外文翻译----离心泵在化工生产的应用

CENTRIFUGAL PUMP INCHEMICALPRODUCTIONAPPLICATIONCentrifugal pump in chemical production, this is most widely used because of its performance wide range (including flow, pressure head of media properties and ShiYing sexual), small volume, simple structure, easy operation, flow uniformity, low malfunction, long service life, CaoZuoFei are lower cost and prominent advantages.(1)centrifugal pump principle of workCentrifugal pump working principle is: centrifugal pump so can turn the water away is because only centrificating. Water pump before work, pump body and feed water full line must be cans in vacuum condition, when the impeller fast turns, leaf prompted water quickly spin, spin in the water under the action of the centrifugal force, pump impeller flew in from the water was thrown in the central part of the impeller, after forming vacuum area. Water in the water atmospheric pressure (or water pressure) under the action of water pipe pressure came through a tube. This cycle unceasingly, can achieve continuous pumped. In the centrifugal pump is worth mentioning: before initiating must to the pump housing filled with water, can start after, otherwise will cause, the vibration of the pump body, thus reduce heat pump, damage to (hereinafter referred to as "cavitation erosion") cause equipment accident!Centrifugal pump is a lot of more phyletic, classification methods common has the following kinds of kind: 1, press the impeller inhaled way points: single suction style centrifugal pump double suction type centrifugal pump. 2, press the impeller number points: single grade centrifugal pump mulfistage centrifugal pump. 3, according to the structure of impeller points: open impeller centrifugal pump impeller half open centrifugal pump closed impeller centrifugal pump. 4, according to work pressure points: low voltage centrifugal pump medium centrifugal pumphigh-pressure centrifugal pump. 5, according to pump shaft position points: horizontal centrifugal pump edge vertical centrifugal pump.(2) basic structure, centrifugal pumpsCentrifugal pump is the basic structure by six parts, it is respectively, pump body, impeller pump shaft, bearing, sealing ring, the stuffing box.1, centrifugal pump impeller is higher than the core part, its great strength, speed and a impeller blades of the main function, impeller before assembly through the static balance experiments. Internal and external surface requirements on the impeller of smooth, to reduce water friction losses.2, the pump body also called pump shell, it is the pump body. Play support fixed effect, and is connected to install bearing bracket.3 and the role of pump shaft couplings and motor was borrowed, will connect to the torque motor impeller, so it is the main component of mechanical transmission.4, bearing is set in the pump shaft support of pump shaft components, a rolling bearing and sliding bearing two kinds. Rolling bearings use butter as lubricant refueling appropriate to general for 2/3 ~ 3/4 volume too much, too little and can calorific a sound and fever! Sliding bearings use transparent oil for lubricant, refuels to oil level line. Too much oil to leak and drift along the pump shaft, too little bearing and melech overheating burnt out cause an accident! The water pump operation process of the highest temperature bearing in general 85 degrees running in about 60 degrees, if gao will find the reasons (whether have impurities, whether black, oily water) and deal with whether!5, sealing ring and say minus leak rings. The import and pump impeller shell of the gap between will cause the water pump high-pressure zone within the clearance flow by low pressure area, the influence of the pump, low efficiency, &safe-durable! Gap with the pump impeller had caused moment shell friction wear. In order to reduce leakage increased reflow resistance, delaying the impeller and pump shell used in the pump housing life, with inner and impeller sealing, department of foreign aid in the gaps remain sealed between 0.25 ~ 1.10 mm advisable.6, stuffing box, mainly by packing rings, packing cone, water storage tube packing gland, composed. The role of the stuffing box is mainly to closed pump shell with the space between the pump shaft, don't let pump of water inside don't flow to the outside to also don't let the outside air into the pump inside. Always keep the vacuum pump inside! When the pump shaft and packing friction heat water controlwater to be about to rely on water circle make packing cooling! Maintain normal operation of pump. So the water pump operation circuit checking process to the stuffing box examination is special attention should be paid to! About 600 hours in operation for packing replacement to.(3) centrifugal pump impeller and other components1. Centrifugal pump impellerCentrifugal pump impeller is the key components.according to the mechanical structure can be divided into closed, semi-enclosed and open 3 kinds. Closed impeller suitable for conveying clean liquid. Semi-enclosed and open impeller suitable for conveying containing solid particles of suspending liquid in the efficiency of, this kind of pump low.Closed and semi-enclosed impeller in operation, leave the impeller's part of high pressure fluid can leak into the impeller and pump shell cavity, between the side because of impeller suction pressure low, liquid at the entrance is liquid in the role of the pressure before and behind impeller to differ, they generate pointing the suction side impeller axial thrust. This force to promote the suction side impeller pump impeller and mobile, cause the contact point of moab shell caused serious damage, the vibration of the pump unit, destroying the normal operation of pump. HouGaiBan in impeller drilled several holes, can reduce the pressure on both sides of the impeller is poor, and decrease the harmful effects of axial thrust, but also reduced the pump efficiency. These holes called balance holes.according to absorb fluid can be divided into different ways of impeller with single suction style double suction type two kinds, single suction style simple structure, liquid only impeller from one side of the inhalation. Double suction style impeller can simultaneously from impeller symmetry to inhaled liquid, it not only hasa greater ability to absorb fluid, and basically eliminate the axial thrust.(3) on the impeller blade according to the geometrical shape, can be bent, radial after blade is divided into three, before and after bending due to bend the kinetic energy transfer liquid leaves, so for static pressure can be used extensively.2. The centrifugal pump impellerIn order to reduce leave the liquid directly into the pump impeller shell caused by impact energy loss in the impeller and pump shell, between sometimes device a fixed blade and contain keep-off device. The blade into the pump impeller shell has gradually turned into the liquid flow, make continuous expansion and partial kinetic energy effectively converted to static pressure can. Multistage centrifugal pump impeller usually are installed.The snail shaped pump, impeller blade and the bent on after all can improve kinetic energy to guide the conversion, and therefore can plenum are regarded as turn can device.3. Shaft sealing deviceBecause of pump shaft rotation and pump shell stationary, and in the axis and the contact point of the pump housing must have certain gap. To avoid pump internal high-pressure liquid leakage along the gap, or prevent outside air from the opposite direction into the pump must set within the shaft seal device. Centrifugal pump shaft sealing device has a filler letter and mechanical (end) seal. Stuffing box is will pump shaft through pump shell ring gap to finish seal, in which loaded soft packing (such as oil or coating graphite baptized of asbestos rope, etc.). Mechanical seal is by an outfit in the acting-ring axis and another fixed in the pump housing formed by static ring. Two rings of end borrow spring force tiejin each other relative rotation, and played the sealing effect. Mechanical seal applies to seal higher occasions, such as the conveying acid, alkali, inflammable, explosive and poisonous liquid.(4)the centrifugal pump introduces below several important performance curve.1, flow - head characteristic curveIt is the basic of centrifugal pump performance curve. Less than 80 than speed centrifugal pump has the characteristics of rise and fall, both sides among (both under convex curved), says hump performance curve. In 80 ~ 150 than speed centrifugal pump has between plain performance curve. More than 150 RPM centrifugal pump performance curves with steep drop. In general, when flow hours, head is high, with the increase of flow is decreasing. Head2, flow - power curveThe shaft power increases with the flow, when flow Q = 0, the corresponding shaft power is not equal to zero, and for certain value (about the normal operation of the 60 percent). The power consumed mainly by the mechanical loss. This is full of water pump, if long time running, will lead to the temperature rising pump, pump shell, bearing can calorific, serious when may make pump body thermal deformation, we called "stuffy head", then head for maximum, when water valve gradually opened, the flow rate will increase, shaft power also slow increase.3, flow - efficiency curveIts curve shape, when flow xiangshan head is equal, efficiency and equal to zero, with the increase of flow, efficiency, but also gradually increase the efficiency increased to a certain value has decreased, after a high efficiency in highest efficiency point near, efficiency is higher, this area is called efficient area.离心泵在化工生产的应用离心泵在化工生产中应用最为广泛，这是由于其具有性能适用范围广（包括流量、压头及对介质性质的失迎性）、体积小、结构简单、操作容易、流量均匀、故障少、寿命长、购置费和操作费均较低等突出优点。