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Compact catalyst packing, also known as directional packing, is a catalyst packing method developed by Atlantic Richfield Company in the United States. With this method, the catalyst particles are arranged horizontally and in a directed manner. Compared to conventional packing methods, it offers the following advantages: higher catalyst packing density, allowing the amount of catalyst used to increase by 10–15%; orderly arrangement of the catalyst particles, resulting in even distribution of the reaction stream and high contact efficiency; compact packing that prevents the bed layer from sinking, thereby reducing channeling effects. If necessary, this compact packing technique can be applied to both the upper and lower layers of a reactor. When product quality requirements remain the same, using compact packing in existing reactors can significantly increase processing capacity while reducing operating costs. When designing new reactors, it is possible to reduce their volume, thus saving on investment costs. Pneumatic packers are used for compact catalyst packing in reactors with a diameter greater than 4.5 feet (1.37 m), while static packers are used for reactors with a diameter less than 4.5 feet. The principle behind compact catalyst packing involves the catalyst falling from a hopper through a downcomer onto a guide plate, where it is pushed radially outward by air streams generated by an air distributor, enabling the catalyst to be arranged neatly and achieving compact packing. The packing speed of the catalyst is primarily regulated by the gap between the end face of the downcomer and the guide plate, and to some extent, it is also influenced by the air flow rate. The distribution radius of the catalyst particles is mainly controlled by the air flow rate. The compact packer is fixed above the packing area using brackets, with its levelness adjusted using screws on those brackets； It facilitates the use of a thrust ring and three adjustment screws to adjust the gap between the end face of the descent tube and the guide plate at the outlet ； A centering device is used to keep the guide plate and the descent tube concentric; once the hopper is filled with catalyst, air supply begins ； For strand extrusion catalysts and reactors with a diameter of around 3 m, an initial operating air pressure of 0.05~0.055 MPa is appropriate ； For reactors with a larger diameter (such as 3.6 m), the wind pressure can be increased to 0.085 MPa. At the beginning of the catalyst loading process, it is necessary to monitor the operation of the loader to check whether the air distributor is functioning properly and whether the catalyst is distributed evenly. After 10–25% of the catalyst has been loaded, it is important to check the density and levelness of the catalyst in the bed ； For reactors with a high bed height and high conversion requirements, it is even more necessary to conduct inspections in advance (some equipment needs to be removed during these inspections). The catalyst loading speed should be consistent with the speed at which the catalyst is lifted from the ground to the hopper. During continuous loading, the maximum catalyst loading speed must not exceed 75 mm/minute; the actual loading speed can be measured using the hopper. Adjusting the air pressure can affect the distribution of the catalyst, so care should be taken. When a significant adjustment to the catalyst loading speed is required, this should be done by increasing the gap between the end face of the drop tube and the guide plate; in such cases, catalyst loading should be temporarily stopped. Quality checks of the bed layer should be carried out at 50% and 75% loading levels. Whenever time permits or after making significant adjustments to the air volume, it is advisable to conduct more inspections of the bed layer