Submersible Slurry Pumps

Submersible Slurry Pumps: Characteristics, Use and Advantages

Submersible slurry pumps are designed to operate while fully submerged in the slurry, making them ideal for handling highly abrasive and/or corrosive fluids. Their construction materials and design are tailored to withstand such harsh conditions better than any other pumps.

Characteristics of Submersible Slurry Pumps

Submersible slurry pumps are preferred in situations dealing with highly abrasive or corrosive fluids, operating in confined spaces, reducing noise and vibration, or managing deep installations are key considerations. Their design allows for efficient and reliable performance in harsh and challenging environments, making them the ideal choice for many industrial applications. They are typically made with special alloys, hard metal or wear-resistant rubber to endure the demanding conditions of slurry transport. They are also equipped with heavy-duty bearings and double mechanical seal to ensure reliable operation under challenging conditions.

The Structure of a Submersible Slurry Pump

Understanding the structure of submersible slurry pumps is crucial for those involved in their operation, maintenance, or selection. This section delves into the components that make up a submersible slurry pump and their functions.

Impeller and Casing

At the heart of a submersible slurry pump is the impeller, responsible for imparting kinetic energy to the slurry, enabling it to move through the pump and out to the discharge point. PEMO submersible slurry pumps are equipped exclusively with semi-open impellers. This design choice enhances the handling of larger solids and reduces the risk of clogging compared to closed impellers.

Surrounding the impeller is the casing, which directs the slurry from the impeller to the discharge. PEMO uses its proprietary abrasion-resistant alloy, Hardalloy, or a rubber-lined casing to maximize efficiency and minimize wear. These special materials are designed to withstand the abrasive nature of slurry and ensure long-term durability.

Agitator

PEMO submersible slurry pumps can be supplied with two different types of agitators:

Mechanical Agitator: mounted at the inlet of the pump on the shaft, this agitator helps stir up settled solids to keep them in suspension and ensures that the suction strainer remains clean.
Hydraulic Agitator: mounted at the outlet of the pump, this agitator uses a portion of the pump’s delivery flow to aid in the suspension of solids and helps in keeping the suction strainer clean.

Sealing System

A robust sealing system is critical for preventing slurry from entering the motor compartment. Submersible slurry pumps typically employ a double mechanical seal made of silicon carbide, providing superior resistance to abrasion and corrosion.

Shaft and Bearings

The pump shaft, made of AISI 431 stainless steel, connects the impeller to the motor, transmitting the rotational force necessary for operation. The bearings are oversized to withstand the most demanding conditions and are lubricated for life, ensuring smooth operation and long-term reliability.

Electric motor

The electric motor is a vital component of a submersible slurry pump. PEMO submersible pumps feature high-efficiency, asynchronous three-phase motors. These motors are available in various temperature classes to suit different operational environments. They are also suitable for use with inverters, providing flexibility in speed control and energy savings. The motors are cooled by the pumped liquid, ensuring efficient thermal management and preventing overheating. Additionally, they are equipped with thermal protection to prevent overheating, enhancing the motor’s durability and operational reliability.

Maintenance and Selection

When selecting a submersible slurry pump, it is important to consider:

Particle Size and Distribution: The size and distribution of solids affect pump performance and design.
Slurry Density: The concentration of solids impacts the required pump power and sizing.
Viscosity: Higher viscosity slurries require more power and affect the flow rate.
Abrasiveness and Corrosiveness: The chemical and physical properties of the slurry influence material choices for durability and resistance.
Flow Rate: The volume of slurry to be pumped per unit of time determines the pump size.
Total Dynamic Head (TDH): The head required, including static lift and friction losses, influences the pump’s performance.

Other important factors to consider include:

Submergence Depth: The depth at which the pump will operate affects pressure and cooling needs.
Sump or Pit Dimensions: The physical size of the installation site impacts pump selection and configuration.

These factors will influence choices related to:

Impeller Type.
Material Selection.
Sealing System.
Agitators.
Suction Strainer.
Motor Size and Efficiency.
Cable Type and Length.

Maintaining submersible slurry pumps involves regular inspection of components like the impeller, seals, bearings, and casings to ensure optimal performance. The pumps’ design facilitates straightforward maintenance, allowing easy access to parts that may require servicing.

The structure of a submersible slurry pump is a simple assembly of components, each playing a vital role in the pump’s operation. From the robust impeller and casing to the efficient sealing system and powerful motor, every part is designed to handle the demanding task of slurry transportation.

With proper understanding and maintenance, these pumps can provide reliable service in the harshest industrial environments.

Uses and Industries

Submersible slurry pumps are essential in various industries where the handling and transportation of slurry—a mixture of solid particles and liquid—is required. Their robust design and capability to handle abrasive and corrosive materials make them suitable for demanding applications in the following sectors:

Mining: Submersible slurry pumps are extensively used in mining operations for dewatering, transferring tailings, and handling other byproducts. They are vital for maintaining water levels in mines and processing mineral slurries.
Dredging: In dredging operations, these pumps assist in the transportation of sediments from the bottom of water bodies.
Construction: In the construction industry, submersible slurry pumps are used for managing waste and transferring concrete. They help in dewatering construction sites, handling bentonite slurries in tunneling, and pumping abrasive mixtures in various construction applications.
Wastewater Treatment: Submersible slurry pumps play a significant role in wastewater treatment plants. They are used for the recirculation of wastewater, transferring sludge, and feeding filter presses. Their ability to handle solids and viscous liquids makes them ideal for processing wastewater and sludge.
Power Generation: In power plants, these pumps are used for handling ash slurry and other abrasive materials. They help in managing the byproducts of coal and other combustion processes.
Chemical Processing: The chemical industry utilizes submersible slurry pumps for transferring corrosive and abrasive chemical slurries. Their resistance to harsh chemicals ensures long-term reliability in processing plants.
Ceramic Industry: In the ceramic industry, submersible slurry pumps are used for transferring ceramic slip. Their ability to handle abrasive materials makes them ideal for processing the fine particles found in ceramic production.
Pulp and Paper: In the pulp and paper industry, these pumps are used for transporting paper pulp and other fibrous slurries. They are essential for processing raw materials and managing waste products.

By offering solutions for handling abrasive and corrosive materials, submersible slurry pumps are indispensable in various industrial applications, ensuring efficient and reliable operation in some of the harshest environments.

Advantages of Submersible Slurry Pumps

One of the main advantages of submersible slurry pumps is their ability to handle solids of various sizes without clogging. This is due to their large apertures and high-efficiency agitators that lift settled solids. They are also highly efficient, capable of pumping high volumes of slurry while using minimal power. Operating underwater also significantly reduces noise and vibration levels, which can be a critical factor in certain environments.

Critical issues in the use of submersible slurry pumps

Like any industrial equipment, submersible slurry pumps are not without their challenges. Understanding these critical issues is essential for maintaining operational efficiency and prolonging the life of the pumps. Here are some common problems associated with submersible slurry pumps:

Cavitation

Cavitation occurs when vapor bubbles form on the suction side of the pump due to low pressure and then collapse or implode on the pressure side, generating shock waves that can cause damage to the impeller and other internal components.

Abrasive Wear

Continuous movement of abrasive particles within the slurry can lead to significant wear and tear on the pump’s components, particularly the impeller and casing. Utilizing wear-resistant materials like Hardalloy and rubber-lined casings, along with routine maintenance, can mitigate abrasive wear.

Corrosion

The chemical composition of the slurry can cause corrosion, affecting the pump’s longevity. Selecting materials that withstand corrosive substances is crucial for the pump’s durability.

Blockages

Solid particles in the slurry can cause blockages, leading to reduced flow and increased pressure. Regular cleaning and the use of strainers or filters can help prevent clogging.

Overheating

Inadequate lubrication can lead to overheating and damage, emphasizing the importance of proper maintenance. For submersible pumps like those from PEMO, being immersed in the slurry helps ensure adequate cooling and lubrication, which are critical for optimal performance and longevity.

Mechanical Seal Failure

Mechanical seals prevent fluid from leaking out of the pump. Over time, these seals can degrade, leading to leaks. Using durable materials for seals and conducting regular inspections can extend their lifespan.

Electrical Issues

Moisture intrusion into electrical components, improper electrical installations, or voltage fluctuations can lead to electrical issues. Ensuring proper waterproofing and electrical integrity is vital for the safe operation of the pump.

Sediment Build-Up

In deep sumps, sediment build-up can be problematic, reducing efficiency and potentially damaging the pump. Regular monitoring and cleaning are necessary to address this issue.

Features of Pemo submersible slurry pumps

PEMO submersible slurry pumps are designed for heavy-duty slurry applications. In particular, Pemo Pumps products guarantee:

High-Efficiency Motor: Class IE3 with power ranging from 1.1 to 90 kW and speeds from 735 to 3,500 rpm (50 and 60 Hz).
Standard Capacities: up to 700 m³/h (3,082 gpm).
Maximum Pressure: up to 7 bar (103 psi).
Double Mechanical Seals: Back-to-back, with silicon carbide or tungsten carbide wear rings, oil lubricated.
Angular Contact Bearings: Life-lubricated and maintenance-free, designed to deliver long life.
Thermal and Oil Level Probes: All PEMO submersible slurry pumps are provided with a thermal probe (for motor temperature control, bimetal switch or PTC on request) and two oil level probes (for slurry leak detection inside the oil chamber).
Electric device: for analyzing signals from the oil and thermal probes is included with the pump.
Mechanical or hydraulic agitators can be added to keep solids suspended in the slurry.

In conclusion, PEMO submersible slurry pumps stand out for their robust construction, high efficiency, and advanced features, making them a reliable choice for handling demanding slurry applications across various industries.

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