Nitrogen content in coke oven gas
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In the coke oven gas produced by our plant, the nitrogen level is generally between 3 and 3.5; there’s no way to reduce it any further. The pressure in the gas collection system is set at 150 pascals, while the oxygen content is 0.4.
It is high during night shifts and gradually decreases during the day
Original poster, is the oxygen level measured at the location of the electrostatic tar catcher or at the outlet of the gas tank? Is it always maintained at 0.4, or does it reach peak values during coal loading? In either case: 1. If the furnace door isn’t sealed properly, the pressure in the gas collection duct increases, causing smoke to come from the upper part of the furnace door while air continues to enter from below. Check for any leaks in the negative pressure pipeline. If the value remains at 0.4 under normal conditions and the oxygen analyzer is functioning correctly, then there must be a leak somewhere; the details on how to check for this are too lengthy to include here ； 2. If the sealing is good, it’s likely that a large amount of air entered during coal loading. This situation often occurs in systems with negative pressure in adjacent rooms, as well as with high-pressure ammonia solutions and smoke extraction vehicles; poor overall control leads to low oxygen levels and excessive nitrogen levels, along with many other problems such as frequent ruptures of M-tubes, leaks, easy clogging of the primary coolers, low quality of tar, and low quality of gas, among others. I’m a civilized beast – if you think this makes sense, we can continue to discuss and research it. After all, the operating conditions vary from one facility to another, right? Hahaha
The oxygen level is measured at the inlet of the gas tank; dust removal is carried out on the ground in our plant, and high-pressure ammonia water is not used. The oxygen level ranges from 0.3 to 0.4 – it’s usually not high. This issue only appeared recently, with the nitrogen level gradually increasing during the day and decreasing at night
The subcoolers, the pipes for liquid drainage from the fans, and other negative-pressure pipes were all checked, and no problems were found
Don’t you use dust removal vehicles exclusively for your night shifts? Manually increase the fan speed and reduce the valve opening, thereby increasing the suction pressure before the primary cooler; check whether the real-time oxygen level is high If it’s not high, it means that negative pressure is not allowing air to enter. The focus is on the furnace door and leaks. Also, has there been any staff rotation for the night shifts at the coke ovens recently? Is the operation the same as during the day? You had better go and take a look at night.