The Twin Screw Pump is a double suction non closed double screw pump. One end of the active screw that extends out of the pump is driven by a prime mover. The active screw and driven screw have different rotation threads. The screw and the pump body are closely fitted. Driven screw is driven by active screw through synchronous gear.
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Application of SEZ Vertical Mixed Flow Pump in Diversion Pumping Station
Abstract: The characteristics and application range of Francis pump are discussed. The structure and main characteristics of SEZ Francis pump are analyzed with the example of Slender West Lake Water Pump station in Yangzhou. Its application in water diversion pumping station is introduced. Key words: pumping station, mixed flow pump, structure, application Introduction Mixed flow pump used in farmland irrigation and drainage, flood control, drainage, sewage treatment, power plants (coal-fired power plants, nuclear power plants, storage power stations, tidal power station) cooling system and other fields. Francis pumps typically have a specific rotational speed in the range of 300-500; their caliber is 100-1 500 nun and some are up to 6 000 mm; their heads are 3-30 m up to 60 m; their flow rates are 200-2 000 Us or Larger, speed 100-1 450 r / min, mixed-flow pump in terms of performance and structure, between the Centrifugal Pump and axial flow pump. Compared with centrifugal pump and axial flow pump, the main advantages of the mixed flow pump are simple structure, small volume, light weight, small area, stable performance, stable power, small change of power when the head is changed, and easy speed regulation. At present, it is very important to strengthen the research and development of the stick flow pump, especially to develop a large mixed flow pump with good anti-cavitation performance, advanced structure and stable operation in order to meet the pump needs of the South-to-North Water Diversion Project. 1 Characteristics of SEZ vertical mixed flow pump 1.1 The main form of vertical mixed flow pump The vertical mixed flow Pump Impeller submerged under water, without starting the vacuum, and the motor installed in the upper, well ventilated, will not be flooded, which Horizontal pump can not be the advantage. Vertical Francis pump with high efficiency, cavitation performance, small size, easy maintenance advantages. According to different structures, can be divided into guide vane and volute two. Vertical vane pump can be divided into the rotor can be pumping double shell type (K type) and the rotor can not pumping the single-shell type (B type). According to the installation method, it can be divided into single base type and double base type. The single base type motor and pump are installed on the same basis, while the double base type motor and pump are respectively installed on their own basis. In order to meet the different use of the blade is divided into two types of fixed and adjustable. At present, the main models are LKX type (fixed blade, rotor can), LBS type (fixed blade, rotor can not pumping), LBX type (fixed blade, the rotor can not be pumping, the outlet pipe installed in the pump base), LKX type Fixed blades, pumping pump rotor, the outlet pipe installed on the basis of the pump), TKK type (adjustable blades, the pump rotor can be pumping, the outlet pipe installed under the pump base), LT (adjustable blades, pump rotor Pumping, outlet pipe installed on the basis of the pump) several, for selection. 1.2 Characteristics of SEZ Vertical Mixed Flow Pump SEZ vertical mixed flow pump is a new type of mixed flow pump with advantages of high lift, high flow rate, high efficiency and wide adaptability (when the lift varies greatly, the change of motor power is very high Small. SEZ, vertical mixing flow pump using a way of support, motor and pump connection as a whole, so the installation is very convenient, small unit vibration, smooth operation .SEZ vertical mixed flow pump structure shown in Figure I. SEZ-type vertical mixed-flow pump has the following characteristics. (1) can be pumping core structure. SEZ-type vertical mixed flow pump can be characterized by the most draffable core structure, including core pumping impeller room, guide vanes, impellers, Shaft, intermediate connector, sheath tube and other parts.It can be extracted from the pump body as a whole, without the need to disassemble the outer cylinder and the connection pipe can easily remove the whole core-pulling, which brought great convenience to the maintenance Draw the core structure of the shape shown in Figure 2. (2) ceramic guide bearings in the vertical pump guide bearings used in the water level above the pool, but not in the pump started before the normal operation, if not from outside water supply , These bearings will be lack of water lubrication, and ri put into normal operation with pumping water lubrication can easily lead to guide bearing wear.SEZ vertical mixed flow pump guide bearing ceramic material, very wear-resistant, when the pump into the normal After running, pump itself can be pumping the muddy water for cooling lubrication, the wear is very small, is a great promotion of the muddy water lubrication of the bearing, to simplify the structure of the pump has great significance. The choice of ceramic bearings The materials are mainly aluminum oxide, zirconium oxide, silicon carbide, silicon nitride (SiA) .These materials still have good thermal conductivity and wear resistance under poor lubrication conditions According to the test, this structure of the bearing has been safe operation of more than 20000 h Figure 1 SEZ-type vertical guide vane mixed flow pump structure Figure 2 sez-type vertical guide vane mixed flow pumping core structure (3) automatic exhaust Device.Pump system in the long water pipeline, the pipeline accumulates a lot of air, the presence of air will cause the start to ask growth, and cause instability.SSEZ vertical mixed flow pump installed with automatic exhaust valve device can be So as to discharge the gas in the pipeline when the unit is started and make the unit run smoothly 2 Application in Diversion Pumping Station of Slender West Lake 2.1 Basic Conditions of Pumping Station Yangzhou Slender West Lake Diversion Pumping Station is located in the north of Yangzhou Power Plant and near the brick factory The project is equipped with SEZ700-595 / 500 vertical guide vane mixed flow pump, equipped with 4 sets of Y3551 and -8 type 200 kW motor, and the designed flow rate is 4 m3 / s. The four pumps are connected in parallel Recipient 1.6 m diameter pipe water, water pipe length 5.6 km, remittances to protect the lake and flows into the Slender West Lake 2.2 using vertical mixed flow pump instead of the original design of centrifugal Submersible pump test by the model conversion test, the Slender West Lake diversion Pump station design flow conditions, the design flow of a single pump Q = 1.0 m3 / S, the total head H = 11.14 m, the normal starting lift H start = 15.87 m, the most unfavorable starting lift H = 18.25 m. The original design selection 700GQ4000-20-315 submersible centrifugal pump, submersible centrifugal pump biggest advantage is that no need to build water pump room, it is more suitable for urban drainage land tension. Cost analysis shows that the price of submersible pumps is far higher than the price of ordinary pumps and motors. Considering that the Slender West Lake Diversion Pump Station is located in the outskirts of the city, land is not the main factor for pumping station investment. On the contrary, the diversion pumping station needs to build a beautiful pumping station and become a sightseeing spot. In addition, because the submersible centrifugal pump in the water blocking the motor and water conditions are relatively poor, the pump efficiency is low. Taking into account the diversion pumping station perennial use, there must be higher efficiency in order to reduce operating costs. The diving centrifugal pump itself, poor water conditions, the export of the motor blockage, especially the original design of the motor power, the water pump plugging a larger role, resulting in effluent efficiency. According to a preliminary analysis, the efficiency of submersible pumps to reduce about 5% of ordinary pump. Taking into account the above factors, coupled with centrifugal pump head deviate from the pumping station design conditions more, so the selection of the SEZ vertical mixed flow pump. This new type of mixed flow pump has the characteristics of high efficiency, good cavitation performance, stable power change, small power change when the lift is changed, and convenient maintenance. In particular, the vertical mixed flow pump does not need to be evacuated during start-up and has little auxiliary equipment. The electric motor is located on the ground floor. The utility model has the advantages of good ventilation, lighting, good heat dissipation and convenient overhaul. The upper machine room is only equipped with a vertical motor. . Therefore, the use of vertical mixed flow pump is the best choice for local conditions. So after comparing a variety of pump-type programs, the final selection of SEZ700-595500 vertical vane-type mixed flow pump. 2.3 Vertical mixed flow pump disassembly order 2.3.1 Installation of the pump cylinder (1) The first part of the cylinder (including the inlet horn and external pipe) hanging man pump well and put it on the support beam. (2) The second part of the cylinder (external pipe) hanging on the first part of the cylinder and assembled. (3) lifting the first and second parts of the cylinder and the bottom plate, removing the outer pipe out of the support beam, lowering the cylinder, with I-beam support at the outer pipe office. (4) similar to the first and second part of the cylinder installation method, step by step in turn installed the entire pump cylinder. 3.3.2 Installation of Pump Core Part (1) Assemble the draw-out core including the impeller chamber, guide vane, impeller, guide bearing, shaft, intermediate connector, sheath tube and other parts and place it vertically to prevent Fall down. (2) The assembly of the pumping part of the core pulled out of the pump outer tube, and the use of I-beam on the water elbow support good. (3) Lift the shaft of the pump (rigid shaft should be installed at the shaft end) and the coupling at the pump shaft end should be well connected, and the reaming bolt and nut should be tightened. (4) lifting the shaft sleeve, bearing bracket, jacket tube aligned to the bearing bracket and screw the relevant bolts, nuts and so on. (5) Lift the whole core pulling component, remove the supporting beam, and slowly lower it to the outer cylinder body so that the cone surface of the impeller chamber is aligned with the lower cone surface of the outer pipe sealing ring. Disassemble the pump in the reverse order. 2.4 Pumping Station Test The vertical mixing pump unit of Slender West Lake Pumping Station tested the efficiency, vibration, noise and spectrum of the unit under different working conditions. From Unit 1 to Unit 4, respectively, running 4 machines to L machine, the main test data shown in Table 1. Through observation and test data analysis, the entire unit runs very smoothly and meets the requirements of design conditions. 3 Conclusion SEZ-type vertical mixed flow pump with smooth operation, high efficiency, good cavitation performance, the power change in the head changes small, easy maintenance and so on core-pulling structure, which combines both centrifugal pump and axial pump Advantages, but also overcome the shortcomings of both. So SEZ T4 vertical mixed flow pump has a very broad application prospects. Reference 1, He Xijie, dry Xihimin mixed flow pump research and development trend of pumping station technology, 2001 (2) 2, reservoir training Liu complex new small 0 pumping station design and transformation technology 3, Zhou Shihai shallow vertical mixing pump application Value Pumping Station Technology 1995 (3) Other author: Jiang Chengqi, male. Yangzhou University School of Water Conservancy and Architectural Engineering fluid mechanics and engineering master's degree