What is Slurry Pump & How Does it Works? (2022 Guideline)

What is a Slurry Pump? (Reference: Fluid-technology.com)

What is a Slurry Pump?

Slurry pumps are specialized pumps that can handle slurry. Slurry pumps, unlike water pumps, are sensitive to wear and are more durable and heavy-duty. Slurry pumps are utilized in situations where the fluid stream contains particles. When handling extremely abrasive or corrosive liquids, application-based pump and material decisions should be made for trouble-free performance. Linquip presents a number of companies that specialize in slurry pumps that are designed to handle a variety of slurry loads, from light to heavy.

A slurry pump is a centrifugal pump that is designed to transport abrasive and frequently corrosive solid particles inside a carrier fluid. The slurry pump should have a low specific speed design, allowing for slower operating speeds than ordinary water pumps to minimize solid particle velocity and hence wear rates. Wear-resistant metallic or elastomeric materials are used in slurry pump components that come into contact with the pumped medium, depending on the application.

Features of Slurry Pumps

There are numerous types of pumps that are suited for pumping slurries, as mentioned below. However, there are a few important factors to make before deciding which technology to utilize. The size and type of the particles in the liquid will influence the degree of physical wear on the pump and its components, as well as whether or not the solids will travel through the pump without being harmed.

The speed and shear inside centrifugal pumps might harm the slurry/solids, which is a problem. Twin-screw pumps, in general, cause the least harm to particles in a slurry. The corrosiveness of the liquid or slurry mixture: more corrosive slurries may wear pump components more quickly, which may determine the material used to build the pump. Because slurries are heavy and difficult to pump, pumps intended for them will be more powerful than those built for less viscous liquids.

Slurry pumps are generally bigger, have more horsepower, and are manufactured with more durable bearings and shafts than conventional pumps. The centrifugal pump is the most popular form of slurry pump. To move the slurry, these pumps employ a revolving impeller, similar to how a water-like liquid would flow using a centrifugal pump.

In comparison to normal centrifugal pumps, slurry-optimized centrifugal pumps would often include the following features:

• Impellers that are larger and made of more material. This is done to compensate for abrasive slurry wear.

• On the impeller, there are fewer and thicker vanes. Solids move through the pump more easily, with 2-5 vanes compared to 5-9 vanes on a regular centrifugal pump.

These pumps can also be manufactured of specialist high wear alloys such as AL-6XN® or Hastelloy® C-22® for pumping abrasive slurries. Expanite and Armoly are two hardening techniques that are commonly used to harden stainless steel for abrasive slurries.

Positive displacement pumps may be a better alternative than centrifugal pumps for some types of slurry pumping applications. These are some of the conditions:

• A slurry flow rate that is too slow
• A person with a large head (i.e., the height to which the pump can move liquid)
• Demand for higher efficiency than centrifugal pumps can provide
• Flow control has improved.

Types of Slurry Pumps

Slurry pumps come in a variety of styles, the most popular of which are centrifugal and positive displacement pumps.

Centrifugal Slurry Pumps

Centrifugal Slurry Pumps (Reference: daepumps.com)

Pumping slurry through pipelines with concentrations below 70% solids by weight is usually done with centrifugal slurry pumps, which have a large capacity but a short head. Vertical, horizontal, or submersible centrifugal slurry pumps are available.

Positive Displacement Slurry Pumps

Pumping slurry via pipes with high solids concentrations requires slurry pumps that can produce high heads with limited capacity.

Submersible Centrifugal Slurry Pump

A Submersible Centrifugal Slurry Pump is a continuous flow pump that can handle abrasive slurries that work underwater. It features an entrance at the pump's suction that speeds up the slurry as it passes between the vanes of a revolving impeller, creating centrifugal force that propels the slurry through the casing to the discharge. The casing is a horn-shaped component that converts pressure into speed.

The design of the casing and impeller determines the pump's performance. The number and design of vanes in the impeller affect its efficiency. Clearances and the requirement to create abrasion-resistant heavy-duty components, taking into account materials, thickness, and other factors, generally impair efficiency while handling slurries.

A submersible slurry pump can be powered by electricity or hydraulics. The impeller is carried by the motor shaft in an electric pump. If it's a hydraulic pump, the motor is connected directly to the pump's main shaft.

Slurry Pump Components

• MOTOR: It may be electric or hydraulic. The electric submersible slurry pump has to be kept cold. A cooling jacket should be included if the slurry pump will be used semi-submerged or dry for long periods. A motor with Class H insulation is suggested for Heavy-Duty Electric Slurry Submersible Pumps. They might also incorporate sensors that detect excessive temperatures and/or wetness.
• IMPELLER: The impeller is the slurry pump's revolving component. The centrifugal force is transferred to the slurry. Typically composed of abrasion-resistant high-chrome spheroidal cast iron. Closed, open, semi-open, or recessed impellers are all options.
• CASING: The casing is usually semi-volute or concentric in form. It is often composed of cast iron, although depending on the purpose, it may be coated to prevent corrosion or manufactured of specific alloys for abrasive applications.
• SHAFT AND BEARING ASSEMBLY: The shaft is responsible for transferring rotary motion from the motor to the impeller. Heavy-duty roller bearings on the shaft prevent it from moving in other directions and decrease vibration.
• SHAFT SLEEVE: Its job is to keep the shaft safe. The shaft sleeve is composed of a corrosion-resistant and abrasion-resistant substance.
• SEALS PACKAGE: Slurry leakage into the motor and bearings is prevented by the seals’ package. Lip seals, mechanical seals, and hybrid seals might all be included in the sealed package.
• UPPER AND LOWER WEAR PLATES: These plates are found on both sides of the impeller. They are prone to deterioration. The pump's efficiency is maximized by calibrating its clearances.
• STRAINER: The strainer prevents big particles from being lodged inside the impeller zone, potentially damaging the pump.
• AGITATOR: This allows the pump to take up sediments while suspending solids. The way it works is that the vanes drive a continuous high-pressure flow of liquid towards the sediments in the shape of a cone, transporting the solids to the impeller's eye and creating a high solids concentration. The agitator also keeps particles from clogging the strainer's pores.

Selecting and Operating a Slurry Pump

Due to the balance of numerous elements such as pressure, flow, abrasiveness, viscosity, particle size, and particle type, selecting the proper pump for your slurry application can be a difficult assignment.

Selecting and Operating a Slurry Pump (Reference: global.weir)

An application engineer who understands how to consider all of these elements can be invaluable in understanding the numerous pump alternatives available. Follow these four simple steps to determine which type of slurry pump is ideal for your specific application:

DETERMINE THE NATURE OF THE MATERIALS BEING PUMPED

Take into account the following:

• The size, shape, and hardness of the particles (which affects the possibility of abrasion and corrosion of the pump's components)
• The slurry solution's corrosiveness
• Linquip’s Slurry Pump Experts can assist if the product's actual in-pump viscosity is unknown.
  
  

CONSIDER THE PUMP'S COMPONENTS

• Are the impeller design and material utilized to manufacture it adequate for pumping slurries if it's a centrifugal pump?
• What type of material was utilized to make the pump? Pumping very abrasive slurries requires higher alloys such as AL-6XN or Hastelloy C-22.
• Is the discharge component of the pump suitable for the slurry to be pumped?
• What is the optimum method of sealing for this application?
• Is it possible for the solid size to travel past the pump?
• How much solid damage will the consumer put up with?
  
  

It's also crucial to think about the slurry's chemical compatibility with any elastomers in the pump. You can choose a prospective candidate slurry pump for the application once you've addressed both the nature of the slurry and the components of various types of pumps.

DETERMINE WHAT SIZE THE PUMP SHOULD BE

The most significant aspect of this calculation is determining the pump horsepower required to achieve a certain fluid flow rate at the desired or required differential pressure. Consider the following:

• Solids concentration in the slurry is expressed as a percentage of total volume.
• The pipeline's whole length. The more pipeline length there is, the more slurry-induced friction the pump will have to overcome.
• The slurry pipe diameter.
• The static head is the height to which the slurry in the pipe system must be elevated.
  
  

DETERMINE THE PUMP'S OPERATING PARAMETERS

Most centrifugal slurry pumps operate at moderate speeds, often less than 1200 rpm, to prevent component wear. Find the sweet spot where the pump can operate slowly enough to avoid solids from settling out of the slurry precipitate and clogging the lines, but rapidly enough to prevent solids from settling out of the slurry precipitate and clogging the lines.

Then, to minimize wear even further, drop the pump's discharge pressure to the lowest setting available. To ensure consistent and uniform delivery of the slurry to the pump, use suitable pipe arrangement and design standards.

You may utilize the comprehensive list of Linquip's Slurry Pump Service Providers to suit all of your needs for additional information.