What are the safety precautions for catalyst loading?

It depends on what kind of catalyst it is – is it a first-time installation or a replacement/reinstallation! Are there any toxic or harmful substances in the confined space?

Pay special attention during loading； 1. To prevent the catalyst from getting damp, it should be loaded on a sunny day. 2. Remove debris from the furnace and check whether the inner walls, refractory bricks, grates, etc. are in good condition. 3. Lay a stainless steel wire mesh on the grate, evenly distribute the refractory balls, and mark a line at the intended filling height. 4. Prepare the loading tools and protective equipment. 5. It should be sieved before loading to remove dust and broken particles. 6. The height difference for loading should be less than 0.5m. 7. The loading personnel should step on wooden planks; it is strictly prohibited to step directly on the catalyst to avoid crushing it. 8. After loading is complete, use a wooden board to level the catalyst. Install the manhole immediately. Special care should be taken when loading the pre-reduction catalyst into the ammonia synthesis tower of an ammonia plant. Large ammonia plants typically use mechanical oscillators to fill the catalyst, ensuring a tight filling and uniform airflow during production. The oscillation should not be too intense, otherwise the oxide layer on the surface of the particles will be worn away. Workers inside the tower must have adequate safety measures, such as wearing oxygen masks to supply oxygen. This is because when a small amount of reduced α-Fe micrograins become exposed, they react with the oxygen in the air to form new oxide films, which reduces the amount of oxygen in the surrounding area. Workers inside the tower are at risk of suffocation if they do not have specialized safety equipment for supplying oxygen. Another risk during loading is excessive oscillation of the oscillator; after a large amount of the oxide film is destroyed, new oxide films form rapidly, causing the temperature to rise quickly. This is because the exothermic reaction 2Fe + O2 = 2FeO can raise the temperature of the catalyst bed ； The rise in temperature, in turn, accelerates the oxidation of Fe, creating a vicious cycle that drives the temperature up to 1000°C or higher. This can lead to catalyst sintering, and the high-pressure cylinder of the ammonia synthesis tower can also be damaged. Therefore, when loading the pre-reduced catalyst, it is necessary to have an adequate supply of inert gas (such as N2) on hand, and the temperature of the catalytic bed should be monitored closely. If there is a rapid rise in temperature, the staff should immediately evacuate, and N2 should be introduced into the ammonia synthesis tower; only after the temperature drops back to normal should loading continue.

a. Before loading the catalyst, each reactor must be ensured to be properly inspected, cleaned, and dried. Piping related to the reactor has been purged and pressure-tested, and blind flanges have been installed on the pipelines connected to the reactor. b. Dry weather should be chosen for the transportation, preparation, and loading of the catalyst, with rain, snow, fog, or humid conditions being avoided as much as possible to ensure that the catalyst does not become damp. c. Essential tools for filling, such as hoppers and funnels, must be prepared before filling, and a necessary check of the functionality of these filling devices should be carried out to ensure smooth operation. d. The manholes and flange connection bolts, nuts, etc., that need to be filled in the reactor must be cleaned thoroughly before filling, and greased, so that the manholes can be sealed promptly after the catalyst is added, preventing the catalyst from getting wet or foreign substances from entering. e. When transporting the catalyst, handle it with care as much as possible; it is strictly prohibited to roll the catalyst tank on the ground. Before loading, the broken particles and dust of the catalyst must be strictly screened; only the catalyst that has passed inspection and screening can be fed into the various reactors. f. Before loading the catalyst, its model and specifications should be verified; catalysts of different models and batches should be properly numbered and stored separately to prevent mixing of different types of catalysts. g. Before loading the catalyst and inert ceramic balls, ensure that the outlet screen at the bottom of the reactor is installed and secured, and that wire meshes of various sizes are cut and ready for use. On the inner wall of the reactor, height marks are made for different fillers according to the predetermined data, and the actual volume of catalyst filled is calculated; all data related to catalyst filling must be recorded by a designated person ； Each bucket of catalyst must be opened for inspection; it must not be used if discoloration, crushing, or similar conditions are observed. h. During the catalyst loading process, the catalyst layer should be made as flat as possible; if necessary, the reactor should be used to level the catalyst layer. To do this, wooden planks should be placed on the surface of the catalyst, and a person should stand on these planks to level the catalyst. i. When loading the catalyst, be careful to protect the thermocouple sheath and avoid damaging it ； To prevent foreign objects from falling into the catalyst, items brought by the operators must not be left behind or lost, and any foreign objects inside the catalyst packaging bags or containers, such as certificates of conformity, should also be removed. j. During the catalyst loading process, if it rains, the catalyst tank lid should be closed immediately, and the reactor’s loading ports must be sealed properly.

There shouldn’t be many new problems; a check should show that everything is qualified! The procedures still need to be carried out and tested. For work, simple protective gear is sufficient: a dust mask, eye protection, and gloves are all that’s needed!

It is best to wear a positive-pressure air respirator. During loading, the dust level is too high.