and raw materials on furnace performance in the COREX process. W. R. Xu et al.5) analyzed the factors affecting fuel rate. But their research results did not consider the factors affecting dome temperature in detail. Lee et al.2) developed a computational code for the COREX melter gasifier. However, their study focused only on the effects of C/O ratio, bed height and steam injection ratio on dome temperature. More detailed studies seem to be necessary in order to understand the factors influencing dome temperature and to provide directions for its prediction and control.
2. Statistical Analysis of Operation Parameters Affecting Dome Temperature Correlation analysis is used to test the significance of the relationship between two variables. Pearson correlation coefficient (Pxy) measures the strength and direction of a linear association between two variables. The value of Pxy ranges from –1 to +1 and is independent of the units of measurement. The case of Pxy=0 indicates little correlation between the variables; the case of Pxy= +1 or –1 indicates a significant correlation. A correlation coefficient of less than 0 indicates a negative correlation. That is, when one variable shows an increase in value, the other variable tends to show a decrease and vice-versa.6) Burden distribution mode is described by coal distribution index and DRI distribution index, which can be calculated by the following Eq. (1). The meaning of Eq. (1) is that burden tends to the edge area of melter gasifier with the increase of BDI. This is attributed to the weight of edge area (5 m ring) is larger than that of central area (0 m ring).
BDI = (d1 × 02 + d2 × 0.52 + d3 × 12 + d4 × 1.52 + d5 × 22 + d6 × 2.52 + d7 × 32 + d8 × 3.5 52 + d9 × 42 + d10 × 4.52 + d11 × 52 ) / (d1 × 0 + d2 × 0.5 + d3 ×1 + d4 × 1.5 + d5 × 2
* Corresponding author: E-mail:
[email protected],
[email protected] DOI: http://dx.doi.org/10.2355/isijinternational.54.43
+ d6 × 2.5 + d7 × 3 + d8 × 3.5 + d9 × 4 + d10 × 4.5 + d11 × 5) .......................................... (1) 43
© 2014 ISIJ
ISIJ International, Vol. 54 (2014), No. 1
Where BDI represents burden (coal or DRI) distribution index; d1, d2, d3, d4, d5, d6, d7, d8, d9, d10, d11 represent the thickness of burden (coal or DRI) at 0 m, 0.5 m, 1 m, 1.5 m, 2 m, 2.5 m, 3 m, 3.5 m, 4 m, 4.5 m, 5 m rings, respectively. Based on the principle of correlation analysis, this paper analyzed the effects on dome temperature exerted by metallization, melting rate, fuel rate, oxygen volume, coke rate, coal rate, moisture of coal, volatile matter, fuel fines fraction, oxygen velocity, burden distribution mode. Table 1 shows statistical results of Pearson correlation coefficient and the range of operation parameters used for correlation analysis. It can be observed that the dome temperature has positive correlations with metallization, oxygen volume, oxygen velocity, coal distribution index while it has negative correlations with melting rate, fuel rate, coke rate, coal rate, moisture of coal, volatile matter, fuel fines fraction, DRI distribution index. The larger the absolute value of Pxy, the stronger the linear relationship between two variables, so the main parameters affecting dome temperature are metallization, melting rate, fuel rate, coal rate, coke rate, oxygen volume. Based on the correlation analysis, multiple regression analysis7,8) was carried out to study the quantitative relationship between operation parameters and dome temperature. Because of multicollinearity existing in multiple regression, the variance of parameter estimation value become larger and analysis results are inaccurate. Then stepwise regression analysis was proposed for decreasing the degree of multicollinearity. The factors, which are not significant and diagnosed as existing multicollinearity, have been removed to ensure the accuracy of the results. The regression output is presented in Eq. (2).
Table 1. Correlation analysis for parameters and dome temperature.
DT = 1 233.188 + 0.782 ⋅ Met-0.140 ⋅ FR-0.128 ⋅ .... (2) Coal-0.400 ⋅ Coke + 0.003 ⋅ OB
Pearson correlation coefficient
Range
Metallization
0.538
40–70%
Melting rate
–0.528
100–160 t/h
Fuel rate
–0.463
900–1 600 kg/tHM
Coal rate
–0.341
600–1 000 kg/tHM
Coke rate
–0.291
30–300 kg/tHM
Oxygen volume
0.230
17 000–25 000 m3/h
Oxygen velocity
0.214
100–200 m/s
Moisture in coal
–0.152
4–7%
Volatile matter in coal
–0.222
30–38%
Fuel fines fraction
–0.146
10–25%
Coal distribution index
0.045
2.5–3.8
DRI distribution index
–0.154
3–4
Fig. 1.
Where DT is the dome temperature (K), Met, FR, Coal, Coke and OB are metallization (%), fuel rate (kg/tHM), coal rate (kg/tHM), coke rate (kg/tHM) and oxygen volume (m3/h), respectively. The plant data in April 2011 of COREX-3000 are used to verify the regression equation as shown in Fig. 1. It can be seen that the predicted dome temperature matches well with the actual values and the determination coefficient (R2) is 0.73. And the regression standardized residual follows the normal distribution. The difference between predicted and actual values is within ±2% for dome temperature in the range of 1 323 K to 1 358 K. The developed regression equation provides a good direction to predict dome temperature.
Actual and predicted dome temperature.
reduced by CO and H2 respectively. Then iron-bearing materials discharged into melter gasifier include sponge iron and unreduced ferrous oxides. According to practical operation, the calcination degrees of limestone and dolomite are assumed as 0.5 and 1 respectively. The ratio of CO consumed by combustion reaction in the melter gasifier was set as 0.09 while H2 was set as 0.11. On this condition, the degrees of direct and indirect reduction were calculated to be 0.15 and 0.22 respectively. In addition to combustion reaction and reduction of residual iron oxide, the chemical reactions taken place in the melter gasifier also include the decomposition of carbonates, carbon solution reaction, water gas shift reaction, devolatilization of coal and formation of methane. Table 2 shows the heat input and output based on material balance and chemical reactions. It is found that carbon combustion reaction in the raceway generated a lot of heat and provided almost 60% of the total heat required in the melter gasifier. On the other hand, 36% of the total heat was taken away by reduction gas which is the biggest heat consumption item. Secondly, hot metal and slag also took a lot of heat which accounted for 23.79% of the total heat. The rest of heat consumption was for endothermic reactions and heat loss. In this model, the heat loss was 11.33% and the value was kept constant for further investigation when operation parameters were changed.
3. Theoretical Calculation Analysis of Operation Parameters Affecting Dome Temperature A comprehensive model was developed based on material and heat balance.9–15) The data used in the calculation model are from COREX-3000 actual production in October 2010. Material balance was calculated by means of the element balance of Fe, C, H and O. Heat balance was calculated based on chemical reactions, heat input and output. In the pre-reduction shaft furnace, iron oxides are gradually reduced. It is assumed that ferric oxides are completely reduced to ferrous oxides by CO and ferrous oxides are © 2014 ISIJ
Parameter
44
ISIJ International, Vol. 54 (2014), No. 1 Table 2.
The heat balance of melter gasifier.
Heat input
Quantity of heat (MJ/tHM) Percentage (%)
Combustion reaction in raceway
4 520.44
59.68
CH4 reaction
155.30
2.05
Discharged burden
835.09
11.03
H2combustion reaction
453.05
5.98
1 424.66
18.81
185.87
2.45
CO combustion reaction Slag generation Total heat input
7 574.41
Heat output
100
Quantity of heat (MJ/tHM) Percentage (%)
Reduction of iron oxides
391.47
5.17
Reduction of Mn, Si, P and S
181.77
2.40
Water gas shift reaction
319.13
4.21
Carbon solution loss
240.45
3.17
Decomposition of carbonates Hot metal
273.08
3.61
1 221.68
16.13
Slag
579.97
7.66
Gas
2 703.92
35.70
Decomposition of coal
695.31
9.18
Furnace dust
109.08
1.44
Heat loss
858.55
11.33
Fig. 2.
The comparison of actual and predicted slag rate.
Table 3. The comparison of gas composition in the literature and present model. CO (%) H2 (%) CO2 (%) H2O (%) N2 (%) CH4 (%) Present model
64.41
18.87
9.59
3.86
0.50
2.76
Literature
68.55
23.13
4.37
2.53
0.42
1.00
Differences
–4.14
–4.26
5.22
1.33
0.08
1.76
Fig. 3.
Thus, the dome temperature can be calculated based on the model at the effect of different operation parameters. The plant data in October 2010 of COREX-3000 are used to verify the calculation model, the comparison of predicted and actual slag rate is shown in Fig. 2. It can be seen that the predicted slag rate matches well with the actual values. The difference between predicted and actual values is within ±10% for the slag rate in the range of 240 kg/tHM to 351 kg/tHM. Slag basicity is calculated by mass balance equations and CaO/SiO2, which ranges from 1.18 to 1.37. The variation of predicted and actual slag basicity is shown in Fig. 3. The maximum difference between predicted and actual slag basicity is 0.11 which shows that the present model can predict slag basicity in an exact range. Export gas volume can be calculated based on generator gas, reducing gas, top gas, cooling gas and dust by present model. The measurement value from operation practice in October 2010 ranges from 1 633.43 m3/tHM to 1 813.75 m3/tHM as shown in Fig. 4. The average predicted export gas volume is 1 740.94 m3/tHM while the actual value is 1 721.93 m3/tHM. The relative error is 1%, which shows that the predicted results are in good agreement with operation practice results. Qu et al.9) has developed the generator gas composition module, the gas volume of meter gasifier is 30.37 m3/tHM lower than that in present model and the difference is 1.82%. This is due to high fuel rate and carbon content in
Fig. 4.
The comparison of actual and predicted slag basicity.
The comparison of actual and predicted export gas volume.
this model. The comparison of gas composition between two models is shown in Table 3. The metallization in Qu et al.’s research is assumed to be 85% while it is 61% in present model, so the content of CO in present model is 4.14% lower than their results and CO2 is 5.22% higher. The results of this model are quite close to the results from Qu et al.’s research. Through the comparison with operation practice and previous work, the present model is verified to be accurate. Based on the theoretical calculation model, the effects of DRI metallization, fuel rate, coal rate, coke rate, oxygen 45
© 2014 ISIJ
ISIJ International, Vol. 54 (2014), No. 1
volume and coal species on dome temperature are studied. The quantitative relationship between operation parameters and dome temperature provides prediction and control for dome temperature. 3.1. Effect of DRI Metallization The metallization degree greatly affects dome temperature because the FeO content determines the heat consumption in the reduction process. Higher metallization degree of DRI requires less quantity of heat and reductant. The amount of reduction reactions and gas volume decreases with the decrease of ferrous oxides. In the base model, the volume of reduction gas is 1 700.54 m3/tHM. When the metallization degree is increased by 5%, the content of CO2 in reduction gas is reduced by 10.20 m3/tHM, which is generated by indirect reduction. The amount of FeO consumed by indirect reduction is decreased by 32.80 kg/tHM which results in the quantity of releasing heat occurred on the top of char bed decreasing by 6.20 MJ/tHM. On the other hand, with the metallization degree increasing, the amount of FeO consumed by direct reduction is decreased by 28.37 kg/tHM and the heat consumption occurred on the top of tuyeres and dome of melter gasifier is decreased by 59.89 MJ/tHM. Therefore, the excess heat caused by metallization degree increasing is proportionally distributed to every item of the heat output. The heat taken away by reduction gas is increased from 2 703.92 MJ/tHM to 2 718.72 MJ/tHM. As a result, the dome temperature is increased by 5.16 K. The effect of DRI metallization on dome temperature is shown in Fig. 5. According to the Eq. (2), keeping other parameters constant, when DRI metallization is changed, the statistical value of dome temperature could be calculated. Compared to the statistical value, the calculated value was from the theoretical calculation model. It was observed from Fig. 5 that the calculated and statistical values of dome temperature show an increase tendency with the increase of metallization degree. For every 5% increase in metallization degree, the calculated and statistical values of dome temperature are increased by an average of 5.16 K and 3.91 K respectively. The statistical value is smaller than the calculated value due to the multiple variables, but the tendencies are the same. Therefore, keeping the metallization degree at a high level is one of the most important measures to maintain a stable dome temperature, to reduce the thermal load of dome zone and to get a low fuel rate.
Fig. 5.
Fig. 6.
Effect of fuel rate on dome temperature.
tendency with the increase of fuel rate, as shown in Fig. 6. For every 100 kg/tHM increase in fuel rate, the calculated and statistical values of dome temperature are decreased by an average of 13.36 K and 14.00 K respectively. The calculated value verifies that the results of calculation analysis are in good agreement with those of statistical analysis and also proves the accuracy of statistical analysis. The difference between calculated and statistical values is within ±5%. 3.3. Effect of Coal Rate Coal is becoming more and more important to maintain char bed permeability which is required to have a good strength and less fines. The combustion reaction between coal and oxygen releases a large amount of heat and generates reduction gas. Coal releases moisture and volatile matter as it is heated under the dome temperature of more than 1 000°C. Hydrocarbons dissociate with C and H2 and become a part of reduction gas.16,17) With the increase of coal rate, the moisture and volatile matter amount are higher, which demand more heat and lead to a higher thermal load in dome zone. The coal rate is 830.07 kg/tHM in the base model. When the coal rate is increased by 30 g/tHM, the heat consumption of coal decomposition is increased by 22.75 MJ/tHM and gas volume is increased by 50.79 m3/tHM leading to the heat taken away by reduction gas increased by 75.98 MJ/tHM. In addition, the heat consumed by water evaporation and
3.2. Effect of Fuel Rate When the fuel rate is increased by 100 kg/tHM, the heat consumption of water gas shift reaction and the decomposition of coal are increased by 25.24 MJ/tHM and 56.35 MJ/tHM respectively. Al2O3 and SiO2 amounts in the gangue also increased with the increase of fuel rate. The more fuels lead to a larger amount of slag, as a result, the heat taken away by slag is increased by 20.87 MJ/tHM. The fuel rate significantly affects the volume of reduction gas. With the fuel rate increasing by 100 kg/tHM, the gas volume is increased by 171.43 m3/tHM, causing that the heat taken away by reduction gas is increased by 226.94 MJ/tHM. Taking the changes of heat input and output into consideration, dome temperature is decreased by 12.89 K. The calculated and statistical values of dome temperature have a decrease © 2014 ISIJ
Effect of DRI metallization on dome temperature.
46
ISIJ International, Vol. 54 (2014), No. 1
Fig. 7.
Fig. 8.
Effect of coal rate on dome temperature.
Effect of coke rate on dome temperature.
water gas shift reaction is increased by 2.73 MJ/tHM and 8.53 MJ/tHM respectively. Taking all the changes of heat input and output into consideration, the dome temperature is decreased by 3.12 K. The calculated and statistical values of dome temperature have a decrease tendency with the increase of coal rate, as shown in Fig. 7. For every 30 kg/tHM increase in coal rate, the calculated and statistical values of dome temperature are decreased by an average of 3.16 K and 3.84 K respectively. 3.4. Effect of Coke Rate The COREX process still demands a quantity of coke for maintaining stable char bed and for a good permeability with the poor conditions of low metallization, high fuel fines fraction and bad permeable char bed. With the increase of coke rate, the gas volume is increased, which leads to the increase of the heat consumed by water gas shift reaction and taken away by reduction gas, thereby dome temperature decreases. The calculated and statistical values of dome temperature show a decrease tendency with the increase of coke rate as shown in Fig. 8. For every 10 kg/tHM increase in coke rate, the calculated and statistical values of dome temperature are decreased by an average of 3.82 K and 4.00 K respectively. The results of fuel rate, coal rate and coke rate affecting dome temperature in this paper showed reasonably good agreement with the results of Lee et al.2) Their work mainly focused on C/O ratio affecting the transport phenomena in melter gasifier. In this study, the increase of fuel rate, coal rate and coke rate means that larger amounts of carbon fall into dome zone of melter gasifier, which results in high C/O ratio. Because the CO forming reaction emits less enthalpy than the CO2 forming reaction, the dome temperature is decreased.
Fig. 9.
Effect of oxygen volume on dome temperature.
oxygen volume, the heat generated by combustion is increased by 83.51 MJ/tHM, which improves the thermal condition in dome zone. Due to the increase of gas volume, the heat taken away by reduction gas is increased by 9.39 MJ/tHM. Keeping the heat loss constant, the excess heat causes dome temperature increasing by 3.28 K. The effect of oxygen volume on dome temperature is shown in Fig. 9. It can be observed that the calculated and statistical values of dome temperature increase with the increase of oxygen volume. For every 1 000 m3/h increase in oxygen volume, the calculated and statistical values of dome temperature are increased by an average of 3.32 K and 3.00 K respectively. The difference between calculated value and statistical value is within ±10%. Under the condition of high oxygen volume, the heat released by combustion reaction is increased, thereby the excessive heat is used to increase the dome temperature after meeting the requirement of heat demand in dome zone. Based on the results of above research, the variation of operation parameters caused by dome temperature increasing 1 K is shown in Table 4. In order to maintain stable dome temperature, the “matching adjustment” of different operation parameter is used to control dome temperature based on the rules shown in Table 4. When dome temperature is low, operators can add the amount of positive correlation factors such as oxygen volume or reduce the amount of negative correlation factors such as coal rate to control the dome temperature at a suit-
3.5. Effect of Oxygen Volume There are four dust burners and six oxygen burners located around the circumference of the melter gasifier. The dust is recycled to the melter gasifier through dust burners and combusted with oxygen injected through the burners. Oxygen plays a vital role in the dome of melter gasifier for the generation of heat to meet the thermal demand for heat consumption. Dome temperature is controlled via adding or reducing the oxygen volume. The oxygen volume is 22 485 m3/h in the base model, for every 1 000 m3/h increase in 47
© 2014 ISIJ
ISIJ International, Vol. 54 (2014), No. 1 Table 4. The variation of parameters with dome temperature increasing 1 K. Parameters
Statistical results Calculated results Relative error
DRI metallization
+1.28%
+0.97%
24%
Fuel rate
–7.14 kg/tHM
–7.49 kg/tHM
5%
Coal rate
–7.81 kg/tHM
–9.49 kg/tHM
22%
Coke rate
–2.50 kg/tHM
–2.62 kg/tHM
5%
3
+333.33 m /h
Oxygen volume Table 5.
3
+301.20 m /h
10%
The chemical composition of different coal species.
Coal species
Fixed carbon (%)
Ash (%)
Volatile matter (%)
Moisture (%)
Coal A
60.00
6.55
33.45
9.56
Coal B
54.12
9.69
36.19
4.43
Coal C
51.94
14.62
33.44
6.06
Coal D
51.07
14.35
34.58
6.20
Coal blend
53.43
11.00
35.57
4.89
Fig. 10.
oxygen velocity should be controlled at a high level while the amount of negative correlation factors such as fuel rate, coal rate and fuel fines fraction should be reduced. The most significant factors influencing dome temperature are metallization, melting rate, fuel rate, coal rate, coke rate and oxygen volume. Based on the quantitatively rules between operation parameters and dome temperature, the dome temperature should be controlled within a certain range by using the method “matching adjustment” of different operation parameters. The coal species with low moisture and high volatile matter are expected to be selected and discharged into the melter gasifier. Coal B has positive effect on dome temperature because of the less heat consumption. On the other hand, if the amount of Coal A, Coal C and Coal D is too high, the thermal load in dome zone will increase, which is bad for the stability of dome temperature.
able range. In this way, operators can accurately predict the trend of dome temperature, which is useful for the stability of dome temperature. 3.6. Effect of Coal Species Coal should have certain physical properties, high temperature properties and chemical composition to meet the requirement of heat and gas balance. In practice, coal blend consists of several coals, the composition of these coals is shown in Table 5. In the base model, it is assumed that the coal blend consists of single coal to study the chemical composition of different coal species on dome temperature, as shown in Fig. 10. It is found that when Coal B is used, the dome temperature is the highest, 10.76 K higher than that of base model. The reason is that the low moisture and ash content in Coal B lead less heat to be consumed by gasification and by decomposition of water and to be taken away by slag. Additionally, high volatile matter content in Coal B results in the increase of the mole percent of H2 and CO in the dome zone, which could promote the combustion reaction. As a result, the dome temperature is increased which verified the previous work.18) Because of the high moisture content in Coal A, the dome temperature is 22.63 K lower than that of base model. The chemical composition of Coal C is almost the same as Coal D. High moisture and ash content in Coal C and Coal D result in low dome temperature. Compared to the base model, the dome temperature with using Coal C and Coal D are decreased by 27.39 K and 30.10 K respectively. High moisture leads to high gas volume and high heat consumption. The volatile matter gets dissociated and generates reduction gas. When selecting coal species, the moisture content should be low and the volatile matter content should be high so as to decrease the thermal load and to keep the dome temperature stable.
REFERENCES 1) X. L. Liu, G. Pan, G. Wang and Z. Wen: Energ. Fuel., 25 (2011), 5729. 2) S. C. Lee, M. K. Shin, S. Joo and J. K. Yoon: ISIJ Int., 40 (2000), 1073. 3) P. P. Kumar, Y. S. Rao and K. Chidambaran: Steel Res. Int., 80 (2009), 179. 4) P. P. Kumar, S. C. Barman and B. M. Reddy: Ironmaking Steelmaking, 36 (2009), 87. 5) W. R. Xu, Y. L. Guo and C. Wang: Ironmaking, 5 (2011), 45. 6) B. G. An, J. H. Guo and H. S. Wang: Comput. Stat. Data Anal., 62 (2013), 93. 7) R. X. Liu, J. Kuang and Q. Gong: Comput. Meth. Prog. Bio., 71 (2003), 141. 8) J. C. M. Pires, F. G. Martins and S. L. V. Sousa: Environ. Modell. Softw., 23 (2008), 50. 9) Y. X. Qu, Z. S. Zou and Y. P. Xiao: ISIJ Int., 52 (2012), 2186. 10) P. P. Kumar, L. M. Garg and S. S. Gupta: Ironmaking Steelmaking, 33 (2006), 29. 11) N. Wang, X. M. Xie, Z. S. Zou, L. Guo, W. R. Xu and Y. S. Zhou: Steel Res., 79 (2008), 547. 12) S. Pal and A. k. Lahiri: Metall. Mater. Trans. B, 34 (2003), 103. 13) C. Thaler, T. Tappeiner, J. L. Schenk and W. L. Kipplinger: Steel Res., 83 (2012), 181. 14) C. Thaler, J. L. Schenk and J. F. Plaul: Stahl Eisen, 2 (2011), 31. 15) C. Thaler, J. L. Schenk and J. F. Plaul: Bilanzmodell des FINEX1Prozesses zur Abscha¨tzung von CO2-Emissionen, 10th DepoTech, VGE Verlag, Essen, Leoben, Austria, (2010), 649, ISBN: 978-3-20002018-4. 16) P. P. Kumar, B. S. L. Raju and M. Ranjan: Ironmaking Steelmaking, 38 (2011), 412. 17) P. S. Assis, L. Guo and J. Fang: Ironmaking Steelmaking, 35 (2008), 303. 18) S. C. Lee, M. K. Shin, S. Joo and J. K. Yoon: ISIJ Int., 39 (1999), 319.
4. Conclusions When dome temperature is low, the positive correlation factors such as metallization degree, oxygen volume and © 2014 ISIJ
Effect of coal species on dome temperature.
48
