Abstract: Based on the characteristics of pump room operating conditions in sprinkler irrigation project, the application of pump speed regulation technology in engineering is studied from the performance of pump operation. Keywords: Condition Speed ​​Regulation Efficiency 1. General Pressure water distribution in general sprinkler works is mostly done by motor pumps. Pump electricity accounts for a large proportion of sprinkler operating costs. Therefore, the effect of pump operating efficiency on sprinkler operating costs is very significant Big. Large area of ​​sprinkler irrigation projects are often used pie slice work. The topography of the area, and the pump room distance and the number of nozzles vary, making the pump requirements are not the same. In order for all sprinklers to function properly, the pump is usually selected based on conditions that will satisfy the most adverse pressure conditions. This operating point is generally the normal working point of the pump, that is rated point. For low and close to the pump area is the use of off-valve throttling to adjust the nozzle pressure. In this way, there will be excess head loss on the valve, causing the pump to deviate from the efficient work area, resulting in a lot of energy wasted and a serious non-economic operation. For this purpose, speed control technology is adopted to enable the pump to adjust the output characteristics according to the working conditions of different areas and adapt to the working requirements of the nozzle. In addition, the pump can operate efficiently under various operating conditions to achieve the effect of saving electricity and stabilizing pressure. This article only from the pump performance and speed governing principle of pump speed governing technology in sprinkler irrigation engineering application. 2, pump room condition analysis and pump speed saving principle Water pump in sprinkler works are generally vane pump, vane pump characteristics Q ~ H, Q ~ N, Q ~ η curve represents the head, shaft power, efficiency The relationship with the flow, see Figure 1. Figure 1 pumps different modes of transfer flow chart Other pump working system characteristics, often Q ~ G curve. Where H = Hn + Hf, Hf = CQ2, Hn = H net + H spray C - hydraulic coefficient of the pipe from the pump to the nozzle; H net - net head of the pump where the nozzle is located; H spray - working pressure of the nozzle. H = Hh + CQ2 is a quadratic curve through the Hh point, Q ~ H and Q ~ G curve of the intersection A is the normal operating point of the pump, usually the most adverse pressure area work at this point, usually the pump rated point. The pump will operate in the following conditions when a zone other than the normal operating point is enabled. H net decreases, the pump head is higher than the nozzle rated working pressure, the nozzle flow is greater than the rated flow, the pump operating point lower than the normal working point, that is, Q ~ G curve down to Q '~ G' and Q ~ H intersection A 'point. If H net reduction more, the pump will work in non-efficient area. When the area at a low terrain, the number of sprinklers and less, H net reduction, the pump head is higher than the nozzle rated working pressure. At the same time the number of nozzle less, the need to reduce the flow area, the system pressure will be high, but also make the nozzle pressure is greater than the rated pressure, so that the nozzle flow is much larger than the rated flow, the pump operating point lower than normal, that Q ~ G The curve is at the lowest point where Q "~ G" and Q ~ H intersect at point A. The terrain elevations are the same as those in the normal working point, but when the number of nozzles is small, the system pressure will be high due to the decrease of flow in the area, Pressure and flow are greater than the rated value, the pump operating point higher than the normal point. Q ~ G curve up to Q "~ G", and Q ~ H intersection at the point A. Obviously the above conditions, the nozzle are Non-rated work, affecting the use of results, serious damage to the nozzle. So you must take measures to make the nozzle work within the allowable pressure range, the project commonly used in the following ways. (1) off small work area inlet valve Or shut off the small water pump outlet gate valve, a considerable increase in the pipe resistance coefficient, so that Q ~ G curve rises, and the pump Q ~ H intersects the flow point required for the area, the excess head waste on the valve. (2) Choose several pump combinations with different lift and different flow rate, choose pump or pump combination according to the head and flow of different zones, there is no pressure loss in this way, but in the project with complicated topography and uneven nozzle distribution , Will increase the number of pumps more. (3) pump speed: Pump speed, the basic efficiency of the same, so you can reduce the speed, so that the characteristic curve and the intersection of system characteristics curve required flow in B ', B " And B? Point. At this time its corresponding speed is to meet the needs of traffic, without any head waste, and its work efficiency is higher. Although the pump speed control measures, but its investment is large, but not in any case are economically reasonable, in order to prevent blindness in the work should be carried out before the application of energy-saving calculations and economic comparison. 3, the choice of speed control equipment (1) speed pump characteristics should be selected so that the speed control pump in the design portfolio to meet the maximum design of water on the basis of speed control as much as possible the characteristic curve, close to the system characteristics curve. (2) speed control equipment selection: speed control equipment, many different types of performance are also different in the sprinkler pumping station speed control should use variable frequency or electromagnetic slip clutch. Frequency control technology is relatively new, higher efficiency, better maintenance conditions, but requires a higher management technology, investment is larger. Electromagnetic slip clutch control part of the simple, low price, easy maintenance, but the transmission efficiency at low speed is low, suitable for high speed and high rate of change or financial constraints, the management of low technology conditions. (3) Pressure regulation during operation of pump room: After starting the pump, the zones are respectively enabled to adjust the pump speed so that the water pressure in the pump room is suitable for the nozzle work. The pressure is the corresponding control pressure in each area. As long as the operation of the area according to the opening, pump room water pressure to the corresponding control pressure can be.
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