Weekly Topic for Ammonia Production: What issues should be considered when loading medium- and low-temperature shift catalysts?

The loading of the catalyst is a very important step; it must be done in layers. After each layer about 1 meter thick has been loaded, it needs to be leveled before the next layer is added. The bed formed after loading must be even and uniform, to prevent uneven distribution that could lead to channeling and affect the performance of the catalyst. If the catalyst has high strength, it generally does not require screening before loading. However, if improper handling during transportation or loading/unloading causes the catalyst to wear or break, it must be screened. When loading the catalyst, it can be done by pouring it directly from the barrel, or using various methods such as cloth bags, chutes, or filling pipes. However, regardless of the loading method used, it is necessary to ensure that the free-fall height of the catalyst does not exceed 1 meter. During loading, if one needs to walk on the catalyst, wooden planks must be placed to distribute the body weight over their surface. To prevent the catalyst from being blown out by high air currents or damaged due to turbulence that may occur during startup and shutdown processes, a stainless steel mesh (with diameters of 4–5 mm and 10–12 mm), as well as an inert material that is heat-resistant, corrosion-resistant, and free of silicon, must be used to cover the top of the catalyst bed. Heat-resistant aluminum balls with diameters of 25 mm and 45–50 mm can also be used for this purpose.

1. Catalyst loading must be carried out after the system has been purged and pressure-tested. 2. All electrical equipment (including microcomputers), instruments, self-regulating valves, lighting, signaling, alarm systems, interlocks, etc. shall be installed and tested properly and kept in standby. 3. Perform oiling of valves and lead screws in the system once. 4. Personnel have completed their role-specific training and are fully familiar with all the loading, heating, and startup procedures, so as to have a clear understanding of them. 4. All operating equipment has been tested and is in good condition, ready for use without affecting the startup schedule. The equipment is placed in standby after undergoing individual testing or joint testing first. 5. The electric heating unit has been tested and found to be in good condition; it is now ready for use and integrated into the vulcanization system. 6. During catalyst loading, a dedicated person must be assigned to supervise and record the process. 7. Clear all debris from the site, secure the manhole covers, and keep fire-fighting equipment and protective gear in good condition for use. 8. Check that the packing and catalysts used in the conversion furnace, as well as the CS2 used for heating, have arrived, and verify whether their models, specifications, and quantities meet the requirements. Check that the catalyst, as well as the steel wire meshes laid above and below the packing layer, and the refractory balls are all present in sufficient quantity, and that their types and quantities match. 9. Catalyst loading: Calculate the loading amount based on the specifications of each catalyst package. 10. Method of catalyst loading: Upper layer: First, lay two layers of stainless steel wire mesh with a pore size of 10 mesh on the castor bean plate; then place refractory balls with a diameter of Φ50mm and a thickness of 100mm on top of the mesh, and finally lay another layer of stainless steel wire mesh with a 10 mesh pore size ； The mesh wire should be attached to the tower wall and curled upward by 10 cm, with flat steel or round steel used to secure it against the tower wall. Then, the fine catalyst is fed into the tower through the manhole using a discharge pipe ； After installing the catalyst, a layer of 10-mesh stainless steel wire mesh is placed on top of it, with Φ25mm refractory balls spaced 100mm apart ； Lower section: First, install Φ50mm refractory balls to the same height as the gas collection box at the bottom of the tank; then fill in Φ25mm refractory balls to a height of 75mm. Lay two layers of 10-mesh steel wire mesh on top, with the mesh wires pressed against the tower wall and curled upward by 10 cm. After that, use 10 bags of catalyst to compress the edges of the mesh before starting to fill in the catalyst. Once filling is complete, place another layer of 10-mesh stainless steel wire mesh on top, followed by Φ25mm refractory balls stacked to a height of 100mm ； 11. Precautions for catalyst loading: (1) Check that all internal components of the converter are present, that the interior of the furnace is clean, and that the thermocouples have been calibrated and are ready for use. (2) As required, lay two layers of 8-mesh stainless steel wire mesh alternately at the bottom of each catalyst layer; fold the edges by 300 units and press them with an annular iron plate. The interlocking parts of the stainless steel wire mesh are woven with wires. A 1-meter square wire mesh should be laid separately at the discharge hole. (3) After notifying the civil masonry team to install durable fire bricks in the discharge holes of each section, inspect and seal the discharge holes of each section of the low-voltage transformer. (4) Load the catalysts for each section according to the plan and specifications, loading from bottom to top, and record the actual amount loaded in a timely manner. At the beginning of loading, the operator must ensure that the mesh edges are pressed against the furnace wall using catalyst at the bottom of the furnace, so that there are no curled edges and no catalyst leakage occurs. After loading a portion (40 bags), it should be leveled before continuing to load the remaining amount; direct pouring from the manhole is prohibited to avoid uneven loading. To prevent the catalyst from being crushed during loading, the loading workers must stand on wooden planks and must not step directly on the catalyst. (5) The catalyst absorbs moisture easily; if it is loaded on rainy days, the packaging inside the tower must be removed to prevent the catalyst from absorbing water. (6) After the catalyst is loaded, it should be leveled manually; a scaffold must be used for leveling the catalyst – stepping on it directly is strictly prohibited. Bending or climbing on the thermocouples is also strictly forbidden. (7) After the top layer is filled, level it out. Then, as required, lay a layer of 8-mesh wire mesh on top of the filler, followed by 100 mm thick φ50 refractory balls and φ25 refractory balls. Conduct a thorough inspection; once everything is confirmed to be in order, remove personnel and debris from the furnace, and immediately construct refractory bricks to seal the manhole. (8) Fill the catalyst from top to bottom in sequence, seal the manhole, and complete the work. (9) Clean the site and prepare for catalyst heating for vulcanization.

1. Preparations before loading: a) Prepare 1 set of screens (around 10 mesh) + 1 platform; 2 wooden rakes with handles of 600 mm and 3000 mm length each (removable), and 10 iron shovels with handles； 1 500kg scale, 2 20Kg scales ； 2 catalyst funnels, 10 loading funnels, 10 small metal shovels, 14m of Ф50 aluminum pipes (or stainless steel pipes for decoration) ； 50 canvas bags of Φ200mm×12m, and 400 bags of Φ64×2000mm ； 100m of hemp rope with a diameter of 5–6mm, 60m of nylon rope with a diameter of 10mm, 10Kg of wire of size 8#, 10Kg of binding wire ； b. Prepare 2–3 forklifts, 1 16-ton crane, 3 sets of bucket hooks, and 4 Ф25 hoses. c. Prepare 2 low-voltage lamp shades with protective covers, 10 low-voltage light bulbs, and about 20 meters of power supply wires ； Temporary lighting for the furnace top platform and floor ； d. Prepare 2 sets of long-tube masks, 50 pairs of goggles, 100 dust masks, 6 sets of safety belts, 500 pairs of gloves, and 1 axial flow fan ； 1 tape measure (20m) ； 3 rainproof covers ； e. Prepare a 10m long flexible ladder, along with two wooden planks measuring 400×30×800 ； 1 oscillator ； Vacuum catalyst unloading device ； f. 1 set of endoscopes ； Flexible tape measure (20m), 2 pieces ； 1 set of dedicated differential pressure testing device ； g. Compressed air with stable pressure ≤ 0.5 MPa ； h. Mark lines according to the height of the refractory balls and catalyst bed indicated on the equipment drawings ； g. Sieve the catalyst to remove fines. i. Conduct loading tests to refine the loading method, and determine the volume occupied by a certain weight of catalyst as well as the optimal shaking time. 2. Loading shall be carried out in accordance with the requirements of the design drawings, following the marked lines: fire-resistant balls, wire mesh, catalyst, wire mesh, fire-resistant balls, (Lassie rings for medium-frequency furnaces), grating plates, and retaining rings, from bottom to top ； 3. Precautions: a. Loading work must not be carried out in rainy weather ； b The site must have adequate lighting and sufficient ventilation ； The entire process must be under the supervision of a dedicated person, with close coordination between all involved. Workers should wear dust masks or long-tube respirators as well as safety helmets. There should always be two people working inside the furnace so that they can look after each other. Someone must be assigned to monitor safety from outside the furnace, and communication signals should be agreed upon in advance; in case of any abnormalities, it is necessary to contact those outside the furnace promptly ； Ensure safety ； d All catalysts must be loaded according to the design requirements; mixing, incorrect loading, or omission must be avoided ； When loading the catalyst, do not step on it; instead, stand on a wooden board ； A dedicated person is assigned to keep records, ensuring that data such as model, particle size, weight, and height are recorded accurately and completely ； When staff install the catalyst, it is prohibited to bring in any items unrelated to the work, in order to prevent foreign objects from falling into the catalyst bed. (such as keys, lighters, phones, ID cards, etc.).

11. Precautions for catalyst loading: 1. Check that all components inside the converter are present, that the interior of the furnace is clean, and that the thermocouples have been calibrated and are ready for use. 2. As required, lay two layers of 8-mesh stainless steel wire mesh alternately at the bottom of the catalyst in each layer; fold the edges by 300, and press on annular iron plates. The interlocking parts of the stainless steel wire mesh are woven with wires. A 1-meter square wire mesh should be laid separately at the discharge hole. (3) After notifying the civil masonry team to install durable fire bricks in the discharge holes of each section, inspect and seal the discharge holes of each section of the low-voltage transformer. 4. Load the catalyst for each section according to the plan and specifications, loading from bottom to top, and record the actual amount loaded in a timely manner. At the beginning of loading, the operator must ensure that the mesh edges are pressed against the furnace wall using catalyst at the bottom of the furnace, so that there are no curled edges and no catalyst leakage occurs. After loading a portion (40 bags), it should be leveled before continuing to load the remaining amount; direct pouring from the manhole is prohibited to avoid uneven loading. To prevent the catalyst from being crushed during loading, the loading workers must stand on wooden planks and must not step directly on the catalyst. 5. The catalyst absorbs moisture easily; if it is loaded on rainy days, the packaging inside the tower must be removed to prevent the catalyst from absorbing water. 6. After the catalyst is loaded, it should be leveled manually; a scaffold must be used for leveling the catalyst – stepping on it directly is strictly prohibited. Bending or climbing on the thermocouples is also strictly forbidden. 7. After the top layer is filled, level it out. Then, as required, lay a layer of 8-mesh wire mesh on top of the filler, fold the edges by 100 units, and add φ50 refractory balls and φ25 refractory balls. Conduct a thorough inspection; once everything is confirmed to be in order, remove the personnel and debris from the furnace, and immediately construct refractory bricks to seal the manhole. Sequentially, load the catalyst from top to bottom and brick up the manholes until completion. Clean the site and prepare the catalyst for heating and vulcanization.

Well said – screen it. Various methods such as cloth bags, chutes, or filling pipes are used during catalyst loading. During loading, if one needs to walk on the catalyst, wooden planks must be placed to distribute the body weight over their surface. To prevent the catalyst from being blown away by high air currents or damaged due to turbulence that may occur during startup and shutdown processes, a stainless steel wire mesh must be placed at the top of the catalyst bed, with additional layers of such mesh installed between the different layers