Technical Transformation of Large Cement Turbine Pumping Station

Shanghai Huangpu Jiangyuan Water Plant Two raw water pumping stations, namely Linjiang Pumping Station and Yanqiao Pumping Station, were built in 1987, each equipped with six large vertical concrete volute mixed flow pumps, which are responsible for the better water quality in the upper reaches of the Huangpu River The raw water is delivered to the respective waterworks in Shanghai by two relay stations, with a daily delivery 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 pump station basic situation

Linjiang pumping station and Yan Qiao pumping station original 1800HLWB-12 vertical mixed flow pump, pump installation form shown in Figure 1.

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 = 7.792m 3 / s, H = 12.2m, n = 300r / min, m = 87.2%, matching motor power 1600kW.

3 the original pumping station the main problems

(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 transformation program and implementation

For the main problems of the original pump station, the pump performance, pump structure, pump suction runner, the basis of the installation of the pump to redesign, that is, wet pit sink suction vertical ramp pump, only the original matching motor unchanged; Motor mounting base layer rearranges anchor bolts. After the transformation of the pump room structure and inflow channel plan shown in Figure 2.

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 = 9m 3 / s; head H = 12m; speed n = 300r / min ns = 3.65nQ1 / 2 / H3 / 4U510.

Use L500 excellent hydraulic model for model conversion design, the new pump model is set to 88LKSE-18J.

The theoretical performance shown in Figure 3 double-dotted line. Physical pump after real machine test, the performance parameters to meet the design requirements, the test performance curve shown in Figure 3, solid line.

5 after the transformation of the structural characteristics of the pump

Figure 4 shows the modified vertical oblique flow pump structure, compared with the original pump-type structure, the structural features are:

(1) was originally a cement-type mixed-flow pump; now all-metal guide vane mixed flow pump;

(2) The original pump impeller chamber is embedded in the cement, and the corresponding parts of the impeller are spherical; the impeller chamber can be extracted with the rotor parts of the pump and the corresponding parts of the impeller are cone surfaces, so the replacement and maintenance are convenient;

(3) The standard elevation of cavitation of the original impeller is 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 NPSH increases 1.55m, help to avoid the occurrence of cavitation;

(4) The original impeller cantilever length of about 1.1m, the impeller is only about 0.6m in length. Therefore, the stress of the lower bearing of the pump is greatly improved, which prolongs the bearing life, reduces the swing of the impeller and reduces the wear between the impeller and the impeller chamber.

(5) New pump There is an adjusting nut between the coupling of the pump and the pump, which can conveniently adjust the relative height position of the impeller through the pump shaft. During installation and maintenance, it is convenient to adjust the clearance between the impeller blades and the impeller chamber, So that the gap always maintain the design value requirements, so that the pump operating efficiency is not reduced due to increased clearance;

(6) The new pump shaft seal with a general packing seal, the part of the pump at the highest office, less leakage and 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 carried out in the motor installation base layer, without drilling into the pump repair welding, grinding, not only to ensure the quality and efficiency of maintenance; and greatly improve the maintenance work surroundings.

6 Conclusion

This technological transformation has been piloted since 1998 and completed by 2001. It has been in operation for the longest period of more than four years. Field test results compared with the original pump test results:

(1) pump running efficiency up to 88%. In the annual delivery of cubic meters of water, compared with the original pump, can save electricity costs 9.6 million yuan. If operated under the design load of 3.5 million tons / day, the annual electricity savings will reach over 14 million yuan and the investment funds for reconstruction will be recovered within three years.

(2) New pump 3 to 4 years a major overhaul, maintenance cycle extended by 3 to 4 times, the maintenance workload and maintenance costs have also been reduced;

(3) Unit vibration intensity below 5mm / s, shaft seal leakage is normal, improve the operational safety and reliability, reducing the maintenance operation;

(4) No cavitation damage on the leaves has been observed since 4 years of operation;