How can synthetic catalysts be best protected during shutdown?
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How can synthetic catalysts be best protected during shutdown? Is it better to maintain heat and pressure, or to release pressure and fill with nitrogen?
It depends on how long you park. For long-term parking, it is best to relieve pressure, purge with nitrogen, and install a blind flange. In the short term, simply maintaining heat and pressure is sufficient. Pay attention to monitoring the furnace temperature
If it’s a short-term parking, of course, it’s important to maintain heat and pressure； In the case of a long-term parking period, it is necessary to lower the temperature of the catalyst and protect it with nitrogen. If the catalyst cools down naturally, it may be oxidized, as a decrease in temperature leads to a reduction in the volume of the gases, allowing air to enter.
If the shutdown time is less than 8 hours, maintain heat and pressure; if the shutdown time is less than 24 hours, reduce the temperature appropriately while still maintaining pressure. Pay attention to the temperature of the tower walls – if this temperature exceeds a certain limit, pressure must be released. For long-term parking of more than 24 hours, the temperature should be reduced cyclically to below 150 degrees; after pressure release, high-purity nitrogen should be used for protection (if undergoing major repairs, a blind flange should be installed to isolate the system)
In the case of short-term parking, the system pressure can be appropriately reduced; it is sufficient to maintain the insulation and pressure of the system； In the case of long-term parking, lower the temperature to below 300°C before parking, release pressure from the system, then close the inlet and outlet valves of the synthesis tower. Install blind flanges at the tower’s inlet and outlet, and introduce qualified nitrogen through the sampling pipe at the tower inlet to maintain a positive pressure inside the tower.
This post was last edited by hech0810 on 2010-3-14 21:09. We recently carried out parking for maintenance; after cooling in a cycle, we sealed the tower. However, the catalyst temperature is abnormal after driving; it seems there is still an issue with heating and reduction.