Handling of shutdown in synthetic ice machines
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May I ask, what should be done if all the chillers shut down under full load conditions in ammonia synthesis? How should it be handled? The reason for getting out of the vehicle was the high exhaust pressure of the chiller.
Treatment of the synthesis system column. The syngas compressor is operating at low speed or has stopped. Driving can be resumed in the short term, with the previous system operating at reduced load. If it is shut down for a long time, the entire system will come to a halt.
To fundamentally solve the problem of chillers shutting down prematurely, it is necessary to reduce the exhaust pressure at the outlet; currently, many units use evaporation cooling, which yields good results.
I’m not sure if the chiller owned by the poster is equipped with a vent valve; generally, when the exhaust pressure is high, we slightly open the vent valve to regulate it. The exhaust valve is connected to the flare.
The reason for the machine shutdown was high pressure at the outlet of the chiller; it is not necessary to conduct further investigations – the machine can be started immediately. Production can be resumed right away due to this issue. The specific steps are as follows: first, reduce the flow rate, use the vent at the chiller’s outlet to control the pressure, then start the chiller. Once the pressure stabilizes, integrate it into the system. The flow rate can be adjusted accordingly to prevent the same problem from occurring again.
If the reason for stopping the machines is high pressure at the outlet of the chillers, the ammonia addition valve should be closed first to reduce the evaporation load; then one or two chillers should be started immediately to restore production. However, the energy supply to the chillers can be reduced appropriately based on the outlet pressure, in order to prevent the same problem from occurring.
The load can be reduced through the refrigeration system, and the amount of vent gas can be increased appropriately. Furthermore, the pressure in the storage tank at the chiller outlet can be reduced directly (by venting the tank) to start the chiller as soon as possible. If the molecular sieve or cryogenic box system at the front end is affected, a complete shutdown of the synthesis system is required.
This situation occurs very rarely, but when it does happen, the ammonia synthesis system must be operated at a reduced capacity; the valves for cooling and adding ammonia should be closed, and electric heaters should be gradually activated to maintain the tower temperature. Furthermore, the chillers can be restarted immediately, as the inlet pressure rises sharply after a trip, reducing the compression ratio of gaseous ammonia; thus, starting them one by one poses no problem. In such cases, a full shutdown of the entire line can generally be avoided; there is only a short-term reduction in operation volume. . .
The ability of the chief scheduler to have an overall understanding of the situation becomes extremely crucial at this point, especially since in some companies, the water cooling system used in the air separation pre-cooling process is integrated with the cooling system used for ammonia synthesis. This situation must under no circumstances disrupt the battle. . . It is necessary to ensure that the system experiences as little load reduction as possible, and that the time required to restore the load is as short as possible.
Investigate the root cause to determine whether there is a shortage of heat exchange equipment or an issue with the circulating water. It is recommended to use evaporative cooling for technical upgrades; it’s really a good option. . .
The syngas compressor should be shut down via interlock or operated at a reduced speed, while the synthesis tower should maintain its insulation and pressure. Syngas is vented to the pre-system. To find the cause of the shutdown of the ammonia compressor, the possible reasons are as follows: 1. Inert gases such as air or nitrogen have entered the ammonia refrigeration system. (Especially in systems with negative pressure) 2. Problems with the ammonia condenser, such as scaling on the heat exchange tubes, poor quality of cooling water, high water temperature, etc. 3. Inadequate discharge from the inert gas emission system. 4. Nitrogen enters the ammonia compressor through the dry gas seal system, and it is not discharged in a timely manner.