What is a vortex pump
What is a vortex pump?
Table of Contents
Vortex pump refers to a pump in which the impeller is an integral disc with many small blades on the outer edge, and the liquid makes repeated vortex movement in the blade and pump channel. Although vortex pump belongs to the category of vane machinery, its working process, structure and the shape of characteristic curve are different from centrifugal pump and other types of pumps.
Vortex pump is a kind of vane pump. In terms of principle and structure, it is different from centrifugal and axial-flow pumps. It is called vortex pump because it sucks and discharges liquid by the action of vortex motion when the impeller rotates.
The main components of vortex pump include impeller, pump body, pump cover and their annular flow channel. Vortex pump impeller is different from centrifugal pump impeller. It is a disc with radial blades on the outer wheel. The liquid enters the flow channel through the suction pipe, obtains energy through the rotating impeller, and is transported to the discharge pipe to complete the working process of the pump.
The specific speed of vortex pump is usually between 6 and 50. It is a small flow and high head pump, which is suitable for conveying liquid or gas-liquid mixture with viscosity no more than 5 ° e, no solid particles and no impurities. Its flow range is 0.18 ~ 45 M ³/ h. The single-stage lift can reach about 250 M.
Vortex pumps are usually used in petroleum and chemical industries, especially in chemical fiber, medicine, chemical fertilizer and small boiler feed water.
Classification of vortex pumps
1) Closed vortex pump
Closed vortex pump adopts closed impeller and open channel structure. Closed impeller refers to a kind of impeller whose blade part is provided with a middle diaphragm and the blade is relatively short. The suction and discharge ports of the pump are separated at the tongue part. The flow channel directly connected with the suction and discharge ports is called open flow channel. Closed vortex pump must be equipped with open flow channel.
There are many forms of blades and flow channels of closed vortex pump. Generally, the flow of rectangular section channel is large, but the head and efficiency are low. The semi-circular section channel has higher head and efficiency, but smaller flow. Therefore, the medium and low specific speed vortex pumps mostly use semi-circular section channel, while the medium and high specific speed vortex pumps mostly use rectangular section channel. Radial straight blades are widely used in blade shape, and backward curved blades are also used in low specific speed vortex pumps.
In the closed vortex pump, the liquid flow enters the pump from the outer edge of the impeller with large circumferential velocity. Therefore, the cavitation performance is poor and the cavitation allowance must be large. Moreover, since the discharge port of the closed vortex pump is located at the outer edge of the flow channel, the gas gathered at the root of the blade is not easy to discharge. Therefore, without special measures, the closed vortex pump has no self-priming capacity and cannot pump the gas-liquid mixture. The efficiency of closed vortex pump is higher than that of open vortex pump, which can reach 35% ~ 45%.
2) Open vortex pump
Open vortex pump adopts open impeller and closed channel structure. Open impeller is a kind of impeller with long blades without intermediate diaphragm. Closed flow channel refers to the flow channel whose suction and discharge ports cannot be directly connected. The suction and discharge ports of the open vortex pump are generally opened at the pump side cover close to the root of the blade. On the one hand, the gas is easy to be discharged, which is conducive to improving the self suction and pumping capacity of the pump; on the other hand. The circumferential velocity at the inlet is relatively small, so the anti cavitation performance is better than that of closed vortex pump. However, the efficiency of open vortex pump is low. If the closed channel with the worst efficiency is adopted, the efficiency is only 20% ~ 27%. Even if the centripetal open channel with small hydraulic loss is adopted, the efficiency can only be improved to 27% ~ 35%.
3) Centrifugal vortex pump
Compared with centrifugal pump, the head of vortex pump is higher, which is easier to achieve self-priming, but the cavitation performance is poor, while the head of centrifugal pump is low, but the cavitation performance is relatively good. Centrifugal vortex pump combines the two pumps together, that is, the first stage is centrifugal impeller to reduce the necessary cavitation allowance of the pump; The second stage is the vortex impeller to improve the pump head. In this way, not only the cavitation performance is good, but also the pump head is high.
Working principle of vortex pump
Many radial blades are milled on the impeller of vortex pump. The end face of the impeller is close to the pump body, and its axial clearance is 0.10 ~ 0.15mm. The flow passage is composed of an annular cavity between the impeller, the pump body and the pump cover. The section in the flow channel where the suction port is separated from the discharge port is called the spacer tongue. The radial clearance between the spacer tongue and the impeller is very small to prevent the high-pressure liquid at the discharge outlet from leaking to the suction inlet. The blade of the open vortex pump is long, and the inner diameter of the blade is less than the inner diameter of the flow channel. The liquid enters the impeller from the suction port and then into the flow channel. The blade of the closed vortex pump impeller is short, and the inner diameter of the blade is equal to the inner diameter of the flow channel. The liquid enters the flow channel from the suction port, and then enters the impeller from the outer circumference of the impeller.
Now take the closed pump as an example to illustrate its working principle. The fluid enters the flow channel and impeller from the suction port. When the impeller rotates, because the centrifugal force of the moving liquid in the impeller is greater than that of the moving liquid in the channel, a vortex motion is generated between them, and its rotation center line is along the longitudinal direction of the channel, which is called longitudinal vortex. Under the action of longitudinal vortex, the liquid can enter and exit the impeller many times in the whole process from suction to discharge, which is similar to the flow condition of liquid in multistage centrifugal pump. Every time the liquid flows through the impeller, it obtains energy. When the liquid flows from the impeller to the runner, it is mixed with the liquid moving in the runner. Due to the different velocities of the two streams, momentum exchange occurs in the mixing process, which increases the energy of the liquid in the channel. Vortex pump mainly relies on this longitudinal vortex to transfer energy.
Characteristics of vortex pump
Compared with other types of pumps, vortex pump has the following characteristics:
- (1) Vortex pump is the simplest high lift pump. Compared with the centrifugal pump of the same size, its head is 2 ~ 4 times higher than that of the centrifugal pump; Compared with the positive displacement pump with the same head, its size is much smaller and its structure is much simpler.
- (2) The efficiency of vortex pump is very low (due to the large impact loss of liquid in the flow channel), the maximum is no more than 45%, usually 15% ~ 40%. Therefore, it is difficult to make a high-power pump. Judging from the vortex pump produced today, the power generally does not exceed 30 kW. However, the efficiency of centrifugal pump with low specific speed is lower than it. Therefore, there are many occasions for vortex pump to replace centrifugal pump with low specific speed.
- (3) Most vortex pumps have self-priming capacity, and some vortex pumps can also pump air or steam liquid mixture, which is beyond the power of general centrifugal pumps.
Specifically, the closed impeller vortex pump can be self-priming as long as a simple additional device is set. For the vortex pump with open impeller and closed channel, it has self-priming capacity and is usually used for air extraction; The vortex pump with open impeller and open channel is used to transport liquid and can not be self-priming. Usually, the two pumps are assembled together. The former is used as a vacuum pump and the latter is used as a working pump. For example, there are vortex pumps for refueling vehicles and vortex pumps with other structures.
Application of vortex pump
Vortex pumps have also been more and more widely used in many sectors of the national economy, such as:
- (1) To transport acid, alkali and other corrosive liquids in the chemical industry, the pump is required to have small flow, high head, slow chemical reaction speed and high corrosion resistance. Because the working parts of the vortex pump are simple, it is easy to realize the above requirements.
- (2) Pump liquids with low medium density (such as gasoline, alcohol, etc.). Because these liquids are easy to volatilize, they are mostly mixed transportation of vapor and liquid, such as airports, automobile oil distribution stations, and even aircraft refueling. The vortex pump can carry out the mixed transportation of steam and liquid. Generally, the working time is short under the above conditions. Therefore, the low efficiency is not the main problem.
- (3) Pump liquid containing gas and liquid containing highly elastic gas (such as propane, butane, etc.). Pump the partially evaporated liquid in the suction pipe.
- (4) It is used for small automatic pump station and agricultural water supply.
- (5) It is used for urban public construction, such as booster auxiliary pump, domestic water, etc.
- (6) Instead of liquid ring pump, it is used as truth pump and low-pressure compressor.
- (7) Used for steam out and marine washing, drinking water, fire fighting and other auxiliary equipment.
- (8) It is used for small boiler auxiliary equipment to supply water.
Source: Network Arrangement – China Pipe Fitting Manufacturer – Yaang Pipe Industry (www.epowermetals.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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