Why is the density of the coke cake higher than that of the coal cake after it matures?
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Our company’s most recent mixture includes Russian lean coking coal, with a proportion of 18% or more. However, after using this mixture in the coke ovens, there are leaks everywhere in these ovens, and the problem is worse than it was when they first started operating. We’re not sure what’s causing this. Additionally, the contraction is minimal; the gap between the coke oven walls is only 5 mm. Our measurements show that the height of the coke cakes is even less than that of the coal cakes, meaning the coke cakes are higher than the coal cakes. We’ve never encountered such a situation before – usually, the coke cakes are lower than the coal cakes. What’s going on this time?
The coal charged into the furnace affects the shrinkage of the coke cake, but it should not have a negative effect. Leakage or let’s analyze the heating regime instead.
This coal has high expansion pressure, which causes leakage in the furnace; moreover, the coke cake does not shrink as it matures
I’m not sure what type of furnace you use; our factory uses rammed coke ovens. Last year, when we used Russian lean coking coal, we encountered the same problems, as well as a large amount of secondary coke. In the end, it was concluded that the expansion pressure of the coal was too high, that its proportion should not exceed 7%, and that the permeability of its vitrinite layer was poor.
The amount of lean coking coal used is too high; in addition, the expansion pressure is excessive while the degree of shrinkage is insufficient
It’s probably because there’s too much low-calority coal – the person in charge must have removed the coke from the furnace. When our coking plant first used rammed coke ovens to produce grade 1 coke, too much lean coal was used; as a result, the coke clumped together with little to no shrinkage, making it difficult to push the coke out. The entire oven had to be emptied of its coke, and there were widespread leaks in the coke ovens (in practically all of the carbonization chambers).
Moreover, the expansion pressure is too high, resulting in leakage along the furnace walls; the coal cakes and coke cakes expand upward while contracting less.
Here we use 6.25-meter ramming coke ovens; the reasons identified through subsequent analysis are the same as what everyone thought – excessive expansion pressure caused leakage