Hydrogen production halted.
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During hydrogen production shutdown, the feed system is shut down to stop hydrogen supply, while the conversion system has its pressure relieved in preparation for switching to large-cycle operation, followed by a switch to dual-cycle operation. Is it okay to do this?
In case of problems, normal procedures involve emergency shutdown or interruption of feed supply; the pressure must not be released. When shutting down, the feed must be cut off first to prevent overpressure in the conversion system during shutdown. Then, if dry desulfurization is used before the conversion process, it is also necessary to cut off the feed from the dry desulfurization system to the conversion system; cool down the dry desulfurization system, stop supplying hydrogen, and once the temperature reaches your specified control levels, switch to circulation mode. When stopping the feed to the dry desorption unit, the temperature on the conversion side also needs to be reduced; more feed steam can be used to prevent the furnace temperature from rising too high. Remember, when you need to stop production, you must first reduce the volume and temperature on the conversion side by about 20–50 t/h, and pay attention to the backpressure. Overpressure air defense or flare. In the end, the steam generated internally had to be modified for air defense purposes
Actually, I don’t think there’s any absolute order for shutting down operations. By focusing on the key points, you can choose a parking option that suits your needs. There are plans for emergency shutdowns, and there are also plans for planned shutdowns; the approaches to emergency shutdowns vary depending on the situation, and these plans are not entirely the same in all cases. It’s impossible to determine whether there is an error based solely on the few sentences provided by the poster; in our installation, the system goes into full circulation mode as soon as the plant stops operating, and neither the desulfurization nor the conversion systems are isolated. .
Before the conversion system establishes a large loop, the hydrogenation reactor is removed. Prevent methanation reactions from occurring
Reply to 4# lgc1986: Haha, we completed the nitrogen purging process before setting up the large cycle: lol, nothing needs to be cut. .
Reply to 2# yang715097370: I’m not quite sure what you mean by a ‘large loop’ Does it refer to the desulfurization system and the conversion system being connected in series for circulation? Here at Dalian Petrochemical, it is strictly prohibited to allow materials to enter the conversion unit after the furnace is shut down; therefore, steam and hydrogen are used in a certain ratio to purge and relieve pressure in the conversion system, followed by displacement with nitrogen ； Nitrogen displacement after direct pressure relief for desulfurization. After passing the replacement test, the two systems cool down independently.
What was said on the 4th floor is incorrect; during shutdown, dry distillation cannot be integrated into the conversion process, as an alkylation reaction would occur. There is one scenario in which a large cycle can be established: when the feed pump stops operating suddenly during normal operation and the backup pump fails, the circulation pump can be used to create a large cycle for dry distillation conversion
The shutdown involves changing the large circulation system, removing the hydrogenation reactor, and then removing the desulfurization unit. Transformation system replacement
Please explain in detail the alkylation reaction in the context of hydrogen production