Abstract : This paper first describes two adjustment methods for centrifugal pumps, and through comparison, elucidates the basic principle of energy saving in centrifugal pumps. Secondly, it briefly introduces the basic working principle of frequency converters and the composition of the entire frequency conversion control system. It can be seen that using frequency converters to automatically control the adjustment of centrifugal pumps has the advantages of energy saving and convenience. Keywords : Centrifugal pump; Frequency converter; Variable frequency speed regulation; Energy saving; Pump 1. Introduction In chemical production, fluid transportation is the most common, and even indispensable, unit operation. Centrifugal pumps are the main fluid transportation machinery in chemical production processes. They use impellers to subject the fluid flowing through the impellers to centrifugal force, thereby increasing the mechanical energy of the fluid and overcoming the mechanical energy loss along the fluid transportation process. The demand for pumps in China is very large; 20% to 25% of the annual electricity generation is consumed by pump products, of which centrifugal pumps account for about 80% of the total pump volume. Usually, the head, flow rate, and pipeline requirements of the selected centrifugal pumps are inconsistent. When selecting a centrifugal pump, some people choose based on the maximum flow rate instead of the normal flow rate, and then further increase the value by a factor to leave a margin, resulting in a situation of "overpowered pumps for small loads." Furthermore, process parameters often change during actual operation, and when the actual operating parameters of the pump deviate significantly from the rated parameters, the pump's efficiency will be greatly reduced. When the pump flow rate needs to be adjusted, the traditional method is to adjust the opening of valves on the pipeline to control the flow rate. This method is simple to operate but incurs energy loss at the valves. Changing the speed adjustment method can effectively avoid this. With the development of power electronics technology, microelectronics technology, and control theory, frequency converters are widely used for AC motor speed control. Frequency converters can achieve arbitrary adjustment of motor speed, realizing smooth stepless speed regulation. This energy-saving effect is even more evident in situations where pump load changes frequently and significantly. 2. Centrifugal Pump Adjustment Methods When a centrifugal pump is operating on a pipeline, if the production task changes, and the pump's operating flow rate is not suitable for the production requirements, or if the flow rate provided by the selected centrifugal pump may not meet the delivery task requirements, the pump's flow rate needs to be adjusted to change the pump's operating point. The pump's operating point is determined by the characteristics of the pump and the pipeline. Therefore, changing any of the characteristic curves can achieve the purpose of flow regulation. 1) Changing the valve opening : Application of frequency converters in centrifugal pump energy saving (full text download)