Abstract : Pulping pumps are widely used in closed-loop pulp supply systems of high-speed paper machines. This paper introduces a frequency conversion retrofit method for pulping pumps based on the speed control principle of papermaking processes, which achieves PID control by adding a pressure transmitter. Practice has proven that installing a frequency conversion control system can adapt to changes in usage at different machine speeds and for different product types, ensuring that the pulping pump operates at high efficiency and greatly stabilizing process conditions. Using frequency converter speed regulation to replace valve regulation of pulp flow reduces the energy consumption of the pulping pump, achieving an energy saving rate of over 30%. Keywords: Frequency conversion control; Energy saving; Pulping pump 0 Introduction Papermaking enterprises are high-energy-consuming enterprises. In paper mills, over 50% of the load consists of fans and pumps, which currently rely primarily on valves or baffles to regulate airflow or liquid flow, resulting in significant energy consumption. For the flow delivery system in papermaking processes, there are numerous and powerful pulping pumps; therefore, frequency conversion energy saving retrofits for pulping pumps are always a primary consideration in paper mill renovations. However, since papermaking is a continuous production process, energy saving must adhere to process requirements. Taking the pulp pump in the pulp delivery system as an example, its frequency conversion energy-saving retrofit must first meet the following requirements: ① The amount of pulp delivered to the wire section of the paper machine must be stable, with an error not exceeding ±5%; ② The pulp ratio and concentration must be stable and uniform; ③ The pulp must be purified and refined, etc. This study mainly introduces the frequency conversion control principle and energy-saving application of the pulp pump. 1 Application Principle of Frequency Conversion Control in Pulp Pumps The headbox is a key piece of equipment in the forming section of the paper machine. In medium and high-speed paper machines, air cushion pressurization is used to increase the pulp speed. Currently, the pulp speed control of domestically produced sealed air cushion pressure headboxes is mostly manually adjusted. From the actual operation of many factories, these headbox quantitative adjustment systems currently in use generally have many problems: ① High power consumption; ② Inconvenient operation, resulting in unstable paper basis weight; ③ The headbox is prone to clogging; ④ The installation pipeline of the paper machine is relatively complex. [b][align=center]For details, please click: Application of AC Frequency Converter in Paper Pulp Pumps[/align][/b]