What are the characteristics of progressive cavity pumps? What are the advantages and disadvantages

A progressive cavity pump is a fluid transfer pump, which is mainly composed of a screw (generally there are types such as single-head screw, double-head screw and three-head screw) and a pump casing. It utilizes the meshing between the screws to create a closed cavity to transfer fluids. Screw pumps are widely used in petroleum, chemical, food, pharmaceutical and other fields.

Here are some of the main features of progressive cavity pumps:

Stable conveying capacity: The screw pump has good conveying capacity, and the output flow of the pump is proportional to the speed of the screw, which can achieve continuous and stable conveying.

Strong self-priming performance: Progressive cavity pumps have a strong self-priming capacity, so they have an advantage when pumping liquids with gases or containing foam.

Smooth operation: the screw pump runs smoothly, with low vibration and low noise. These features make it suitable for high precision and demanding applications.

Wide adaptability: Progressive cavity pumps can convey various types of fluids, including high viscosity, high solids, high gas content, corrosive and abrasive fluids, with high adaptability.

Simple structure: The progressive cavity pump has a simple and compact structure, which is easy to install and maintain.

High efficiency and energy saving: Due to the structural characteristics of the progressive cavity pump, the energy loss in the conveying process is small, and it has high energy efficiency.

Reversibility: The progressive cavity pump can reverse the direction of the conveying flow by changing the screw steering, which makes it advantageous in some special application scenarios.

It is important to note that although progressive cavity pumps have many advantages, they still need to be evaluated according to the actual application and fluid characteristics when choosing to ensure that the right pump type is selected.

1. The screw sealing line formed by the contact between the stator and the rotor of the screw pump separates the suction chamber from the discharge chamber (pressure chamber)*, so that the pump has the isolation effect of the valve.

2. Compared with other forms of pumps, the screw pump has a higher suction capacity (up to meters).

3. The screw pump can realize the multi-phase mixed transportation of liquid, gas and solid.

4. The volume of fluid flow in the screw pump does not change, and there is no turbulence, agitation and pulsation.

5. The viscosity of the medium conveyed by the screw pump can reach 3,000,000MPas, and the solid content can reach 60%.

6. The volume formed by the elastic stator of the progressive cavity pump can effectively reduce the wear and tear of the medium containing solid particles.

7. The flow rate of the screw pump is proportional to the speed, and the flow rate can be automatically adjusted with the help of the governor.

8. Constant pressure control of screw pump, protection against dry operation.

Advantages of progressive cavity pump:

1. Wide range of pressure and flow. The pressure is about kgf cm2 and the flow rate can reach 100 cm3 minutes.

2. There is a wide range of types and viscosities of the liquid to be transported.

3. Because the inertia force of the rotating parts in the pump is low, a high speed can be used.

Disadvantages of progressive cavity pumps:

1. The processing and assembly requirements of the screw are high.

2. The performance of the pump is sensitive to the change of viscosity of the liquid.

3. The pump body vibrates violently or produces noise.

Design parameters: 1) installation inclination angle ( ) installation inclination angle refers to the angle between the screw pump shaft and the horizontal plane. It directly affects the efficiency and flow of the pump. According to relevant information, the efficiency decreases by about 3% for every degree increase in inclination. It is generally considered economical to have an inclination angle of 30° or 40°.

2) Clearance. Clearance refers to the gap between the spiral blade and the housing. The smaller the gap, the less water leakage loss and the higher the efficiency of the pump.

How it works:

The device of the screw pump comprises three parts: the prime mover, the variable speed transmission device and the screw pump, and is specifically made up of the screw blade 1, the pump shaft 2, the bearing seat 3 and the shell 4. The screw pump is installed inclimatically between the upper and lower pools, and the lower blades of the screw pump are immersed below the water surface.

When the pump shaft rotates, the spiral blades push the water in the pool into the leaf groove, and the water is lifted up along the spiral shaft step by step under the action of the rotating blades of the spiral until the outlet of the screw pump. The screw pump only changes the potential energy of the fluid, which is different from the vane pump, which converts the mechanical energy into the potential energy and kinetic energy of the liquid.

The screw pump is a propulsion positive displacement pump, the main components are the rotor and the stator, the rotor is a large lead, large tooth height and a small screw inner diameter of the screw) stator is a matching double-ended spiral and screw sleeve, so that the space between the rotor and the stator is formed to store the medium, when the rotor is running in the stator, the medium is discharged from the suction end along the axial direction.

From the above working principle, it can be seen that the progressive cavity pump has the following advantages:

1. Wide range of pressure and flow. The pressure is about.

Kilogram-force cm

2. The flow rate is reachable.

18600cm3/

Divide; 2. There is a wide range of types and viscosities of the liquid to be transported.

3. Because the inertia force of the rotating parts in the pump is low, a high speed can be used.

4. Good inhalation performance and self-priming ability;

5. The flow rate is uniform and continuous, the vibration is small, and the noise is low;

6. Compared with other rotary pumps, it is less sensitive to incoming gases and dirt;

7. The structure is solid, and the installation and maintenance are easy.

The disadvantages of the screw pump are: the processing and assembly requirements of the screw are high; The performance of the pump is sensitive to changes in the viscosity of the liquid.

Progressive cavity pumps:

The performance of the progressive cavity pump is mainly expressed by its flow, power, speed, diameter, temperature and other parameters. At the same time, through these parameters, it shows its characteristics, which not only have the advantages of the progressive cavity pump, but also its disadvantages. Next, we will analyze the advantages and disadvantages of progressive cavity pumps.

Advantages of progressive cavity pump:

1. Wide range of pressure and flow. The pressure is about kgf cm2 and the flow rate can reach 100 cm3 minutes.

2. There is a wide range of types and viscosities of the liquid to be transported.

3. Because the inertia force of the rotating parts in the pump is low, a high speed can be used.

4. Good inhalation performance and self-priming ability;

5. The flow rate is uniform and continuous, and the vibration is small;

6. Compared with other rotary pumps, it is less sensitive to incoming gases and dirt;

7. The structure is solid, and the installation and maintenance are easy.

Disadvantages of progressive cavity pumps:

1. The processing and assembly requirements of the screw are high.

2. The performance of the pump is sensitive to the change of viscosity of the liquid.

3. The pump body vibrates violently or produces noise.

Through the above analysis of the advantages and disadvantages of the screw pump, we can clearly understand that the screw pump is a kind of pump equipment with large working pressure and working flow. Although it also has shortcomings, its use has been affirmed by many people.

Abstract:As a kind of water pump, screw pump has many advantages, such as low speed, wide flow channel, small foundation excavation depth, wide pressure and flow range, good suction performance, easy initial installation and maintenance, and is widely used. However, it also has disadvantages such as large size, low head, high processing and assembly requirements, etc., which need to be paid attention to when using. The core components of the screw pump are the stator and the rotor, during the working process, the medium will wear them, so the durability is limited, the screw pump produced by a good manufacturer, pay attention to the case of controlling the speed according to the conveying medium, the screw pump is still relatively durable.

Let's take a look at the advantages and disadvantages of progressive cavity pumps. First, the advantages and disadvantages of screw pump.

Screw pump is a commonly used water pump, composed of shaft, spiral blades, shell, mostly used for irrigation, drainage, and lifting sewage, sludge and other occasions, this kind of pump has both advantages and disadvantages:

a) Advantages of progressive cavity pumps.

1. Low speed (generally 20r min 90r min), small mechanical wear, no cavitation.

2. The flow channel is wide, which can convey water containing solid matter.

3. The structure of the pump body is half-open, and the operation of the pump can be observed.

4. The suction side flow state has little impact on the hydraulic performance, there is no special requirement for the suction pool, the foundation excavation depth is small, the construction of hydraulic buildings is simple, and the civil engineering cost is small.

5. Wide range of pressure and flow.

6. A wide range of types and viscosities of liquids to be transported.

7. Good inhalation performance and self-priming ability.

8. The flow rate is uniform and continuous, and the vibration is small.

9. Compared with other pumps, it is less sensitive to incoming gases and dirt.

10. The structure is solid, and the installation and maintenance are easy.

2) Disadvantages of progressive cavity pumps.

1. The size is large and the floor area is also large.

2. Restricted by machining conditions, the pump shaft should not be too long, so the head is low, generally not more than 10m.

3. The height of the suction surface and the outlet surface should not change too much, otherwise it will affect the work efficiency and increase the energy consumption.

4. The processing and assembly requirements of the screw are high.

5. The performance of dry screw pump is sensitive to the change of viscosity of liquid.

6. The pump body vibrates violently or produces noise.

Second, is the screw pump durable?

As a kind of water pump, the advantages and disadvantages of the progressive cavity pump are obvious, and everyone may be more concerned about the durability of the progressive cavity pump, so is the progressive cavity pump durable?

Generally speaking, the core components of the progressive cavity pump are the stator and the rotor and the permeable bar, which will inevitably cause wear and tear to the stator in the process of conveying the medium, so its durability is limited. In fact, the service life of the screw pump is mainly related to the manufacturing process and actual use, and the plex lead screw pump produced by a good manufacturer is definitely more durable.

Of course, in addition to the quality of the product, the durability of the progressive cavity pump also depends on the medium it transports, the larger the viscosity and particles of the conveyed medium, the greater the wear of the stator. Conversely, if only clean water or mild sewage is delivered, the service life will be longer. In practical use, in order to reduce the wear of the medium on the stator and prolong the service life of the progressive cavity pump, it is recommended to adjust the corresponding speed according to the characteristics of different media.

The advantages of progressive cavity pumps include:

When conveying the medium, there is no eddy current, circulation and dead angle, the flow is uniform and continuous, the adaptability to the medium is strong, and the energy-saving effect is good.

It has good sealing performance and can pump out gases, liquids, solids, solid-liquid mixtures and media containing suspended solids.

High speed, strong self-priming ability, idling, axial and radial blocking force is small.

Compact structure, easy to install and maintain.

Small size and light weight.

The disadvantages of progressive cavity pumps include:

Difficult for media with viscosity of more than 100 centipoise.

The particulate material should be filtered to prevent clogging of the pipeline.

Gases, solids, mixtures of liquids, and liquids containing dissolved solids cannot be pumped.

Gases, volatile liquids, and liquids that are too light or too heavy cannot be pumped.

When the speed is reduced or the displacement of the socks is reduced, the progressive cavity pump may become clogged.

The inhalation performance is poor, and it is not suitable for pumping liquid residual body with viscosity lower than that and liquid containing impurities in the free state at room temperature.

The disadvantages of progressive cavity pumps include:

It is not suitable for conveying large particles or high viscosity materials, and it is easy to block or damage the pump body.

It is not suitable for conveying high or low temperature media, because the tightness of the progressive cavity pump is poor, and it is prone to leakage problems.

The pumping flow rate and pressure of the liquid are affected by various factors such as environmental factors, temperature changes, and medium viscosity, and the stability is not as good as that of centrifugal pumps.

The maintenance cost is high, and the inside of the progressive cavity pump needs to be cleaned and maintained frequently, which is difficult to maintain.

In the process of long-term operation, it is easy to produce noise and vibration, which will affect the equipment and working environment.

The disadvantages of progressive cavity pumps include:

1.Higher requirements for medium: progressive cavity pump is suitable for conveying medium with high viscosity and less solid particles, and for medium with lower viscosity and more solid particles, the conveying efficiency of screw pump is lower.

2.High maintenance cost: The structure of progressive cavity pump is relatively complex, and it needs to be maintained and maintained regularly, and the maintenance cost is high.

3.Not suitable for high-pressure conveying: Progressive cavity pumps have a small pressure range and are not suitable for high-pressure conveying.

4.Not suitable for high-speed conveying: The screw pump has a low rotational speed and is not suitable for high-speed conveying.

Disadvantages of progressive cavity pumps:

1. The processing and assembly requirements of the screw are high.

2. The performance of the pump is more sensitive to the change of viscosity of the liquid, such as;

3. The pump body vibrates violently or produces noise.

Progressive cavity pumps can be mainly divided into the following types:

Progressing cavity pump (also known as progressing cavity rotary lobe pump or mono pump): A progressing cavity pump consists of a rotor in the shape of a screw and a stator with internal threads. The rotor is usually made of stainless steel, and the stator is usually made of an elastic material.

The progressing cavity pump has the characteristics of simple structure, stable operation, low noise and convenient maintenance, and is suitable for conveying media with high viscosity, solid particles, and easy to precipitate or crystallize.

Twin screw pumps: Twin screw pumps consist of two screws that mesh with each other and rotate in the same direction. The twin screw pump has high conveying efficiency and low pulsation, and is suitable for conveying liquids, gases, liquids and liquid-solid mixtures with high viscosity.

There are usually two types of twin screw pumps: non-self-priming twin screw pumps and acre wheel self-priming twin screw pumps.

Triple screw pump: The triple screw pump consists of three screws that mesh with each other and rotate in the same direction. Among them, one is the main screw and the other is the slave screw.

The three-screw pump is mainly used to transport liquids with good lubrication, such as lubricating oil and fuel, and has the characteristics of high pressure bearing capacity, low noise and high efficiency.

Multi-screw pumps: Multi-screw pumps typically consist of four or more screws to meet specific application needs. The multi-screw pump can be customized as required with high conveying efficiency and low pulsation.

Mixed Flow Progressive Cavity Pump: A mixed flow progressive cavity pump is a pump that combines the characteristics of a progressive cavity pump and a centrifugal pump. It has the self-priming capacity of a progressive cavity pump and the high head of a centrifugal pump, which is suitable for conveying highly viscous media and liquids containing gases.

Each of these progressive cavity pumps has its own characteristics and is suitable for different working conditions and application scenarios. When selecting a progressive cavity pump, the appropriate type should be determined according to the specific conveying medium, working condition requirements and use scenarios.