Hydrogenation catalyst loading: Why do experienced workers say “30% is the catalyst, 70% is the loading”?

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The 25th National \"Safety Production Month\" in 2026: Everyone talks about safety, and everyone knows how to handle emergencies; identifying and addressing risks and hazards -------------------------------------------------- Hydrogenation catalyst loading: Why do experienced workers say \"three parts are the catalyst itself, and seven parts are the loading process\"? In refineries, the hydrogenation reactor functions like a giant pressure cooker. And the catalyst is the “ingredient” in the pot. But you know what? Whether this pot can produce delicious food depends only to 30% on the ingredients themselves; the remaining 70% depends on how those ingredients are arranged in the pot. Today, let’s talk about this reactor interior construction that is comparable to \"high-end finishing\". https://mmbiz.qpic.cn/sz_mmbiz_gif/RRz5icUSmRfLRniaZYw8SbqT9BzHDs8vBG4sn7f1usibpz1XQvzOdHeZn4jCKs0coibHkicOQQRtl9l4OCibRbDDRtgZWehp0HJ4gVM1icnsj8Itib8/640?wx_fmt=gif&from=appmsg#imgIndex=001 If it isn’t loaded properly, “mushrooms” will grow inside the reactor; if the reactor is compared to a bed, then the catalyst is equivalent to the springs in the mattress. What happens if the springs are uneven and not evenly spaced? How will it feel to sleep on them? ——Some places have collapsed, and some are really uncomfortable to stand on. In the reactor, this kind of \"stinging sensation\" is called a hot spot. When the catalyst is not evenly packed, the recycled hydrogen (in gas phase) tends to take the easy route, passing through areas with low resistance and large gaps more quickly ； Meanwhile, the crude oil (liquid phase) is forced into compact areas. The feed oil reacts violently under the action of the catalyst, releasing heat; however, the gas phase moves too quickly and is unable to carry away this heat, resulting in a sharp rise in local temperature and the formation of hot spots. Once a hot spot is formed, it acts like a switch for a vicious cycle: the higher the temperature, the faster the catalyst cokes ； The more coking occurs, the greater the pressure drop in the bed layer ； The greater the pressure drop, the more the fluid flows elsewhere, and the higher the temperature at the hot spots becomes… This can result in a shortened startup time in mild cases, or even pose a threat to the safety of the installation in severe cases. The key to loading quality lies in three words: radial uniformity, axial compactness, and proper gradation. In simple terms, every catalyst needs to \"take its proper position and stand in the right place.\" https://mmbiz.qpic.cn/mmbiz_png/RRz5icUSmRfJCK0JDLzricAiaOWib9BpwcLR3FtyCtpIDlIzJ3cdoUtwkG0ja4AQNguxdX2rPhuEmgpiaG5J29Ak3LM97eia6DgVLUicZ3349lltrc/640?wx_fmt=png&from=appmsg#imgIndex=1 https://mmbiz.qpic.cn/sz_mmbiz_gif/RRz5icUSmRfLILicN5F1BBRl5zCz5mwHLxYnoJzXb44x9Tg58nfs8uyO54aWJywJ0NaLBJL6evZIuwZqsuKiaCyibicB1X5RSpsVlnWLgzFg5je0/640?wx_fmt=gif&from=appmsg#imgIndex=2 The “thorough cleaning” done before starting work is more formal than you might think; the preparations prior to loading are like sterilizing a operating room – no carelessness is allowed. First, the inside of the reactor must be “spotless”. The temperature must be reduced below 45°C, and rust, slag, residual oil, and standing water must all be removed. All internal components — distribution plates, cold hydrogen pipes, thermocouple sleeves — must be checked thoroughly; those that need to be installed should be installed, and those that need to be removed should be removed. Secondly, the reactor must be “isolated from the world.” All pipelines connected to the outside world—hydrogen pipes, feed oil pipes, gas pipes—must be equipped with isolation blind plates. Why? Since the catalyst is still a “baby” at this stage, it’s extremely vulnerable to hydrogen and hydrocarbon gases sneaking in and triggering reactions prematurely. Finally, the workers must be “fully equipped”. Protective clothing, dust masks, walkie-talkies, safety ropes, portable gas detectors… none of them can be missing. After all, when working inside a sealed reactor that is dozens of meters high, safety must always come first. https://mmbiz.qpic.cn/sz_mmbiz_gif/RRz5icUSmRfKvNc6P4NQlL5bYL4k6DbAJibTuOltibgjypjsRRG61ibQImSteVVRYpaxkubYFrFE4ttwLkjFnSTgoOHAkEoCtpib4YQNdR4oiaD2c/640?wx_fmt=gif&from=appmsg#imgIndex=303 There are two “methods” of laying: the bag method vs. the dense-phase catalyst loading method. There are mainly two ways to load catalysts, just like when laying flooring – one is the ordinary laying method (bag loading), and the other is the dense-phase laying method. The ordinary loading method is the most commonly used \"homegrown\" approach in China: a long canvas hose is extended from the top to the bottom of the reactor, and the catalyst slides into the reactor like going down a slide. This method is simple and practical; it does not require any patented technology, and spherical, cylindrical, and strip-shaped catalysts can all be used. The dense packing principle is “high-end customization”. It requires specialized equipment and patented technologies, and is particularly suitable for strip catalysts. During loading, the catalyst particles are arranged neatly in a radial pattern, like Tetris pieces, minimizing the gaps. The advantages of dense packing are very attractive: with the same reactor, 10%~25% more catalyst can be loaded ； The device has a higher processing capacity, or it can achieve a lower reaction temperature at the same processing capacity ； The bed layer is more uniform, and it is less prone to collapse and channeling ； The operating cycle is longer. Of course, the trade-off is that there will be a slightly greater pressure drop at the beginning of operation, and it is necessary to bring in \"external help\" – professional technical teams and equipment. https://mmbiz.qpic.cn/mmbiz_gif/RRz5icUSmRfKHibYMT2mxX6zmlNam7FF6Nxp4Jy5KD4vwuKiaDnvUgZezhlTB9jic3MDiaOfZMNAFEiaNWbOXOe8kcKQxiaTG4wh4YAW84mlNz5bwM/640?wx_fmt=gif&from=appmsg#imgIndex=404 At the construction site, every detail is attended to with “millimeter-level” precision. When the actual filling process begins, the skilled workers’ operations are incredibly meticulous—truly astonishing. 1. The catalyst must not “free-fall”. The height from which the catalyst particles fall from the hose outlet to the surface of the bed must be controlled to within 1.0–1.5 meters. Too high? It’s broken! Catalysts are very delicate; a free fall of more than 1 meter can cause them to disintegrate. Therefore, the hose must be continuously cut shorter as the material level rises, so as to always maintain “low-altitude dispensing”. 2. People must not step directly on the catalyst; when entering the reactor, they need to place a wooden board measuring at least 500mm×500mm under their feet to distribute the pressure, similar to how skis do. Step on it directly? The catalyst will be crushed into powder, blocking the bed. 3. There is a \"sweet spot\" for the loading rate; if it’s too fast, the catalyst falls in like a downpour, resulting in a low loading density and a loose bed layer ； It’s too slow; it’s delaying the schedule again. The typical speed is 4 to 9 cubic meters per hour; experienced workers can determine whether the speed is appropriate by listening to the \"rustling sound\" based on their experience. 4. For every 1 meter of elevation, the bed layer must be “raked flat” once; a wooden rake must be used to level it out to ensure a smooth surface. When the material level is about 900 mm away from the lifting disk, it is necessary to shape it into a concave surface; this allows the catalyst to be filled more completely without any unused spaces. 5. The ceramic balls should be arranged in order from large to small; inert ceramic balls need to be filled at both the bottom and top of the reactor, just like the bread slices in a sandwich. The loading sequence must strictly adhere to the grading principle of \"from large to small\": large porcelain balls are used as a foundation at the bottom, followed by intermediate sizes, with small porcelain balls on top to protect the catalyst. If the order is wrong and larger particles fall into the layer of smaller particles, it’s like stones hitting a pile of sand, which will damage the catalyst. https://mmbiz.qpic.cn/mmbiz_gif/RRz5icUSmRfIhIY5uLEko1ZNwZqJ7l1HbnarTfhI2WK0Yp09tjr9DRwf1QQuCiayljL9RtsOAcF75TPcHYsc4UxBNCiaoibcbnxan9MLQgLYPu4/640?wx_fmt=gif&from=appmsg#imgIndex=505 Once the catalyst has been loaded, work cannot start yet; it must first be \"dried\". Many beginners think that they can start using oil right away after loading the catalyst. Wrong! It still needs to be dried. The vast majority of hydrogenation catalysts use alumina as a carrier, which absorbs water like a sponge, with a water content that can reach 1%–3%, or even higher. If it is not dried, when hot oil and gas enter during operation, the moisture vaporizes instantly; upon encountering the cold bed layer below, it condenses and releases heat. This alternation of hot and cold conditions causes the catalyst to behave like a glass cup into which boiling water has been poured, resulting in a sharp decline in its mechanical strength and even its disintegration. High-purity nitrogen is used for drying (purity >99.5%, oxygen content