Learn - Oct. 11, 2023
The screw pump is also known as Progressive Cavity Pump, Mono Pump, and Rotary Positive Displacement Pump, according to the different structural form which are divided into single screw pump, double screw pump and three screw pump. Screw pumps are used to transport high-viscosity liquids, pastes, neutral or corrosive liquids, liquids mixed with air, liquids with foam, and even medium containing fiber solid components.
A single screw pump belongs to positive displacement pumps, which wetted parts are composed of stator and rotor. The rotor is a screw with large lead, large tooth height and small inner diameter of thread. The stator is an elastic bushing with double-headed spiral. The rotor and the stator cooperate with each other to form a sealed cavity without communication. When the rotor turns inside the stator, the cavity progresses spirally along the shaft of the pump without changing either shape or volume.
By selecting different materials like carbon steel, AlSl 316 stainless steel, 22Cr duplex and 25Cr duplex stainless steels to suit a wide range of applications, the goal is to provide the end user with optimized pumping solutions for viscous medium handling. Progressive cavity pumps perfectly handle with viscous mixtures in petroleum, water management, hydrocarbon sludge, and other industries.
When the rotor of screw pump rotates in the stator, the sealing cavity moves from the suction end to the discharge end, and then the high viscosity medium transported is discharged continuously in the sealing cavity. According to this working principle, the single screw pumps or progressive cavity pumps are reversible and could discharge mud or sludge in reverse.
3.2 Rotor: The rotor of a single screw pump is manufactured from high strength carbon steel, and can be customized as stainless steel, duplex stainless steel, titanium, or other materials against the corrosive or abrasive fluids. The rotor can be coated with special coatings to reduce the friction between rotor and stator.
3.3 Stator: The stator of a progressive catity pump can be made from nitrile(NBR) or fluorocarbon elastomer. Both ends are sealed and flanged, and the rubber bushing and metal bushing are connected into one integrated part.
3.4 Pressure wetted parts: That is welded construction with materials options to suit a wide range of applications for consideration of corrosion or wear resistance.
3.5 Shaft Sealing: Single or double cartridge mechanical seal could be selected according to the characteristics of the medium.
3.6 Bearing: Bearings own longer lifetime and better grease lubrication.
3.7 Gear box: Helical gear reducer, minimum service factor 1.5.
4.1 Waste water treatment
The sludge produced in all aspects of the sewage treatment plant, including concentrated sludge, floating sludge, dilute sludge and dehydrated sludge, which are transported and treated by single screw pumps. The single screw pump perfectly meets the requirements of complete closure, no leakage, no odor, continuous operation and automatic management when conveying sludge in medium and short distance.
4.2 Coal water mixtures, coal water slurry and coal water transportation
The coal water slurry refers to the mixture of pulverized coal and water, and a certain amount of additives are added. The phenomenon of soft precipitation and stratification should be avoided during the transfer of coal water mixtures. The single screw pump is the ideal choice for coal water mixtures transportation because the volume of the pump chamber remains constant and the medium is almost not stirred in the pump.
4.3 Other typical applications that require progressive cavity pumps
● Pulp, paper and board industry
● Stoichiometry; Coating and coloring process; 10~25% medium concentration pulp transport
● Oil, gas, crude oil and other petroleum industry
● Oil and gas mixed transport;
● Oil-water separation and waste oil recovery system;
● Polymer transport.
● All kinds of chemical paste;
● All kinds of milk;
● All kinds of suspension;
● All kinds of gas-containing and solid-containing liquids;
● All types of media not subject to agitation and shearing.
● Production and preparation of titanium dioxide, kaolin, calcium carbonate, etc. in mineral engineering, feed the swirling fluid and filter body; Chemical dosing; Loading and grouting
● The wetted parts of single screw pumps can be made of food-grade stainless steel material, which is used in food industry dairy products; Fruit juice, fruit puree, vegetable pulp; Ground meat and condiments.
A single screw pump, also known as progressive cavity pump, is the typical low & middle pressure pumping device for mediums of high viscocity. After going through this article, you may get a basic understandings to those pumps. However, the correct model selection of pumps is the first step guarantee of trouble-free operation in the future, should you have any further doubts in the selection and maintenance of the screw pumps, as a single screw pump manufacturer with decades' experience, we will be always happy for offering comprehensive pumping solutions to clients all over the globe.
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