Screw Slurry Pump: How they work and What you need to know

What is a Screw Slurry Pump?

Screw slurry pump transfer liquids, solids, or liquid-solid mixtures from one location to another. It’s a simple yet effective method for moving liquids, sludge, grains, and other materials via a chute or tube without clogging. screw slurry pump operate constantly, reducing the likelihood of the unit requiring maintenance or wearing out, making them a cost-effective piece of equipment. While these pumps can handle almost anything, one use where they excel is pumping muck.

How do screw pumps work?

One clear operation of hydraulic cylinders or crew slurry pumps was for agriculture and drainage. The screw pump is set in water in a low-lying area, while the top collection area is situated in a higher position. As that screw twisted, water accumulated in the spiral tube and traveled upwards to the collection chamber at the top. Water was carried from a lower region, such as a river, up a bank or slope to the garden beds or fields above.

What Factors You Should Weigh When Choosing a Screw Pump

A screw slurry pump is capable of moving more than just water. They can transport oil and other sticky substances, such as sludge. Sludge is a mixture of fluids and particles forming a thicker substance than mud. Most sludge brought to water treatment plants is pumped out of the household and commercial septic tanks and transported via truck. Still, it can also come from various other sources. Screw pumps can transport grains from a truck to a storage container in an agricultural scenario. Food and beverage plants, such as breweries, wineries, and dairy processors can also produce sludge.

This is critical while shopping for a screw slurry pump. You will require equipment that is appropriate for your intended purpose. Keep the following factors in mind when shopping for a sludge screw slurry pump.

What are the advantages of an open screw pump?

They can manage fluctuating capacity without the need for extra controls. They are effective and non-clogging. There is no need to pre-screen the filth you receive. They require little maintenance and do not require a wet well to operate.

Enclosed screw pumps have higher efficiency with Type C. If the pump needs to be replaced, the new pump may simply be slid into position, making replacement far more economical. Concrete and grout are required for an open system. Enclosed screw pumps do not necessitate costly grouting or concrete work.

Efficient

Screw pumps are renowned for being efficient due to their acceptable clearances within the pump. Because a gearbox is not always required, mechanical efficiency is among the highest when compared to other pumps that require such accessories, such as a gear or vane.

They may work at high speeds due to the design of internal parts and screws with low inertia during fluid transmission.

Self-Priming 2 Idler Screws, 1 Driving Screw

Due to their design, they are self-priming up to 7.5M. Providing screws are oiled before startup, units can be run dry for a limited time.

Proportional Flow and Non-Pulsating Flow

Fluid delivery is non-pulsating due to its rotating motion. Furthermore, its design makes flow proportionate to speed, allowing for a predictable flow rate.

Reversible

Because of their design, units can be run in reverse, except for the relief valve, which can only operate in one direction.

Design of a Triple Screw Pump with an Integrated Relief Valve

Units are often equipped with a relief valve that protects the pump from damage if the output pipework becomes clogged, restricting the pump’s ability to create high pressure.

Running in the Dry

Providing screws are oiled, units can dry running, making them excellent for tank stripping as they can also handle tiny volumes of entrained gas and air.

Low noise and vibration

Pumps have low vibration and noise levels due to their efficient mechanical movement.

NPSH

Screw pumps’ NPSH requirements can be as low as 1.5M, with designs available for immersion in fluids with high viscosity or low NPSH.

Handling a variety of viscosities

Pumps can manage a wide range of viscosities up to 35,000cst due to the ability to modify pump speed via a gearbox, with changes in fluid viscosity usually having little influence on pumped flow rate.

What are the Disadvantages of Screw Pumps?
Solid Handling

Models are not ideal for abrasive solid handling, which might reduce screw life due to tight clearances and abrasive effects. Coatings can decrease wear, but hard solids more significant than 1mm cannot be satisfactorily accommodated. These devices can easily handle soft products such as polymerized rubber, mince, molasses, yogurt, and jams.

Part Replacement

Internal parts can be expensive to replace, with idler and driving screws needing to be replaced as one to ensure parts intermesh without issue and efficiency is maintained.

Screw Pump Design

There are typically three design types:

Singular Screw

This is another term for a progressive cavity pump, with a single screw rotated by a motor within a stator. This is covered in our cavity pump progress guide.

Twin screw / quadruple screw with external Timing Gear

A pair of twin screws revolve within a pump case, with the side of the screw by the side. Both screws at the inlet suck fluid in before pushing it towards the outlet in the center or top of the casing.

The motor drives one screw, while external timing gears at the opposite end of the device rotate the other. Screws can be mounted in pairs, therefore, a pump can have up to four screws. All screws mesh together, ensuring fluid flows from the intake to the output.

Triple screw

A driving screw and two idler screws are used in Triple Screw designs. The motor shaft turns the driving screw, which turns the twin intermeshing idler screws.

Pumps can be powered by a motor attached to a gearbox or directly coupled to the head, allowing speeds up to 3600rpm.

The faster the rotational speed of components, the lower the viscosity of the pumped fluids. Higher viscosity fluids, such as Heavy Fuel Oil, molasses, bitumen, or other slow-moving viscous liquids, must be handled at slower speeds to allow the fluid enough time to enter the pump’s input and avoid cavitation. Reduced rotational speed also aids in the NPSH required by pumps.

Application of Screw Slurry Pump

Units can be assembled in a variety of materials ranging from Cast Iron to ductile, Stainless Steel, Bronze, and Duplex Steels, allowing them to be utilized with a wide range of liquids in industries such as:

  • Industrial: Transfer of fuel, lubricant transfer, chemical unloading and transfer
  • Lube oil systems, fuel transfer, sludge transfer, bilge pumping, oily water separator feed, cargo loading and unloading, inert gas generator burner feed
  • Bitumen transfer, lubricant transfer, benzene, phenol, and toulene production, and mud transfer are all examples of oil and gas activities.
  • Resin transfer, polymer transfer, and chemical transfer are all examples of chemical transfers.
  • Dairy, meat, creams, fudge, liquid sugar mixes, syrups, juice concentrates, wine, oils, honey greases, mousse, and mayonnaise are all handled in the food industry.
  • Transfer of pharmaceutical, cosmetic, personal care, and biopharma products
Features of Screw Slurry Pump
Flow Rate

How quickly do you need muck moved? What’s the consistency of the sludge? Flow rates vary, and you must ensure that the screw pump you select can move the sludge as quickly as you require. At the same time, check the PSI and horsepower to ensure that the system will perform efficiently for you. We have open screw pumps that can move as little as 90 gallons per minute up to 55,000 gallons. If an enclosed screw pump is required, the Type S can handle 90 to 10,000 gallons per minute, and the Type C can hold 540 to 35,000 gallons per minute.

Size

Not every screw pump will function in a confined location. When space is restricted, the screw pump’s inclination must work with the available square footage. Consider a screw pump. If you have enough room for the screw pump’s installation, you will have additional possibilities.

Durability

You want a system that is built to last. You want to get your money’s worth, including choosing a system that won’t require much care and upkeep. Screw pumps are designed to prevent friction, which damages the screw pump’s parts. The screw pumps require very little maintenance to keep them running like new ones.

Open vs. Closed Screw Pumps

It can be either open or closed. This is crucial to understand because it can influence your final decision.

Open screw pumps are housed in a steel or concrete trough. The top of the track is open, exposing the spiral screw to the elements. Whether immersed or not, the bearings are protected by a sealed sleeve or have a lubrication system that helps prevent wear. For the screw pump to perform well, the trough must be at an angle of 22 to 40 degrees. Given the incline, a significant amount of room is required when installing this screw pump.

If you have any questions about the screw slurry pump, please contact us as soon as possible.

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