What is the working principle of centrifugal pumps?
What is a centrifugal pump?
A centrifugal pump refers to a pump that delivers liquid by the centrifugal force generated when the impeller rotates. A centrifugal pump operates through a rotating impeller within a casing that is usually driven by an electric motor or petrol / diesel engine.
A Centrifugal Pump is an automatic system made up of two main parts. The two parts Centrifugal Pump are a pump and an electrical motor. Centrifugal pumps are simple and efficient low-cost solutions to most low-pressure, high-capacity pumping applications involving low-viscosity fluids.
Parts of centrifugal pumps
The basic structure of a centrifugal pump is composed of six parts. They are impeller, pump body, pump shaft, bearings, sealing ring, stuffing box.
1. The impeller is the core part of the centrifugal pump. It has a high speed and high power. The blades on the impeller play a major role again. The impeller must pass the static balance test before assembly. The inner and outer surfaces of the impeller are required to be smooth to reduce the frictional loss of water flow.
2. The pump body of the centrifugal pump is also called the pump casing. It is the body of the pump. It plays a role of support and fixation, and is connected with the bracket on which the bearing is installed.
3. The function of the pump shaft is to connect with the motor by the coupling. The torque of the motor is transmitted to the impeller. So it is the main component that transmits mechanical energy.
4. The sliding bearing uses transparent oil as lubricant. Too much oil will cause oil to seep along the pump shaft. Too little oil will cause the bearing to overheat and burn out and cause an accident. During the operation of the water pump, the temperature of the bearing is up to 85 degrees, and generally runs at about 60 degrees.
5. The sealing ring is also called the leak reducing ring.
6. The stuffing box is mainly composed of stuffing, water seal ring, stuffing barrel, packing gland and water seal tube. The function of the stuffing box is mainly to close the gap between the pump casing and the pump shaft. Do not let the water in the pump flow to the outside and do not let the outside air enter the pump. Always maintain a vacuum inside the pump. When the friction between the pump shaft and the packing generates heat, the water sealing pipe is injected into the water sealing ring to cool the packing. Keep the water pump running normally. Therefore, special attention should be paid to the inspection of the stuffing box during the inspection tour of the pump operation. The packing will be replaced after about 600 hours of operation.
Types of centrifugal pump
1. Classified by the number of impellers
1) Single stage centrifugal pump
Single-stage centrifugal pumps have only one impeller on the pump shaft.
2) Multistage centrifugal pump
Multistage centrifugal pumps have two or more impellers on the pump shaft. At this time, the total head of the pump is the sum of the heads produced by n impellers.
2. Classified by working pressure
1) Low pressure centrifugal pump
The pressure is less than 100 meters water column.
2) Medium pressure centrifugal pump
The pressure is between 100 and 650 meters of water column.
3) High pressure centrifugal pump
The pressure is higher than 650 meters water column.
3. Classified by impeller suction method
1) Single side water inlet pump
Single-side inlet pumps are also called single-suction pumps. There is only one water inlet on the impeller.
2) Double side water inlet pump
The double-inlet pump is called a double-suction pump, that is, there is a water inlet on both sides of the impeller. Its flow is twice as large as that of a single-suction pump. It can be approximated as two single-suction pump impellers placed back to back.
4. Classified according to the combination of the pump casing
1) Horizontal split centrifugal pump
The horizontal split pump has a joint seam on the horizontal plane passing through the axis line.
2) Centrifugal pump with vertical joint surface
The vertical joint surface pump is that the joint surface is perpendicular to the axis line.
5. Classified by pump shaft position
1) Horizontal pump
The pump shaft is in a horizontal position.
2) Vertical centrifugal pump
The pump shaft of the centrifugal pump is in a vertical position.
6. Classified by impeller output method
1) Volute centrifugal pump
After the water comes out of the impeller, it directly enters the pump casing which has the shape of a helix.
2) Guide vane centrifugal pump
After the water comes out of the impeller, it enters the guide vanes arranged outside it. Then enter the next stage or flow into the outlet pipe.
7. Classification by installation height
1) Self-priming centrifugal pump
The pump shaft is lower than the pool surface of the suction pool. No watering is required at startup. The self-priming centrifugal pump starts automatically.
2) Suction centrifugal pump (non-self-priming centrifugal pump)
The pump shaft of the centrifugal pump is higher than the pool surface of the suction pool. Before starting, the pump casing and suction pipe need to be filled with water. Then drive the motor to make the impeller rotate at high speed. The water is thrown out of the impeller by centrifugal force. Negative pressure is formed in the center of the impeller. The water in the suction pool enters the impeller under the action of atmospheric pressure. It is also affected by the high-speed rotating impeller. It is thrown out of the impeller and enters the pressurized water pipe.
8. Centrifugal pump can also be classified according to the purpose
Centrifugal pumps are classified according to their uses, including oil pumps, water pumps, condensate pumps, ash discharge pumps, circulating water pumps, etc.
Features of centrifugal pumps
1. According to the way of inhalation
In a single-suction centrifugal pump, the liquid flows into the impeller from one side, and there is an axial force.
Double-suction centrifugal pump liquid flows into the impeller from both sides, there is no axial force. The flow rate of the pump is almost double that of a single suction pump.
2. By series
Single-stage centrifugal pumps have only one impeller on the pump shaft.
A multistage centrifugal pump is equipped with two or more impellers on the same pump shaft. The liquid flows through each stage of impeller in turn, the more stages, the higher the head.
3. According to the pump shaft orientation
The horizontal centrifugal pump shaft is placed horizontally.
Vertical centrifugal pump shaft is perpendicular to the horizontal plane.
4. According to the shell type
The segmented pump casing is a plane part perpendicular to the axis, and the segments are connected with long bolts.
The split pump casing is split on a plane passing through the axis.
The volute pump is a centrifugal pump with a spiral pressure water chamber, such as the commonly used end suction cantilever centrifugal pump.
The turbine pump is a centrifugal pump equipped with a vane-type pressurized water chamber.
5. Special structure
The pipeline centrifugal pump is used as a part of the pipeline, so there is no need to change the pipeline during installation.
The submersible pump and the electric motor are made into one and submerged in water.
The pump body of the submerged centrifugal pump is immersed in the liquid.
The canned pump impeller is integrated with the motor rotor. And in the same sealed housing. No sealing structure is required. It is a leak-free pump.
The magnetic centrifugal pump is fully enclosed except for the inlet and outlet. The connection between the pump and the motor is driven by the mutual attraction of magnetic steel.
Self-priming centrifugal pump, no need to prime when the pump starts.
The high-speed pump increases the speed of the pump shaft by the speed increase box, and the general speed can reach more than 10000r/min. It can also be called a partial flow pump or a tangential booster pump.
The inlet and outlet pipes of the vertical cylindrical centrifugal pump are at the same height on the upper part. There are inner and outer shells, and the inner shell is composed of rotor, guide vane and so on. The outer casing is an inlet guide channel, and the liquid is sucked from the lower part.
Advantages of Centrifugal Pumps
1. Compact structure
2. Wide range, flow and head range
3. Suitable for mildly corrosive liquids
4. Various control options
5. Uniform flow, stable operation and low vibration. No special shock-absorbing foundation is required.
6. The installation, maintenance and repair costs of the centrifugal pump are relatively low.
Uses Of Centrifugal Pumps
The test run of the centrifugal pump should meet the following requirements:
①The steering of the driver should be the same as that of the centrifugal pump.
② Find out the steering of pipeline pump and coaxial centrifugal pump.
③The fixed connection parts should not be loose. The specification and quantity of lubricant added to each lubricating part shall comply with the provisions of the equipment technical documents.
④ Parts with pre-lubrication requirements should be pre-lubricated according to regulations.
⑤ All indicating instruments and safety protection devices should be sensitive, accurate and reliable.
⑥ Turning should be flexible, without abnormal phenomenon.
⑦ For high temperature centrifugal pumps, the pump body should be preheated before trial operation. The temperature should rise evenly. The temperature rise per hour should not exceed 50°C. The temperature difference between the surface of the pump body and the process pipeline with the working medium inlet should not be greater than 40°C.
⑧Set up connection devices to eliminate the influence of temperature rise. Set up a bypass connection to provide cooling water.
Pay attention to the following points when operating the centrifugal pump:
① It is forbidden to run without water, do not adjust the suction port to reduce the displacement, and it is forbidden to run at a too low flow rate.
② Monitor the running process, completely prevent the stuffing box from leaking, and use new stuffing when replacing the stuffing box.
③Ensure that the mechanical seal has sufficient flushing water flow, and excessive water flow is prohibited for water-cooled bearings.
④ Do not use too much lubricant.
⑤ Check according to the recommended cycle. Establish operating records, including operating hours. Adjustment and replacement of packing. Add lubricant and other maintenance measures and times. The suction and discharge pressure, flow rate, input power, temperature of washing liquid and bearing, and vibration of the centrifugal pump should be regularly measured and recorded.
⑥ The main engine of the centrifugal pump relies on atmospheric pressure to pump water from a low place to a high place. Atmospheric pressure can only support a water column of about 10.3m at most. Therefore, the main engine of the centrifugal pump cannot work 12 meters away from the water surface.
Applications of Centrifugal Pumps
Centrifugal pumps can be widely used in electric power, metallurgy, coal, building materials and other industries to transport slurry containing solid particles. Centrifugal pumps can be used for hydraulic ash removal in thermal power plants, slurry transportation in metallurgical beneficiation plants, coal slurry and heavy medium transportation in coal washing plants, etc. When the centrifugal pump is working, the pump needs to be placed on land. The suction pipe is placed in the water, and the priming pump is also required to start. The mud pump and the submerged centrifugal pump are limited by the structure, and the motor needs to be placed above the water surface during operation. The pump goes into the water, so it must be secured. Otherwise, the motor will be scrapped if it falls into the water. The length of the major axis of the centrifugal pump is generally fixed. Therefore, the installation and use of the pump are more troublesome, and the application occasions are subject to many restrictions.
What is the working principle of centrifugal pumps?
Centrifugal pumps work by rotating the impeller to cause the water to move centrifugally. Before starting the centrifugal pump, the pump casing and suction pipe must be filled with water. Then start the motor to make the centrifugal pump shaft drive the impeller and water to rotate at high speed. The water undergoes centrifugal motion and is thrown towards the outer edge of the impeller. The flow channel of the volute pump casing flows into the pressure water pipeline of the water pump.
The basic principle of operation of centrifugal pumps is – force vortex flow. This means, when a body of liquid is acted upon by an external torque, it increases the pressure head of the rotating liquid. This increase in pressure is directly proportional to the velocity of the liquid.
Price of Centrifugal Pumps
The Centrifugal Pumps Price will change randomly with factors such as production cost, transportation cost, international situation, exchange rate, market supply and demand of raw materials. Sino Mechanical, as one of a Centrifugal Pump manufacturers aims to provide you with high quality and best price Centrifugal Pumps. If you are looking for Centrifugal Pumps, please kindly contact us to get the latest Centrifugal Pumps price.
Supplier of Centrifugal Pumps
Sino Mechanical, as one of global Centrifugal Pumps Companies, has more than 20 years extensive experiences in the performance, application and cost-effective manufacturing of Centrifugal Pumps. We are global Centrifugal Pumps supplier and Centrifugal Pumps company. We have Centrifugal Pumps for sale. If you are looking for Centrifugal Pumps, don't hesitate to contact us anytime. We will get back to you within 24 hours.
