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I. Overview: Nantong Pharmaceutical Factory primarily produces active pharmaceutical ingredients, using raw materials such as ***, methanol, and ethanol, which are highly harmful to human health. All workshops use SS-800 centrifuges for solid-liquid separation. Due to the open discharge port, the drum rotates at high speed, which results in the release of a large amount of gas during production; this contaminates the environment and endangers the health of workers. To improve the working conditions for these workers, a suction hood was initially used (Figure 1). However, since the cross-sectional size of this hood was smaller than that of the hot air jet generated by the centrifuge, and due to the influence of lateral air currents, gas still managed to escape into the surrounding space. In addition, the suction hood interfered with operations, resulting in poor performance. Later, an exhaust system arranged along the edge of the tank was adopted (Figure 2). This method effectively removes harmful gases, but it requires a lot of space; moreover, the cover plate has to be removed during discharge, and the plastic exhaust hood is prone to damage during operation, making it inconvenient to use. According to available information, the exhaust method using the lower outlet of the centrifuge yields good exhaust results, requires less space, and is easy to operate. Therefore, it was decided to modify the exhaust system of the phenylbutazone reduction centrifuge. II. Brief introduction to the principle of exhaust ventilation at the lower outlet: Based on an analysis of the aerodynamic conditions at the discharge outlet of the centrifuge, it can be seen that a negative pressure is generated at the center of the centrifuge, while the density increases in the peripheral area, resulting in higher pressure. To reduce the wind pressure in the peripheral area, exhaust outlets must be installed there. The discharge outlet of the centrifuge can fulfill this function while discharging the mother liquor (Figure 3). The mother liquor is led to the inlet of the exhaust fan through a tank, where the exhaust fan removes the harmful gases, allowing the mother liquor to flow into the drainage channel. To prevent gas short circuits, a liquid seal groove must be added (Figure 4). Figure 3: Schematic diagram of exhaust system Figure 4: Liquid seal tank. III. The overall layout design for the renovation measures is shown in Figure 5 [The values within parentheses in the figure represent elevations]. The centrifuges are the original 2 SS-800 type centrifuges; with a required air volume of 2170 m3/h, a 4-72-A4# fan is sufficient. The mother liquor tank is made of φ320 mm polypropylene pipes, while the connection pipes are made of φ89 mm polypropylene pipes. The floor tank and the liquid seal tank are integrated, constructed from 8 mm thick Q235A steel plates with dimensions of 1500 mm × 1500 mm × 1000 mm. The height of the liquid seal was determined to be 0.38 m through calculation. The redesigned system has a reasonable layout; aside from the two pipes that extend above the ground, all other pipelines are buried underground. The control room is spacious and well-lit, facilitating operation and equipment maintenance. The exhaust performance is good after being put into use. W04.10-22 Fig. 5 System layout diagram