lesson 12 centrifugal pumps...
Flowserve 公司及产品介绍
In many cases, the Flowserve pump heritage companies grew and developed along with emerging industries. Oil and gas production, pipeline, refining, chemical and petrochemical processing, power generation (fossil and nuclear fueled), cryogenics – all required special purpose engineered pumping innovations. Entrepreneurial engineers with limited resources found niche markets and exploited them. As a result, their product lines grew and they expanded into other markets, including pulp and paper, mining and mineral processing, primary metals, desalination, food and beverage, and other industrial segments. Yet, the earliest of the Flowserve heritage brands addressed the more routine needs of their day: potable water treatment and transmission; dewatering; and maritime applications.
Centrifugal Pumps计算
u −u c −c w −w Ht = + − 2⋅g 2⋅g 2⋅g
2 2 2 1 2 2 2 1 2 2
2 1
Euler’s pump equation
u 2 ⋅ c u 2 − u 1 ⋅ c u1 Ht = g
u −u c −c w −w Ht = + − 2⋅g 2⋅g 2⋅g
2 2 2 1 2 2 2 1 2 2 2 2 2 1 2 1
⇒ c m1 = K m1 ⋅ 2 ⋅ g ⋅ H = 6,4 m s
w1 c1= cm1 u1
Dhub
D1 = 0,405 D2
D1 = 0,405 ⇒ D1 = 0,405 ⋅ D 2 = 0,34 m D2
We choose:
D1m
D hub = 0,5 ⋅ D1 = 0,17 m
2 D1 + D 2 hub = = 0,27 m 2
Q1 Π ⋅ D1 ⋅ B1 ⋅ c m1 D1 n1 = = = Q 2 Π ⋅ D 2 ⋅ B2 ⋅ c m 2 D 2 n 2 ⇓ D2 0,45 Q2 = ⋅ Q1 = ⋅1 = 0,9 m 3 s D1 0,5
D2 0,45 ⋅ H1 = H2 = ⋅100 = 81 m 0,5 D1 D2 0,45 ⋅ P1 = P2 = ⋅123 = 90 kW 0,5 D1
2 2 p2 w2 u2 p1 w1 u1 + 2 − 2 = + − ρ⋅g 2⋅g 2⋅g ρ⋅g 2⋅g 2⋅g
Rothalpy
The rothalpy can be written as:
(ω ⋅ r ) w p I= + − = cons tan t ρ⋅g 2⋅g 2⋅g
离心泵工艺流程简图
离心泵工艺流程简图英文回答：Centrifugal pumps are commonly used in various industrial processes to transport fluids. The process flow of a centrifugal pump can be summarized as follows:1. Suction: The pump is connected to the source of the fluid, such as a tank or a reservoir, through a suction pipe. The fluid is drawn into the pump through the suction inlet.2. Impeller: Inside the pump, there is a rotating component called the impeller. The impeller consists of curved blades or vanes that rotate rapidly when the pump is in operation. The impeller is responsible for imparting kinetic energy to the fluid.3. Centrifugal force: As the impeller rotates, it creates a centrifugal force that pushes the fluid away fromthe center of rotation. This centrifugal force increases the fluid's velocity and pressure.4. Discharge: The fluid exits the pump through a discharge pipe connected to the pump's outlet. The increased pressure and velocity of the fluid allow it to be transported to the desired location.5. Control: The flow rate and pressure of the pump can be controlled by adjusting the speed of the impeller or by using valves and throttling devices in the piping system.Example: Let's say I work in a chemical plant, and we use centrifugal pumps to transfer chemicals from storage tanks to various reactors. The process starts by connecting the suction pipe of the pump to the tank containing the chemical. The impeller inside the pump rotates rapidly, creating a centrifugal force that pushes the chemical towards the outlet. The chemical then exits the pump through a discharge pipe and is transported to the desired reactor. We can control the flow rate and pressure by adjusting the speed of the impeller or by using valves inthe piping system.中文回答：离心泵是工业流程中常用的输送流体的设备。
离心泵的工作原理及主要部件性能参数
离心泵的工作原理及主要部件性能参数离心泵——生产中应用最为广泛，着重介绍。
§ 2.1.1 离心泵 （Centrifugal Pumps ） 一． 离心泵的工作原理及主要部件 1．工作原理如左图所示，离心泵体内的叶轮固定在泵轴上，叶轮上有若干弯曲的叶片，泵轴在外力带动下旋转，叶轮同时旋转，泵壳中央的吸入口与吸入管相连接，侧旁的排出口和排出管路9相连接。
启动前，须灌液，即向壳体内灌满被输送的液体。
启动电机后，泵轴带动叶轮一起旋转，充满叶片之间的液体也随着旋转，在惯性离心力的作用下液体从叶轮中心被抛向外缘的过程中便获得了能量，使叶轮外缘的液体静压强提高，同时也增大了流速，一般可达15～25m/s 。
液体离开叶轮进入泵壳后，由于泵壳中流道逐渐加宽，液体的流速逐渐降低，又将一部分动能转变为静压能，使泵出口处液体的压强进一步提高。
液体以较高的压强，从泵的排出口进入排出管路，输送至所需的场所。
当泵内液体从叶轮中心被抛向外缘时，在中心处形成了低压区，由于贮槽内液面上方的压强大于泵吸入口处的压强，在此压差的作用下，液体便经吸入管路连续地被吸入泵内，以补充被排出的液体，只要叶轮不停的转动，液体便不断的被吸入和排出。
泵离心泵旋转泵漩涡泵 往复泵由此可见，离心泵之所以能输送液体，主要是依靠高速旋转的叶轮，液体在离心力的作用下获得了能量以提高压强。
气缚现象：不灌液，则泵体内存有空气，由于ρ空气<<ρ液，所以产生的离心力很小，因而叶轮中心处所形成的低压不足以将贮槽内的液体吸入泵内，达不到输液目的。
通常在吸入管路的进口处装有一单向底阀，以截留灌入泵体内的液体。
另外，在单向阀下面装有滤网，其作用是拦阻液体中的固体物质被吸入而堵塞管道和泵壳。
启动与停泵：灌液完毕后，此时应关闭出口阀后启动泵，这时所需的泵的轴功率最小，启动电流较小，以保护电机。
启动后渐渐开启出口阀。
停泵前，要先关闭出口阀后再停机，这样可避免排出管内的水柱倒冲泵壳内叶轮，叶片，以延长泵的使用寿命。
化工原理英文教材流体输送与计量泵设备Transportation and metering of fluids
If the suction pressure is actually less than the vapor pressure, cavitation will occur in the suction line, and no liquid can be drawn into the pump.
化工原理 Principles of Chemical Industry
Transportation and metering of fluids
The engineer is concerned with practical problems in transporting fluids from one place to another and in measuring their rates of flow.
Such devices increase the mechanical energy of the fluid.
The energy may be used to increase the velocity, the pressure, or the elevation of the fluid.
W
pb
gZb
ub2 2
pa
gZa
ua2 2
(8-1)
The equation(8-1) can be divided by g, gives
H
pb
g
Zb
ub2 2g
pa
g
Za
ua2 2g
(8-1a)
The quantity H is called developed (total) head, in which each term has the dimension of length.
阿法拉伐(泵)Centrifugal Pumps介绍PPT
• Fits all IEC framed motors • 1.5 kW to 37 kW • The adapter is stainless steel as standard © Laval Slide 17 • AlfaModular design
1.5 Kw motor adaptor
© Alfa Laval
Slide 28
• 注水机械密封 • 可以形成一个注水屏障，如果系统中有真空出现，可
以避免气体中的物质透过机械密封污染产品。
© Alfa Laval
Slide 29
Double Mechanical Seal
Flush medium 0,25 – 0,5 l/m Max 5 bar Product
Silicon Carbide
© Alfa Laval
Slide 30
LKH External Shaft Seal - FAB: s
Features
External shaft seal
Pump Shaft Mechanical Shaft Seal Components
© Alfa Laval Slide 7
Pump Casing
Sanitary Design
© Alfa Laval
Slide 8
Pump Operation Principle
Product out
Product in
© Alfa Laval
Slide 9
The LKH Pump Casing
Casing: 8 mm
Close Tolerances, 0,5 mm
水泵英语单词 -回复
水泵英语单词-回复Water PumpA water pump is a mechanical device used to move water from one place to another. It plays a crucial role in various industries and settings, including agriculture, construction, and household applications. In this article, we will explore the different types of water pumps, their functions, and how they work.The primary function of a water pump is to create a pressure difference that allows water to flow. Water pumps come in various types, including centrifugal pumps, reciprocating pumps, and submersible pumps. Each type has its unique features and applications.Centrifugal pumps are the most common type of water pump. They work by converting rotational energy from a motor into fluid energy, which creates a flow of water. Centrifugal pumps consist of several components, including an impeller, casing, and motor. The impeller is a rotating device that pushes the water towards the outlet of the pump, while the casing provides a confined space for the water to pass through. The motor is responsible for providingthe rotational energy needed to operate the pump.Reciprocating pumps, also known as piston pumps, use a piston or plunger to create pressure and move water. These pumps rely on the reciprocating motion of the piston to draw water into a cylinder and then force it out through a discharge valve. Reciprocating pumps are commonly used in high-pressure applications where a strong flow of water is required.Submersible pumps, as the name suggests, are designed to be submerged in water. These pumps are typically used for deep wells or in applications where water needs to be lifted from a lower level. Submersible pumps consist of a motor and an impeller enclosed in a waterproof casing. The motor powers the impeller, which generates the pressure needed to push water to the surface.Now that we have covered the different types of water pumps let's delve into their working principles. Starting with centrifugal pumps, the process begins with the motor spinning the impeller. As the impeller rotates, it creates a centrifugal force that pushes the water from the center towards the outer edges of the impeller. This action generates kinetic energy, which is then converted into pressureenergy as the water flows through the casing. Finally, the water is forced out through the pump's outlet.Reciprocating pumps work by using the motion of a piston or plunger. When the piston moves in one direction, it creates alow-pressure area that allows water to enter the cylinder through an inlet valve. As the piston moves back in the opposite direction, the inlet valve closes, and the outlet valve opens, forcing the water to flow out through the discharge valve. This reciprocating motion is repeated continuously, creating a constant flow of water.Submersible pumps operate by utilizing the principles of centrifugal force. The motor spins the impeller, which then pulls water into the casing. As the impeller spins faster, the water is forced towards the surface through the casing, creating the desired flow.In conclusion, water pumps are vital devices that enable the movement of water in various industries and settings. They come in different types, including centrifugal, reciprocating, and submersible pumps, each with its unique functions and workingprinciples. Understanding the different types and how they work can help individuals choose the right water pump for their specific needs.。
华东理工大学过程装备与系统（双语）
华东理工大学过程装备与系统（双语）Chapter 1 Introduction to Process EquipmentKey TermsAxial bearings轴向轴承: devices designed to prevent back-and-forth movement of a shaft; also called thrust bearings.Boiler锅炉: a type of fired furnace used to boil water and produce steam; also known as a steam generator. Compressors 压缩机: mechanical devices designed to accelerate or compress gases; classified as positive displacement or dynamic.Coupling联轴器: a device that attaches the drive shaft of a motor or steam turbine to a pump, compressor, or generator.Driver: a device designed to provide rotational energy to driven equipment.Heat exchanger换热器: an energy-transfer device designed to transfer energy in form of heat from a hotter fluid to a cooler fluid without physical contact between the two fluids.Pumps泵: devices designed to move liquids from one place to another; classified as positive displacement or dynamic.Reactor反应器: a device used to combine raw materials, heat, pressure, and catalysts in the right proportions to form chemical bonds that create new products.Steam turbine蒸汽轮机: an energy-conversion device that converts steam energy(kinetic energy) to useful mechanical energy; used as drivers to turn pumps, compressors, and electric generators.Valve阀: a device used to stop, start, restrict(throttle), or direct the flow of fluids.Questions:1.Identify the purpose of a steam turbineThe purpose of a steam turbine is to converts kinetic energy to useful mechanical energy in order to drive pumps, compressors, and electric generators. (P9)2.Describe the importance of equipment lubrication.Lubrication protects the moving parts of equipment, helps remove heat generated and provides a fluid barrier between the metals parts to reduce friction, thus ensuring the good operation of process equipment. (P10)3.Explain the purpose of bearings and seals.Bearings prevent up-and-down and side-to-side or back-and-forth movement of a rotating shaft.Seals prevent leakage between internal compartments in a rotating piece of equipment. (P10)Rotary equipment uses seals and bearings to maintain operation integrity. (P20)4.What is the difference between rotary and stationary equipment?Rotary equipment is characterized by a circular movement and is composed of a driver, a connector, and the driven equipment. (P4)However, stationary equipment is static. (自己编的)5.How is power transmission in rotary equipment classified?Power transmission in rotary equipment is classified as speed-to-torque conversion or torque-to-speed conversion. (P6) Chapter 2 ValvesKey TermsCheck valves止回阀: mechanical valves that prevent reverse flow in piping.Control valves: automated valves used to regulate and throttle flow; typically provide the final control element of acontrol loop.Disc阀瓣: a device made of metal or ceramic that fits snugly in the seat of a valve to control flow.Gate valve闸阀: a device that places a movable metal gate in the path of a process flow.Globe valve止通阀: a device that places a disc in the path of a process flow.Safety/relief valve安全/释放阀: device set to a automatically relieve pressure in a closed system at apredetermined set point; relief valve valves are used for liquids; safety valves are used for gases. Stuffing box填料函: the section of a valve that contains packing.Throttling节流: reducing or regulating flow below the maximum output of a valve.Trim: the flow-control element and seats in a valve.Questions:6.Explain the purpose of valves in industrial manufacturing.The primary purpose of a valve is to direct and control the flow of fluids by starting, stopping, and throttling (restricting) flow to make processing possible. (P25)7.Identify the basic components of a gate valve.P27 Figure 2.28.List the main types of valves.Gate valves. Globe valves. Ball valves. Check valves. Butterfly valves. Plug valves. Diaphragm valves.Relief and safety valves. Automatic valves./doc/b718128130.html,pare a relief valve to a safety valve.Relief valve valves are used for liquids; safety valves are used for gases.10.List the four types of check valves.Swing check valve. Lift check valve. Ball check valve. Stop check valve.Chapter 3 Tanks, Piping, and VesselsKey TermsAlloy合金: a material composed of two or more metals or a metal and a nonmetal.Blind盲板: a device used in piping to gain complete shutoff.Butt-weld piping: pipe on which the parts to be joined are the same diameter and simply welded together. Corrosion腐蚀: electrochemical reactions between metal surfaces and fluids that result in the gradual wearing away of the metal.Flanges法兰: used to connect piping to equipment or where piping may have to be disconnected; consist of two mating plates fastened with bolts to compress a gasket between.Floating-roof tank: has an open top and a pan-like structure that floats on top of the liquid and moves up and down inside the tank with each change in liquid level.Grounding: is described as procedure designed to connect and object to the earth with a copper wire and a grounding rod.Radiographic inspection: use of X-rays to locate defects in metals in much the same manner as an X-ray is taken of a broken bone.Socket-welded piping: type of piping in which the pipe is inserted into a larger fitting before being welded to another part.Tank farm罐区: a collection of tanks used to store and transport raw materials and products. Questions:11.List the different types of aboveground storage found ina tank farm.Low, medium, high pressure. (P51)12.What two types of blinds do we use?Paddle blinds and figure-eight blinds. (P64)13.How does increased temperature affect the performance of metals?In general, as temperature increases, the strength of metals decreases and corrosion rate increases. (P66) 14.What is an alloy steel?Steel that contains alloy elements is called alloy steel. (自己编的)15.What is corrosion, and how is it manifested?Corrosion is electrochemical reactions between metal surfaces and fluids that result in the gradual wearing away of the metal (定义). In a word, corrosion is metal loss. (P60)Corrosion attack manifests itself in many ways, such as general loss of metal, pitting, grooving, cracking, or other kinds of selective attack. (P60)Chapter 4 PumpsKey TermsCentrifugal pumps离心泵: a dynamic pump that accelerates fluid in a circular motion.Impeller叶轮: a device attached to the shaft of a centrifugal pump that imparts velocity and pressure to a liquid.Positive displacement正位移、容积式: class of equipment such as pumps and compressors that move specific amounts of fluid from one place to another; can be rotary or reciprocating.Priming灌液: becoming filled with fluid.Pulsation dampener缓冲器: a device installed close to a pump, in the suction or discharge line, to reduce pressure variations.Reciprocating pump往复泵: a positive displacement pumpthat uses a plunger, piston, or diaphragm moving in a back-and-forth motion to physically displace a specific amount of fluid in a chamber.Rotary pump回转泵: a positive displacement pump that uses rotating elements to move fluids.Slip泄漏: the percentage of fluid that leaks or slips past the internal clearance of a pump over a given time. Vapor lock气缚: condition in which a pump loses liquid prime and the impellers rotate in vapor. Questions:16.Describe the scientific principles associated with centrifugal pump operation and identify keycomponents.P8917.List the various types of rotary pumps.Screw pump, external gear, internal gear, sliding vane, flexible vane, lobe pumps.18.List the various types of reciprocating pumps.Piston, plunger, diaphragm.19.What are the advantages of centrifugal pumps?Centrifugal pumps are cheaper and require less maintenance and space.They will operate with a constant head pressure over a wide capacity range.It is easier to change the element on a centrifugal pump than on a PD pump, and it is easier to change the driver.A final advantage is the adaptability of the selected driver----variable horsepower and fixed or variablespeed. (P92)Chapter 5 CompressorsKey TermsAftercooler后冷却器: a heat-exchange device designed to remove excess heat from the discharge side of a multistage compressor.Compression ratio: the ratio of discharge pressure(psia) to suction pressure(psia). Multistage compressors use a compression ratio in the 3 to 4 range, with the same approximate compression ratio in rach stage. Demister除雾器: a cyclone-type device used to swirl and remove moisture from a gas.Dryer: removes moisture from gas.Lobe compressor罗茨压缩机: a rotary compressor that contains kidney bean-shaped impellers.Oil separator: removes oil from compressed gases.Stage: each cylinder in a compressor; specifically, the area where gas is compressed.Questions:20.List the two types of compressors.Dynamic, positive displacement, thermal.21.List the three rotary compressors.Rotary screw, lobe compressor, liquid ring, sliding vane, scroll.22.List the basic components of a centrifugal compressor. P12123.List the main difference between a single-stage and a multistage compressor.Single-stage compressors compress the gas once, whereas multistage compressors deliver the discharge of one stage to the suction of another stage. Single-stage compressors are designed for high gas flow rates and low discharge pressures; multistage compressors are designed for high gas flow rates and high discharge pressures. (P121)24.What is the difference between dynamic and positivedisplacement compressors?Dynamic compressors operate by accelerating the gas and converting the energy to pressure. They can deliver much higher flow rates than PD compressors. Positive displacement compressors operate by trapping a specific amount of gas and forcing it into a smaller volume. (P140)Chapter 7 Heat ExchangersKey TermsCondenser冷凝器: a shell-and-tube heat exchanger used to cool and condense hot vapors.Conduction传导: the means of heat transfer through a solid, nonporous material resulting from molecular vibration. Conduction can also occur between closely packed molecules.Convection对流: the means of heat transfer in fluids resulting from currenst.Counterflow逆流: refers to the movement of two flow streams in opposite directions; also called countercurrent flow.Fixed head固定头: a term applied to a shell-and-tube heat exchanger that has the tube sheet firmly attached to the shell.Laminar flow层流: streamline flow that is more or less unbroken; layers of liquid flowing in a parallel path. Radiant heat transfer辐射传热: conveyance of heat by electromagnetic waves from a source to receivers. Reboiler再沸器: a heat exchanger used to add heat to a liquid that was once boiling until the liquid boils again.Shell-and-tube heat exchange管壳式换热器: a heat exchanger that has a cylindrical shell surrounding a tube bundle.Turbulent flow湍流: random movement or mixing in swirls and eddies of a fluid.Questions:25.What is a heat exchanger?A heat exchanger is an energy-transfer device designed to transfer energy in form of heat from a hotterfluid to a cooler fluid without physical contact between the two fluids. (第一章)26.What is meant by the term floating head?Floating head heat exchangers are designed for high temperature differentials above 200℉(93.33℃).During operation, one tube is fixed and the other “floats”inside the shell. The floating end is not attached to the shell and is free to expand. (P163)27.List five types of heat exchangers.Pipe coil exchangers, double-pipe heat exchangers, shell-and-tube heat exchangers, reboilers, plate-and-frame heat exchangers, air-cooled heat exchangers, spiral heat exchangers.28.Explain the purpose of using finned tubes in heat exchangers.Fins provide more surface area and allow greater heat transfer to take place. (P172)29.Contrast parallel and series flow through a heat exchanger.In series flow, the tube-side flow in a multipass heat exchanger is discharged into the tube-side flow of the second exchanger. This discharge route could be switched to shell side or tube side depending on how the exchanger is in service. The principle is that the flow passes through one exchanger before it goes to another. In parallel flow, the process flow goes through multiple exchangers at the same time.(P167)Chapter 8 Cooling TowersKey TermsAir intake louvers进风口: slats located at the bottom or sides of a cooling tower to direct airflow.Basin水池/槽: concrete storage compartment or catch basin located at the bottom of the cooling tower. Blowdown排污/清洗: a process of controlling the level of suspected solids in a cooling tower by removing a certain amount of water from the basin and replacing it with makeup water.Capacity可冷却的水量: the amount of water a cooling tower can cool.Cooling towers冷却塔: are evaporative coolers specifically designed to cool water or other mediums to the ambient wet-bulb air temperature.Drift eliminators收水器: devices used in a cooling tower to keep water from blowing out.Evaporate蒸发: to turn to vapor; evaporation removes heat energy from hot water.Forced-draft强制通风: type of mechanical-draft cooling tower that uses fans to push air into the tower. Induced-draft诱导通风: type of mechanical-draft cooling tower that uses fans to push air out of the tower. Questions:30.List and describe the basic components of a cooling tower.Water distribution header, splash bars, fill, basin, cooling water supply header, process exchangers, cooling water return header, drift eliminator. (P195自己看着抽出来的)31.Describe the relationship between heat exchangers and a cooling tower.In the manufacturing environment, heat exchangers and cooling towers work hand in hand to create a water-cooling system. Balabala… (P200)32.List five factors that affect the efficiency of a cooling tower.Evaporation, relative humidity, temperature, wind velocity, tower design, water contamination. (P194) 33.Which tower is most efficient: forced-draft or induced-draft? Why?Induced-draft. In an induced-draft cooling tower, the tower fan, located on the top of the tower, produces discharge rates strong enough to lift the hot air above the tower, so hot air is not recirculated into the tower. However, in a forced-draft cooling tower, the exiting air slows so much that it is recirculated back into the tower, cutting efficiency by 20%. (P198, 199)。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
• 当聚集的水从叶轮中心孔流向四周时， 其压力增加，小气泡中的水蒸汽变的 不稳定并凝结为液体，导致气泡闪发。
• These implosions in the tiny vapor
bubbles in the water mass have enough energy to cause pitting in the adjoining material of the impeller as the pump casing.
• As the pump operates at a particular
available net positive suction head, the cavitation is found occurring at a particular on the pump impeller and its casing.
Lesson 12
Centrifugal Pumps Maintenance, Operational Problems and Remedies
• During the operation of the centrifugal
pumps (see Fig. 12-1), several problems are faced which have to be looked into during their operation in order to get trouble-free service from these pumps.
• 在泵浦的操作过程中，聚集的水 通过叶轮中心孔流向四周，为叶 轮中心孔和吸入管创造出真空。
• If the temperature of the water passing
through the suction pipe and the eye of the impeller happens to be higher than the saturation temperature of the water at the prevailing vacuum, some of the water may evaporate to form tiny vapor bubbles,
• After several years of use , the pitting
causes the wastage in the impeller and the casing material sufficient to
['pɪtɪŋ]
make it weak requiring replacement.
• 其它有关离心泵操作的问题主要 是运动部件因摩擦而造成的磨损， 这将会导致：
• Increase in the clearance between the impeller neck and the wear rings resulting in reduction in volumetric efficiency, replacement of wear rings is the only remedy for this
• 离心泵所面临的典型问题是汽蚀， 汽蚀是由于这些泵是在吸入压力 大大低于大气压的情况下工作的
• this occurs mainly in the pumps used
for transferring water. Other problems faced by these pumps are mainly due to normal wear and tear of materials over a period of time.
• 经过几年的使用，点蚀造成的叶 轮和泵壳的材料损耗足以使其性 能变差，需要换新。
• The only remedy to prevent cavitation in
any pump is to ensure that temperature of the water passing through the suction pipe and the eye of the impeller is maintained below the saturation temperature at the
• 盘根压盖处的叶轮轴的损坏可以通过 换新轴来解决，或者，如果轴配备了 轴套，换新轴套解决问题
• Wearing off damage to the bearing
replacement of the bearing .
leading to increased power consumed by the pump . This may be rectified by
• 这些聚集的水中的小气泡闪发具 有足够大的能量，可造成叶轮和 泵壳的材料点蚀。
• This process of impeller and the casing
material wastage
called cavitation.
[ˈwestɪdʒ] (消耗; 废物)is
• 这种叶轮和泵壳致 容积效率的减少， 更换水封环是解决 这一问题的唯一办 法。
• Damage to the impeller shaft in the
way of gland packing which may be rectified(矫正的，调整的) by replacement of the shaft or , if the shaft is fitted with a sleeve, by replacing sleeve .
• 轴承磨损会导致泵耗功的增加， 这可通过换新轴承来解决。
• Removal of Pump for Inspection and
Maintenance
• 泵的拆检和维护
• 1. Isolate pump electrical circuit
operate -Men at Work •)
breaker on main switch board and attach a warning notice. (Do NOT
• 1.断开主配电板上泵电源的断路器， 挂上警示牌(禁止合闸-有人作业)
• 2.Switch off and lock pump supply at
•
its local supply panel . Attach a warning notice to pump local panel. 3.Close suction and discharge valves ,
• 这主要发生在输送水的泵中。这 些泵面临的其它问题主要是一段 时间内材料的正常磨损。
• Operational Problems
• 操作问题
• During the pump operation, as the
water mass [mæs] (集中，聚集)passes from eye of the impeller towards its periphery, is creates vacuum at the eye of the impeller and inside the suction pipe .
• 4.打开泵的吸排管路上的排向舱底的 放残阀；小心的分开管路和泵的法兰 接头，确保泵已放空且可以安全的打 开。
• 5.Fix a shackle to lifting pad eye above
pump and hang chain block ; ensuring SWL(safe working load)of block ,slings and shackles are satisfactory.
• 此外，泵壳的内部可以覆盖硬的 环氧树脂涂层以使汽蚀的影响最 小化。
• Other problems related to the centrifugal pump operation are mainly due to wear and tear in the moving parts due to friction, this will result in:
which travel though the impeller.
• 如果流经吸入管路和叶轮中心孔的水 温高于当前真空下水的饱和温度，一 些水可能会蒸发形成微小的汽泡，流 过叶轮。
• As the water mass passes from eye of
the impeller towards its periphery, its pressure rises and the vapor in the tiny bubble becomes unstable and condenses back to liquid causing small implosions in these bubbles.
• 在离心泵运转期间(如图12-1)，要 了解离心泵运转期间会面临的一 些问题以使这些泵无故障的工作
• The main problem typical to centrifugal
pumps, faced by these pumps is cavitation , which is caused by the fact that these pumps operate with suction pressure much below the atmospheric pressure.
chain and lock hand wheels.
• 2.把泵的本地配电板电源切断并锁死， 挂上警示牌。 • 3.关闭泵的吸排阀，用链条锁死阀盘
• 4.Open pump suction and discharge
pipe drain valves to bilge and when water ceases to flow ; crack open the pipes/pump flange joints carefully to ensure that pump has drained off and is safe for opening .