Self-priming centrifugal pump impeller and other components introduced
October 18 15:02:32, 2024
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).