*3.1. Base Model*

The gas compositions at the top of the blast furnace calculated from this model were verified against some measured results of practical production as shown in Table 3, where H2O is not listed since it was not measured in the practice. The maximum relative error between the measured and calculated results is 6.3%. Therefore, the present model is considered to be applicable to carry out the further simulation.


**Table 3.** Comparison between practical values and simulated values.

Figure 3 shows the mass fraction distribution of carbon in the blast furnace under base operational condition.

**Figure 3.** Coke mass fraction distribution in the blast furnace under base operational condition.

It can be seen from Figure 3 that the carbon mass fraction in the blast furnace firstly increases, then decreases after reaching a maximum in the middle. The reason for the increase is that the reduction reactions take place in the middle-upper part of blast furnace, and this leads to the decrease of the ferrite oxide mass fraction. The reason for the decrease of the carbon mass fraction is that carbon solution loss takes place in the lower part of the blast furnace.

The absolute consumption amount of carbon at a certain height of the blast furnace can be calculated based on the material balance. The carbon solution loss ratio of coke can be calculated by

$$y\_{\mathbb{C}} = \frac{m\_{\mathbb{C}-\mathbb{C}}}{m\_{\mathbb{C}-T}} \times 100\% \tag{13}$$

where *mC*−*<sup>C</sup>* and *mC*−*<sup>T</sup>* are the amounts of carbon consumed by the carbon solution loss reaction and the total carbon input from the blast furnace top, kg.

The carbon solution loss reaction taking place in the middle-upper part of blast furnace further reduces the quality of the coke and results in the poor performance of the blast furnace. Therefore the mean temperature of the cohesive zone is adopted as the boundary of the carbon solution between the middle-upper part and the lower part of the blast furnace. The average temperature of the boundary is 1300 ◦C. The *yC* at this boundary is 18.61%.
