Mixed gas for coke oven heating
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Our plant uses a mixture of blast furnace gas and coke oven gas for heating the coke ovens. According to the technical operating procedures, the mixing ratio of coke oven gas to blast furnace gas must not exceed 7%. Why is that?
Blast furnace gas must be preheated in the regenerator; after being mixed with some coke oven gas, this coke oven gas as well is exposed to the high temperatures in the regenerator, causing the methane present therein to crack and form graphite, which then blocks the grid bricks. To reduce clogging of the grid bricks, use as little coke oven gas as possible. Therefore, the regulations specify no more than 7%.
One of the reasons is that blast furnace gas has a low calorific value, and its proportion in the mixture is too high; as a result, the calorific value of the mixture does not meet the requirements for coke oven fuel.