1、 Catalyst loading: precise control and safety protection

Preprocessing and Loading

Catalysts (such as palladium/carbon, Raney nickel) need to be treated in an inert atmosphere (nitrogen). Active catalysts such as Raney nickel should not be dried and should be kept moist with ethanol or water to avoid spontaneous combustion. When loading, use specialized tools to slowly add the catalyst into the kettle to avoid powder flying. The loading capacity should not exceed one-third of the capacity of the kettle to prevent excessive reaction.

Layered loading and raking

Add catalyst layer by layer according to the process requirements, with a height of no more than 500mm per layer, and level it with a rake to ensure uniformity of the bed. For example, in petroleum hydrogenation refining, the height difference of the catalyst bed should be controlled within 100mm to avoid local reaction overheating.

Sealing and leak detection

After loading is completed, tighten the kettle cover bolts symmetrically in diagonal order, gradually applying force in three stages to ensure uniform force on the sealing surface. After closing all valves, introduce nitrogen gas to 1MPa and check for air leaks at the valve, kettle cover, and pipeline connections with soapy water. If the pressure drops by ≤ 0.05MPa within 20 minutes, the airtightness is qualified.

2、 Hydrogen control: safe displacement and pressure management

Hydrogen replacement

Replace the air inside the kettle with nitrogen three times, and discharge after each nitrogen filling to 0.3MPa. Repeat the process until the oxygen content drops below 2%. During the replacement process, turn on the mixer and run it at low speed to ensure that the gas in the dead corners is fully replaced.

Hydrogen Charging and Reaction Control

The hydrogen inlet valve should be slowly opened, with an initial flow rate not exceeding 5L/min. When the pressure rises to 1/3 of the working pressure, pause and check for any abnormal sounds at each connection point. Set the temperature controller to gradually increase the temperature, not exceeding 3 ℃ per minute. When the pressure reaches the design value, adjust the back pressure valve to maintain a constant operating condition. For example, in the synthesis of pharmaceutical intermediates, the hydrogen pressure needs to be stable at 6MPa to avoid pressure fluctuations that may cause the reaction to lose control.

Security monitoring and emergency response

Real time recording of temperature, pressure, and flow data, and immediate activation of interlock protection upon discovery of abnormalities. When the pressure exceeds 10% of the set value of the safety valve, manually open the emergency relief valve. If a hydrogen leak occurs, immediately cut off the hydrogen supply, open the ventilation system to dilute the hydrogen concentration, and replace it with nitrogen gas.