Retrofit of circulating pump in 300 MW unit of Zhujiang Power Plant
December 16 06:27:22, 2022
For the Pearl River Power Plant circulating pump inadequate water supply, pump blade strength is not enough and other issues, the circulating pump energy-saving technological transformation. Without changing the original water pump supporting motor, pump casing and pipes under the conditions of the blade angle from the original design counterclockwise to increase 3 °, and the blade surface to be properly modified, while the original combination of impeller structure change For the overall casting structure, and optimize the impeller processing technology, through this series of improvements to achieve the blade strength, increase circulation pump flow goals. Experiments show that technological innovation can improve the economic operation of the plant level and safety and reliability, and its economic efficiency is very significant. Keywords: Circulation pump; Technical retrofit of circulating water pumps for 300 MW generating units in Zhujiang Power Plant ZAN Yuming (Shenzhen Kingon (Group) Co., Ltd., Shenzhen, Guangdong 518040, China ) Abstract: In view of the insufficient water supply and blade intensity of the circulating water pumps in Zhujiang Power Plant, the circulation water pumps were retrofitted with the aim of increasing flow and saving energy. Woutout the original motor, pump case and pipes, the blade angle was increased by 3 degrees counterclockwise; the blade molding surface was modified suitably; the combined type impeller was changed to monoblock cast impeller, and the manufacturing procedures for the impeller optimized. All these measures enhance the blade intensity and increase the flow of the circulating pumps, thus improving the economic efficiency and the reliability of the plant with significant economic benefit obtaine 4 sets of 300 MW domestic-made imported turbogenerator units in Zhujiang Power Plant are equipped with 8 sets of 1600HLB-16 vertical mixed flow pumps. The original design parameters of the pump are as follows: the flow rate is 19 600 m3 / h, head 16.77 m, speed 370 r / min, pump efficiency 87%. Rated motor parameters: Power 1 250 kW, current 158 ​​A, voltage 6 kV, frequency 50 z, speed 370 r / min. As the condenser area of ​​the steam turbine generator used in the Pearl River Power Plant is relatively small compared with that of the same type of domestic unit, the condensing effect is poor, resulting in insufficient vacuum in the unit and affecting output. In addition, the 1600HLB-16 circulating pump impeller used in the power plant is a combined structure with low strength and cracks and ruptures at the root of the blade. The actual output of the pump can not meet the design requirements. These problems seriously affect the safe and economic operation of the unit, and the circulating pump is one of the main consumers of electricity in the power plant, which accounts for about 20% of the electricity consumption of the entire unit. Therefore, the circulating water pump in the Pearl River Power Plant is retrofitted , Can improve exhaust vacuum, operating efficiency and safety and reliability, has a very significant economic value and social benefits. A circulating pump retrofit Circulating pump due to large size, heavy weight, more expensive, in order to increase the flow and the impeller shell all the transformation, is bound to cause a great waste. And the shell and the impeller all re-design and manufacture, the pump installation size, import and export flange diameter also changed, to bring great inconvenience to the installation. Therefore, the actual transformation, the use of the shell does not move, the motor does not change, only to transform the small change program of the impeller. The specific requirements are as follows: a) When the modified impeller is installed, it is completely interchangeable with the original impeller, and other parts of the pump do not change; b) The modified pump impeller performance parameters must satisfy the original system and the original matching motor unchanged , Pump flow from the original design of 19.6 × 103m3 / h, increased to 21 × 103 ~ 22 × 103m3 / h, to ensure that the motor does not exceed the power; c) the modular structure of the impeller into a whole cast impeller to improve blade strength. 1.1 impeller hydraulic technology improvement Because the improvement of the pump casing is not fixed, only to improve the impeller, so the impeller design by the original pump housing geometry and fluid mechanics characteristics of the restrictions, and the flow of a substantial increase after the transformation, will inevitably lead to over-circulation Road, the flow rate increased significantly, hydraulic losses also will increase. In this condition, to ensure that the pump efficiency does not decline, you must use advanced design methods, optimize runner passages such as runner, study the relationship between the matching flow components, the minimum hydraulic losses, to obtain the best performance. In order to enhance the strength of the pump blades, the original impeller pump will be transformed into an integral casting impeller. Combination of experiments and experience to determine the new impeller blade placement angle from the original 0 ° to 3 ° counterclockwise increase. The blade design is based on the similar conversion method. After the initial axial dimensions of the impeller are obtained, the impeller inlet neck diameter and hub diameter are corrected according to the size of the housing and the shaft. Correction to improve the anti-cavitation pump performance, increase the import of flow impeller area. After the correction is reasonable but also for axial fluid cross-sectional area of ​​?? water changes in the inspection and check the flow lines. Find unreasonable phenomenon and then re-amended, and then check until reasonable. Impeller design selection of reliable and efficient hydraulic model, the model performance curve shown in Figure 1, the model conversion formula is: Where: λ - amplification factor, λ = 4.1; qV, p - physical pump volume flow, m3 / h ; QV, m - the model pump volume flow, m3 / h; Hp - physical pump head, m; Hm - model pump head, m; np - physical pump speed, 370 r / min; Pump speed, 1 450 r / min; ηp - physical pump efficiency,%; ηm - model pump efficiency,%. 1.2 Processing and Manufacturing Optimization As the high speed centrifugal pump blades for the twisted leaves, using ordinary wood mold casting impeller will have a greater deviation, the impeller over-flow surface is also rough. Therefore, in the manufacture of retrofit pump impeller, mining
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