What is the issue with high-direction heating using coke oven gas dehydrogenation off-gas or methanol purge gas in 6.25-meter rammed coke ovens?
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The last edit to this post was made by angryant on 2019-3-30 at 11:13. Hello, fellow sailors. Our company has newly installed 6.25-meter coke ovens; previously, furnace gas was used for heating these ovens； Currently, coke oven gas is used as a feedstock for hydrogen extraction, with the hydrogen-rich off-gas being sent back to the furnace for heating. The density of the gas returning to the furnace is 0.79 kg/Nm3, and its calorific value is 5800 kcal/Nm3 ； Can the combustion of gas returned to the furnace after hydrogen addition, as proposed above, meet the high-direction heating requirements of coke ovens? Is it necessary to add nitrogen to gas in order to reduce its calorific value? Are there any other things to keep in mind?
The calorific value of the gas after hydrogen removal is higher, and the flame becomes shorter; the upward heating effect is poor. Adding nitrogen can lengthen the flame, but it increases the nitrogen oxides in the flue gases
This post was last edited by angryant on 2019-3-30 at 11:17. 1. For the dehydration of coke oven gas, it’s definitely not feasible to use a gas with too high calorific value, as the high temperature at the bottom can damage the furnace walls. Mixing in nitrogen is an option, but this will lead to excessive NOx levels; moreover, there will be significant variations in the air supply volume. It’s uncertain whether the coke oven’s regenerative chambers and combustion system can adapt to such conditions； 2. Methanol off-gas is rich in hydrogen; hydrogen being the smallest molecule, it diffuses too rapidly, and there is also a risk of burning out the furnace walls due to the high temperatures at the bottom.
In short, it should be mixed into the coke oven flue gas in amounts not exceeding 10%; otherwise, it will affect the increase in the temperature of the coke oven
Have you guys done it already? Where does the data come from?
Does your company use the above methods for desulfurization and denitrification? Our company has developed its own denitrification catalysts, and we have successful project experience in this field; I was wondering if you might be interested
Blast furnace gas has a low calorific value, so it can be mixed with coke oven gas. Similarly, if the calorific value of coke oven gas becomes too high after hydrogen extraction, the gas can be diluted
Note: The analyzed gas has a high sulfur content! Direct combustion affects compliance with standards!
This post was last edited by caocheng on 2019-4-1 17:29. Your suggestion is theoretically sound, but since blast furnace gas is available, isn’t it better to use it directly?
Coke oven flue gas and VOCs exhaust gases can be mixed, but not in excess of 10%