Energy is a crucial material foundation for developing the national economy and improving people's living standards. With China's rapid economic development and the increasing scarcity of global energy resources, energy conservation has become a focus of attention. Pumps, belonging to fluid machinery, have a very large domestic demand, consuming 20%-25% of annual electricity generation. Centrifugal pumps account for about 50% of the demand for pumps, making them indispensable machinery in China's economic construction. Therefore, energy conservation efforts targeting centrifugal pumps are extremely important and urgent. 1. Technical Analysis of Centrifugal Pump Energy Conservation In the past decade, with the rapid development of science and technology, many advanced research achievements and high-level machining equipment have emerged, which are highly beneficial to energy conservation in pump products. This is mainly reflected in the following aspects: 1.1 Development of Design Technology The rapid development of computer technology has brought ideal tools for centrifugal pump design research. The application of CAD and CFD technologies in centrifugal pump design is of great significance to improving the design level of centrifugal pumps and brings good prospects for energy conservation. 1.2 Development of Advanced Manufacturing Technology The rapid development of CAM technology and its application in pump production is highly beneficial to improving the efficiency and technical indicators of centrifugal pumps. Currently, some companies in the pump industry have applied this technology to the production of hydraulic model molds and the manufacturing and processing of parts, greatly improving the accuracy of hydraulic dimensions and the roughness precision of flow surfaces or channels, thus improving efficiency. 1.3 Development of Corresponding Supporting Technologies Supporting technologies related to centrifugal pumps have recently seen significant development, such as motor design and manufacturing, automatic speed regulation, automatic control, automatic alarms, transmission systems, sealing design and manufacturing technology, new materials, and testing technologies. The comprehensive development of these technologies is conducive to improving the efficiency, reliability, and other performance indicators of centrifugal pump systems, promoting energy conservation efforts. 2 High-Efficiency and Energy-Saving Technical Measures For decades, there have been no major breakthroughs in technical design methods, resulting in a relatively backward technological level. To date, the design methods for centrifugal pumps mainly employ similarity transformation methods and speed coefficient methods. Extensive reliable data and rich practical experience are crucial for design success; designers should continuously improve their design capabilities based on the actual needs of technological development. 2.1 Application of CAD/CFD Technology With the rapid development of computer technology and the emergence of CAD/CFD technology, it is beneficial to explore the internal flow laws of centrifugal pumps and improve the advancement of centrifugal pump design methods. Modern centrifugal pump design methods must combine advanced computer technology and CAD/CFD technology. Advanced computer technology can solve the calculation problems of complex internal flow fields in centrifugal pumps. By applying CAD/CFD technology, we can further understand and master the objective laws of internal flow in centrifugal pumps, so as to optimize the design of centrifugal pumps. The characteristics and advantages of CAD/CFD technology are very important for improving the technical level of centrifugal pump design methods. Modern centrifugal pump design methods cannot be separated from centrifugal pump testing. Experimentation is an important means of scientific and technological research, characterized by its authenticity and reliability. CAD/CFD uses a finite information system to approximate a real infinite information system. Due to human errors in the mathematical model, discretization process, format, mesh generation, and boundary condition handling, the results may deviate from reality. The success of CAD/CFD application needs to be verified by experiments. Therefore, modern centrifugal pump design methods should be a combination of traditional design methods, CAD/CFD technology, and experimental methods; none of the three can be dispensed with. 2.2 Improvements and Enhancements to Traditional Design Methods 2.2.1 Design of High-Cavitation-Performance Hydraulic Model Library Cavitation performance is a crucial technical indicator for centrifugal pump performance, primarily determined by the hydraulic dimensions of the suction chamber and impeller inlet. In similarity conversion algorithms, due to differences in impeller inlet dimensions and pump speeds, achieving geometric similarity in impeller inlet dimensions is difficult, let alone kinematic and dynamic similarity. Consequently, the similarity conversion results for cavitation performance show significant deviations. Previously established hydraulic model libraries primarily used efficiency indicators as selection criteria. For pumps designed with high cavitation performance, it is difficult to meet the requirements through model conversion algorithms alone; therefore, a high-cavitation-performance hydraulic model library should be established. 2.2.2 Establishment of a Comprehensive and Reasonable Hydraulic Model Library When selecting models for traditional hydraulic model libraries, the primary reference standard is the pump's efficiency indicator, along with many other factors that need to be considered, such as pump performance curves, the matching of pump performance parameters, and pump structural factors. 2.2.3 Improvement and Enhancement of the Velocity Coefficient Method Based on the theoretical head equation of centrifugal pumps, design experience, and experimental analysis, factors affecting the velocity coefficient, besides the pump's specific speed, include other important factors. Among these, the main factors affecting the outlet circumferential velocity coefficient include the pump's structure, blade outlet angle, and number of blades; the main factors affecting the inlet velocity coefficient include the pump's structure, blade inlet angle of attack, and number of blades. The degree of influence of these factors should be analyzed and statistically analyzed, and the changing patterns of these factors should be summarized to determine the range of values ​​for these factors on the standard velocity coefficient curve. Corrections should be made based on the patterns of influence, which will significantly improve the accuracy of the velocity coefficient method. 2.3 Application of CAM Technology in Pump Manufacturing In the product manufacturing process, CAM (Computer-Aided Manufacturing) is currently a relatively advanced technology. The application of CAM technology in the centrifugal pump manufacturing process will bring very ideal results to the energy-saving work of centrifugal pumps. Currently, some leading enterprises in the pump industry have successively carried out production practices in this area. 2.3.1 Centrifugal Pump Hydraulic Model Mold Making The hydraulic model of a centrifugal pump is an important component that determines the hydraulic performance and technical level of the product. Due to the complex internal flow channel shapes of hydraulic model parts, they are difficult to machine, and most companies use casting. Before casting, sand casting is required. Traditional mold making is mostly done by hand, which has the drawback of large errors, making it difficult to accurately guarantee the shape of the hydraulic model's flow profile, resulting in low efficiency and difficulty in ensuring hydraulic performance. The application of CAM technology will overcome these shortcomings. 2.3.2 Centrifugal Pump Hydraulic Model Parts Manufacturing The main hydraulic model parts of centrifugal pumps include impellers, pump bodies, guide vanes, etc. The traditional manufacturing method for these parts is to form blanks through casting, and then use mechanical equipment to machine the blanks to form finished parts. After the surface of the parts is cast, no further machining is performed. Due to some reasons in the sand casting process, the surface dimensions will have large errors, and the roughness will be poor, which will have a significant impact on hydraulic performance and efficiency, and the flow rate and head will be difficult to guarantee. To address this deficiency, the pump industry has formulated relevant casting standards, but these cannot fully meet the requirements. By applying CAM technology and using CNC machining equipment, impellers, pump bodies, and other components can be directly manufactured according to the hydraulic dimensions required by the design. This ensures high-quality accuracy of the flow profile, improves dimensional precision and surface roughness, and guarantees flow rate and head, thereby increasing efficiency. 2.3.3 Manufacturing of other components: Improving the machining precision of components reduces the cumulative machining errors of rotor and stator components, which is beneficial to improving the assembly quality of the entire centrifugal pump and enhancing its overall hydraulic performance. 2.4 Improving casting technology: The main components of centrifugal pumps are all cast parts, such as pump bodies, impellers, pump covers, bearing housings, and bases. The level of casting technology directly affects the quality of components. The hydraulic dimensions of the cast hydraulic model directly affect the pump's performance parameters. The surface roughness of the cast components is directly related to the pump's efficiency. Casting technology has a significant impact on the pump's performance indicators. The following are measures to improve casting technology: 2.4.1 Improving the Manufacturing Quality of Centrifugal Pump Hydraulic Model Molds The quality of centrifugal pump hydraulic model mold manufacturing directly affects the casting quality of hydraulic model casting blanks. Traditional hydraulic model molds are all handmade, resulting in large dimensional deviations and affecting the technical indicators of hydraulic performance. Currently, a more advanced manufacturing method is to use CAM technology and apply CNC machining equipment for mold processing, which is beneficial to improving the efficiency indicators of centrifugal pumps, with excellent results. 2.4.2 Improving the Material Grade of Centrifugal Pump Hydraulic Model Molds Centrifugal pumps are general-purpose mechanical products with large consumption and wide application. There are many product specifications, with tens of thousands of pump performance specifications in the entire pump industry, which requires the production of a large number of hydraulic model molds. However, the batch size of each specification is not large. In order to reduce manufacturing costs, many companies often use wooden molds for the pump body and metal molds for the impeller, or wooden molds for the pump body and the front and rear cover plates of the impeller and metal molds for the impeller blades. Wooden molds have large dimensional deviations, are prone to deformation, and have poor surface roughness in cast blanks. Compared with metal molds, their performance in all aspects is significantly inferior. To further improve the quality of hydraulic model blanks and ensure the technical indicators of various hydraulic performances, the material grade of centrifugal pump hydraulic model molds should be greatly improved, so that all molds are made of metal materials. However, this increases manufacturing costs. 2.4.3 Adopting advanced precision casting methods Traditional casting methods use ordinary sand casting, resulting in poor quality of cast blanks, excessive thickness of castings, material waste, increased costs, large dimensional errors in blanks, difficulty in ensuring hydraulic dimensions and performance, and poor surface roughness, increasing hydraulic losses. Advanced precision casting methods can effectively overcome the above shortcomings, such as improving sand quality and using investment casting methods. 2.5 Energy-saving methods for adjusting rotation speed Adjusting rotation speed has good energy-saving effects, which has been proven by many domestic and foreign production practices. In many pump applications, sometimes the pump's performance parameters need to remain constant, and sometimes they need to change according to the operating conditions. Adjusting the speed can achieve this purpose, and at the same time, it significantly improves the efficiency of the device by increasing pipeline efficiency. The main speed adjustment methods are as follows: ① belt drive speed adjustment; ② gearbox speed adjustment; ③ hydraulic coupling speed adjustment; ④ diesel engine speed adjustment; ⑤ electric motor speed adjustment. 2.6 Improving the Design Level of Centrifugal Pump Selection Due to various reasons, there are many unreasonable phenomena in pump selection and design, resulting in energy waste and significantly impacting energy conservation efforts. 2.6.1 Centrifugal pump selection should follow these principles: ① The user unit should reasonably determine the pump's performance parameters and necessary operating conditions; ② The design department should reasonably determine the pump type and parameters to reasonably meet the on-site operating conditions; ③ Comprehensively consider the pump's maximum efficiency and its range, as well as actual operating efficiency indicators; ④ Conduct a technical and economic comparison and select a technically advanced and economically reasonable solution. 2.6.2 Improving the Efficiency Indicators of Centrifugal Pump Systems Energy conservation efforts for centrifugal pumps should not be limited to studying the efficiency of the pump itself, but should more broadly examine the efficiency indicators of the entire system to achieve overall system efficiency and energy saving. There is significant potential in this area. 3. Constraints on High-Efficiency Energy Saving The implementation of high-efficiency energy saving for centrifugal pumps faces many constraints in practice. We must correctly understand these problems in order to take corresponding measures. 3.1 Weak Energy Conservation Awareness and Lack of Policy Guidance On the one hand, insufficient government attention and publicity regarding energy conservation have led to a lack of awareness among the public. On the other hand, the absence of national policies and preferential measures for energy conservation has resulted in centrifugal pump users neglecting energy conservation factors and focusing only on the product's operating conditions during procurement. Furthermore, the high price of high-efficiency energy-saving centrifugal pumps increases production costs for users. To reduce costs, users generally disregard energy conservation indicators and choose cheaper centrifugal pumps. 3.2 Incorrect Traditional Energy Concepts The traditional concept of energy conservation focuses on improving the efficiency indicators of centrifugal pumps, but this concept is inaccurate. A scientific concept of energy conservation should not only consider efficiency indicators but also many other factors, namely, minimizing various consumption costs of centrifugal pumps throughout their total service life, such as design, manufacturing, and maintenance costs. 3.3 Complexity of Centrifugal Pump Operating Conditions Centrifugal pumps operate under complex conditions, requiring them to possess various performance characteristics, such as hydraulic performance indicators, materials, sealing performance, reliability, overall structure, and high-temperature resistance. Some of these characteristics are difficult to test in laboratories, and testing is extremely expensive. However, these performance characteristics are closely related to energy conservation in centrifugal pump systems. This complexity significantly hinders the further development of energy conservation efforts and is one reason why centrifugal pump energy conservation efforts are not widely accepted by users. 4 Conclusion In summary, from a technical perspective, carrying out energy conservation work on centrifugal pumps is entirely feasible, and the technical capabilities are available. However, considering other constraints, the resistance to implementing energy conservation work is considerable. To truly promote energy conservation in centrifugal pumps, the government needs to take action, implement mandatory measures, introduce preferential policies, establish a dedicated department to oversee energy conservation, conduct widespread public awareness campaigns, and eliminate unfavorable factors that hinder energy conservation efforts. Only then can energy conservation enter a virtuous cycle.