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Fundamentals of the working principle of centrifugal pumps: In many fields of industrial production and the national economy, it is often necessary to transport or pressurize liquids. Machines that can perform such tasks are called pumps. And those that rely on centrifugal force are called centrifugal pumps. Due to its simple structure, stable performance, ease of maintenance, simplicity of operation, and strong adaptability, the centrifugal pump is widely used in chemical production; statistics show that it accounts for over 80% of liquid transfer equipment. Therefore, the operation of centrifugal pumps is the most fundamental operation in chemical production. A centrifugal pump consists of a suction pipe, a discharge pipe, and the pump body. The main body of a centrifugal pump is divided into a rotating part and a stationary part. The rotating part is driven by a motor to rotate, transferring energy to the part being conveyed; it mainly includes the impeller and the pump shaft. The fixed components include the pump casing, guide wheel, sealing device, etc. The impeller is the component in a centrifugal pump that imparts external energy to the liquid. The function of the pump shaft is to transfer the energy from the motor to the impeller. The pump casing is a spiral-shaped shell with a gradually increasing cross-sectional area of the channel; it contains the liquid within a certain space and converts most of the liquid’s kinetic energy into static pressure energy. The guide vane is a set of blades that are aligned with the rotation direction of the impeller and are fixed to the pump casing. The function of the sealing device is to prevent liquid leakage or air from being drawn back into the pump. After starting the centrifugal pump filled with the liquid to be pumped, the motor drives the pump shaft, which in turn causes the impeller to rotate. The blades of the impeller push the liquid surrounding them, causing it to move; under the effect of centrifugal force, the liquid is flung toward the edges of the impeller and gains kinetic energy ； Guided by the idler wheel, the fluid flows along the pump casing, whose flow cross-sectional area gradually increases, toward the discharge pipe; as a result, the flow velocity of the fluid decreases while its static pressure energy increases. The pressurized liquid from the discharge pipe can be sent to its destination via the pipeline. At the same time, a certain vacuum is created at the center of the impeller as the liquid is expelled. Since the pressure above the liquid level in the tank is greater than that at the center of the impeller, under the effect of this pressure difference, liquid continuously flows into the pump through the suction pipe to fill the space left by the liquid that has been discharged. Therefore, as long as the impeller keeps rotating, the liquid is continuously drawn in and discharged. Thus, the reason why a centrifugal pump can transport liquids is mainly due to the high-speed rotating impeller. There are two phenomena that should be avoided during the operation of centrifugal pumps: air locking and cavitation. Air locking occurs when the pump is not filled with the liquid to be transported before it is started, or when air gets into the pump during operation. Since the density of gas is lower than that of liquid, the centrifugal force generated is insufficient to expel the air, resulting in a vacuum level at the center of the impeller that is not enough to draw liquid into the pump. Even though the impeller keeps rotating, the centrifugal pump loses its self-priming ability and is thus unable to transport liquid; this phenomenon is known as air locking. Cavitation occurs when, at a constant pressure on the surface of the tank, the pressure at the center of the impeller drops to equal the saturated vapor pressure of the liquid being transported at that temperature. This causes numerous bubbles to form in the liquid at the inlet of the impeller; as these bubbles move into areas of higher pressure, they are quickly crushed and condensed, creating a vacuum in their vicinity. The liquid particles around them then rush toward the center of these bubbles at high speeds, generating an instantaneous shock pressure that can rapidly damage parts of the impeller. This phenomenon is accompanied by vibrations in the pump, noise generation, as well as a significant decrease in the pump’s flow rate, head, and efficiency. This phenomenon is called cavitation.