Evaluating Effect of Coke Layer Thickness on Permeability by Pressure Drop Estimation Model

Abstract

Recently, low coke rate blast furnace operation has been required in response to the rising cost of coking coal. However, the thickness of the coke layer decreases in low coke rate operation. Since it is known that the gas permeability of the blast furnace deteriorates as the coke layer thickness decreases, it is important to determine the minimum coke layer thickness for stable blast furnace operation. On the other hand, the minimum coke layer thickness has not been clarified due to a lack of equipment capable of measuring the effect of the coke layer thickness on permeability.In this study, a new experimental device called the cohesive zone simulator was developed to clarify the minimum coke layer thickness. In the cohesive zone, gas flows horizontally along the coke layer. In order to quantify the effect of the coke layer thickness on permeability, this horizontal gas flow should be simulated. Therefore, this simulator simulates a horizontal gas flow.Next, the effect of the coke layer thickness was quantified by using the cohesive zone simulator. The results showed that melting iron ore penetrated into the coke layer and closed part of the layer. These phenomena caused a deterioration of permeability under thin coke layer thickness conditions. Finally, a pressure drop estimation model considering penetration of the coke layer by melting ore was developed with the aim of quantifying the minimum coke slit thickness.

A Novel Measurement of Voidage in Coke and Ferrous Layers in Softening and Melting under Load Test Using Synchrotron X-ray and Neutron Computed Tomography

“…This is consistent with a previous study, which showed the bed voidage in a layer of 10 mm coke particles was 41.8%. 2) An increase in coke voidage can be observed at the bottom and top of the crucible (0 and maximum sample height) due to the end effect.…”

“…Particularly, the measured permeability or pressure drop results are of great importance as they relate to the operational stability and productivity of the BF. To gain insights into this complex process, many studies have examined the quantitative relationship between pressure drop and bed height/contraction, using approaches such as the well-known Ergun equation, 1,2) Sugiyama model 3,4) and permeability resistance formula. 5,6) In those studies, the key factor bed voidage of the ferrous layer is usually assumed or estimated from physical models.…”

The Study of the Distribution and Deformation of Burden Layer in 250 Ton/Day Mini Blast Furnace Using Discrete Element Method

“…So the large gas flow will be concentrated in this area which would be distributed to upper areas. If it is compared with coke in Blast Furnace, the pressure drop increased with decreasing coke layer thickness [14].For layer thickness less than ≤ 1 m, the pressure drop will be greatly influenced by void of packed bed [15]. In this case, variable 3 has the largest void compared to other variables because of the greater portion of coal.…”

Melting Behaviour of Iron Ore Pellet Bed under Nut Coke Mixed Charge Conditions

“…Furthermore, it was reported that for good permeability at least 2 to 3 discrete layers of regular coke particles are required inside the blast furnace. 4,15) Although these studies were not performed in the light of nut coke utilisation, experimental research indicates that regular coke thinning will have a negative impact on the overall gas permeability. 15) Since the idea of nut coke use is as the replacement of regular coke; it is of utmost importance to understand the effect of the nut coke use on the bed permeability.…”