Screw Pumps

What is a screw pump? Why is it called a screw pump? What are the advantages and disadvantages of screw pumps? And how are they used? In this article, Thai Khuong will answer your questions.

The screw pump is popularly known as the chicken intestine pump, or in some places, it is called the mouse tail pump. The reason for this name is that a helical screw drives the internal structure of the pump body, and the inside of the pump body looks like a chicken intestine. There are many types of screw pumps, often referred to as single-twist, double-twist, or multi-twist.

Depending on the liquid to be pumped and the pump temperature, the screw pump will be 304 stainless steel, 316 stainless steel, plastic, or carbon,…

What is a screw pump?

Screw pumps are industrial pumps used a lot in pumping viscous liquids, high viscosity, and corrosive liquids,…

For example, Food industry, molasses pump application in the sugar manufacturing industry, sludge pump in wastewater treatment, raw material pump in the plastic industry,…

Screw pumps have a structure and operating principle utterly different from other industrial pumps. Accordingly, they simulate the twisting action of a screw and are defined as follows:

“A screw pump is a type of rotary pump equipped with screws connected and rotating in a cylindrical cavity or bushing. Liquid enters from the suction side of the pump and moves linearly along this screw to the discharge side of the pump. The clearance between the screw and the bushing is minimal, so liquid increases in pressure while moving through the pump.”

To learn more, follow the content that Thai Khuong shared below.

Classification of screw pumps

The classification of screw pumps is also relatively straightforward for us to remember. There are two ways to classify screw pumps as:

Sort by several axes:

• • Three-screw pump type
  • Two-screw pump type
  • Progressing cavity pump type
  • There are also 4-axis, 5-axis pumps on the international market, but they rarely use.

Classification by way of installation:

• • Vertical screw pump
  • Horizontal screw pump,…

Structure of screw pump

The standard line of progressive cavity pumps, it usually makes up of the following parts:

• • Pump body: Also known as pump chamber is the entire outer shell of the pump. This part is usually made of stainless steel or galvanized steel, painted in color. The pump body is usually small, has a long cylindrical shape, and is very durable
  • Pump shaft: Also known as rotor. The pump shaft of the machine is a special part and also the most important part of this pump line. The pump shaft is usually made of stainless steel or galvanized steel, but the shaft is not straight, but twisted. In the image above, you can see that the pump shaft is connected to a special screw, with this type of structure usually for pumping fluids with high solids.
  • Reducer Motor: This is a speed reducer to help the pump operate more smoothly and efficiently
  • Stator: Also known as the pump chamber, is the part that helps reduce friction in the screw pump. This is also a relatively important part in the structure of the screw pump, which is usually made of PTFE rubber, soft, with high friction resistance. And they also have a twisted shape.
  • Pump fan: A part located on the pump body, at the top of the motor, with the same material as the pump shaft material, which has the function of cooling the engine and cooling the fluid during operation.
  • Pump power source: Including pump motor, power source, control cabinet, … these parts help the pump work.
  • Other parts: In addition to the main parts above, the machine structure also has other parts such as gaskets, valves, seals, output ports, inlet ports…Each part of the device has different roles. for pump operation.

Structure of two shaft screw pump (Two-Screw pump)

Twin-screw pumps, also known as twin-screw pumps, are the most common type for large capacity applications such as pumping oil on pipelines. There is driven by the motor from the power supply, and the second screw will follow the first screw by a 2-axis linkage gear. The structure of the two-axis screw pump is as follows:

• • Inlet fluid suction head
  • Outlet outlet
  • Active screw
  • Passive screw
  • Pump body (pump chamber)
  • Pair of gears that engage at both ends of the screw

Structure of three-axis screw pump (Three-Screw pump)

3-screw pumps are typically used for small applications, such as lubrication systems. One of the screws is driven from the power source by the motor, then rotates the other two screws around it without using gears.

Their structure includes:

• • Fluid inlet
  • Fluid output
  • Active screw
  • Passive screw 1
  • Passive screw 2
  • Pump body

Screw Pump Accessories

Screw pump accessories include many different details. Currently, Thai Khuong has all the details – components of the screw and progressing cavity screw pump line represented and distributed by Thai Khuong in Vietnam. Can provide and support repair and replacement of machine parts nationwide. If you need maintenance, installation, or replacement of industrial pumps of all kinds, please get in touch with Thai Khuong!

Working principle of screw pump

The screw pump works on the general principle of rotating its screw. It will direct the liquid to move along the screw thread from the suction side to the discharge side of the pump. Due to the minimal clearance inside the pump, there is a high volumetric efficiency, especially with viscous liquids (because it eliminates the degree of fluid sliding from the high-pressure side to the low-pressure side). The feature of the screw pump is that it does not create pressure. It only moves the liquid. But in reality, it is the system that makes back pressure due to the loss of friction.

Principle of progressing cavity pump

• • Still based on the principle of “nut movement.”
  • When the screw rotates around the shaft, it will create inside the pump casing fluid chambers (conductive fluid); the liquid will act as a plastic nut that is pushed gradually from the suction end to the discharge end of the pump.

Principle of two-axis screw pump

The principle of the two-axis screw pump describes as that when the active screw rotates, the passive screw will follow thanks to the gears installed at the ends of these two screws. When both screws turn, they seal and push the fluid from the suction end to the pump discharge end.

Dual-flow, self-priming, twin-screw pumps are available in four spindle configurations. These pumps are fully axially and radially balanced to avoid dependence on special thrust bearings and ensure long service life. Flow is separated as it enters the pump housing and routes to each side of the dual-flow spindle package, pressuring for general discharge.

The rotors must manufacture from a single block of material. This feature increases the structural integrity and life of the rotating shafts, resulting in more excellent operational reliability. If necessary, it can make a particular modification to the spindle profile, which results in lower pump noise.

The drive shaft torque transmits to the drive shaft through oil-lubricated timing gears. Ensures pump operates without any contact between the spindles and the housing. An essential feature of this pump is its ability to pump liquids with viscosities from 0.4 cSt to more than 10,000 cSt. Furthermore, it can transport flow rates up to 5,000 m³/h with just one pump. This volumetric pump also allows dry running with liquids with low vapor pressure and when emptying tanks or pipes.

Principle of three-axis screw pump

Similar to the two-axis screw pump, the three-axis screw pump has the following operating principle: When the power supply, the active screw associated with the motor will rotate, this dynamic shaft rotates at the same time, making The outer gear turns and pulls the two passive poles along. Due to the use of three screws, the sealing ability of the three-screw pump is better.

The three-axis Leistritz screw pump is a self-priming, single-voltage, three-shaft displacement pump for the low-pressure range. They are used to transport non-abrasive lubricating fluids.

Advantages and disadvantages of screw pumps

There are many different types of pumps. Each type of pump will have its characteristics and advantages, and disadvantages to suit a particular application. And the same goes for screw pumps. Through this article, we will learn about the advantages and disadvantages of screw pumps.

Advantages of screw pump

• • The machine is durable if used according to the correct standards and selected the type of liquid to pump.
  • Compact pump design, sturdy pump body.
  • Pumps operate at various frequencies when installed with an inverter.
  • The pump works relatively quietly; the flow is even and stable.
  • High-efficiency pump with great intensity, continuous operation
  • Less foaming and eddy currents in the medium
  • It can be applied to pump various liquids that other pumps cannot do, such as high viscosity liquids, viscous liquids, etc…

Disadvantages of screw pump

• • The manufacturing and manufacturing process is quite complicated, requiring high mechanical precision.
  • Hard to repair
  • Need to compensate pressure if pumping long distance
  • High price

Application of screw pump

There are many applications for screw pumps in many different industries, including Manufacturing, Mining, and Oil & Gas. Most of these applications deal with highly viscous liquids, such as oil or asphalt, or juices mixed with vapors and impurities,… Here are some examples of where screw pumps use:

• • Lubrication and hydraulic systems: Many lubrication systems and hydraulic systems use screw pumps. These are usually three-shaft screw pumps. Lubrication and hydraulic systems use to provide lubrication to large machinery, provide hydraulic power to high-pressure hydraulic systems, or operate elevators in buildings.
  • Crude Oil Pipeline: Screw pumps are the ideal solution for moving oil through pipelines when pumping high viscosity crude oil. Capable of pumping higher viscosity than centrifugal pumps and can pump higher flows than piston (piston) pumps. In this application, concrete screw pumps often use to achieve the required flow rate. Large electric motors or diesel engines usually drive these pumps.

Pumps mixtures of liquids and vapors together and is one of the most challenging pumping applications. Severe damage can occur to the compressor when fluid enters, just as severe damage can happen to most pumps when air enters. When properly built, a screw pump can be a combination of a screw pump and compressor, handling both liquids and gases. And the common application, in this case, lies in many industries, typically oil and gas.

The article has provided you with the most comprehensive knowledge about the screw pump line. You can refer to some lines that Thai Khuong represents through the information below!

Thai Khuong is distributing the screw pump lines of EU origin: