Dredge Pump Selection 101

Dredge pump selection can be a challenging task, lets try to simplify the process. How to Select a Dredge Pump or Slurry Pump

Dredge Pump Selection Introduction

Dredge pump or slurry pump selection could be a challenging process which could be simplified with the understanding of the primary factors behind smooth pump operation. Apart from delivering a more efficient performance for dredging operations, the right dredge pump requires lesser maintenance, reduced power and has a relatively longer life.

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Slurry pump and dredge pump terms may be used interchangeably.

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Figure 1: A specialized dredge pump attachment for excavators, in the dredging process

Definition of Dredge Pump and Slurry Pump

Slurry pumps are the mechanical devices utilized for pressure-driven transport of a fluid mixture (aka slurry). The fluid mixture by and large consists of water as a liquid with solids being minerals, sand, gravel, human waste, drilling mud or most of the crushed materials.

Dredge pumps are a special category of heavy-duty slurry pumps that are utilized in the process of dredging. Portable dredge pumps tend to be smaller, but pump solids, handle abrasive slurries and perform sediment removal for maintenance dredging projects equally well (albeit on a lower level). Dredging is referred to as the process of transport of underwater sediments (usually sand, gravel, other abrasive granular materials or rocks) from one region to another (a piece of typical dredging equipment is shown in Figure 1). Dredging takes place in shallow water areas of lakes, rivers or ocean for the purpose of land reclamation, desilting, flood prevention, creation of new ports or expansion of existing ports. Hence, various industries that utilize dredge pumps are the construction industry, mining industry, the coal industry, and oil & gas industry.

The dredge's suction pipe connects directly to the pump casing's sealed frontal portion and plays a crucial role in absorbing the slurry and transporting the material through the discharge pipeline.

Primary selection requirements for dredge pumps

Apart from economic considerations, two primary selection considerations for dredge pump operation are no settlement of sediments in the pump and minimum amount of wear and tear in the pump due to the flow operation. The dredge pump's discharge plays a crucial role in the overall system, as it is connected to a separate discharge line and is responsible for transporting the material through the discharge pipeline. The key design parameters to keep in mind to satisfy the primary requirements are the type of installation, critical flow rate, total discharge head, and the pump design material.

Know your slurry type:

Before moving on to estimating the design parameters of 'your' slurry pump, an extremely crucial step is being familiar with the material that needs to be transported. Therefore, estimation of pH and temperature of the slurry, the specific gravity of slurry and concentration of solids in the slurry is the first crucial step towards the direction of 'your' ideal pump selection. Dewatering pumps are essential for efficient water removal in various projects such as construction sites and mining operations, ensuring sites remain dry and operational.

Critical flow rate estimation:

Critical flow rate is the transition flow rate between a laminar and a turbulent flow and is calculated based on grain diameter (size of slurry particles), the concentration of solids in the slurry and the pipe diameter. For minimal settlement of sediments, the actual pump flow rate of 'your' pump should be higher than the calculated critical flow rate for your application. However, it is important to be careful with the selection of the pump flow rate as the increase in flow rate will increase the wear and tear or abrasion of the pump material and hence reduce the lifetime of the pump. Hence, for an uninterrupted performance and extended lifetime, the pump flow rate should be optimized.

Discharge head estimation:

Total discharge head is a combination of static head (actual elevation difference between the surface of the slurry source and the discharge) and friction loss in the pump. Along with dependence on the geometry of the pump (pipe length, valves or bends), friction loss is also affected by the pipe roughness, flow rate and slurry concentration (or percentage of solids in the mixture). The friction losses increase with the increase in pipe length, the specific gravity of the slurry, concentration of the slurry or the slurry flow rate. The pump selection procedure requires that discharge head of 'your' pump is higher than the calculated total discharge head. On the other hand, it is crucial to note that the discharge head should be kept as low as possible to reduce the pump abrasion due to slurry flow.

A separate discharge line connected to the dredge pump's discharge can help reduce friction losses and improve efficiency by facilitating the transport of material through the discharge pipeline.

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If you need help with pump selection, sales or engineering support, call 619-404-.

Pump power rating:

The power consumption by the dredge pump is estimated from the discharge head, flow rate and specific gravity of pumped slurry. It is critical to verify that power rating of the selected pump is higher than the calculated power consumption after taking into account reasonable variations in operating conditions.

Material selection:

Typical material used for the construction of slurry pumps are cast iron, stainless steel, and high chrome steel. Some slurry pumps come with a lining to better deal with problems of slurry abrasion. A few elastomers which are used in the lining material are natural rubber, polyurethane or neoprene. The selection of lining material depends on the operating temperature, pH of slurry and the presence of specific abrasive fluids used in the dredging process.

Type of slurry pump installation:

Based on the shaft orientation, the slurry pumps can be divided as horizontal pumps and vertical pumps with horizontal pumps having the shaft in a horizontal position while the vertical pumps have a vertically aligned shaft.

Horizontal pumps are the most common types of slurry pumps used, and hence have the advantage of ease of installation or maintenance, a wide range of selection of flow parameters and choice of design materials. However, the vertical pumps among other benefits have the advantage of requiring relatively much lesser ground space for installation.

Another method to classify the type of installation for slurry pumps is dry installation or wet installation. Dry installation pumps have the hydraulic end and the drive located outside the liquid while the wet installation pumps such as submersible pumps operate inside the sump or the slurry. The submersible pumps do not require much support structure, hence, do not occupy much space. Depending on the kind of operation and installation desired the preferred method of pump installation is decided. Certain pumps are also capable of pumping sea water and handling abrasive particles.

Pro Tip ' How to Choose a Pump Essential Questions

• What type of material will be pumped? (sand, mud, coarser particles, sludge, etc)
• Flow rate target goals? (400 GPM, e.g.)
• Length of pipeline? (700 FT or M, e.g.)
• Elevation rise of pipeline? (20 FT or M, e.g.)
• Type of pipeline? (plastic, metal, e.g.)
• What is the density of the material?
• What is the viscosity of the material?
• Have you considered positive displacement pumps for projects requiring longer maintenance intervals and higher efficiency?

These are all things you should know about your project. These items are important in determining the proper EDDY Pump for your project. Hopefully, any company you get a quote from is asking these questions. This is especially important in the pumping of sludge, slurry, muck, mud, and other viscous materials. Call us for a consultation.

Call for sales or support

If you need help with pump selection, sales or engineering support, call 619-404-.

Pump Clogging:

Due to an extremely varied grain size distribution of materials handled by dredge pumps clogging of the suction or discharge of the pumps is a damaging phenomenon which leads to expensive maintenance procedures and more importantly high downtime. Our patented technology at EDDY pump has a high tolerance of sizes of materials handled, with a capacity to handle sizes as large as 12 inches. The open rotor design lets anything which can go through the inlet pass through the discharge without any setbacks. A typical high tolerance dredge pump manufactured at EDDY Pumps is shown in Figure 2. Figure 2: A high tolerance EDDY Pump. 3-inch Pump Designed For Non-Clogging and Heavy Slurry. Call for details.

Abrasion:

Massively abrasive nature of slurry's solid particles causes an enormous amount of wear and tear in pumps. Due to the harsh environments in which slurry pumps operate, EDDY pump gives utmost importance to use the finest material for the impeller, seal, and casing to prolong the lifetime of the pump.

Conclusion:

Hopefully, you have a better understanding of the elements needed for proper pump selection. Even better is talking with us to help with your project specific needs. View our videos, pump page and explore the site.

At EDDY Pump we are committed to providing best-in-class dredge pumps to our customers; hence, each component is thoroughly tested to deliver supreme quality, reliability and versatility. Our unique technology provides us with an extraordinary capability to easily handle materials with enormous volumes and high specific gravity in tough conditions. We are dedicated to offering innovative dredging solutions for various industries, including construction, mining, and environmental remediation.

With an on-site R&D facility, we constantly strive hard to improve our products and stay best in the market for pump technology. or Call Us with Pump Questions 619-404-

EDDY PUMP VIDEOS

Why EDDY Pumps Are Better ' Highlights

This video shows how EDDY Pump transports high slurry and abrasive materials. Talk To About Any Question?

Dredge Pump FAQs

What is a dredge pump?

A dredge pump is a type of centrifugal pump specifically designed to remove and transport sediment, silt, or debris from bodies of water. It is a crucial component of dredging equipment used in various industries, such as mining, construction, and environmental remediation.

How does a dredge pump work?

Dredge pumps use centrifugal force to create a vacuum that draws in sediment-laden water. The rotating impeller then imparts kinetic energy to the mixture, accelerating it through the pump casing and discharging it through the pump outlet.

What factors should be considered when selecting a dredge pump?

Factors to consider when selecting a dredge pump include:

• Type of material to be dredged (e.g., sand, mud, gravel)
• Dredging depth and distance
• Required flow rate and head pressure
• Pump efficiency and wear resistance
• Operating conditions (e.g., temperature, pH)
• Budget and project timeline.

What are the different types of dredge pumps?

Common types of dredge pumps include:

• Submersible dredge pumps
• Hydraulic dredge pumps
• Cutter suction dredge pumps
• Horizontal dredge pumps.

How do you determine the appropriate size of a dredge pump?

The size of a dredge pump is determined based on factors such as the volume of material to be dredged, dredging depth, required flow rate, and head pressure. Hydraulic calculations and pump performance curves select a given application's most suitable pump size.

What are the advantages of submersible dredge pumps?

Advantages of submersible dredge pumps include:

• Ability to operate underwater without the need for priming
• Compact design for easy deployment and maneuverability
• High efficiency and performance in abrasive environments
• Minimal noise and vibration during operation.

How do you ensure the longevity of a dredge pump?

Regular maintenance and proper operation are essential to ensure a dredge pump's longevity. This includes:

• Inspecting and replacing worn parts as needed
• Lubricating bearings and seals
• Flushing and cleaning the pump system
• Monitoring performance and addressing any issues promptly.

What are the critical considerations for pump installation and setup?

• Critical considerations for pump installation and setup include:
• Proper alignment and positioning of the pump
• Adequate support and anchoring to prevent movement
• Correct installation of inlet and outlet piping
• Ensuring sufficient clearance and access for maintenance.

How do you troubleshoot common issues with dredge pumps?

Common issues with dredge pumps include cavitation, wear of impeller and liners, and blockages. Troubleshooting involves identifying the root cause of the problem and implementing appropriate solutions, such as adjusting pump speed, replacing worn parts, or clearing blockages.

What are the safety considerations when operating a dredge pump?

Safety considerations when operating a dredge pump include:

• Proper training for personnel
• Adherence to safety protocols and regulations
• Use of personal protective equipment
• Regular inspection and maintenance of equipment
• Implementation of emergency response plans.

What is a dredge pump?

A dredge pump is a type of centrifugal pump specifically designed to remove and transport sediment, silt, or debris from bodies of water. It is a crucial component of dredging equipment used in various industries, such as mining, construction, and environmental remediation.

If you are looking for more details, kindly visit Dredge Pump Casting Spares.

What machine is used for dredging?

Dredging is typically performed using specialized equipment such as dredges, which may include:

• Cutter suction dredges
• Hydraulic dredges
• Excavator dredges
• Clamshell dredges.

What is the purpose of dredging?

The purpose of dredging is to:

• Maintain navigable waterways for shipping and maritime traffic
• Prevent flooding by improving drainage and water flow
• Restore aquatic habitats and ecosystems by removing sediment and debris
• Support construction projects such as bridge and port infrastructure.

How does a water dredge work?

A water dredge uses hydraulic or mechanical forces to excavate sediment from the bottom of bodies of water. The dredged material is transported via pipelines or barges to a designated disposal site or processing facility.

What is dredging and its types?

Dredging removes sediment, silt, or debris from the bottom of bodies of water to maintain navigable channels, improve water quality, or reclaim land. Common types of dredging include:

• Hydraulic dredging
• Mechanical dredging.

How is dredging good?

• Dredging can have several positive effects, including:
• Maintaining navigable waterways for shipping and maritime traffic
• Preventing flooding by improving drainage and water flow
• Restoring aquatic habitats and ecosystems by removing sediment and debris
• Supporting construction projects such as bridge and port infrastructure.

How is dredging done?

Dredging is typically done using specialized equipment such as dredges, which may employ hydraulic or mechanical methods to excavate sediment from the bottom of bodies of water.

What are the three significant effects of dredging?

The three significant dredging effects are:

• Maintaining navigable waterways
• Preventing flooding
• Restoring aquatic habitats and ecosystems.

What is the depth of dredging?

The dredging depth depends on project requirements, maritime needs, and environmental considerations. Dredging depths can range from shallow areas to deeper channels.

What is the cost of dredging?

Dredging costs vary depending on project size, duration, location, equipment, and disposal methods. For large-scale projects, they can range from thousands to millions.

How is dredging quantity calculated?

Dredging quantity is calculated based on factors such as the volume of material, dredging depth, and sediment density. Hydraulic calculations and survey data estimate the amount of material to be removed.

What are the two main types of dredging?

The two main types of dredging are hydraulic dredging and mechanical dredging. Hydraulic dredging uses water jets or suction to excavate sediment, while mechanical dredging uses buckets, scoops, or cutting devices to remove material.

Related Products

HD (Heavy Duty) Slurry Pumps / Dredge Equipment

ARTICLES

Popular Slurry Pump & Dredging Articles

Elevate your business with the state-of-the-art dredge pump engineering and slurry pump manufacturing company.

Last week, Carsten Markus graduated on his assignment with our research department Damen Dredging Equipment. He investigated the alloys that are used to cast our impellers and the responses of the materials under operating conditions. We are always improving our dredge pumps and Carsten's work has been a great contribution for our development.

For every dredging application, the material for the dredge pump parts can be carefully selected according the specific requirements on the sediment handled. Off course, one would like to have the hardest, most erosion resistant material available. Less erosion is less wear and a longer lifetime1.

However, there is a downside to choosing very hard material: it will be very brittle also2. Basically, the ultimate tensile stress coincides with the yield stress. There is no reserve for the load. When the stress surpasses the yield strength, it just snaps. Conversely, a tough material has a lot of reserve. After deformation beyond the yield stress, the load can still increase without a catastrophic failure. Usually, the stresses would not be that high, the thickness of the wear parts is dimensioned for erosion reserves and thick parts have low stresses. The high stresses can come from concentrations. Either when the wear reserves are eroded, or when a heavy load is concentrated on a very small area. Usually stones. Stones are a very common problem in a dredging project. So, next to the hardness of an alloy, also the toughness will be a very important characteristic. And toughness is related to the yield elongation after failure.

For the various materials you would like to know how the base load relates to the tensile stress. This would be an indication whether there is reserve in the elastic region to accommodate the impact of an occasional stone. This base load depends on many factors in the pumping process. Mainly the pressure generation in the mixture over the blades. Most known literature is about the force distribution in the volute of the pump, as this is directly related to the radial forces and consequently the bearing and shaft calculations. The CFD simulations in this graduation project revealed the skewed load on the volute and consequently the load variations on the impeller.

Transient CFD simulation of a dredge pump. The rotation appears wrong , but is correct (Wagon-wheel effect).

As emphasised before, it is very beneficial to operate your dredge system around the Best Efficiency Point (BEP). Not only the shaft and bearings suffer less, also the impact of the stresses and their variations in the impeller are less. If the operating point differs from the required capacity, the BEP can be moved by changing the dredge pump speed. As long as head requirements permit the adjustment.

As a result of Carsten's research, we were able to improve our operating load models for the whole dredge pump and gained insight into the material responses to these. Thank you Carsten.

Due to the measures taken for the containment of the Corona virus, the graduation itself and the party to celebrate it, where done remotely over internet. Let's enjoy the real beer later, after all this commotion is over. Stay home, stay safe.

References

1. Do You Have Wear Parts For Spare?, Discover Dredging
2. Brittleness, Wikipedia

See also

• Innovation, Damen
• Welcome to the best years of your life, Damen

Last week we had another of our training courses for service engineers and field service engineers1. The interaction with people actually working with our products is quite refreshing and every time I understand their issues better. One of those issues is that they have to discuss with the client are spares for the wear parts. In a planned maintenance context, wear parts are a little odd. Sometimes, they are worn away or break down unexpectedly. And that is the moment customers call for spares. We do have a lot of spares on stock, but sometimes even we run out of stock or we advise to use a special execution of the concerned part for the specific operation of the client. And then we have to inform the service people and the client that there is a long lead time. Several times, they are filled with disbelief and under such circumstances it is very difficult to explain the reasons behind it. So, that is why I developed this little game to experience the waiting time for special wear parts.

It is based on the old board game of 'Snakes and Ladders'2. All it takes are the board, one dice and as much tokens as players. All start at the first position. The places are all phases in the manufacturing of the wear parts and each have their specific issues.

1. Each pattern is used multiple times and wears down, itself. Also, some patterns have to be configured for the specific application, execution or material of the wear part.
2. Moulding: the pattern is placed in a casting box and filled with sand.
3. Sometimes there are more casting boxes needed and they have to be stacked carefully. Depending on the configuration, this step might be very short. Then you go directly from 2 to 4.
4. Part of the casting system is already in the sand box with the pattern, but it has to be finished as the last part of the preparation.
5. The material is melted in the furnace. This can take some time, depending on the size of the cast.
6. The actual casting is done in minutes. Fifteen, at the most.
7. But the cooling in the casting box takes weeks. Wait one turn.
8. Sometimes the casting has not gone properly and the cast have to be done again. Back to square one.
9. Satisfied with the cast, then it has to be touched up at the fettling station.
10. A special heat treatment brings the final hardness and toughness to the product.
11. The fitting surfaces of the wear parts have to be machined.
12. Rotating parts have to be balanced. For non-rotating parts, this can be skipped.
13. Then there is the bottle neck: quality control. If there is a deviation that can n ot be mitigated, you have to go back to square one.
14. Depending on the location, transport can take weeks.
15. Don't start me about customs handling. Your anticipated spares are in bonded storage and customs is missing a document, wait some weeks or skip a turn.
16. Finally, you've made it! Installation on the dredge.

Message of the game: keep your warehouse well stocked with wear parts3,4, or your dredge will be idle for months, before you can work again. Have fun!

References

1. A well-trained team makes all the difference, Damen
2. Snakes and Ladders, Wikipedia
3. Do You Have Wear Parts For Spare?, Discover Dredging
4. Options for Repairing Parts That Ought to be Replaced, Discover Dredging

See also

• DOP Shop, Damen
• Van Voorden Foundry
• Downloads, Discover Dredging

Yesterday, Suman Sapkota graduated at the University of Twente on: 'Technical and Sustainability Analysis of Sediment Erosion of Impeller Blades of Dredge Pumps'. We are very proud he worked for us on this topic and graduated with a grade 8 for it. As such, he stands in a long line of Master students1, who graduate with an 8 or even higher2. We value good students and we like to work with them only if the work they deliver is useful for us. This requires an intensive supervision and the results are correspondingly. This does not guarantee a good result, but you can always try3.

Suman graduated on a topic covered by the chair of 'Sustainable Energy Technology'4. The objective was to study the economic and environmental impact of worn wear parts. When wear parts have to be rejected too early, they increase their environmental footprint. On the other end, if an impeller is severely worn, the efficiency decreases and the environmental footprint increases also. Our question was whether it was possible to improve the design of the dredge pump for a longer lifetime by checking the wear rate of the improvement in a simulation. To understand the problem and answer the question Suman had to start investigating the wear process itself.

From literature he evaluated different erosion models. Basically, what is the effect when a defined particle impacts the concerned surface under certain conditions. And the conditions will be depending on the flow pattern and the influence of the fluid on the particle trajectories. The second research part was the investigation of this flow pattern and simulated with a CFD application. The flow pattern and the particle properties were combined. This way, the movement of the particles can be traced from inlet to outlet.

Particle tracking in CFD simulation of an impeller

Between inlet and outlet, the particles bounce against several areas of the blade. The bouncing can be counted and mapped. Together with the information of the impingement conditions and the erosion model, an estimation of the erosion rate can be made for different flow conditions and soil properties. The mapping can be transformed into an erosion density map. These maps can be checked for pump capacity and particle sizes.

With these maps, we can finally evaluate in advance where impellers will wear down and if we can improve their lifetime by modifying the design. Thus we can reduce their environmental footprint and contribute to a more sustainable business.

Suman, thank you very much for working for us. You were a pleasure to work with. We wish you good luck on your career and a happy life.

Contact us to discuss your requirements of Pump Volute Casing. Our experienced sales team can help you identify the options that best suit your needs.

References

1. Graduation reports, Discover Dredging
2. Ben Sloof Nominated For KIvI Best Offshore Graduate Student
3. Internship Vacancies, Damen
4. Kipaji scholarship for Nepalese student, University of Twente

See also

• Do You Have Wear Parts For Spare?
• Options for Repairing Parts That Ought to be Replaced