Pumps in tap water production lines make up a wide range of applications, a variety of specifications. Its classification methods are also different, according to their working principle can be divided into three categories: vane pumps, positive displacement pumps, other types of pumps. In our factory production most of the single-stage double-suction centrifugal pump is a vane pump, because this pump is working by rotating the impeller high-speed rotation of the blade to make the liquid centrifugal force to complete the pump Therefore, this pump is called centrifugal pump. Centrifugal pumps are used in a wide variety of applications in many sectors of the national economy. In the water supply system is almost an indispensable device, if the water pipe network as the body's vascular system, then the centrifugal pump on the pressure to send blood to the heart. As the centrifugal pump is an important equipment, and its operation to consume a lot of power! In order to rationally and economically select and use water pumps to ensure water supply to the waterworks, we must understand the working principle and basic performance of the centrifugal pumps. First, the basic structure of the centrifugal pump is composed of six parts The basic structure of the centrifugal pump is composed of six parts are the impeller, pump body, pump shaft, bearings, seal ring, packing box 1, the impeller is the core part of the centrifugal pump, its speed is high, the impeller blades play a major role in the impeller assembly before static balance experiment. The inner and outer surfaces of the impeller require smoothness to reduce frictional loss of water flow. 2, also known as the pump casing, it is the main pump. To support the role of fixed, and with the bearing bracket to connect. 3, the role of the pump shaft is connected to the motor by a coupling, the motor torque to the impeller, so it is the main component of mechanical energy transmission. 4, the bearing is set on the pump shaft supporting the pump shaft components, there are two types of rolling bearings and plain bearings. Rolling bearings using butter as a lubricant to the appropriate general volume of 2 / 3-3 / 4 Too much heat, too little sound and fever! Slide bearings are used as a transparent oil lubricant, refueling to the oil level line. Too much oil to bleed along the pump shaft and cheap, too little bearing but also overheating and burn accident! In the process of running the pump bearing temperature up to 85 degrees generally run at 60 degrees, if high, we must find out the reason (whether impurities, whether the oil is black, whether the water) and timely treatment! 5, seal ring, also known as leakage ring. The gap between the impeller inlet and the pump casing is too large, causing the water in the high-pressure area of ​​the pump to flow to the low-pressure area through this gap, affecting the output of the pump and reducing the efficiency. The gap is too small will cause impeller and pump shell friction wear. In order to increase the backflow resistance to reduce the internal leakage and delay the service life of the impeller and the pump shell, a sealing ring is arranged on the inner edge of the pump shell and the external aid of the impeller, and the sealed gap is maintained at 0.25-1.10mm. 6, packing box mainly by packing, water seal ring, packing tube, packing gland, water seal tube. The purpose of the packing box is mainly to close the gap between the pump housing and the pump shaft so that the water in the pump does not flow to the outside and the outside air does not enter the pump. Always keep the pump vacuum! When the pump shaft friction with the filler to generate heat to rely on the water seal to live in the water ring so that the filler cooling! Maintain the normal operation of the pump. Therefore, in the process of pump running tour inspection on the packing box is a special note! Filler needs to be replaced after about 600 hours of operation. Second, the over-current components of the centrifugal pump Centrifugal pump over-current components are: suction chamber, impeller, pressure chamber three parts. The impeller chamber is the heart of the pump and the heart of the flow component. Pump through the impeller on the liquid work, to increase its energy. Impeller according to the direction of liquid out of three categories: (1) Radial impeller (centrifugal impeller) The liquid flows out of the impeller in a direction perpendicular to the axis. (2) Diagonal impeller (Francis impeller) The liquid flows out of the impeller in a direction inclined to the axis. (3) Axial impeller The direction of liquid flow parallel to the axis. Impeller by inhalation is divided into two categories: (1) Single-suction impeller (ie impeller sucks liquid from one side). (2) double suction impeller (ie impeller suction fluid from both sides). Impeller by the cover form is divided into three categories: (1) closed impeller. (2) open impeller (3) semi-open impeller. One closed impeller is widely used, the aforementioned single suction impeller double suction impeller belongs to this form. Third, the working principle of centrifugal pumps The working principle of centrifugal pump is: centrifugal pump so water can be sent out due to the role of centrifugal force. Pump before work, the pump body and the inlet pipe must be filled with water into a vacuum state, when the impeller is rapidly rotating, the blade to promote rapid rotation of water, rotating water from the impeller in the centrifugal force of the fly, the pump After the water is thrown out, the central part of the impeller forms a vacuum area. Suwon's water pressure in the air pressure (or water pressure) under pressure through the pipe into the water pipe. This endless cycle, you can achieve continuous pumping. It is worth mentioning that: before starting the pump must be filled with water to the pump casing before starting, otherwise it will cause the pump body heat, vibration, reduce the amount of water, causing damage to the pump (referred to as "cavitation") Cause equipment accident! Many types of centrifugal pumps, classification methods are common in the following ways 1 by the impeller inhalation points: single suction centrifugal pump, double suction centrifugal pump. 2 according to the number of impeller points: single-stage centrifugal pump. Multistage centrifugal pump. 3 according to the structure of the impeller: open impeller centrifugal pump semi-open impeller centrifugal pump closed impeller centrifugal pump. 4 according to the working pressure points: low pressure centrifugal pump medium pressure centrifugal pump high pressure centrifugal pump. 5 points by the pump shaft position: horizontal centrifugal pump, vertical centrifugal pump. Fourth, the following centrifugal pump introduces several important performance curves Pump performance parameters such as flow Q, head H-axis power N speed between the existence of a certain relationship. The relationship between the magnitude of their changes is represented by a curve, which is called the performance curve of the pump. Pump performance parameters of the relationship between mutual change and mutual restraint: first of all, the rated speed of the pump for the line conditions. Pump performance curve has three main curves: flow - lift curve, flow - power curve, flow - efficiency curve. A. Flow - lift characteristic curve It is the basic performance curve of a centrifugal pump. Than the speed of less than 80 centrifugal pump has the characteristics of rising and falling both in the middle of the bulge 9, two over the bend), said the hump performance curve. Centrifugal pumps with speeds greater than 80-150 have a flat performance curve. Centrifugal pumps with a specific rotational speed of more than 150 have steep fall performance curves. In general, when the flow is small, the lift is high, and as the flow increases, the lift gradually decreases. B. Flow - power curve The shaft power is increased with the flow rate. When the flow rate Q = 0, the corresponding shaft power is not equal to zero but a certain value (about 60% of normal operation). This power is mainly consumed by mechanical losses. At this time the pump is full of water, if the long run, will lead to continuous temperature rise in the pump, the pump housing, bearings will be heated, may cause severe thermal deformation of the pump body, we call "stuffy head" at this time The maximum lift, when the valve is gradually opened, the flow will gradually increase, the shaft power is also slowly increasing. C, flow - efficiency curve Its curve like the shape of the hill, when the flow is zero, the efficiency is equal to zero, with the flow rate increases, the efficiency also gradually increased, but increased to a certain amount of efficiency after the decline, the efficiency of a Highest value, near the highest efficiency point, the efficiency is relatively high, this area is called the high efficiency area. Five, a reasonable allocation, safe operation, high-quality water supply The above four aspects of the centrifugal pump to understand the structure, working principle, characteristic curve, how to rationally configure the power of the motor pump is to ensure the safe operation of pumps, water supply, reduce production costs, the key to reasonable allocation of pump power, pump the best work The safe operation of the region, the actual situation of our factory water supply, sufficient description of the importance of the rational allocation of equipment, reliability and economy. 1. The importance of a reasonable configuration of pump equipment. The main task of the water plant is to ensure that the people of the city's production and domestic water supply, the largest daily water supply in South Water 900,000 tons, influent, effluent to meet the pressure in the region, but the last ten years, with municipal relocation, large water users Migration, water supply decreased, with the improvement of people's living quality, the demand for water quality is getting higher and higher, factory water reached 0.3NTU How to ensure the quality of water supply, enterprises have taken a series of measures: (1) to adjust the rational allocation of pump equipment, the implementation of the best combination of pedestrian. (2) Plus in technological innovation, invest a lot of money to transform the original backward water purification equipment. (2) invest funds, transform old equipment, old pipe network, improve hydraulic conditions, install static mixer and so on. (4) Install 40 sets of instruments and use modern monitoring system to monitor and control the whole process of water quality to ensure high-quality water. These measures fully demonstrate the importance of rational allocation of pump and water purification equipment. 2, pump equipment pump safe operation of the reliability. In order to ensure the safe operation of pump equipment, pump equipment more standardized management of enterprises, major maintenance once a year, the monthly secondary maintenance, once-a-level maintenance system, these ISO9002 quality management is to ensure that the pump equipment Safe operation of the various measures, in order to ensure the safe operation of the safe operation of the technical quality of workers operating the training, improvement, the implementation of safety procedures should be strictly enforced, the implementation of these safe operation system is to ensure the reliable operation of pump equipment Sexual guarantee. 3, the safe operation of pump equipment economy. When it comes to economy, it is the cost of making water for enterprises, including alum, chlorine and ammonia. It is necessary to control the economic activities and economic benefits of enterprises in the safest mode of operation, the best mode of commissioning and the lowest cost of water system. In this regard, enterprises have accumulated some experience. Such as: the safest mode of operation, Shanghai's urban water supply network is interoperable, the company center dispatching to control the pressure of water supply in the region, too high likely to cause squibs, to the people, the country caused property damage, the water pressure is too low, the impact Some users of water, resulting in a bad corporate image. Therefore, the pressure during the day to maintain the region is 30-35 kPa, nighttime pressure stays below 30 kPa. According to the requirements of pipe network pressure, open the pump during the day to open the pump, the night open high and low lift combination, effectively control the factory water pressure to ensure that the regional pipe network and hotel high-rise water, using these best pump combination, both Saving power consumption, but also reasonable control of the pressure, these methods ensure the safe operation of pump equipment economy. With the continuous development of science and technology, the degree of modernization of pumps has also been constantly improved, reducing the number of operations for management. Mostly now using computer monitoring of automatic mode of operation, which also raised the operator's own quality requirements. Because of a pump abnormalities affect the entire water supply network, with serious consequences. After several years of practical work and theoretical study, the learned knowledge can be applied to practical work, and the water allocation and scheduling can be reasonably arranged. Utilizing the characteristics of each pump to reach the maximum output of the water pump with minimum power, Best operating condition And to be safe, high quality, low consumption of water supply!