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The first section commonly used pump classification, name, code, structure and use of a. Pump classification 1. Dynamic pump Dynamic pump is through the high-speed rotation of the impeller or high-speed motion of the fluid energy is applied to be fed continuously to the pump, so that the speed within the pump housing increased to a maximum, then, through the pump housing The cross section of the inner flow channel changes slowly and its kinetic energy is partially converted into the pressure at the pump outlet. Power pump can be divided into blade and jet (special role in the pump) two categories. According to the flow direction of fluid in the pump housing, but also further divided into centrifugal pump, axial flow pump. 2. Positive displacement pump Positive displacement pump relies on periodic changes in the volume of several closed spaces by applying pressure to the liquid by means of squeezing to increase the pressure directly to the desired value for delivery of the liquid through the valve or orifice Go to the pipeline. According to the movement characteristics of booster components, positive displacement pumps can basically be divided into two types of reciprocating and rotor. Each category can be further subdivided into several forms. 3 • Centrifugal pump classification 1). According to the method of liquid suction impeller: (1) single suction pump: impeller only one side of the suction port, the liquid from the impeller side into the impeller. (2) Double Suction Pump: Suction ports on both sides of the impeller,? Liquid enters the impeller from both sides. 2). According to the impeller series: (1) Single-stage pump: only one impeller. (2) Multistage Pump: Two or more impellers mounted in series on the same pump shaft. 3) According to the form of pump body: (1) Volute pump: The housing is in a spiral shape. After the liquid is thrown out of the impeller, it enters into the helical volute chamber and then into the discharge pipe, such as the Y-type pump. (2) double volute pump: impeller discharge side of the shell with double scroll chamber. (3) cartridge pump: the pump inner shell mounted in an outer cylinder double shell centrifugal pump. In addition, the pump can be divided into different media pump water pump, pump, corrosion-resistant pumps. two. Centrifugal pump model, the meaning Centrifugal pump model representation generally consists of the first, middle and tail of the three components, the first number, said the pump size, size, pump inlet diameter (mm or inch); the middle of Chinese Pinyin that pump type, feature or use, such as D that multi-stage, Sh single-stage double suction, F corrosion resistance pump, Y centrifugal pump; Single-stage rated head, multi-stage pump series. If the pump is fitted with a cut impeller, add the words A, B, C on the back of the trailer. For example: 80AY100 × 2A Third, the structure of centrifugal pumps and the main components 1. Introduction: A centrifugal pump mainly by the pump, impeller, seal ring, shaft, shaft sealing and other components, and some centrifugal pumps are also equipped with guide Wheels, induction wheel, balance plate and so on. 2. Pump body: the pump housing, including the suction chamber and the pressure chamber. (1) inhalation chamber: its role is to make the liquid flow evenly into the impeller. (2). Pressurized liquid chamber: Its role is to collect liquid and send it to the lower impeller or guide discharge pipe, at the same time reduce the liquid velocity, the kinetic energy further into pressure energy. The pressure chamber has a volute and guide wheel in two forms. The volute is named after the runner is spiral. Fluid flows along the helix and decreases velocity as the cross section of the runner increases. As a result, the kinetic energy becomes pressure energy. The stator is commonly found in segmented multistage pumps. So that the structure is simple and compact. The energy conversion between the primary impeller and the secondary impeller adopts a guide wheel, and the liquid flows along the guide passage defined by the guide wheel to the entrance of the secondary impeller. 3. Impeller: It is the only element in the centrifugal pump that delivers energy to the liquid. The pump, through which the pump becomes the pressure energy of the liquid, increases the pressure of the liquid. Impeller key fixed on the shaft, with the shaft driven by the prime mover rotation, the prime mover through the leaves of the energy transfer to the liquid. According to the passage of liquid into the impeller, it can be divided into single suction impeller (with an inlet on one side of the impeller) and double suction impeller (liquid flows symmetrically from both sides of the impeller into the impeller flow passage). In accordance with the liquid flow direction relative to the main axis of rotation of the classification, the impeller can be divided into: radial impeller, axial impeller and Francis impeller. According to the structure of the impeller classification, can be divided into closed impeller, open impeller and semi-open impeller. Closed impeller consists of a number of blades and their cover and wheel on both sides of the composition of the adjacent two leaves and wheel cover, the disk is surrounded by the liquid space is the flow path; open impeller, only the leaves, no Wheel cover and wheel disc; Semi-open impeller, only on one side of the blade wheel. 4-axis: it is an important part of the transmission of mechanical energy, the torque of the prime mover is transmitted to the impeller through it. Pump shaft is the main part of the pump rotor, the shaft is equipped with impeller, bushings, balance disc and other parts. Pump shaft bearing support at both ends, in the pump for high-speed rotation, so the pump shaft to carry capacity, wear resistance, corrosion resistance. Pump shaft material is generally used carbon steel or alloy steel and quenched and tempered. 5 • Sealing ring (split ring) The sealing ring is a seal installed between a rotating impeller and a stationary pump housing (mid-stage and guide vane assembly). Its role is to control the gap between the two methods to increase the resistance of liquid flow between the high and low pressure pump chamber to reduce leakage. 6 • Sleeve Sleeves are used to protect the pump shaft from corrosion and wear. When necessary, the sleeve can be replaced. 7 • Shaft seal The shaft seal between the shaft and the front and rear covers is referred to as a shaft seal to prevent fluid leakage and air from entering the pump to seal and prevent cavitation of the pump. Shaft seal in the form of three general: with a skeleton of the rubber seal, packing seal and mechanical seal. 8 • Axial force balance device (1) Causes of axial force a. Axial force A1 due to different fluid pressure distributions on both sides of the impeller (low pressure on the wheel cap side and high pressure on the wheel disc) is oriented from the impeller back to the impeller inlet. b. The reaction force A2 generated by the fluid flowing in and out of the impeller in a different direction and at a different speed, in the opposite direction to A1. Therefore, the total axial force A = A1 - A2 is generally in the same direction as A1 (generally, A2 is small). (2) balance of axial force a. Adopting double-suction impeller: the impeller is symmetrical on both sides, the fluid is sucked in from both ends, and the axial force automatically cancels to balance. b. Open the balance hole or install the balance pipe: A: Open several balance holes on the impeller wheel with respect to the suction inlet. B: In order to avoid opening the balance hole, due to the disturbance caused by the mainstream to increase the hydraulic loss, Balance pipe can be set to replace the balance hole, which uses a small tube inlet pressure to the back of the roulette. C: the use of balanced blades: cast a few radial ribs in the back of the impeller disk,? Pieces of the impeller to drive the fluid in the back of the gap to accelerate the rotation, increasing centrifugal force, so that the impeller back pressure was significantly reduced. c. The use of thrust bearing axial force. Generally small single suction pump thrust bearing can withstand all the axial force to prevent the shaft from moving. (3) multi-stage centrifugal pump axial force balance: a single-stage centrifugal pump with the same method b symmetrical arrangement of the impeller c using the balance drum to partially balance the axial force d automatic balancing plate, all automatic balance shaft To the force. Centrifugal pump working principle and the main working parameters I. Centrifugal pump working principle 1. Pumping: Centrifugal pump before starting, the pump should be filled with liquid, this process is called filling pump. Did you notice that there was a process of pumping the pump before it was pumped? In refineries, centrifugal pumps also need to be pumped, but most are quite simple. Because the inlet line of the pump is filled with pressurized liquid, the pump can be filled by simply opening the inlet valve. 2.Working principle: The driving machine (motor) drives the impeller to rotate through the pump shaft, and the impeller blades drive the liquid to rotate together, resulting in the centrifugal force. Under this centrifugal force, the liquid is thrown to the impeller exit along the flow path of the vane. The shell collects into the discharge tube. The liquid takes energy from the impeller, increases the pressure energy and velocity, and relies on this energy to deliver the liquid to the work site. When an impeller can not get enough liquid energy, the impeller can be used in series or in parallel to work on the fluid. At the same time as the liquid is thrown to the exit of the impeller, a low pressure is formed at the center of the inlet of the impeller, a pressure difference is generated between the liquid at the center of the suction tank and the impeller, and under the action of this pressure difference, Continuously through the suction pipe and pump suction chamber into the impeller. In this way, the impeller in the process of rotation, while constantly inhaling the liquid, while continuing to inhale the liquid to a certain amount of energy, the liquid discharged, the centrifugal pump to work continuously. Centrifugal pump main working parameters 1. Flow: the amount of liquid pump discharge in the unit of time, usually expressed in volume units, symbol Q, the unit has m3 / h, m3 / s, l / s, etc. When When the weight flow rate G is expressed in units of kgf / h and kgf / s, the relationship between G and Q is: G = Q × γ (γ is the liquid weight at the delivery temperature in kgf / m3). 2. Head: the weight of the liquid transport unit from the pump inlet (pump inlet flange) to the pump outlet (pump outlet flange), the value of its energy, with H that single
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