Problems with the methanation reactor in ethylene plants
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3.jpg Role of the methanation reactor in the ethylene plant: CO in hydrogen reacts with hydrogen under the action of a catalyst to produce methane and water； This unit experienced two emergency shutdowns (shutdown of the pyrolysis gas compressor and the propylene plant), with a disruption in the feed to the pre-cooling system; the methanation reactor was shut down manually, and the interlocks functioned correctly. The operator on site immediately instructed the crew to use nitrogen to raise the temperature (the operating procedures and cards state that heating should only take place after the temperature returns to normal levels) ； Question for assistance: After the methanation reactor is stopped manually or via interlock, when can heating be resumed? What are the risks if heating is started immediately?
Whether to increase the temperature immediately depends on whether the upstream system can return to normal operation. If the supply of pre-cooled gas can be restored right away and the amount of crude hydrogen is also normal, then it’s okay to increase the temperature of the methanation reactor immediately; otherwise, I don’t think it makes much sense. There’s no significant risk in increasing the temperature right away, as low-temperature methanation reactions are being used nowadays.
As long as it is above 200°C, it’s fine to feed the material by directly increasing the temperature. We used to recover urgently in this way after an accident-induced stop.