The water pump is used to transport or pressurize the liquidMechanics。It willmechanical energyOr other external energy is transmitted to the liquid to increase the energy of the liquid, which is mainly used to transport the liquid includingwater, oil, acid-base solutionEmulsion, suspension emulsion andliquid metalEtc.
It can also transport liquid, gas mixture and liquid containing suspended solids.Technical parameters of pump performance include flow, suction headlift、Shaft power, water power, efficiency, etc;According to different working principles, it can be divided intovolumeType of water pump, vane pump, etc.Positive displacement pumpIt uses the change of the volume of its working room to transfer energy;Vane pumpIt uses the interaction between rotating blades and water to transfer energy, includingcentrifugal pump、Axial flow pumpandMixed flow pumpEtc.
1. Positive displacement pump: use the periodic change of the volume of the working chamber to transport liquid.
Water pump
2. Vane pump: use the interaction between blades and liquid to transport liquid.
give an example
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centrifugal pump
1. Working principle of centrifugal pump
Before the pump starts, fill the pump and the inlet pipe with water. After the pump runs, under the centrifugal force generated by the high-speed rotation of the impeller, the water in the impeller passage is thrown around and pressed into the volute. A vacuum is formed at the inlet of the impeller. The water in the pool is sucked along the suction pipe under the external atmospheric pressure to supplement this space.Then the water sucked in is thrown out by the impeller and enters the outlet pipe through the volute.It can be seen that if the impeller of the centrifugal pump rotates continuously, it can continuously absorb and pressure water, and water can be continuously lifted from the low to the high or far away.To sum up, the centrifugal pump is called centrifugal pump because it lifts water to a higher place under the centrifugal force generated by the high-speed rotation of the impeller.
2. General characteristics of centrifugal pumps
(1) The flow direction of water along the centrifugal pump is along the axial suction of the impeller and perpendicular to the axial outflow, that is, the inlet and outlet flow directions are 90 ° to each other.
(2) Since the centrifugal pump forms vacuum water absorption by the impeller inlet, it is necessary to inject water into the pump and the suction pipe before starting, or use a vacuum pump to extract air to form a vacuum. Moreover, the pump shell and the suction pipe must be strictly sealed, without air leakage, otherwise it will not form a vacuum, and it will not be able to absorb water.
(3) Since it is impossible to form an absolute vacuum at the impeller inlet, the suction height of the centrifugal pump cannot exceed 10 meters. In addition to the loss along the water flow through the suction pipeline, the actual allowable installation height (the height between the pump axis and the suction surface) is far less than 10 meters.If the installation is too high, it will not absorb water;In addition, since the atmospheric pressure in mountain area is lower than that in plain area, the installation height of the same pump should be lowered when it is installed in mountain area, especially in high mountain area, otherwise it can not absorb water.
The working principle of axial flow pump is different from that of centrifugal pump. It mainly uses the thrust generated by the high-speed rotation of impeller to lift water.The lift force generated by the rotating blades of the axial flow pump on the water can push the water from below to above.
The blades of the axial flow pump are generally immersed in the pool where the water is sucked.As the impeller rotates at a high speed, under the lifting force generated by the blade, the water is continuously pushed upward to make the water flow out along the outlet pipe.The impeller rotates continuously, and the water is continuously pressed to the high place.
2. General characteristics of axial flow pump
(1) The flow direction of water in the axial flow pump is along the axial suction and axial outflow of the impeller, so it is called the axial flow pump.
(2) Low lift (1~13m), large flow, high efficiency, suitable for irrigation and drainage in plains, lakes and rivers.
(3) There is no need to fill water before starting, and the operation is simple.
becauseMixed flow pumpThe shape of the impeller is between the impeller of the centrifugal pump and the impeller of the axial flow pump, so the working principle of the mixed flow pump has both centrifugal force and lift force. With the combined effect of the two, the water flows out of the impeller at a certain angle with the shaft, and the water is lifted to a higher place through the volute chamber and pipeline.
2. General characteristics of mixed flow pump
(1) Compared with centrifugal pump, mixed flow pump has lower head and larger flow, and compared with axial flow pump, it has higher head and lower flow.It is suitable for irrigation and drainage in plain and lake areas.
(2) Water is sucked in and out along the flow direction of the mixed flow pump at a certain angle with the impeller shaft, so it is also calledDiagonal flow pump。
Common agricultural pumps
centrifugal pump
Centrifugal pump models, varieties, specifications and their variants are the most in agricultural pumps.Centrifugal pumps include single-stage single suction centrifugal pump, single-stage double suction centrifugal pumpMultistage centrifugal pump, self-priming centrifugal pump, motor pump, diesel pump, etc.
The old pump models include BA and B single-stage single suction centrifugal pumps. In the 1980s, according to the international standards and the actual situation of drainage and irrigation machinery, China updated and developed the centrifugal pump products, and produced IB and IQ typesSingle-stage centrifugal pumpA series of products have been listed as national professional standards and industry standards.
The single-stage single suction centrifugal pump is called single-stage single suction centrifugal pump because the water enters the impeller from one side of the axial direction and there is only one impeller.It is characterized by higher head, smaller flow, simple structure and convenient use compared with mixed flow pump and axial flow pump.
IQ single-stage single suction centrifugal pump (also called light and small centrifugal pump) is designed to meet the national conditions and the requirements of users for simple structure, light weight, low price, good performance and convenient matching. There are 84 kinds of products in total, divided into 3 derivative series and 413 specifications and models.
(1) Performance range: the pump diameter is 50~200mm, the flow is 12.5~400m3/h, the lift is 8~125m, the supporting power includes diesel engine direct connection, belt drive, motor direct connection, the power is 1.1~110kW, and the speed is 1450~2900 rpm.
(2) The structural type of light and small centrifugal pump is an axial suction single-stage single suction suspension centrifugal pump. The pump body is opened at the back, the outlet is located at the center upward, the rear cover is a press fit type, the bearing body is directly connected with the pump body, the pump foot is located below the pump body, the bearing is lubricated with grease, and the shaft seal is divided into soft packingMechanical seal, rubber oil seal.Impellers are closed, and the transmission is divided into coupling transmission and belt transmission.Pump impeller rotation: seen from the pump inlet direction, the impeller rotation is clockwise, and when the pump is directly coupled with the diesel engine, it is counterclockwise.The pump outlet can be equipped with a manual pump, which can remove the bottom valve, reduce hydraulic loss, and enable the pump to self-priming.
It is a single-stage double suction centrifugal pump that feeds water from both sides of the impeller. Because the pump cover and pump body are assembled with horizontal joints, it is also called horizontal split centrifugal pump.Compared with single-stage single suction centrifugal pump, it has high efficiency, large flow and high head.However, it is bulky and bulky, and is generally used for fixed operations.It is suitable for irrigation areas with medium areas in hills and plateaus, as well as factories, mines, urban water supply and drainage.
Single stage double suction centrifugal pumps include S type, Sh type, SA type and SLA type. The difference between S type and Sh type is that from the drive end, S type pump isClockwiseDirection rotation, Sh typeanti-clockwiseDirection rotation.SLA type is a vertical single-stage double suction centrifugal pump.
Performance range of S-type pump: flow: 160~18000 m3/h, head: 12~125 m, inlet diameter: 150~1400 mm, speed: 2950, 1450, 970, 730, 585, 485, 360 rpm.
(1) The performance range of D-type pump is 6.3~720 m3/h flow, 16~600 m head, 50, 75, 100, 125, 150, 200 mm inlet diameter, of which the 50-125 mm pump type has a high speed of 2950 rpm and the 150-200 mm pump type has a speed of 1480 rpm.
(2) Type D multi-stage centrifugal pump is horizontal multi-stage (2~12 stages), with single suction impeller and segmented pump body.When the first stage impeller is double suction, it is represented by DS; when two speeds are specified at the same time, the low speed is represented by DA; and the multi-stage centrifugal pump used for boiler feed water is represented by DG.
Self priming pump is a single-stage single suction centrifugal pump, which produces self-priming effect by relying on the special structure of the pump itself. It is called self-priming centrifugal pump.Compared with ordinary centrifugal pumps, there are significant differences in pump body structure: first, the pump inlet position is improved, and sometimes a suction valve is installed;Second, a gas water separation chamber is set at the water outlet side.
Self priming pump outside the pump is a self-priming device attached to the pump, such as vortex pump, water ringVacuum pump, jet pump, manual pump, etc.
Compared with the ordinary centrifugal pump, the self-priming pump has a compact structure and simple operation, which not only saves the trouble of filling a large amount of water before starting, but also saves the low valve of the water inlet pipe, reduces the water inlet resistance, and increases the output of the pump. However, compared with the ordinary centrifugal pump of the same specification, the efficiency is 3%~5% lower.Self priming pumps are mostly used in light and small sprinkler irrigation units and pipeline irrigation units.
Submersible pump
Magnetic suspension submersible pumpIt realizes the worldSubmersible pumpA major breakthrough in the field has effectively solved various drawbacks of traditional submersible pumps, such as low conversion efficiency, high power consumption, limited head, vulnerable bearings, frequent maintenance, etc.It is widely used in water supply and drainage of industrial and mining enterprises, farmland irrigation, and water supply in plateau and mountain areas.
The magnetic suspension submersible pump has changed the manufacturing process of the submersible pump with its unique patented technology,conversion efficiency It has reached an astonishing new level and created huge benefits of energy conservation and consumption reduction.
The magnetic levitation submersible pump has solved the axial force problem that restricts the development of the world's submersible pump field. The head of the submersible pump has been improved dramatically, filling the market gap of ultra-high head (single unit head is designed to be more than 1000 meters) and super large flow (high load) submersible pump;The head and flow curves tend to be flat.Its conversion efficiency and the highest head of a single machine are world leaders.
The magnetic suspension submersible pump is a new generation of submersible pump, which realizes the vertical magnetic suspension (maintaining high efficiency under different working conditions) without wear and tear, prolongs the service time and maintenance cycle by several times, saves frequent regular maintenance work, can continuously operate for tens of thousands of hours, and saves maintenance and repair costs.
Submersible sewage pump
The magnetic suspension submersible pump has passed the inspection of the national laboratory and Shandong Pump Product Quality Inspection Center.Test data proof,Magnetic suspension submersible pumpOfconversion efficiency Compared with the traditional submersible pump, the user's use condition, combined with the experimental data and field comparison, further proves its characteristics of high efficiency, energy saving, world leading conversion efficiency, world leading single unit lift, high bearing capacity, super flow, inspection free, long life, etc!
During the working process of the pump, the water flowing in the pump is affected by the friction between the pump and the surface of the flow passage and the pump impeller, as well as the viscosity of the water body. The energy consumed by the pump is mainly used to resist the flow friction and vortex resistance of the water surface.The energy (head loss) consumed by water in the flow process is used to overcome the internal friction and the friction between water and equipment interface.If the surface of pump and impeller is smooth (this surface is called hydraulic smooth surface), the surface resistance is small.The energy consumption is small. Polymer composite materials are sprayed on the pump flow surface and impeller to form a hydraulically smooth surface. The surface finish of the ultra smooth surface coating is 20 times that of the polished stainless steel. This extremely smooth surface reduces the stratification of the fluid in the pump, thus reducing the turbulence in the pump, reducing the volume loss and hydraulic loss in the pump, and reducing the power consumption.The purpose of reducing the flow resistance loss is achieved, so as to improve the hydraulic efficiency of the pump. At the same time, the mechanical efficiency and volumetric efficiency can be improved to a certain extent.The compactness of the molecular structure of the coating can isolate air, water and other media andPump impellerBase metal contact to minimizeelectrochemical corrosion And corrosion.In addition, the polymer composite material isPolymerIt has chemical corrosion resistance, which can improve the corrosion resistance of the pump and greatly enhance the pump's resistance to erosion and corrosion.
purpose
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practical application
It is widely used in shipbuilding, oil exploitation, truck, etc.In 2008, the ship output reached 15000 tons, and the deadweight tons accounted for 21% of the world market. By 2015, it will become the world's largest shipbuilding country.In order to ensure the normal navigation or mooring of the ship and meet the living needs of the crew and passengers, each ship should be equipped with a certain number of marine pumps that can play a corresponding role,Marine pumpIt is one of the important auxiliary machines.According to incomplete statistics, among various marine auxiliary machinery and equipment, the total number of marine pumps of various types and purposes accounts for 20% - 30% of the total amount of marine machinery and equipment, and the price of marine pumps also accounts for a large proportion of the cost of marine equipment.In the total cost, marine pumps account for about 4% - 8% of the cost of marine equipment. Generally, the purchase of marine pumps for a medium-sized ship or above can reach more than 10 million yuan.When it comes to the key pump market, we must say that our country has completed“West East Gas Transmission"Project", "West East Gas Transmission Project" also needs pump products. At the same time, the country will also build other natural gas transmission pipelines, in these projects also need a large number of pump products.
noSame purpose
Water pumps have different purposes, different conveying liquid media, different flow ratesliftTherefore, its structural form and materials are different. To sum up, it can be roughly divided into:
1. Urban water supply 2. Sewage system 3CivilBuilding system 4. Agricultural water conservancy system 5. Power station system
6. Chemical system 7, petroleum industry system 8, mine metallurgy system 9, light industry system 10, ship system
classification
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Classification by use
Delivery pump、Circulating pump, fire pumpPressure test pump、Sewage pump, metering pump, sanitary pump, dosing pump, gelatinization pump, infusion pump, defoaming pump, process pumpOil pump, water supply pump, drainage pump, drainage pump, dredge pump, sprinkler pumpBooster pumpHigh pressure pump, heat preservation pump, high temperature pump, low temperature pump, condensate pump, heat supply network pump, cooling pump, HVAC pump, deep well pump, pain relief pump, chemotherapy pump, air pump, blood pump, extraction pump, sulfur removal pump, shear pump, grinding pump, fuel pump, fish suction pump, bathtub pump, source heat pump, filter pump, oxygen pump, shampoo pump, injection pump, inflation pump, gas pump, art pump, odorization pumpChopping pump
1. If the geographical environment permits, the pump should be as close to the water source as possible to reduceSuction pipeLength of.The foundation where the water pump is installed shall be firm, and a special foundation shall be built for the fixed pump station.
twoWater inlet pipeThe road shall be sealed reliably and must be provided with special support. It shall not be hung on the water pump.The inlet pipe with bottom valve shall be installed vertically with the axis of the bottom valve and the horizontal plane as far as possible, and the included angle between the axis and the horizontal plane shall not be less than 45 °.When the water source is a channel, the bottom valve should be more than 0.50 meters above the water bottom, and the screen should be added to prevent sundries from entering the pump.
3. The machine and pump bases shall be horizontal and firmly connected with the foundation.When the machine and pump are driven by the belt, the tight edge of the belt is at the bottom, so that the transmission efficiency is high, and the rotation direction of the pump impeller should be consistent with the direction indicated by the arrow;When coupling transmission is used, the machine and pump must be on the same axis.
4. The installation position of the water pump shall meet the requirements of the allowable vacuum suction height, and the foundation must be horizontal and stable to ensure that the rotation direction of the power machine is consistent with the rotation direction of the water pump.
5. If there are multiple units in the same machine room, there should be a distance of more than 800mm between the units and between the units and the wall.
6. The water pump suction pipe must be well sealed, and elbows and gate valves should be minimized. Air should be exhausted when filling water, and no air should accumulate in the pipe during operation. The suction pipe is required to be slightly inclined upward to connect with the water inlet of the pump, and the water inlet should have a certain submergence depth.
matters needing attention
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1. If the water pump has any small fault, remember not to let it work.If the packing of the water pump shaft is worn, it should be added in time. If the water pump continues to be used, it will leak.The direct impact of this is that the motor energy consumption will increase, which will damage the impeller.
2. If a strong vibration occurs during the use of the water pump, you must stop and check the reason, otherwise the water pump will be damaged.
3. When the bottom valve of the water pump leaks, some people will fill the inlet pipe of the water pump with dry soil and flush it with water to the bottom valve, which is really undesirable.Because when the dry soil is put into the water inlet pipe, it will enter the pump when the pump starts to work, which will damage the pump impeller and bearing, thus shortening the service life of the pump.When the bottom valve leaks, it must be repaired. If it is serious, it needs to be replaced.
4. After the pump is used, attention must be paid to maintenance. For example, when the pump is used up, the water in the pump should be drained. It is better to remove the water pipe and flush it with clean water.
5. The tape on the water pump should also be removed, washed with water and dried in the light. Do not put the tape in a dark and humid place.The adhesive tape of the water pump must not be stained with oil, let alone coated with something sticky.
6. Carefully check whether there are cracks on the impeller and whether the impeller is loose on the bearing. If there are cracks and looseness, repair them in time. If there is mud on the pump impeller, clean it up.
Main problems
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Unable to start
First, check the power supply: whether the connector is firmly connected;Whether the switch contact is tight;Whether the fuse is broken;Whether the three-phase power supply is equal.In case of open circuit, poor contactFuseIn case of fusing and phase loss, find out the causes and repair them in time.Secondly, check whether it is the mechanical fault of the pump itself. The common reasons are: the packing is too tight or the impeller and the pump body are blocked by sundries;The pump shaft, bearing and leakage reducing ring are rusted;The pump shaft is severely bent.Troubleshooting: loosen the packing and dredge the drainage channel;Disassemble the pump body to remove sundries and rust;Remove the pump shaft for calibration or replace it with a new one.
Water pump heating
Cause: bearing damage;Rolling bearingOr the clearance of bracket cover is too small;The pump shaft is bent or the two shafts are not concentric;The tape is too tight;Lack of oil or poor oil quality;The balance hole on the impeller is blocked, and the impeller loses balance, increasing the thrust to one side.Troubleshooting: Replace the bearing;Remove the rear cover and install shims between the bracket and the bearing seat;Investigate the pump shaft or adjust the concentricity of two shafts;Properly loosen the belt tightness;Fill with clean grease, which accounts for about 60% of the clearance in the bearing;Remove the blockage in the balance hole.
Water pump
Unable to absorb water
The reason is that there is air in the pump body orWater inlet pipeThere is gas accumulation, or the bottom valve is not closed tightly enough to fill and divert waterVacuum pumpThe packing has serious air leakage,Gate valveOr the shutter is not closed tightly.Troubleshooting: First increase the water pressure, then fill the pump with water, and then start the machine.Check at the same timeCheck valveWhether it is tight, and whether there is air leakage in the pipeline and joints. If there is air leakage, apply lubricating oil or mixed paint on the joints after disassembly, and tighten the screws.Check the water pump shaftoil sealIf the ring is severely worn, replace it with a new one.The pipeline leaks water or air.The nut may not be tightened tightly during installation.If the leakage is not serious, cement or water mixed with asphalt oil can be applied at the place with air or water leakageslurry。For temporary repairs, apply some wet mud or soft soap.If there is water leakage at the joint, the nut can be tightened with a wrench. If there is serious water leakage, it must be reassembled and replaced with a cracked pipe;Reduce the lift and press the nozzle of the water pump into the water for 0.5m.
convulsion
The main reasons are as follows: the electric rotor is unbalanced;coupling Poor combination;The bearing is worn and bent;Loose and broken parts of rotating parts;The pipeline support is not secure.Adjustment, repair, reinforcement, straightening, replacement and other measures can be taken respectively.
Motor overheat
There are four reasons.One is the power supply: the voltage is too high or too lowloadIf the voltage variation range should be beyond+10% to - 5% of the rated value, the motor will overheat;Power SupplyThree phase electricityThe voltage is asymmetric, and the imbalance between the three phases of the power supply voltage exceeds 5%, which will lead to overheating of the winding;Experience shows that more than 85% of agricultural motors burned out due to open phase operation, so open phase protection devices should be installed for motors.Second, the reason for the pump: the power is not matched,The pony pulls the cartThe motor is overloaded for a long time, which makes the motor temperature too high;The motors that are started too frequently and rated for short time or intermittent working system work continuously.The starting times shall be limited, the thermal protection shall be selected correctly and used according to the rated value on the motor.The third reason is the motor body: the connection method is wrong, and the △ shape is wrongly connected to the Y shape, which makes the temperature of the motor rise rapidly;stator winding In case of interphase short circuit, turn to turn short circuit or local grounding, the motor will overheat locally in light cases, and the insulation will burn out in serious cases;The squirrel cage rotor bar is broken or defective, and the iron core temperature rises rapidly when the motor runs for 1 to 2 hours;If the ventilation system fails, check whether the fan is damaged, whether the rotation direction is correct, and whether the ventilation duct is blocked;Bearing wear and rotor eccentric bore cleaning make the stator and rotor iron cores rub together and make metal impact sound, the iron core temperature rises rapidly, and in serious cases, the motor smokes, or even the coil is burned.The fourth reason is the working environment: the motor winding is damped or dust, oil stain, etc. are attached to the winding, resulting in the reduction of insulation.The insulation resistance of the motor shall be measured and cleaned and dried;The ambient temperature is too high.When the ambient temperature exceeds 35 ℃, the high inlet air temperature will make the temperature of the motor too high, so try to improve its working environment.Such as putting up a shed to shade the sun.Note: In case of failure due to electrical reasons, electricians with professional qualification certificates should be invited to repair. People with only a little knowledge should not repair blindly to prevent personal injury accidents.
First, look at the difference between the current of the pump running at this time and the current of the pump running normally.If it is smaller than normal operation (based on 2 3 of normal current), there will be problems such as impeller wear and blockage of check valve at the top of pump head.If the current is the same as usual, it is caused by the leakage of pipe cushion, pipe and pump body.If the current is higher than that during normal operation, it can be determined that it is the wear of vulnerable parts.In addition, if the cable is damaged, the amount of water is the same as usual, but the current will increase.The current of 3-phase 380V motor is generally 2.2A.The above reasons can be found out by the maintenance personnel who often maintain the deep well pump.
The cavitation of water pump is caused by the vaporization of water. The so-called vaporization is the process of water changing from liquid to vapor.The vaporization of water has a certain relationship with temperature and pressure. Under a certain pressure, when the temperature rises to a certain value, water begins to vaporize;If the pressure drops to a certain value at a certain temperature, the water will also vaporize. This pressure is called theVaporization pressure。If the pressure in a local area is equal to or lower than the vaporization pressure corresponding to the water temperature during the flow process, the water will vaporize there.After vaporization, many small bubbles mixed with steam and gas will be formed.When the steam bubble flows from the low-pressure area to the high-pressure area along with the water flow, the steam bubble will break under the action of the high-pressure, and the high-pressure water will flow to the space occupied by these original bubbles at a very high speed, forming an impact force.Metal surfaceWater hammerUnder the action of pressure, fatigue is formed and severely damaged.Therefore, the partial process of the formation, development and rupture of bubbles, which results in the destruction of materials, is calledCavitation phenomenon。
Reasons for efficiency decline
1. Due to the scouring of the water flow, the inner wall of the pump channel and the water surface of the impeller become rough and uneven, the friction coefficient of the pump inner channel increases, and in addition, the flow rate of water in the pump is large, and the head loss increases.The hydraulic efficiency is reduced.
2. Due to the dosing of drugs or water quality in front of the pump, there is serious scaling or corrosion in the pump casing.Serious fouling in the pump casing can increase the pump casing wall thickness by about 2 ram, and scale tumors are formed on the inner wall of the pump to make the pump bodyvolumeShrinkage, reduced pumping capacity, and rough flow channel, increased head loss.Both passenger product efficiency and hydraulic efficiency are reduced.
Diaphragm pump
3. Cavities or cracks occur in the pump flow passage due to casting defects, cavitation, abrasion, corrosion, chemical erosion and other reasons caused by the pump processing technology. Vortex occurs when water flows, resulting in energy loss.The hydraulic efficiency is reduced.
4. Cavitation of impeller surface.Due to the negative pressure generated during the operation of the blade back surface, when the pressure Pk<Pva, cavitation and honeycomb surface will be generated, which will cause cavitation of the pump blade under the action of electrochemical corrosion.
5. Volume loss and mechanical loss.As the pump has been used for a long time, the leakage and resistance caused by mechanical wear increase, which reduces the volumetric efficiency and mechanical efficiency.
The above reasons make the performance of the water pump worse.The operating efficiency is reduced by 2~5%, and the pump efficiency can be reduced by more than 10% in serious cases.
Vibration cause analysis
The unit andPump roomThere are many reasons for building vibration, some of which are related and interact with each other, which can be summarized as follows:.
Electrical
Submersible pump
The motor is the main equipment of the unit. The imbalance of magnetic force inside the motor and the imbalance of other electrical systems often cause vibration and noise.asasynchronous motorDuring operation, the radial alternating magnetic tension between the stator and rotor caused by the interaction of harmonic magnetic flux between the stator and rotor teeth, or largeSynchronous motorDuring operation, the inconsistent magnetic centers of the stator and rotor or the air gap difference in each direction exceeding the allowable deviation value may cause periodic vibration and noise of the motor.
Mechanical
The motor and water pump rotating parts have unbalanced mass, rough manufacturing, poor installation quality, asymmetric unit axis, swing exceeding the allowable value, poor mechanical strength and stiffness of parts, wear and damage of bearings and sealing parts, and the critical speed of water pump has always caused resonance with the natural frequency of the unit, which will produce strong vibration and noise.
Hydraulic aspects
Water pump control valve
Pump inlet flow rate andpressure distribution Uneven, pump inlet and outlet working liquidpressure fluctuation . Liquid bypass, bias flow and flow separation, non rated working conditions and pump cavitation caused by various reasons are common causes of pump unit vibration.Water pump startAnd shutdown, valve opening and closing, condition change, emergency shutdown and other dynamic transition processesWater transmission pipelineRapid changes in internal pressure andwater hammerThe vibration of the pump room and the unit is often caused by the action.
Hydraulic and other aspects
crewinflow runner Unreasonable design or mismatch with the unit, improper submergence depth of the pump, and unreasonable startup and shutdown sequence of the unit will worsen the water inflow conditions, generate vortices, induce cavitation or increase the vibration of the unit and pump room.Use destructive siphonvacuumIf the air entrainment in the hump section is difficult when the unit with flow cut is started, the siphoning time is too long;The design of the unit flap valve with the flap valve cutoff is unreasonable, which is open and closed from time to time, constantly hitting the flap valve seat;The uneven settlement of the foundation supporting the water pump and motor or the poor rigidity of the foundation will also lead to the vibration of the unit.
When selecting a water pump, the user should go to a sales point recognized by the agricultural machinery department, and be sure to recognize the manufacturer.It is recommended to give priority to the purchase of water filled submersible pump, and see the brand and product quality certificate clearly.Never buy "three no" (i.e. no manufacturer, no production date, no production license) products, or if there is a problem, users will be helpless.
As a user, due to the limitation of professional knowledge, it is difficult to make a decision. The best way is to consult an expert in water pump, and also to consult some old water pump users, especially those who are close to their own use conditions. It is a wise choice to buy products that are trustworthy, reliable and more mature.At the same time, single-phase pump or three-phase pump shall be selected according to the local power supply.
Noise causes
Water pump
The noise of water pump may be caused by the following aspects:
(1) Impact of rotary vane on cylinder block, residual volume of water pump andPressure oilVocalization;
(2) Impact of exhaust valve plate on valve seat and supporting parts;
(3) Echo and bubble cracking sound in the box;
(4) Bearing noise;
(5) Noise caused by a large amount of gas and oil impacting the oil baffle;
(6) Others.Such as the noise caused by the drive, the fan noise of the air-cooled water pump, etc.
(7) Motor noise is a crucial factor.
Water leakage fault
1 The cooling water added to the cooling water radiator by the operator is sea water, which causes damage to the internal water channel and external interface of the diesel engine.Therefore, the diesel engine must be operated in strict accordance with the provisions of the diesel engine.
2 The antifreeze and corrosiveness of the water supply radiator added by the operator is strong, which causes damage to the water channel components of the diesel engine.
3. The seal ring is worn or aged, resulting in the sealing surface can not be sealed, resulting in water leakage.
Troubleshooting
1 Remove the damaged parts in the diesel engine, and replace the damaged diesel engine parts after flushing the water radiator and the internal water channel with fresh water.
2 After assembly, adjustment and commissioning, the diesel engine is found to be normal, and the fault is eliminated.
Water contamination
The methods of mixing water with fuel include intake pipe spraying water and emulsified diesel oil.
1. Intake pipe spray
The main function of intake pipe spray is to absorb heat and dilute fuel density.When a small amount of water enters the combustion chamber and atomizes well, the oil drops will be broken into smaller oil drops due to the "micro explosion" of water vapor, thus promoting the formation and combustion of the mixture.During the combustion process, the maximum combustion temperature can be reduced due to the heat absorption of water. For example, the fuel density can be reduced by mixing water and oil, which further reduces the maximum combustion temperature. Therefore, NOx emissions can be reduced.It should be noted that the water storage tank needs to be antifreeze in winter, and the water spraying amount should be automatically adjusted according to the load.
2. Emulsified diesel
The diesel oil is mixed with water, that is, emulsified diesel oil. Due to its "detonation" effect, its fuel atomization is good. The well promotes the formation of strong turbulence in the air in the combustion chamber, the distribution of fuel oil and air is more uniform, and the generated soot is reduced.The water gas reaction of water vapor also reduces soot emissions.In addition, emulsified diesel oil can reduce the maximum combustion temperature, so NOx generation is reduced.
Maintenance plan
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During the long-term operation of water pump, the bearing frame of water pump often appearsBearing chamberWearBearing positionWear, crack and fracture of pump body, cavitation of water pumperosive wear Etc.After the above problems occur, the traditional solution for enterprises isRepair weldingorBrush platingPost machining repair, but both of them have certain disadvantages: the thermal stress caused by the high temperature of repair welding cannot be completely eliminated, which is easy to cause material damage, resulting in bending or fracture of parts;However, brush plating is subject to the coating thickness, which is easy to peel off, and the above two methods are both metal repair, which cannot change the "hard to hard" coordination relationship, and will still cause re wear under the combined effect of various forces.Contemporary western countries use more for the above problemsPolymer compositesIt has super adhesive force, excellent compressive strength and other comprehensive properties.It can be repaired with polymer materials without disassembly or machining.It is not affected by the thermal stress of repair welding, and the repair thickness is not limited. At the same time, the metal materials of the product do not have the flexibility, which can absorb the shock and vibration of the equipment, avoid the possibility of re wear, and greatly extend the service life of equipment components, save a lot of downtime for enterprises, and create huge economic value.
Static balance of impeller
Structure of centrifugal pump
When the pump rotor works at high speed, if its mass is uneven, a largecentrifugal force, causing vibration or damage to the water pump.The rotor is balanced by its various components (includingBracket axis, impeller, shaft sleeveBalancing discAnd so on), so the static balance calibration shall be carried out for the newly installed impeller.The specific methods are:
(1) Install the impeller on theFalse axisAnd put it on the static balance test bench that has been leveled.There are two tracks on the test bench, on which the dummy shaft can roll freely.
(2) Mark the side where the impeller is biased.If the impeller mass is unbalanced, the heavier side always automatically turns to the lower side.Add a weight block at the symmetrical position of the heavy place (i.e. the lighter side) (stick it with a surface or use a clamp to add a reducing iron plate) until the impeller can stop at any position.
(3) Weigh the weight of the weighting block.Instead of adding weight on the lighter side of the impeller, the balance of the impeller is achieved by reducing weight on the heavier side.Available for weight reductionMilling machineMilling or grinding with grinding wheel (when the removal amount is not large), but note that the depth of milling or grinding shall not exceed 1/3 of the thickness of the impeller cover plate.For the impeller after static balance, the allowable deviation value of static balance shall not exceed the product of the outer diameter value of the impeller and 0.025g/mm.For example, for an impeller with a diameter of 200mm, the allowable deviation is 5g.
Disassembly and assembly of coupling
Water pump coupling
(1) When disassembling the coupling, it is not allowed to knock directly with a hammer, but should be padded withCopper rodAnd the coupling shall be openedhubThe outer edge of the coupling can not be hit because it is easy to be damaged here.The most ideal method is to disassemble the coupling with a clutch.For mediumSmall water pumpFor example, the coupling is easy to remove because of its small interference fit.For larger water pumps, there is a large interference between the coupling and the shaft, so the coupling must be heated during disassembly.(2) When assembling the coupling, pay attention to the serial number of the key (for the coupling with more than two keys).When striking with a copper rod, the striking position must be noted.For example, when striking the end face at the shaft hole, it is easy to cause the shaft hole to shrink, so that the shaft cannot pass through;If the outer edge of the coupling is knocked, the straightness of the end face will be easily damaged, and the measurement accuracy will be affected when the feeler gauge is used for alignment in the future.For couplings with large interference, they shall be heated before installation.
(3) Coupling pinNut, gaskets and rubber pads must ensure their respective specifications and sizes are consistent, so as not to affect the dynamic balance of the coupling.Coupling boltCorresponding marks shall be made on the corresponding coupling pin holes to prevent wrong installation.
(4) The coupling and shaft are generally fitted with transition fit, which may cause a small amount of interference or clearance. For the coupling with a long hub, a loose transition fit can be used. Because of its long shaft hole and rough surface processing, some interference will naturally occur after assembly.If the fitting between the coupling and the shaft is too loose, which affects the concentricity of the hole and shaft, repair welding shall be carried out.It is an expedient measure to make pits on the shaft or pad copper skin, which cannot be used as an ideal method.
technical requirement
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The so-called head refers to the required head, not the lifting height, which is particularly important for the selection of pumps.Pump headIt is about 1.15~1.20 times of the lifting height.For example, if the vertical height of a water source to the water consumption point is 20 meters, the required lift is about 23~24 meters.
The water pump shall be selectedNameplateThe upper head should be close to the required head, and the deviation should not exceed 20%. In this case, the pump has the highest efficiency, is more energy-saving, and is more economical to use.If the lift on the nameplate is far less than the required lift, the pump often cannot meet the needs of users. Even if it can pump water, the amount of water is poor.On the contrary, when a high lift pump is used for a low lift, the flow will be too large, leading to motor overload. If the motor runs for a long time, the temperature will rise, and the winding insulation will gradually age, or even burn the motor.
Introduce the requirements of horizontal water pump for service conditions
Features of horizontal water pump
The water pump produced by the plant is suitable for pumping sewage and sludge under various harsh environments.The water pump is a downdraft type, which can drain the surface water on the working surface. The motor is a water filled three-phase submersible motor.Able to work in long-term diving or work out of the water.Small floor area, convenient installation and use, reliable and durable, and long service life.Here is a brief introduction to the service conditions of horizontal water pump.
Service conditions of horizontal water pump
The horizontal water pump is a water lifting machine that is directly connected with the motor and water pump to work in the water.It is mainly applicable to water supply and drainage projects of farmland irrigation, cities, industrial and mining enterprises.
Power requirements for horizontal water pump:
1. The rated frequency is 50 Hz, and the rated voltage at the motor terminal shall be 380 plus or minus 5%Three phase AC power supply(If the user's voltage is 660V, special order is required)
2. The load power of transformer shall not exceed 75% of its capacity.
3. When the transformer is far from the well, the voltage drop of the transmission line should be considered. For motors with power greater than 45KW, the distance from the transformer to the wellhead is required to be no more than 20 meters. When the distance is greater than 20 meters, the specification of the transmission line is required to be two grades larger than the specification of the distribution cable, and the voltage drop of the line should be considered.
Water quality requirements for horizontal water pump:
1. General non corrosive clean water
2. Sand content in water is not more than 0.01% (mass ratio)
3. The pH value is within the range of 6.5-8.5.
4. Chloride ion content in water is not more than 400mg/l
5. Hydrogen sulfide content is not more than 1.5 ml g/l
6. The water temperature is not higher than 20 ℃.
Summary of service environment and conditions of horizontal water pump:
1. Three phase AC power supply with power frequency of 50 hz and rated voltage of 380v or 660v (charging tolerance of plus or minus 5%).
2. The solid volume ratio of the conveying medium is less than 2%, and the density of the conveying medium is 1.2 x 10.
3. The temperature of conveying medium shall not exceed 40 ℃.
4. The PH value of the conveying medium is 4-10.
5. SleevelessSewage submersible pumpFor the unit, from the motor cooling state, the electric pump motor is allowed to operate out of the water for no more than 0.5 hour for a short time.
6. The submergence depth shall not exceed 20m based on the impeller center.
Purchasing method
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The flow of the pump, that is, the water output, should not be too large, or it will increase the cost of purchasing the pump.It shall be selected as required, such as those used by the user's familySelf priming water pumpThe flow should be as small as possible;For example, the user can choose the submersible pump with larger flow for irrigation.
Water pump
1. Water pumps should be purchased according to local conditions.frequently-usedAgricultural water pumpThere are three types, namely centrifugal pump, axial flow pump and mixed flow pump.The centrifugal pump has a high lift, but a small water yield, which is suitable for mountain areas and well irrigation areas;Axial flow pump has a large water output, but the lift is not too high, which is suitable for use in plain areas;The output and head of mixed flow pump is between centrifugal pump and axial flow pump, which is suitable for plain and hilly areas.Users should purchase according to the ground conditions, water sources and water lifting height.
2. The water pump shall be properly selected for exceeding the standard.After the type of water pump is determined, its economic performance shall be considered, especially the selection of head, flow and supporting power of water pump.It must be noted that the head (total head) indicated on the water pump label is different from the outlet head (actual head) when in use, because the water flows throughWater delivery pipeThere will be some resistance loss near the pipeline.Therefore, the actual head is generally 10% - 20% lower than the total head, and the water output is also correspondingly reduced.Therefore, in actual use, it can only be estimated according to 80%~90% of the head and flow indicated on the nameplate. The matching power of the water pump can be selected according to the power indicated on the nameplate. In order to make the water pump start quickly and use safely, the power of the power machine can also be slightly higher than the power required by the water pump, generally about 10% higher;If there is power, when selecting a water pump, you can select a matching water pump according to the power of the power machine.
3. Strictly follow the procedures to purchase water pumps.The "three certificates", namely, agricultural machinery promotion license, production license and product inspection certificate, shall be examined when purchasing. Only when the three certificates are complete can the purchase of obsolete products and inferior products be avoided.
Number selection
1. Generally, only one pump is used for normal operation, because one large pump is equivalent to two small pumps working in parallel, (meaning that the head and flow are the same), and the efficiency of the large pump is higher than that of the small pump, so from the perspective of energy conservation, it is better to choose one large pump instead of two small pumps, but in the following cases, the parallel cooperation of two pumps can be considered: the flow is large, and one pump can not reach this flow.
2. For large pumps that need 50% standby rate, two smaller pumps can be used, two for standby (four in total)
3. For some large pumps, pumps with 70% flow requirements can be selected for parallel operation without standby pumps. When one pump is overhauled, the other pump still undertakes 70% of the transportation in production.
4. For pumps that need to operate continuously for 24 hours, three pumps shall be standby, one for operation, one for standby and one for maintenance.
Distinguish true from false
First, the product packaging of the original water pump or the supporting manufacturer is generally relatively standard, with clear and regular handwriting, and detailed product name, specification, model, registered trademark, factory name, address and telephone number;The counterfeit parts are generally poorly packaged, and the factory address and name are not clearly printed.
Second, the qualified water pump has smooth surface and good workmanship.The more important the spare parts are, the higher the processing precision will be, and the more strict the anti rust and anti-corrosion packaging will be.When purchasing, if parts are found to have rust spots or rubber parts are cracked, lose elasticity, or journal surface has obvious processing lines, they should not be original accessories.
Third, the appearance of inferior water pumps is sometimes good.However, due to the poor manufacturing process, it is easy to be damaged. When purchasing, as long as you observe the edges, corners and other concealed parts of the accessories, you can see the quality of the accessories' process.
Fourth, some water pumps are renovated from old parts. At this time, as long as the paint on the surface of the parts is removed, the old paint can be found. Such water pumps should not be used.
Fifth, the purchased parts should be installed in the car according to whether they can be well matched with other parts.Generally, the original parts can be well allocated to the vehicle, while low-quality parts are difficult to match with each other due to poor workmanship and large processing errors.
Sixth, in order to ensure that the assembly relationship of the water pump meets the technical requirements, some regular parts are engraved with assembly marks to ensure the correct installation of accessories. If there is no mark or the mark is illegible, it is not qualified accessories.
Seventh, the normal water pump assembly and components must be complete to ensure smooth loading and normal operation.Some small parts on the assembly parts are missing, which is easy to cause difficulties in the initial installation. Such parts may be fake parts.
VIII. Some important accessories, especially assemblies, are usually delivered with instructions and certificates to guide users in installation, use and maintenance. Fake assemblies generally do not have detailed installation instructions to guide these.
Development trend
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The requirements for developing agricultural water pumps are to improve efficiency, reduce energy consumption and make full use of themNatural energy。Replacing several small pumps with one large pump can improve unit efficiency, save materials, reduce energy consumption and project cost, and facilitate automatic management.Therefore, various largeAxial flow pumpandMixed flow pumpThe development is fast, the maximum impeller diameter reaches 4.6 meters and 6.2 meters respectively, and the supporting power reaches 12500 kilowatts. The mixed flow pump has the tendency to replace some high lift axial flow pumps and low lift centrifugal pumps.Submersible electric pumps are mainly developed for deep well water lifting, with the maximum diameter of 1m, and some of them use 6000VHigh voltage motorThe maximum power is 2500 kW.Hydraulic pump、Wind pull rod pump、Screw pump, driven by various human and animal forcesDiaphragm pump、Piston pumpAnd pumps specially used for matching sprinkler irrigation equipment have also received different degrees of attention in China and other countries.
Energy conservation and emission reduction have become the primary content of China's economic development planning outline. In particular, more stringent emission reduction policies have been put forward for high energy consumption in industries such as power, steel, nonferrous metals, petrochemical, water treatment, etc.As the fluid transportation equipment in the industrial center, the water pump occupies the primary part of energy consumption, and has become the primary problem to be solved in energy-saving operations.
The most common driving mode of water pump is to use motor to drive.The energy saving method of the pump is to make the pump unit (pump, prime mover and some transformation) run at the highest power, so that its power consumption of external input can be reduced to the lowest point.The energy saving of pump is a comprehensive skill, which touches on the energy saving of pump itself, system energy saving, application management and operation, etc.
The meaning of pump energy saving is serious: pump is a big power consumer. According to the calculation of General Machinery Industry Association, the power consumption of pump accounts for about 20% of the national power generation. The promotion of pump power has serious implications for energy conservation and emission reduction.
The State Council《Property Management Regulations》Article 4 "The State encourages the adoption of new technologies and methods, and relies on scientific and technological progress to improve property management and service levels".Power saving has always been one of the key tasks of property equipment management.With the continuous promotion of China's urbanization construction, there are more and more high-level communities and properties. The high-efficient energy-saving pumps that ensure energy efficiency in shopping malls have become hot products.
In order to respond to the national demand for building a resource conserving society, photovoltaic water pump has become a new research trend. The photovoltaic water pump system uses the persistent energy of the sun to work at sunrise and rest at sunset, without the need for personnel to look after, without the need for public power grids, and operates independently and reliably.The system can be matched with modern energy-saving irrigation facilities such as drip irrigation, sprinkler irrigation, infiltration irrigation, micro moisture irrigation, etc., to solve the problems of drinking water, farmland irrigation, water and soil conservation and desert control in remote arid areas.The photovoltaic water pump system effectively saves water and electricity, greatly reduces the input of traditional energy, achieves zero CO2 emissions, and truly conforms to the national social development strategy of "resource saving" and "environment-friendly".Solar water pumpAlso known as photovoltaic water pump, it is the most attractive water supply mode in the sun rich areas in the world today, especially in remote areas where there is no electricity. Using the solar energy that is available everywhere and inexhaustible, the system automatically works out of the sun and stops at sunset. No personnel are required to take care of it, and the maintenance workload can be minimized. It is an ideal economicGreen energy system integrating reliability and environmental protection benefits.PV water pump system isCEC Solar Energy Research InstituteAnother new energy application system after photovoltaic (wind) power station, photovoltaic building integration and photovoltaic lighting system.
Parameter selection
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Water supply booster station is an effective measure to alleviate the pressure shortage of urban water supply. Its core is to lift the pump station, and the core of the pump station is the pump.The selection of pump not only affects whether the water supply booster station can work normally, but also directly affects the operation cost of the pump station.
Centrifugal pumps are commonly used in domestic water supply booster stations. Centrifugal pumps have the advantages of simple structure, no pulsation in infusion, simple flow regulation, etc.According to the actual situation of the project, first select the category of centrifugal pump, and consider as follows.
(1) Select the characteristic pump according to the medium characteristics.Such as clean water pumpCorrosion resistant pump, orChemical process pumpAnd impurity pump, etc.When the medium is highly toxic, valuable or radioactive and other substances that are not allowed to leak, consider selecting leak free pumps (such as canned pumps, magnetic pumps, etc.) or those with leakage collection and leakage alarm devicesDouble face mechanical seal。If the medium is volatile liquid such as liquefied hydrocarbon, low NPSH shall be selected, such as barrel pump.
(2) Horizontal pump and vertical pump (including submerged pump pipeline pump) shall be selected according to site installation conditions.
(3) Single suction pump, double suction pump or small flow centrifugal pump shall be selected according to the flow.
(4) Single stage pump, multi-stage pump or high-speed centrifugal pump shall be selected according to the lift.
After the above items are determined, the appropriate pump series can be selected according to the characteristics of different series of pumps and the conditions of the manufacturer.After the pump type, series and materials are selected, the pump model is determined according to the samples and relevant parameters provided by the pump manufacturer.[1]
