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Technical Renovation of Large Cement Turbine Pumping Station
1. Introduction Huangpu Jiangyuan Water Plant in Shanghai built two raw water pumping stations in 1987, namely Linjiang Pumping Station and Yanqiao Pumping Station, each equipped with six large vertical concrete volute mixed-flow pumps, assuming the upper reaches of the Huangpu River The better raw water is delivered to the respective waterworks in Shanghai by two relay stations, with a daily capacity of 3.5 million tons. Since its commencement of operation to 1997, ten years gradually exposed some problems, Changsha Pump Factory Co., Ltd. should be required by the owners and in cooperation with the relevant departments in Shanghai, the two pumping stations to transform (nearly 30 million investment in the transformation funds). From 1998 to 2001, 12 cement elbow-inhaled volute-flow mixed-flow pumps have all been transformed into wet-pit sink suction diagonal-flow pumps, greatly improving the operation efficiency and reliability of the pump sets, resulting in significant energy-saving effects and Economic benefits. 2. The basic situation of the pump station Linjiang pumping station and strict original pump 1800HLWB-12 vertical mixed flow pump. The structural features are as follows: elbow cement suction runner, cement volute mixed flow pump, semi-adjustable, semi-open impeller, impeller chamber embedded in cement matrix, floating ring shaft seal, pump motor rigid shaft coupling pump rotor Axial force by the motor thrust bearing. Pump design point performance parameters: Q = 7.792m3 / s, H = 12.2m, n = 300r / min, m = 87.2%, supporting motor power 1600kW. 3. The main problems of the original pumping station (1) low operating efficiency. According to the field calculation, the pump operation efficiency is only 60% ~ 70%. The reason is that the gap between the vane and the impeller chamber can not meet the design requirements (0.8 ~ 1.0mm). (2) poor sealing reliability. The original pump shaft seal with floating ring seal structure, poor sealing stability. Therefore, during operation, a submersible pump was placed on the pump cover and a full-time inspector was set up on the level. Once it is found that the pump leaks too much, immediately start the submersible pump pumping leak water to prevent the pump house was submerged. (3) short pump maintenance cycle. When the original pump is running for about one year, strong vibration, big seal leakage, greatly reduced pump efficiency and other problems must be shut down for maintenance. (4) blade cavitation damage. When overhauling each year, the impeller blades have cavitation damage to the pits. Each time the overhauls are repaired and polished, the maintenance personnel are labor-intensive and the working environment is poor. 4. Reconstruction program and implementation of the main problems for the original pumping station, the pump performance, pump structure, pump suction runner, the basis of the installation of the pump redesign, that is, wet pit sink suction vertical ramp pump, only the original Matching motor unchanged; but the motor base layer to re-arrange the anchor bolts. According to the past operation and the analysis of the characteristics of the pump device, the design parameters of the new pump are determined as follows: flow Q = 9m3 / s; head H = 12m; speed n = 300r / min = 3.65nQ1 / 2 / H3 / 4U510. Use L500 excellent hydraulic model for model conversion design, the new pump model is set to 88LKSE-18J. Physical pump after real machine test, the performance parameters to meet the design requirements. 5. After the transformation of the pump structural characteristics compared with the original pump-type structure, the structural features are: (1) was originally a turbine-type mixed-flow pump; now all-metal guide vane mixed flow pump; (2) the original pump impeller chamber Embedded in the cement fixed, and the corresponding parts of the blade is spherical; the impeller chamber can be extracted with the pump rotor components, and the corresponding parts of the blade is a cone, so replacement, easy maintenance; (3) the original standard impeller cavitation elevation of about -1.95m , The standard elevation of cavitation of impeller is about -3.5m, and the elevation of impeller is reduced by 1.55m. Therefore, under the same suction water level, the equipment cavitation allowance increases by 1.55m, which is helpful to avoid cavitation; The original impeller cantilever length of about 1.1m, the impeller is only about 0.6m in length. So the lower part of the pump bearing greatly improved the stress conditions, extending bearing life, help reduce the swing of the impeller and reduce the blade and impeller room between the wear and tear; (5) the new pump in the coupling between the pump coupling An adjusting nut can adjust the relative height position of the impeller conveniently through the pump shaft. During installation and maintenance, it is convenient to adjust the clearance between the impeller and the impeller so that the clearance always maintains the designed value, (6) The new pump shaft seal with a general packing seal, the part of the pump at the highest point, less leakage, and the leakage of water can be discharged into the sump, without the need to set up a special post inspection and drainage ; (7) The new pump rotor parts can be drawn from the top, pump maintenance work can be installed in the motor base layer, without drilling into the pump repair welding, grinding, not only to ensure the quality and efficiency of maintenance; and greatly improve the overhaul working environment. 6. Conclusion The technical renovation has been piloted since 1998 and completed by the year 2001, with the longest running time of more than eight years. Field test results compared with the original pump test results: (1) pump operating efficiency up to 88%. In the annual delivery of 800 million cubic meters of water in the circumstances, compared with the original pump can save electricity 9.6 million yuan expenditure. If the 3500,000 tons / day design load operation, annual savings of up to more than 14 million yuan in electricity costs, the transformation of the investment funds can be recovered within three years; (2) 3 to 4 years a new pump overhaul, overhaul The period is extended by 3 to 4 times, and the maintenance workload and maintenance cost are correspondingly reduced; (3) The vibration intensity of the unit is below 5 mm / s, the shaft seal leakage is normal, the safety and reliability of operation are improved, and the maintenance and operation positions are reduced; (4) No cavitation damage on the blades has been found since 4 years of operation; (5) The working environment and labor intensity of operation and maintenance personnel have been improved and lightened.