According to statistics, energy consumption in water supply project accounts for 30 to 70% of water supply cost, and energy consumption of water pump accounts for about 90% of total energy consumption. In actual operation, most of the pump efficiency is less than 60%, the overall efficiency of the pumping station less than 50%, there is a big waste of energy. 1. In today's tight energy supply, water pump energy-saving technologies are used in engineering design. Properly designing pumping stations so that water pumps can run frequently and efficiently will be of great economic significance. Water pump removed from the water to the user or water purification plant; the purified water to the water supply network; long-distance water in the water pressure; in the partial pressure water supply system to increase the pressure on the pipe network; water The peak season to regulate the water supply pipe network; in industrial circulating water supply system to enhance the cooling water and add fresh water. In accordance with the functional division, the pump constitutes a water pumping station (primary pumping station), a water pumping station (secondary pumping station), a pressurizing pumping station, a regulating pumping station and a circulating pumping station in all aspects of the water supply system. It can be said pump station is the hub of the water supply system, the pump is the heart of this hub. For the selection of pumps, the operation of the system is closely related to saving energy, reducing costs and improving economic efficiency. 2. Pump Selection Pump selection is based on the required flow, lift and its variation, taking into account the water pump can often determine the efficient operation of water. A pumping station, pumping station is designed according to the highest daily average water consumption to meet the highest daily water supply and lift to determine the pump and the number of units. Pumping station according to water supply by the hourly water change design to meet the maximum daily maximum water supply and head to determine the pump and the number of units. 2.1 The choice of water pump In the pumping station of a pumping station in the head, access to water design low water level. In fact, the probability of a low water level in a water source is small, most of the time above this low water level, resulting in a pump lift higher than the lift required most of the time. This factor is even more influential in water where the water level fluctuates significantly. For the highest daily volume of water used for pumping, the highest daily volume of water in a year usually accounts for only a few percent. Most of the time is lower than the maximum daily water used for pump selection. The head loss in a water pipe changes as the square of the change in water volume. Obviously, most of the time, the amount of head and water required on the system is less than the head and amount of water when pumping. 2.2 The choice of water pump The water supply network of secondary pumping station is not a fixed amount of water. It is year after year, month by day, day by day and hour by day. The head loss of the pipe network also changes with the change of the water into a square relationship, and the water pressure required by the pipe network also changes with the change of the water volume. Select the pump head and water to take the point of both, with large and small value method, not only increased the initial cost of equipment, but also because of the low efficiency of the pump for a long time caused by waste of energy, economically is not allowed. For complex pipelines, it is not possible to select a suitable pump type when piping characteristics can not be found accurately. Improper pump parameters, the pump can not be efficient operation. 2.3 Pump Configuration General centrifugal pump efficiency is about 80%, the selection often consider the equipment to tap the potential in use, pump parameters left margin, resulting in the initial low-efficiency operation of the pump. Even if the initial use of small pumps to run, there are inefficiencies. For the head, water changes in the larger operating conditions, if the pump to run efficiently most of the time, in fact, can not be done. In view of the above circumstances, the election pump, to meet the maximum conditions, under the premise of large changes in the amount of water required and water conditions, the use of more than the performance of different combinations of pumps to run, but the number of units, models More management trouble. Can also consider more than one with the same type of pump running in parallel with a single pump operation of a combination of independent, pump selection should be selected in parallel operation of each pump operating point near the leftmost boundary of the most efficient area, when the pump is running alone , The working point moves to the right and can still be operated in the high efficiency zone. The result of this selection can promote the high operating efficiency of the pump in the entire working condition range. In this way, also because of the number of units, the management of trouble. Therefore, in the pump water supply system, the use of a variety of other energy-saving measures is very necessary. 3. Pump to adapt to flow, lift changes in the regulation of the pump in accordance with the maximum operating conditions, and the actual operating conditions vary greatly, reducing pump efficiency. To this end, the operating conditions according to the flow and head changes in pump operating conditions, the common adjustment methods are the following. 3.1 Flow Regulation 3.1.1 to reduce the valve opening This is the production of the commonly used transfer method. When the working lift of the pump is higher than the water pressure required by the pipeline, in order to meet the requirements of the pipeline, the opening degree of the pump outlet valve is reduced so that the head loss added by the valve is exactly equal to the amount of water supply. Need to pressure difference, change the characteristics of the pipeline to meet the corresponding water supply pump lift. The adjustment method enables a large amount of power loss to reduce the damping caused by the valve opening degree, and causes the working condition to move to the left on the characteristic curve of the pump, reducing the system operation efficiency and consuming more electric energy. 3.1.2 Parallel Operation of Multiple Pumps As mentioned above, in the water supply system with large variation in water volume, multiple sets of pumps of the same type or with different types are set in parallel and the flow adjustment is performed by adjusting the number of pumps to adapt Pipe network changes in water requirements. This mode of operation, the number of units can not be too much, not only because of the number of units to bring management trouble, reduce operating efficiency, but also increase the pump open and stop times, shorten the service life of equipment, this approach can not continuously adjust the flow changes, but also Can not be used to adjust the time of change. See Figure 1 3.2 pump characteristics adjustment 3.2.1 adjust the installation angle of the pump blades In the installation of axial flow pump or mixed flow pump, the pump can be used to adjust the blade so that its operating parameters with blade mounting angle and thus Change the characteristics of the pump. Pump blade installation angle increases, the flow increases, the efficiency of the pump also increased. However, the overall efficiency of the pumping station is not necessarily high, to be determined by calculation. The regulation of the whole regulation and semi-regulation of two, full regulation in the operation of the pump to adjust the use of regulatory agencies. Semi-regulation is in the pump to stop running, the blade installation angle adjustment. 3.2.2 Turning Impeller Diameter or Changing Impeller with Different Diameter Changing impeller diameter can change the performance of the pump. According to the change of flow rate, calculate the impeller diameter which meets the requirement of working conditions when the pump is running efficiently. If the working condition is long-term stable, only turn it once. If the conditions change with the seasons, it can be equipped with impellers of different diameters for replacement. This method is limited by the range of impeller diameter changes. In this way instead of adjusting the valve opening degree of flow regulation, can save energy consumption, but only for less variable conditions. 3.2.3 adjust the speed by changing the motor speed or change the motor and pump speed ratio can change the characteristics of the pump to adapt to large changes in water supply system operating conditions. Practice has proved that the method of adjusting the speed has a good energy-saving effect, which can simplify and facilitate the pumping plant equipment scheduling, easy to achieve automatic control. 4 pump speed control characteristics and energy-saving principles The above adjustment methods, with the pump speed adjustment, is the best way to reduce energy consumption. The reason is that in changing the pump speed and the speed change within ± 20% range, to maintain similar internal flow of the pump body, then the pump body water flow velocity and speed is proportional to the flow and speed ratio is proportional to the head and speed ratio The square is proportional to. The shaft power is proportional to the cube of the speed ratio. Q = Q0 (n / n0) (2) N = N0 (n / n0) 3 (3) where n0 is the rated speed and Q0 is the rated speed , H0 is the lift at rated speed, N0 is the shaft power at rated speed, is the speed after speed control, Q is the flow at n speed, H is the lift at n speed, and N is the shaft power at n speed. H = (H0 / Q022) Q2 Where H is the lift of any operating point in the operation of the pump Q is the flow rate at any point in the operation of the pump H0 / Q0 is the specific constant for the specific conditions H0, Q0 at the best operating point. Refers to the rated speed of the head and flow ratio. It can be seen from equation (4) that it is a parabolic equation with the coordinate origin as the vertex. The conditions at each point on this parabola are similar and can be called the parabola with similar working conditions. When the rotation speed changes by ± 20% Within, pump efficiency can be basically unchanged, also known as high efficiency parabola. The principle shown in Figure 2, Figure 3 Figure 2 is the same as the net head of a single pump speed energy-saving schematic. Q-H curve for a single pump rated speed n0 when the curve, Q'-H 'curve for a single pump speed n when the characteristic curve, Q-Σh curve for the pipeline characteristic curve, A point is the pump selected pump Operating point, point A corresponds to QA, HA, ηA, is the main pump parameters. Determined by the pipeline characteristic curve Q-Σh The pump operating conditions in the actual operating point must be in the pump characteristic curve of the best working conditions around 0 move. If the pipe network to meet the requirements of A 'point of work