Power plants and gear or hydraulic machines that use natural energy to raise water from low to high. Widely used in farmland irrigation, drainage and agriculture, animal husbandry, industrial and mining enterprises, urban water supply, drainage and so on. Pumps used for irrigation and drainage in agriculture and agriculture and animal husbandry are called agricultural pumps and are one of the main components of farmland irrigation and drainage machinery.

Types of

According to different working principle can be divided into volume pumps, vane pumps and other types. Volumetric pump is the use of changes in the volume of his studio to transfer energy, there are piston pump, piston pump, gear pump, diaphragm pump, screw pump and other types. Vane pump is the use of rotating blades and water to transfer energy to interact with a centrifugal pump, axial flow pump and mixed flow pump type. Submersible pump pump body part is a vane pump. Other types of pumps have jet pumps, water hammer pumps, internal combustion pumps, respectively, using the principle of jet water hammer and fuel deflagration work. Turbine pump is a combination of turbine and vane pump. The above types of pumps in the following various types of more representative.

Centrifugal pump is the use of centrifugal force to increase the pressure of water and make a flow of a pump. By the pump shell, impeller, shaft and other components. The power machine drives the shaft, the shaft drives the impeller to rotate at high speed in the pump shell, and the water in the pump is forced to rotate with the impeller to generate the centrifugal force. Centrifugal forces liquid from the periphery of the impeller thrown into the high-speed high-pressure water flow through the pump casing discharge pump, the impeller center to form a low pressure, which inhale new water flow, constitute a continuous water flow. The impeller has a reverse curved blade rotation direction, the structure of a closed-type, semi-closed and open 3, mostly agricultural impeller closed, both sides of the leaf by the disk closed. The pump body gradually expands into a volute shape along the outlet pipe. Water flow from the impeller side inhaled single suction centrifugal pump, said suction from both sides of the impeller double suction centrifugal pump. In order to increase the lift, multiple impellers can be installed on the same shaft to be multistage centrifugal pumps. The water discharged from the former impeller enters the water inlet of the latter impeller and is discharged from the latter impeller after being pressurized, so the more the impeller is, the higher the pressure is. Some centrifugal pumps with automatic removal of suction pipes and pump body air device, without starting the pump before the irrigation, said self-priming centrifugal pump, but its efficiency is often lower than the average centrifugal pump.

Centrifugal pumps in agricultural drainage and agriculture and animal husbandry water supply is the most widely used. Used for high lift and flow of small occasions. Single-stage centrifugal pump head is 5 ~ 125 meters, the discharge of uniform flow, usually 6.3 to 400 m 3 / hour, the efficiency of about 86 to 94%.

Axial flow pump

By the pump shell, impeller and shaft and other components. Also known as propeller pump. The impeller has a number of propeller-like blades. When the impeller is driven by the power machine to rotate together with the rotating shaft, the blades push the water to one end, and at the same time draw water from the water source at the other end to make the water produce a continuous Flow, to achieve the purpose of continuous delivery of water. Flow pressure increases due to impeller rotation. The rotating water flow coming out of the impeller passes through the fixed guide vanes to eliminate the rotational speed and make some of its kinetic energy transform into pressure energy due to the diffusion, so that the water flow in the pump shell rises in the axial direction and flows out of the water outlet pipe. Axial flow pumps are mostly used for low head and large flow occasions, the head range of 1 to 25 meters; flow of 2.7 to 60.0 m 3 / s, the efficiency of up to 85 ~ 90.5%. Vertical, horizontal and inclined installation of three kinds, including vertical axial flow pump more (Figure 2). Large axial flow impeller hub on the propeller blade mounting angle can be adjusted, or by hydraulically powered shaft in operation with time to adjust to meet the head and flow changes require higher productivity, so called adjustable shaft Flow pump.

Tubular pump is a horizontal axial flow pump. Which is composed of a motor, a decelerating device and a water pump, and is arranged in a machine pit inside the underwater embankment. The water inlet and outlet runners are arranged in a straight line with an approximate straight cylindrical shape with less water loss, high water lifting efficiency and compact structure, Easy installation, maintenance, pumping station project is simple. Pump is a kind of low-lift axial pump, in addition to the impeller and its outer casing made of metal material, the inlet and outlet flow channels are used masonry or concrete structure, the lift of 2 meters below the flow Large, simple structure, low cost, high efficiency. Suitable for drainage and irrigation in low-lying areas.

Mixed flow pump

Structure and working principle Centrifugal pump and axial pump both the characteristics of a type of pump. When the impeller is driven by the power machinery to rotate, the blades push the water body on the one hand and at the same time it drives the water body to rotate to generate the centrifugal effect. Water in the blade thrust and centrifugal force generated by the flow and increase pressure. Flow from the axial flow into the impeller along the blade oblique outflow, commonly used in the delivery of large displacement and medium pressure occasions. There are usually two types of volute and guide vane. The structure of the volute mixed-flow pump is similar to that of the centrifugal pump, and the kinetic energy obtained after the water flows through the impeller is converted into pressure energy by means of the volute-shaped flow passage. In general, the small-medium-sized mixed flow pump adopts a volute-type structure. Vane-type mixed flow pump, also known as diagonal flow pump, its structure and axial flow pump similar to the smaller radial size, simple and light structure and so on. Large-scale mixed flow pumps are mostly vane-type, and the mounting angle of the blades can generally be adjusted. The flow range of the mixed flow pump is generally 3 to 10.5 meters. The starting power is low and can adapt to the change of water level. The flow rate is 0.1-50 m 3 / s and the efficiency can reach 64-86%. Since the 1970s, the development of large mixed-flow pumps has been rapid and has replaced the large axial-flow pumps on many occasions.

Long axis deep well pump

Most of them are vertical single-suction centrifugal pumps whose impellers are installed below the well water level, the power machine is arranged on the well, the impeller is driven to rotate in the diversion shell through the long axis of the transmission, the water flows along the runner between the guide shell and the impeller, Raise the water up to the ground via the water pipe. High lift can be used when multiple impeller in series multistage centrifugal pump. Due to the high manufacturing and installation precision of the transmission long axis, the efficiency is significantly reduced with the increase of the well depth, so it is generally only used for deep wells of not more than 100 meters.

Submersible pump

Pump impeller and impeller drive motor are dive into the water work of a pump, there are two deep-use and work surfaces. Deep submersible pump through the well into the cable to the motor power, eliminating the transmission shaft, so compact, light weight, easy installation, use and transfer, there is power in the area to replace the long axis deep well pump trend, but Not suitable for wells with high sediment concentration and areas without power supply. Submersible pump motor with dry (motor all sealed), semi-dry (motor stator seal, and the rotor in the water operation), oil-filled (motor oil filled to prevent water invasion into the winding) and wet Water, the stator and the rotor are running in the water) and other types. The first three kinds of need to seal and manufacture and installation of high precision, and thus agricultural deep submersible pumps are usually wet motor, the stator winding using water-insulated wire or stator winding end and groove pouring synthetic resin, water into the motor internal impact Small, sealed structure can be greatly simplified, only requires sand control. Some deep submersible pump head up to 1400 meters, the maximum flow of 1.4 m 3 / s.

Jet deep well pump

Usually by the jet pump and centrifugal pump with the corresponding casing composition. Used to lift water from deep wells within 30 meters. The working principle of the jet pump is that the pressure is sprayed through the nozzle to the inlet of the throat pipe. Due to the lateral turbulent diffusion of the jet, the air in the suction pipe is taken away and a vacuum is formed in the pipe. The well water is sucked in and is jetted into the throat Mix, exchange energy. At the outlet of the throat, the velocity of the two flows is close to each other, and most of the kinetic energy is converted into pressure energy through the diffuser tube to further increase the water pressure and finally discharged from the drainage pipe.

Jet-type deep well pump has two types of combinations: â‘  jet pump in parallel with the centrifugal pump, the pump through the pipeline pressure water into the jet pump, the jet pump will be part of the water and water to be lifted up together, so that small-flow High pressure water into a large flow of low pressure water, mainly for surface irrigation and channel dredging; â‘¡ jet pump and centrifugal pump in parallel, so that the jet pump to the centrifugal pump pressure to increase its suction, and the centrifugal pump Part of the amount of water provided to the jet pump, the rest into the pressure tank or pressure pipe, the water pressure is higher, mainly for irrigation equipment and agriculture and animal husbandry water supply. Compared with the submersible pump and the long axis deep well pump, the jet deep pump has the characteristics of simple structure, reliable operation, convenient manufacture and low cost. However, the efficiency is lower and the power consumption under the same working condition is higher.

Screw pump

Relying on the change of the volume of the pump chamber when the screw is rotated A positive displacement pump that sucks in and delivers water. There are single screw, twin screw and multi-screw type. Used in agriculture is the single screw pump, the pump chamber consists of a steel screw and fixedly installed in the pump casing rubber casing composition. A screw with a single pitch is rotated in a sleeve with a double pitch internal helix and the cavity formed between them moves from the suction end to the outlet end to form a continuous stream of water. Because of its simple structure, small size, easy disassembly, reliable, self-priming performance, and more for mobile sprinkler irrigation system.

Manual diaphragm pump

For low lift, small flow of water lifting operations, from the pump, into the water pipe, inlet and outlet valves, diaphragm and push rod and other components. The pump body can consist of one or two pump chambers. A diaphragm pump with two pump chambers, the diaphragm of which is arranged in the center of the pump body, or two diaphragms are respectively mounted outside the two separated pump chambers. Two people work by hand to manipulate the push-pull rod connected to the diaphragm, pushing the diaphragm for pressure and open reciprocating motion, so that the volume of the two pump chambers alternately expand and contract. When the pump chamber expands, the pressure decreases, the inlet valve opens the outlet valve closes, the water flows into the pump chamber from the inlet pipe; when the pump chamber shrinks, the pressure increases, the inlet valve closes, the outlet valve opens, the water in the pump chamber Outflow from the drain, the two pump alternately suction and drainage, water can be raised 10 to 20 tons per hour.

Rod piston pump

Driven by prime mover, wind turbine or internal combustion engine, it is often used on the grazing land to lift water from the well. By the pump cylinder, piston, inlet and outlet pipes, inlet and outlet valves, rod and transmission and other components. Pistons connected by the rod above it driven in the pump cylinder up and down reciprocating motion. When the piston moves upward, the inlet valve opens, the water in the inlet pipe enters the pump cylinder, and the outlet valve is closed at the same time, the water above the piston is driven to lift upwards; when the piston moves downward, the inlet valve is closed and the outlet valve is opened, The water in the pump cylinder rises from the outlet valve to the piston, so that water is repeatedly inflowed and lifted, so that the water is continuously discharged from the drainpipe.

Performance parameters

Pump performance measurement of the technical parameters of flow, suction lift, lift, shaft power, water power, efficiency, etc .; for vane pumps, there are speed and specific rotation. ① suction stroke. The water pump height. Refers to the vertical distance from the center of the pump body to the water source level, the use of vacuum suction pump body when the water flow to allow suction is generally not more than 7.5 meters. ② head. Namely the water pump lifting height. Refers to the unit weight of water through the pump, the value of energy increases. General pumping station into and out of the pool water level difference is called the actual lift; plus pumping station piping and accessories (such as the end of the valve, elbow, gate valve, etc.) head loss is called the total head. Pump head marked on the nameplate, refers to the pump at a certain speed conditions, the highest efficiency when the lift is the sum of the actual head lift and loss. ③ traffic. Refers to the number of water pumps in the unit of time, also known as water delivery. Commonly used flow units are l / s, m 3 / s, m 3 / h, kg / s, tons / hour and so on. ④ shaft power. Refers to the power delivered to the shaft pump power, that is, the pump input power. ⑤ water power. Also known as effective power. Refers to the unit of time for the water pump for the actual power, that is, the pump output power. ⑥ efficiency. The ratio of water power to shaft power is the pump efficiency, usually expressed as a percentage. It is used to measure the power machinery to the pump energy utilization indicators, reflecting the merits of the pump performance. ⑦ than the number of revolutions. Water pump characteristics that the comprehensive parameters. Usually used to represent nS. nS = 3.65nQ1 / 2H-3/4. Where n is the speed (rpm), Q is the flow rate (m 3 / s), double suction pump should Q / 2 into the type; H for the head (m). The specific pump speed and pump parameters are closely related. Centrifugal pump is generally smaller than the specific speed, because of its large diameter impeller, the outlet width is narrow, high lift and flow is small; and axial flow pump than the number of revolutions, and thus low head and flow large; mixed flow pump is between two Between. Centrifugal pump commonly used than the number of revolutions of 30 to 300, mixed flow pump 300 to 600, axial flow pump 500 to 1800. Two similar geometric vane pumps, the specific rotation must be equal. Thus, the experimental data of the geometric similarity model can be used to predict the performance parameters of large pumps.

Pump supporting power

Reasonable matching pumps and power to ensure the normal operation of the pump, in order to obtain high efficiency and low energy consumption is of great significance. Matching power machine power according to the pump head H (meter) and the flow Q (m 3 / s) according to the following formula: (kW). Head H by the geometric head Hj and pipeline loss HS two components, in the initial selection can be HS = (0.1 ~ 0.2) Hj estimate. After the pipeline is determined according to the type of pipe and fittings or calculated by fluid mechanics method or table lookup. Where K is the power reserve coefficient, commonly used K = 1.05 ~ 1.3, when the power is large, take a small value; η1 is the transmission efficiency, when the power machine and the pump directly connected η1 = 1; η2 is the pump efficiency, .

Out of the water pipe and pool

Pump supporting the diameter of the water inlet and outlet pipe D according to the following formula = 1.13Q1 / 2V-1/2 (m), where V is the flow rate within the tube, the general inlet V ≤ 2 m / s, outlet V ≤ 3 m / s . Such as the use of gradient tube diameter changes, the length of its gradual change should be greater than the average diameter of 5 to 7 times. Centrifugal pumps and axial flow pump inlet set at a distance h1 below the surface of the water pool, h1 = (1.4 ~ 1.6) D1, D1 for the inlet diameter. Axial pump impeller center line is located in the water pool below the distance h3, h2 ≥ (0.75 ~ D) D0, D0 for the impeller diameter. Water inlet height from the bottom of the pool h0 = (0.5 ~ 1) D0. A single pump into the pool width (2 ~ 3) D1. Install multiple pumps into the pool, the adjacent inlet pipe spacing (3 ~ 3.5) D1. Into the water inlet pipe into the pool wall distance (1 ~ 1.5) D1. In order to avoid wasting head, the outlet pipe is usually installed below the surface of the water tank. The distance between the lower edge of the outlet pipe of the small pump and the bottom of the water tank is about 10 to 20 centimeters; the vertical distance from the upper edge of the outlet pipe to the water surface is (1 ~ 2) V ~ 2g; v2 is the outlet water velocity The pool length is (6 ~ 12) D2. D2 is the outlet pipe diameter; outlet pipe and the pool wall distance of 0.2 to 0.5 meters.

development trend

The requirements for developing agricultural water pumps are to increase efficiency, reduce energy consumption and make full use of natural energy. A large pump instead of more than one small pump can improve unit efficiency, save material, reduce energy consumption and project cost, and facilitate the automation and management. Therefore, all kinds of large-scale axial flow pump and mixed flow pump developed rapidly, the maximum impeller diameter reached 4.6 meters and 6.2 meters, respectively, supporting the highest power up to 12,500 kilowatts, mixed-flow pump to replace part of the high-lift axial pump and low-lift centrifugal pump trend. Submersible pump in the deep submersible pumps, the largest caliber has reached 1 m, and some use of 6000 volt high-voltage motors, the maximum power of 2500 kilowatts. Water wheel pumps, wind lever pumps, screw pumps, a variety of human and animal-driven diaphragm pumps, piston pumps and pumps dedicated to supporting the sprinkler equipment, etc., in China and other countries have also received varying degrees of attention. Reprinted please indicate from the Pump Technology Forum - Pump online technical exchanges professional platform.

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