Principles for shutting down hydrogenation units

(1) Follow the principle of cooling first and then reducing the flow rate to prevent the bed layer from overheating. (2) During the cooling and depressurization of the reaction system, strict adherence to the relevant constraints regarding the cooling and depressurization of the reactor is necessary in order to minimize the impact of temper brittleness on the reactor material. (3) During the cooling and pressure reduction of the reaction system, operations must be carried out strictly in accordance with the plan to prevent significant fluctuations and avoid leaks in the equipment, flanges, etc. (4) During the first shutdown of the reactor, before the lowest temperature of the reactor wall (measured by surface thermocouples) drops to 50 °C, the operating pressure must be reduced to less than 1/4 of the design pressure. After one operating cycle and before shutting down, the operating pressure must be reduced to less than 1/4 of the design pressure until the lowest temperature on the reactor wall (as measured by surface thermocouples) drops to 93 °C. (5) During the shutdown, if the high-temperature flange is equipped with a fixed steam protection ring, it should be put into use. (6) If it is necessary to open the reactor after shutdown, an analysis of the CO content in the recycle gas should be conducted before the temperature of any bed in the reaction system drops to 205°C; the CO content in the recycle gas must remain below 30 ppm to prevent the formation of nickel carbonyl during the shutdown process. (7) During the shutdown process, closely monitor the changes in bed pressure drop and bed temperature rise. Outdoor operators should increase their inspections and report any leaks or similar issues promptly for handling. (8) During the shutdown, the reaction system is depressurized, while the nitrogen line continues to supply nitrogen. The fractionation system and the nitrogen lines of the new hydrogen generator system are isolated using blind flanges. When using nitrogen to purge the system, implement proper isolation procedures to prevent the nitrogen from mixing uncontrollably. (9) During the shutdown period, there are significant changes in operating conditions, so close attention must be paid to any deviations from the anti-surge point of the cyclohydrogen compressor. (10) When removing the medium, make sure to remove all remaining medium from the device ； (11) When draining the medium, be sure to prevent overpressure in the downstream equipment due to a drop in liquid level; the safety valves of the downstream equipment should be activated ； (12) For equipment that requires pumping of return fluid, someone must be present on site to prevent the pump from remaining empty for an extended period ； (13) In cases involving upstream and downstream devices, it is necessary to coordinate with those devices before proceeding with the reversal ； (14) After the oil has been drained, the remaining oil must be discharged from the lowest points of the equipment and pipelines in a sealed manner.

Are there any shutdowns for purging purposes, such as those related to energy conservation and cost reduction?