Methanol synthesis catalyst loading scheme and passivation scheme (detailed)

I. Purpose of Loading: Catalyst loading is a task of great importance. The quality of this loading process has a direct impact on the uniform distribution of airflow within the catalyst bed, as well as on reducing the resistance in the bed. It helps to ensure that the catalyst can function effectively and extends its service life. It is therefore necessary to minimize the rate of damage and prevent the occurrence of \"bridging\" phenomena. II. Preparation work for loading 1) Preparation of tools and equipment: Prepare fine nylon rope, funnels (base funnels), scales, rubber mallets, copper weights, winches, steel wires, record books, measuring tapes, lifting frames, buckets, rubber stoppers (of appropriate size), two sets of long-term respirators, one-piece work clothes, goggles, dust masks or face shields, towels, earplugs, leather gloves, flashlights, two rainproof tarpaulins (10*10m), as well as communication equipment and other tools required for catalyst loading. 1. Confirm that the synthesis tower is clean, and that the two discharge ports at the bottom of the tower have been returned to their proper positions. 2. The catalyst loading tool has arrived at the site. 3. Inert balls; the catalyst has been delivered to the site. 4. The relevant personnel jointly confirm that the conditions for loading are met. 2) Quantity of high-alumina refractory balls and catalysts 1. Inert balls: Specifications and quantity, main components: SiO2, Al2O3. 2. Catalysts: Model, specifications, quantity of the methanol synthesis catalyst, filling height inside and on the tubes, volume, etc. 　　 Main components: CuO, ZnO, Al2O3. 2) Personnel preparation: First, draw a schematic diagram of catalyst loading; the personnel responsible for loading the catalyst wear integrated work clothes and carry out the task under the supervision of professionals. Metrology and measurement personnel must carefully and thoroughly record the catalyst amount and filling height. III. Filling with catalyst: The lower head of the synthesis tower, up to the opening above the wall of the cone cap, is filled with high-alumina refractory balls, after which another amount of high-alumina refractory balls weighing approximately 20 tons is added from the top of the tower. Methanol synthesis catalyst is filled inside the reaction tube and within 200 mm above the upper tube sheet. The upper part of the catalyst is covered with a stainless steel mesh, followed by 100 mm of high-alumina refractory balls. IV. Catalyst Loading Method and Precautions 1. Loading of refractory balls: Enter the tower from the bottom of the synthesis tower, and check again whether the two discharge ports are in their proper positions as required. First, remove the flange at the outlet of the reaction gas; from there, one can enter the bottom of the tower. Next, open the hole above the cone-shaped cap. The inert balls are first placed in woven bags and then fed into the tower using a transfer method, so as to fill them evenly at a distance of 100 mm from the tube sheet. Before leaving the tower, confirm the empty area and calculate the approximate cubic volume of the remaining space. Close the upper manhole, then fill the remaining refractory balls from the top of the tower, and seal the manhole at the bottom of the support. People enter the tower through the manhole at the top of the synthesis tower, and the refractory balls (note: the size of these balls is φ10mm at this stage) are dropped from inside the pipes to the bottom of the tower to fill in the empty spaces. Copper weights are used to check whether each pipe has been filled to the lower tube sheet; if not, more balls are added until the pipe is fully filled. Until the copper weight test is passed to confirm that the inert balls are fully installed. 2. Catalyst loading: Lay a 10*10 m canvas on a clean surface, and sieve the new catalyst using a Φ2.5 mm sieve; if there is little dust present, sieving is not necessary. Pour the catalyst into the hopper. The winch (or crane) is started to lift the bucket to the top of the tower; the catalyst inside the bucket is carefully placed into the funnel (base bucket) using control slats. The catalyst then flows down through the funnel (base bucket) into the synthesis tower. Workers wearing integrated suits fill the catalyst evenly into the (4513) tubes inside the tower, following a sequence that starts from the periphery and moves toward the center, continuing this process until the surface of the reactor’s tube sheet is covered. During the loading process, attention should be paid to measuring the height of the space inside the furnace tube, and the height should be adjusted to ensure a uniform distribution of the catalyst. When filling reaches 200 mm above the tube sheet, stop filling and level it out. When loading, one should not step directly on the catalyst; instead, a few pieces of sanded wood should be placed on top of it to prevent it from breaking. 3. Filling with φ10 refractory balls: After filling is complete, a stainless steel mesh panel is placed on top of the catalyst; the stainless steel mesh is connected using stainless steel wires, and a layer of φ10 refractory balls with a thickness of 100 mm is installed on this mesh. After loading is complete, clean the reactor distributor, the manhole at the top of the tower, and the site. Confirm that loading is complete and the manhole is back in place. A schematic diagram of the synthesis tower is attached below. 4. Precautions 1) Handle the catalyst gently when moving it in and screening it to avoid damaging it; follow the loading procedure strictly to prevent bridging. During loading, the falling height of the catalyst at the lower end of the cloth bag exceeds 30 mm. 2) Ensure that the fold at the bag seam does not open during the descent of the catalyst. 3) The operators must wear coveralls and shall not carry any items unrelated to catalyst loading. Persons entering the tower must not bring any foreign objects inside to prevent them from falling into the furnace tubes. Wear protective gear to prevent poisoning. 4) When adjusting the height, the force applied by the rubber mallet should be consistent, and instructions from the personnel on top of the furnace must be followed. 5) The staff should wear the necessary protective equipment to prevent damage to the human body caused by catalyst dust. 6) A dedicated person should be in charge of the entire catalyst loading process, from retrieving it from the warehouse until it is fully loaded. 7) The catalyst should be handled with care during transportation; throwing or dropping it violently is strictly prohibited to prevent damage. 8) Keep proper filling records; filling must be done on sunny days. Catalysts must not get wet; on rainy days, outdoor catalyst tanks should be covered with rainproof tarps. 9) It is strictly prohibited to allow any foreign substances to enter the tower during filling; in particular, Cu-based catalysts must not mix with iron, as iron acts as an active catalyst for methane synthesis within the synthesis tower. 10) When loading the catalyst into the tube sheet, the loader stands on polished wooden planks to prevent crushing the catalyst. 11) After the C-306 catalyst has been loaded, thoroughly clean the distributor of the synthesis tower as well as the manhole at the top of the tower. 12) Once the relevant personnel confirm that loading is complete, the manhole is returned to its original position.

1. Precautions for catalyst loading The quality of catalyst loading has a direct impact on subsequent normal production, energy savings and consumption reduction, as well as on extending the catalyst’s service life; therefore, it is required that: A. A dedicated person should be in charge of the entire catalyst loading process, from retrieving the catalyst from the warehouse until it is fully loaded； During the loading process, the B catalyst should be handled with care; it is strictly prohibited to drop or throw it violently to prevent damage to the catalyst ； The C catalyst must not get wet at all; on rainy days, the catalyst tanks placed outdoors should be covered with rainproof sheets ； It is strictly prohibited to allow any foreign substances to enter the tower during the loading of D catalyst; in particular, when loading copper catalyst, iron must not be introduced, as iron acts as an active catalyst that promotes the conversion of syngas into methane within the synthesis tower ； The E catalyst should be poured into the synthesis tower slowly, and it should be spread evenly in all directions during pouring to ensure that the gaps between the catalyst particles are consistent. 2. Catalyst deactivation: The copper catalysts in the methanol synthesis tower had their copper oxide reduced to metallic copper atoms prior to operation. When these metallic copper atoms are removed from the synthesis tower, oxygen in the air comes into full contact with the catalyst; this allows oxygen to penetrate deep into the catalyst’s interior surface in a short time, generating a large amount of reaction heat. As a result, local temperatures rise sharply, or there is a significant increase in temperature differences. The resulting expansion pressure can cause certain components inside the synthesis tower to deform or even crack, leading to damage to those components. The passivation of a catalyst refers to the slow oxidation of the catalyst by introducing a controlled amount of oxygen into pure nitrogen before removing the catalyst; this process results in the formation of an oxide coating on its surface. This oxide layer prevents further reaction between oxygen and the copper metal atoms, thereby avoiding damage to the components inside the synthesis tower when the copper catalyst is removed, and thus serving to protect those components. During passivation, the oxygen concentration entering the reactor is maintained at 0.4% to 0.8%, while the reaction temperature is kept around 250°C, with a maximum of 300°C. When the oxygen concentration entering the reactor increases gradually to 2% to 3% and the catalyst’s humidity no longer rises significantly, it indicates that the passivation process is complete; the catalyst can then be removed after cooling down.