Self-priming centrifugal impeller and other components 1. Self-priming centrifugal impeller impeller centrifugal pump is a key component of self-priming. (1) According to its mechanical structure can be divided into closed, semi-closed and open three. Closed impeller for conveying cleaning fluid; semi-closed and open impeller for conveying solids containing suspension, such pumps are inefficient. Closed and semi-closed impeller in operation, part of the impeller away from the high-pressure liquid can leak into the cavity between the impeller and the pump housing, because the impeller inlet pressure liquid front is low, so the liquid on the impeller before and after Side of the pressure range, they have to point to the impeller suction side of the axial thrust. The force to promote the impeller to the suction port side of the move, causing the impeller and the pump shell contact at the wear and tear, serious pump vibration caused damage to the normal operation of the pump. Drilling a number of small holes in the impeller rear cover reduces the pressure differential across the impeller, reducing the adverse effects of axial thrust while reducing pump efficiency. These holes are called balance holes. (2) According to the different liquid suction method, the impeller can be divided into single suction type and double suction type. The single suction type impeller has a simple structure and the liquid can only be sucked in from one side. Double-suction impeller can absorb fluid symmetrically from both sides of the impeller at the same time, which not only has a larger suction capacity, but also basically eliminates axial thrust. (3) According to the geometry of the blade on the impeller, the blade can be divided into three kinds after bending, radial and forward bending, which is widely used because kinetic energy of the back bending blade is converted to static pressure energy. 2. Self-priming centrifugal pump guide wheel In order to reduce the liquid from the impeller directly into the pump shell due to the impact of energy loss caused by the impeller and the pump casing sometimes fixed between the device with a blade guide wheel. The vane in the guide wheel gradually turns the liquid entering the pump casing and the runner continuously expands, so that part of the kinetic energy is effectively converted into the static pressure energy. Multi-stage centrifugal pumps are usually installed guide wheel. Snail-shaped pump shell, the impeller on the back of the curved blade and the guide wheel can improve kinetic energy conversion rate to static pressure, it can be seen as a transformable device. 3. Shaft seal device due to pump shaft rotation and the pump housing is fixed, the shaft and the pump housing must have a certain gap at the contact. In order to avoid high-pressure liquid in the pump escaping along the gap, or to prevent the outside air from entering the pump in the opposite direction, a shaft sealing device must be provided. Centrifugal pump shaft seal packing box and mechanical (end) seal. Stuffing box is the pump shaft through the annulus of the pump shell to form a seal, which filled with soft packing (such as oil immersion or graphite coated asbestos rope, etc.). The mechanical seal consists of a moving ring mounted on the shaft and another stationary ring fixed to the pump housing. Two rings of the end face by spring force and relative to each other for the relative rotation, played a sealing role. Mechanical seal suitable for sealing high occasions, such as the transmission of acid, alkali, flammable, explosive and toxic liquid. When the centrifugal pump is started, the pump shaft drives the impeller to rotate at a high speed together to force the liquid pre-filled to rotate between the blades. Under the action of inertial centrifugal force, the liquid moves radially from the center of the impeller to the outer periphery. Liquid flows through the impeller in the process of gaining energy, static pressure can increase the flow rate increases. When the liquid leaves the impeller and enters the centrifugal pump shell, due to the gradual enlargement of the flow channel in the shell and deceleration, some of the kinetic energy is converted into static pressure energy and flows into the discharge pipe in the tangential direction finally. Therefore, the snail-shaped pump housing is not only a collection of components from the impeller out of the liquid, but also a transformable device. When the liquid thrown from the center of the impeller to the periphery at the same time, the center of the impeller to form a low pressure zone, the tank surface and the impeller center of the total potential difference under the action of the liquid was sucked into the impeller center. Depending on the continuous operation of the impeller, the liquid is continuously aspirated and discharged. The mechanical energy obtained by a liquid in a self-priming centrifugal pump ultimately shows an increase in static pressure energy. The role of the impeller is to transfer the mechanical energy of the prime mover directly to the liquid to increase the hydrostatic and kinetic energy of the liquid (mainly increasing the static pressure energy). 1. The role of impeller impeller is the mechanical energy directly to the liquid, in order to increase the hydrostatic pressure and kinetic energy (mainly to increase static pressure). Impeller has open, semi-closed and closed three. The open impeller has no cover plate on both sides of the blade, which is simple in manufacture and convenient in cleaning. It is suitable for conveying materials containing a large amount of suspended matter, which has low efficiency and low pressure of liquid to be transported. The semi-closed impeller has no cover on the suction inlet side Plate, and on the other side of the cover, suitable for conveying easily sediment or particles containing materials, the efficiency is lower; closed impeller impeller on both sides of the blade has a front and rear cover, high efficiency, suitable for the delivery of impurities Clean liquid. Most of the centrifugal pump impeller for such. 2. Pump shell role is to seal the impeller in a certain space, in order to impeller role in the suction and out of the liquid. Centrifugal pump casing made of spiral shape, it is also known as volute. Due to the gradual enlargement of the cross-sectional area of ​​the flow passage, the high-speed liquid thrown out from the impeller gradually reduces the flow velocity and effectively converts part of the kinetic energy into static pressure energy. Pump housing not only brings together the liquid thrown by the impeller, but also an energy conversion device. Centrifugal concept of centrifugal is actually the manifestation of the object inertia.For example, the water droplets on the umbrella, when the umbrella slowly rotates, the water droplets will follow the umbrella rotation, this is because the friction between the umbrella and the water droplets as the centripetal force to the water droplets .But if the umbrella rotates Acceleration, the friction is not enough to make the water droplets in a circular motion, then the water droplets will move away from the umbrella to the outer edge.As with a rope pull the stone to do circular motion, if the speed is too fast, the rope will be broken, stone The block will fly out. This is called Centrifugal. Centrifugal pump is designed according to this principle.High-speed rotation of the impeller blades to drive the water to rotate, the water thrown, so as to achieve the purpose of delivery.Centrifugal pump has a variety of.From the use can be divided into civil and industrial pumps, from the transmission medium Can be divided into water pumps, impurities pumps, corrosion-resistant pumps. Centrifugal pump basic structure The basic structure of the centrifugal pump is composed of six parts, namely: impeller, pump body, pump shaft, bearings, seal ring, stuffing box. 1, the impeller is the core part of the centrifugal pump, it is high speed output power, the blades on the impeller play a major role in the impeller before the assembly through the static balance experiment. The inner and outer surfaces of the impeller require smoothness to reduce the 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 by a coupling and motor, the motor torque to the impeller, so it is the main component of mechanical energy transfer. 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 size of 2/3 ~ 3/4 Too much heat, too little sound and fever! Sliding bearing centrifugal pump structure is the use of transparent oil as a lubricant, refueling to the oil level line. Too much oil to bleed along the pump shaft and drift *, 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 the impeller and the pump shell friction wear. In order to increase the backflow resistance to reduce internal leakage, delay the service life of the impeller and the pump housing, the inner edge of the pump housing and the impeller is provided with a sealing ring at the joint of the outer support, and the sealed clearance is maintained at between 0.25 and 1.10mm. 6, stuffing box mainly by the filler, water seal ring, packing tube, packing gland, water seal tube. The purpose of the stuffing box is to close the empty space between the pump housing and the pump shaft so that the water in the pump does not flow 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 will depend on the water seal to live in the water seal ring so that the filler cooling! Maintain the normal operation of the pump. Therefore, during the inspection of the pump running inspection of stuffing box is a special note! Filler needs to be replaced after about 600 hours of operation.
