Abstract: In the pump of choice, to take into account the characteristics of different pumps. The classification of the pump according to the principle of the pump acting on the liquid is divided into two major categories of vane and volumetric, vane pump is the centrifugal force generated by the blades in the rotation of the pump will be inhaled or discharged liquid. Positive displacement pump is the pump piston or rotor in the reciprocating or rotational movement of the squeezing effect of liquid into or out. Vane pump blade structure is divided into different pump centrifugal pump, axial pump, vortex pump. Positive displacement pump is divided into piston (plunger) pump, rotor pump.
4.1.1 centrifugal pump
Conveying temperature of the liquid viscosity is not greater than 650mm2 / S, or pump efficiency decreased. (When the viscosity is more than 650mm2 / S, centrifugal pump performance decline greatly, generally do not choose centrifugal pump, but because of the centrifugal pump infusion without pulsation, no safety valve and flow adjustment is simple, so we often see in the chemical production of centrifugal Pumps are used to deliver liquids with viscosities up to 1000 mm2 / s).
Large flow, and relatively low head teach
Liquid dissolved or entrained gas is not more than 5% (volume)
Liquid containing solid particles, should choose a special centrifugal pump (such as mud pump)
Requires large changes in flow, lift change is small, should choose a flat flow - Centrifugal lift head curve, requiring small flow changes, large head changes, should choose the steep drop of flow - Centrifugal pump head curve.
4.1.2 positive displacement pump
Conveying temperature liquid viscosity greater than 650mm2 / S, the flow is smaller and the lift is relatively high, should use reciprocating pump.
Gases dissolved or entrained in the liquid allow slightly more than 5% (by volume)
Liquid requires accurate measurement, the choice of plunger metering pumps, liquid strict requirements do not leak, you can use diaphragm metering pump
Lubrication performance of the poor liquid should not be used gear pump and three screw pump, optional reciprocating pump.
Small flow, the temperature is low, the pressure requirements of stability, should use a rotor pump or twin screw pump.
4.2 According to the device required flow and lift, according to the pump classification and the scope of the initial determination of the pump selection, due to simple centrifugal pump structure, infusion without pulsation, flow adjustment is simple, so in addition to centrifugal pump difficult to do the occasion, as far as possible selection Centrifugal pump. After the selection of the pump is confirmed, it is possible to select the pump series and materials according to the process plant parameters and the medium characteristics. Then according to the pump factory to provide samples and technical information to determine the specific pump model (specifications).
4.3 for the delivery of special media
Pump delivery of gas-containing liquid, the pump flow, lift, the efficiency has declined. The greater the gas content, the more rapid decline in efficiency. With the gas content increases, the pump appears additional noise, vibration, severe corrosion or increase when there is no flow, broken axis phenomenon. In order to ensure the reliable operation of the pump, measures can be taken to reduce the gas content of the liquid:
Type Applicable viscosity range mm2 / s
Vane pump centrifugal pump <150
Vortex pump <37.5
Positive displacement pump reciprocating pump <850
Metering pump <800
Rotary piston pump 200 ~ 10000
Single screw pump 10 ~ 560000
Double screw pump 0.6 ~ 100000
Three screw pump 21 ~ 600
Gear pump <2200
4.3.1 Suction liquid pool structure type and pump suction pipe should be arranged so that each parallel pump can suck liquid, pump suction volume in the suction liquid pool should have a certain depth of submergence, from the bottom of a certain degree of dangling height.
4.3.2 suction liquid inlet pipe, return pipe, waste collection pipe to stay away from the suction pump nozzle to prevent the bubble has not disappeared when the pump was inhaled. At the same time suction tube can not be placed in the central pool, not too close to the pool wall, generally more than 1.5D from the pool wall, in order to avoid vortex or taking the time.
Ensure that the pipe joints sealed well to avoid air leakage.
Suction piping arrangement should avoid the formation of air bags.
4.3.3 When conveying liquids containing solid particles, the solid particles suspended in the liquid do not absorb, store or transfer energy as liquids do, nor transfer the kinetic energy to the liquid. The presence of solid particles make the pump head, the efficiency is lower than the transport of water.
4.3.4 transport easily vaporized liquid, the main consideration of the characteristics of easily vaporized liquid on the pump:
4.3.4.1 pump inlet pressure is high
4.3.4.2 vaporization pressure drastic changes with temperature.
4.3.4.3 Strict requirements on the shaft seal of the pump and the effect of suction pressure on the vaporization of the material.
4.3.5 For conveying liquids that are not to be leaked, use a hermetically sealed pump (magnetically driven pump and shielded pump) or a mechanical seal pump with leak collection, alarm and other devices. Magnetic drive pump and shield pump comparison:
Project magnetic drive pump shield pump
Isolation sleeve (or shield) Thickness 3 times the thickness of shield pump shield
Isolation sleeve (or shield sleeve) the consequences of the destruction of the media leak to the atmosphere there is a second leak-proof sleeve (motor housing) to prevent leakage of medium to the atmosphere, but easy to damage the motor stator
Lower efficiency slightly higher
Remote operation is not available at the moment
Lower manufacturing technology and equipment requirements are higher
Drive standard motor or turbine-specific motor
Slight noise (motor with fan) Smaller (motor without fan)
The axial length is shorter
Couplings have couplings that need to be aligned without couplings
Bearing wear monitor is in trial phase
The prices are similar to the basic similar
Normal maintenance and repair easy
The scope of power KW / temperature ℃ / pressure MPA good good
Atmospheric pressure at room temperature, easy to clean the vaporization of the media generally not applicable to a dedicated model
Medium containing solid particles generally not suitable for slightly higher solids containing the occasion, in particular, does not apply to iron-containing particles have a special medium containing solid particles (external cleaning solution)
High melting point easy to crystallize the media generally not suitable for a special model
Strong corrosive media Good Not applicable (due to shielding sleeve restrictions)
4.3.6 For conveying corrosive media should choose corrosion-resistant pump, which is characterized by the over-current part of the use of corrosion-resistant materials, the rest of the corrosion-resistant parts, such as brackets should be protected from corrosion. Seal ring (mouth ring) gap larger than the pump to avoid working under the small flow, so as to avoid the liquid temperature increased corrosion. Parking should promptly close the suction valve, or parking sealed to avoid medium leakage from the pump. Common metal pump, the flow of parts of the material are: ordinary cast iron, high silicon cast iron, stainless steel , high alloy steel, titanium and its alloys, according to the characteristics of the medium and the temperature range of different materials used. High alloy steel, titanium and its alloys are expensive, except as a last resort. Metal pump temperature, pressure and work stability is generally better than non-metallic pump. Pump flow parts nonmetallic materials: polyvinyl chloride, glass steel, polypropylene, F46, fluorine alloy, PVDF, ultrahigh molecular weight polyethylene, graphite, ceramics , sugar glass and the like. Should also be based on the characteristics of the media and temperature range of material selection. Generally non-metallic temperature, pressure is generally worse than the metal. It is commonly used in small flow and temperature, the use of low pressure and occasions.
4.3.7 vacuum pump selection:
A vacuum pump is a type of pump that is used to obtain a vacuum below atmospheric pressure. Usually it is classified according to the size of the vacuum or how much the suction rate is used to determine the type of pump. Usually can be divided into rotary slice, volumetric (piston, screw), water ring.
There are several indicators to illustrate the performance of the vacuum pump:
A, the degree of vacuum: expressed in terms of absolute pressure P, Kpa, Tor, mmHg (1 atm = 101.325Kpa = 1Torr = 760mmHg = 1.01325bar)
B, pumping rate: refers to the unit of time, vacuum suction inlet gas volume (refers to the normal temperature and pressure of the volume flow). Unit cubic meters: cubic meter / hour, liters / second. Vacuum pump suction rate and suction pressure, the higher the suction pressure, the greater the suction rate.
C, the ultimate vacuum: refers to the pump vacuum time to reach the minimum stable pressure value, also known as the maximum vacuum degree.
D, a variety of pump selection:
Mechanical pump piston pump only applies to low vacuum, water vapor less occasions such as W-type reciprocating vacuum pump
Vane pump exhaust large occasions, the need to add auxiliary pump rotary vane vacuum pump, pumping rate is low
Molecular pump for high precision work occasions
Water ring pump for low vacuum, such as excluding water vapor occasions
Jet pump Water jet pump with 0.2 ~ 0.3MPA water as the power, suitable for the exclusion of water vapor and condensable gas is the use of fluid flow static pressure and dynamic pressure can be converted to the principle of fluid suction.
Steam jet pump can adapt to a variety of gases, according to different requirements can choose different series
Oil diffusion pump for high vacuum
Molecular centrifugal pumps are suitable for high vacuum
4.1.1 centrifugal pump
Conveying temperature of the liquid viscosity is not greater than 650mm2 / S, or pump efficiency decreased. (When the viscosity is more than 650mm2 / S, centrifugal pump performance decline greatly, generally do not choose centrifugal pump, but because of the centrifugal pump infusion without pulsation, no safety valve and flow adjustment is simple, so we often see in the chemical production of centrifugal Pumps are used to deliver liquids with viscosities up to 1000 mm2 / s).
Large flow, and relatively low head teach
Liquid dissolved or entrained gas is not more than 5% (volume)
Liquid containing solid particles, should choose a special centrifugal pump (such as mud pump)
Requires large changes in flow, lift change is small, should choose a flat flow - Centrifugal lift head curve, requiring small flow changes, large head changes, should choose the steep drop of flow - Centrifugal pump head curve.
4.1.2 positive displacement pump
Conveying temperature liquid viscosity greater than 650mm2 / S, the flow is smaller and the lift is relatively high, should use reciprocating pump.
Gases dissolved or entrained in the liquid allow slightly more than 5% (by volume)
Liquid requires accurate measurement, the choice of plunger metering pumps, liquid strict requirements do not leak, you can use diaphragm metering pump
Lubrication performance of the poor liquid should not be used gear pump and three screw pump, optional reciprocating pump.
Small flow, the temperature is low, the pressure requirements of stability, should use a rotor pump or twin screw pump.
4.2 According to the device required flow and lift, according to the pump classification and the scope of the initial determination of the pump selection, due to simple centrifugal pump structure, infusion without pulsation, flow adjustment is simple, so in addition to centrifugal pump difficult to do the occasion, as far as possible selection Centrifugal pump. After the selection of the pump is confirmed, it is possible to select the pump series and materials according to the process plant parameters and the medium characteristics. Then according to the pump factory to provide samples and technical information to determine the specific pump model (specifications).
4.3 for the delivery of special media
Pump delivery of gas-containing liquid, the pump flow, lift, the efficiency has declined. The greater the gas content, the more rapid decline in efficiency. With the gas content increases, the pump appears additional noise, vibration, severe corrosion or increase when there is no flow, broken axis phenomenon. In order to ensure the reliable operation of the pump, measures can be taken to reduce the gas content of the liquid:
Type Applicable viscosity range mm2 / s
Vane pump centrifugal pump <150
Vortex pump <37.5
Positive displacement pump reciprocating pump <850
Metering pump <800
Rotary piston pump 200 ~ 10000
Single screw pump 10 ~ 560000
Double screw pump 0.6 ~ 100000
Three screw pump 21 ~ 600
Gear pump <2200
4.3.1 Suction liquid pool structure type and pump suction pipe should be arranged so that each parallel pump can suck liquid, pump suction volume in the suction liquid pool should have a certain depth of submergence, from the bottom of a certain degree of dangling height.
4.3.2 suction liquid inlet pipe, return pipe, waste collection pipe to stay away from the suction pump nozzle to prevent the bubble has not disappeared when the pump was inhaled. At the same time suction tube can not be placed in the central pool, not too close to the pool wall, generally more than 1.5D from the pool wall, in order to avoid vortex or taking the time.
Ensure that the pipe joints sealed well to avoid air leakage.
Suction piping arrangement should avoid the formation of air bags.
4.3.3 When conveying liquids containing solid particles, the solid particles suspended in the liquid do not absorb, store or transfer energy as liquids do, nor transfer the kinetic energy to the liquid. The presence of solid particles make the pump head, the efficiency is lower than the transport of water.
4.3.4 transport easily vaporized liquid, the main consideration of the characteristics of easily vaporized liquid on the pump:
4.3.4.1 pump inlet pressure is high
4.3.4.2 vaporization pressure drastic changes with temperature.
4.3.4.3 Strict requirements on the shaft seal of the pump and the effect of suction pressure on the vaporization of the material.
4.3.5 For conveying liquids that are not to be leaked, use a hermetically sealed pump (magnetically driven pump and shielded pump) or a mechanical seal pump with leak collection, alarm and other devices. Magnetic drive pump and shield pump comparison:
Project magnetic drive pump shield pump
Isolation sleeve (or shield) Thickness 3 times the thickness of shield pump shield
Isolation sleeve (or shield sleeve) the consequences of the destruction of the media leak to the atmosphere there is a second leak-proof sleeve (motor housing) to prevent leakage of medium to the atmosphere, but easy to damage the motor stator
Lower efficiency slightly higher
Remote operation is not available at the moment
Lower manufacturing technology and equipment requirements are higher
Drive standard motor or turbine-specific motor
Slight noise (motor with fan) Smaller (motor without fan)
The axial length is shorter
Couplings have couplings that need to be aligned without couplings
Bearing wear monitor is in trial phase
The prices are similar to the basic similar
Normal maintenance and repair easy
The scope of power KW / temperature ℃ / pressure MPA good good
Atmospheric pressure at room temperature, easy to clean the vaporization of the media generally not applicable to a dedicated model
Medium containing solid particles generally not suitable for slightly higher solids containing the occasion, in particular, does not apply to iron-containing particles have a special medium containing solid particles (external cleaning solution)
High melting point easy to crystallize the media generally not suitable for a special model
Strong corrosive media Good Not applicable (due to shielding sleeve restrictions)
4.3.6 For conveying corrosive media should choose corrosion-resistant pump, which is characterized by the over-current part of the use of corrosion-resistant materials, the rest of the corrosion-resistant parts, such as brackets should be protected from corrosion. Seal ring (mouth ring) gap larger than the pump to avoid working under the small flow, so as to avoid the liquid temperature increased corrosion. Parking should promptly close the suction valve, or parking sealed to avoid medium leakage from the pump. Common metal pump, the flow of parts of the material are: ordinary cast iron, high silicon cast iron, stainless steel , high alloy steel, titanium and its alloys, according to the characteristics of the medium and the temperature range of different materials used. High alloy steel, titanium and its alloys are expensive, except as a last resort. Metal pump temperature, pressure and work stability is generally better than non-metallic pump. Pump flow parts nonmetallic materials: polyvinyl chloride, glass steel, polypropylene, F46, fluorine alloy, PVDF, ultrahigh molecular weight polyethylene, graphite, ceramics , sugar glass and the like. Should also be based on the characteristics of the media and temperature range of material selection. Generally non-metallic temperature, pressure is generally worse than the metal. It is commonly used in small flow and temperature, the use of low pressure and occasions.
4.3.7 vacuum pump selection:
A vacuum pump is a type of pump that is used to obtain a vacuum below atmospheric pressure. Usually it is classified according to the size of the vacuum or how much the suction rate is used to determine the type of pump. Usually can be divided into rotary slice, volumetric (piston, screw), water ring.
There are several indicators to illustrate the performance of the vacuum pump:
A, the degree of vacuum: expressed in terms of absolute pressure P, Kpa, Tor, mmHg (1 atm = 101.325Kpa = 1Torr = 760mmHg = 1.01325bar)
B, pumping rate: refers to the unit of time, vacuum suction inlet gas volume (refers to the normal temperature and pressure of the volume flow). Unit cubic meters: cubic meter / hour, liters / second. Vacuum pump suction rate and suction pressure, the higher the suction pressure, the greater the suction rate.
C, the ultimate vacuum: refers to the pump vacuum time to reach the minimum stable pressure value, also known as the maximum vacuum degree.
D, a variety of pump selection:
Mechanical pump piston pump only applies to low vacuum, water vapor less occasions such as W-type reciprocating vacuum pump
Vane pump exhaust large occasions, the need to add auxiliary pump rotary vane vacuum pump, pumping rate is low
Molecular pump for high precision work occasions
Water ring pump for low vacuum, such as excluding water vapor occasions
Jet pump Water jet pump with 0.2 ~ 0.3MPA water as the power, suitable for the exclusion of water vapor and condensable gas is the use of fluid flow static pressure and dynamic pressure can be converted to the principle of fluid suction.
Steam jet pump can adapt to a variety of gases, according to different requirements can choose different series
Oil diffusion pump for high vacuum
Molecular centrifugal pumps are suitable for high vacuum
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