Can increasing the heating speed improve coke quality?

By increasing the heating speed, what they actually mean is to extend the holding time in the furnace. For example, if coking takes 24 hours under normal conditions – with coke maturing over 22.5 to 23 hours and thus a holding time of 1 hour – then by accelerating the heating process, coke maturation may occur in 21.5 to 22 hours, resulting in a holding time of 2 hours. A longer holding time generally leads to better quality coke; however, too rapid heating can result in a decline in coke quality. Therefore, raising the standard temperature should be done with caution

This post was last edited by 26722672 on 2012-4-10 at 14:53. The coking rate refers to the ratio of the width of the carbonization chamber to the coking time. As I understand it, under standard temperatures with a short coking time, the coke reaches maturity more quickly (it sounds similar to intensified production, hehe); the main advantage is that it improves the coking properties of weakly sticky coals. By increasing the heating rate, some of the liquid products within the colloid do not have enough time to undergo pyrolysis and shrinkage. However, as the solidification temperature of the colloid rises, the temperature range widens, its fluidity increases, and at the same time the amount of gas released per unit time increases, resulting in greater expansion pressure which facilitates bonding. When a large amount of lean coal is used, the granular structure of the coke is severely affected, with an increase in inclusions; the coke structure lacks distinct boundaries, and its pieces are large and not wear-resistant. Upon increasing the heating rate, a comparison of the coke produced showed that its granular structure was indeed improved, and a denser texture could be observed visually in the walls of the coke.

What is rapid heating? How can rapid heating be achieved? For example, as mentioned on the second floor, the turnaround time is 24 hours, the carbonization time is 23 hours, and the furnace holding time is 1 hour. Now I want to heat it up quickly; the maturation time for coke has become 21 hours, and the holding time in the furnace is 3 hours. I think the only solution is to increase the standard temperature. Are there any other methods besides this? Thinking from a different perspective, could we consider it this way: by using a standard temperature with a cycle time of 21 hours and extending the time before taking the product out by 3 hours, it’s equivalent to extending the holding time in the furnace From another perspective, for example, if the turnaround time is 48 hours, even though the temperature is low, the coke has already been fully cooked; let’s assume it is ready after 40 hours, with the remaining 8 hours serving as a period of holding the furnace at that temperature. Does this improve the quality of the coke?

I believe it is right to increase the standard temperature, but since there is already sufficient time for holding the furnace at that temperature (for example, extending it from 30 minutes to 50 minutes), after the coke is fully matured, continuing to hold the furnace for another 2 hours will surely cause it to collapse. No matter how much time is extended, the core temperature of the coke cake can never exceed the temperature of the vertical flame channel. Without considering the temperature of the furnace head (or ensuring that this temperature remains high), in a typical coke oven, after extending the set coking time by 12–17 hours, the temperature reaches 1100–1150°C and can no longer drop. In the case of maintaining heat during major repairs of the oven, 35 hours of heating at 1050–1100°C is sufficient for proper coking; however, in practice the coking time exceeds 100 hours, and the quality of the coke remains good.

Experiments have shown that rapid heating alters the pyrolysis dynamics of coal, increasing the rate at which side chains break to form a liquid phase as well as the formation of carbon networks. This leads to an increased temperature range within the gel phase, altering its fluidity. At the same time, more gas is produced per unit of time, resulting in increased expansion pressure and thus enhanced cohesion of the coal. By using rapid heating, the caking property of bituminous coal, weakly caking coal, and even long-flame coal can be improved, thereby expanding the sources of coal suitable for coking (hot-pressed coke is based on this principle). However, rapid heating is detrimental to the shrinkage of the semi-coke, as increasing the heating rate accelerates shrinkage and strengthens the bonding between adjacent layers, thereby resulting in higher shrinkage stresses and more cracks. Therefore, I believe that a reasonable heating rate should be fast during the bonding stage and slow during the shrinkage stage. But what method do we use to control the heating rate?