FAQ

DAGYEE Horizontal Decanter Centrifuge FAQ

Introduction to DAGYEE Separation Solutions

About This Guide:

This technical guide is intended for process engineers, plant managers, and procurement specialists evaluating high-efficiency separation technologies. While DAGYEE is renowned for various dewatering solutions, our Decanter Centrifuge line represents the pinnacle of high-speed, high-capacity separation. Unlike standard off-the-shelf units, DAGYEE specializes in customizing the bowl geometry, scroll pitch, and drive systems to meet your specific process fluid dynamics.

Section 1: Fundamentals & Working Principles

Q1: What is a Decanter Centrifuge and how does it function?

A Decanter Centrifuge (technically known as a solid bowl scroll centrifuge) is a machine used to separate a single continuous feed into two or three phases based on density differences.

The operating principle relies on high Centrifugal Force (G-Force).

Feed: The slurry enters the center of the machine through a feed pipe.
Acceleration: The slurry enters the rotating bowl. The high speed (often 3000+ RPM) creates a G-force anywhere from 1000 to 4000 times the force of gravity.
Separation: Under this force, the heavier solid particles settle rapidly against the inner wall of the bowl. The lighter liquid forms a concentric inner layer.
Conveyance: A Scroll Conveyor (or screw) rotates inside the bowl at a slightly different speed. This screw pushes the settled solids up a conical "beach" and out of the discharge ports.
Clarification: The clarified liquid flows in the opposite direction and spills over adjustable weir plates.

Q2: What is the difference between Two-Phase and Three-Phase Separation?

DAGYEE manufactures both types depending on your application:

Two-Phase Separation: This is the standard configuration for Sludge Dewatering. It separates the feed into a Solid Phase(cake) and a Liquid Phase (centrate). This is used for municipal sewage, mining tailings, and general wastewater.
Three-Phase Separation (Tricanter): This design separates the feed into one Solid phase and two immiscible Liquid phases of different densities (e.g., Oil and Water). This is critical for Oil Sludge treatment, olive oil production, and refinery waste, where you need to recover valuable oil while removing water and solids simultaneously.

Q3: Why is the "Differential Speed" so important?

Differential Speed is the difference in rotational speed between the outer Bowl and the inner Scroll Conveyor.

If the bowl spins at 3000 RPM and the scroll spins at 3010 RPM, the differential speed is 10 RPM.

This parameter controls the "residence time" of the solids inside the bowl.

DAGYEE Advantage: Our systems use advanced Variable Frequency Drive (VFD) systems to automatically adjust the differential speed in real-time. If the solids load increases, the differential speed increases to push solids out faster to prevent torque overload. If the load decreases, it slows down to squeeze the sludge longer for maximum dryness.

Q4: How does a Decanter Centrifuge compare to a Filter Press?

While both are dewatering devices, they operate differently:
Filter Press: Batch process. Uses pressure and filter cloths. Good for inorganic solids but requires significant operator labor and downtime for cleaning.
Decanter Centrifuge: Continuous Operation. Closed system (no odor). Uses G-force.
Why Choose Centrifuge: It is the best choice for large-volume flows, sticky biological sludges, or applications where Odor Control and automation are priorities. It has a much smaller footprint than a filter press of equivalent capacity.

Section 2: Design, Materials & Customization

Q5: How does DAGYEE protect the machine from abrasion?

High-speed separation of abrasive materials (like sand, drilling mud, or mining tailings) causes wear. DAGYEE implements robust Wear Protection strategies:
Tungsten Carbide Tiles: We weld or bolt replaceable Tungsten Carbide tiles onto the flight edges of the scroll. This is the hardest material available for this application.
Hard Facing: We apply a hard-facing alloy weld to the inner bowl surface.
Ceramic Liners: For discharge ports, we use ceramic or carbide bushings to prevent the exiting solids from eroding the steel.
Customization: We adjust the level of protection based on your slurry analysis. A sewage plant needs less protection than a coal mine

Q6: What materials are used for the Bowl and Scroll?

Because the bowl undergoes massive stress from centrifugal forces, material selection is non-negotiable.

Duplex Stainless Steel (2205/2304): We often use Duplex steel for the bowl because it has higher tensile strength than standard stainless steel and excellent resistance to stress corrosion cracking.
SS316/316L: Standard for the casing and wetted parts in chemical and food applications to ensure corrosion resistance.
Carbon Steel: Only used for the base frame and vibration isolation stand.

Q7: Can DAGYEE customize the "Beach Angle"?

Yes. The "Beach" is the conical section of the bowl where solids are pushed out of the liquid pool.

Shallow Angle: Provides a longer drying zone. Better for difficult, sticky, or fine solids where Cake Dryness is the priority.
Steep Angle: Provides less resistance. Better for coarse, easy-to-separate solids requiring high throughput.

As a custom manufacturer, we design the bowl geometry to match your specific Separation Technology needs.

Q8: What is the Hydraulic Capacity vs. Solids Capacity?

When sizing a machine, we look at two limits:

Hydraulic Capacity: The maximum volume of liquid the machine can accept before the liquid rushes out the solids discharge (washout).
Solids Capacity: The maximum mass of dry solids the conveyor can physically push out.

Example: You might have a low flow rate but a very high solids concentration (thick sludge). In this case, the machine is sized by the torque limit of the gearbox, not the liquid volume. DAGYEE engineers calculate both to select the correct model.

Section 3: Operational Performance & Control

Q9: What Dry Solids Content can I expect?

This depends entirely on the nature of the sludge:

Biological Sludge (WAS): Typically 18% – 25% Dry Solids.
Digested Sludge: Typically 20% – 30% Dry Solids.
Inorganic/Mining Sludge: Can exceed 60% – 70% Dry Solids.
Oily Sludge: Typically 15% – 20% solids, with oil recovery being the primary goal.

To achieve the best results, the Polymer Dosing System must be optimized to create strong flocculation.

Q10: Why is Polymer Dosing necessary?

For fine particles (like biological cells or clay), G-force alone is not enough because the particles settle too slowly.

We inject a polymer (flocculant) into the feed pipe.

The polymer binds the fine particles into larger "flocs."

These heavy flocs settle instantly under centrifugal force.

DAGYEE can supply the complete polymer preparation unit alongside the centrifuge to ensure seamless integration.

Q11: How does the Control System work?

We provide a fully automated PLC control cabinet (Siemens/Schneider/Allen Bradley).

VFD Control: We use VFDs for both the Main Motor (Bowl) and the Back-Drive Motor (Scroll).

Torque Monitoring: The PLC monitors the torque on the scroll. If the sludge gets too heavy, the PLC automatically increases the differential speed to clear the solids.

Vibration Monitoring: Sensors detect any imbalance and shut down the machine instantly to prevent damage.

HMI: A touchscreen interface allows operators to adjust G-Force and speed with a single touch.

Q12: Can the machine run 24/7?

Yes. The Industrial Centrifuge is designed for Continuous Operation. It does not need to stop for cleaning.

However, we recommend a "CIP" (Cleaning in Place) cycle if the machine is shut down for a few days, to prevent residual solids from drying and hardening inside the bowl, which would cause imbalance upon restart.

Section 4: Applications & Industries

Q13: Is this suitable for Food & Beverage applications?

Yes. DAGYEE manufactures "Hygienic" or "Sanitary" Decanters.

Features: Polished internal welds, food-grade seals, and CIP spray nozzles to ensure no bacterial growth.
Uses: Fruit juice clarification, soy protein extraction, brewery yeast recovery, and dairy processing.

Q14: How is it used in the Oil & Gas industry?

This is a major application for our Three-Phase Separation units.

Drilling Mud: Recovering barite and cleaning drilling fluids.
Slop Oil Recovery: Separating oil from lagoon sludge.
Tank Bottoms: Cleaning the heavy crude sludge from storage tanks.
Our units for this industry are often Skid Mounted and explosion-proof (ATEX/IECEx) for safety in hazardous zones.

Q15: Can it handle municipal wastewater sludge?

Absolutely. This is the most common application.

It is used for Sludge Thickening (thickening WAS from 0.5% to 4% before digestion) and Sludge Dewatering (dewatering digested sludge to >20% for disposal).
The high capture rate (>95%) ensures the centrate (liquid discharge) is clean enough to return to the plant headworks without overloading the biological system.

Section 5: Maintenance & Troubleshooting

Q16: What causes vibration in a centrifuge?

Vibration is the enemy of high-speed machinery. Common causes:

Uneven Solids Loading: The machine was shut down with solids still inside, which dried in a clump. Solution: Flush with water before stopping.
Bearing Wear: Main bearings are worn.
Wear on Scroll: The abrasion protection has worn off unevenly, causing weight imbalance.

DAGYEE machines feature automatic vibration cut-off switches to protect the equipment.

Q17: How often do bearings need replacement?

The main bearings are the critical wear components.

With proper lubrication (automatic grease systems are available), bearings typically last 15,000 to 20,000 operating hours.

We use premium bearing brands (SKF/FAG) to ensure longevity.

Q18: Troubleshooting: The centrate (liquid) is cloudy (dirty).

Polymer Issue: Dosage is too low, or the mixing energy is incorrect.
Hydraulic Overload: You are pushing too much water through the machine; the fluid doesn't have time to settle.
Scroll Speed: The differential speed is too high, causing turbulence inside the liquid pool.

Q19: Troubleshooting: The cake is too wet.

Bowl Speed: Increase the RPM (G-Force).
Differential Speed: Decrease the differential speed. This keeps the solids in the machine longer, compacting them more.
Pool Depth: Adjust the weir plates to create a deeper or shallower liquid pool. (A deeper pool improves clarity, a shallower pool improves dryness).

Section 6: Commercial & Logistics

Q20: How do I get a quote for a Custom Centrifuge?

Because we are a custom manufacturer, we don't just send a price list. We need to engineer the solution. Please provide:

Material to be separated: (e.g., Cow Manure, Refinery Sludge, WWTP Sludge).

Flow Rate: (m3/hr or GPM).
Solids Content: (% TSS in feed).
Temperature: (Hot liquids require special thermal expansion tolerances).
Target Result: (Do you want max dryness or max liquid clarity?).

Q21: Do you offer complete skid systems?

Yes. DAGYEE acts as a system integrator. We can provide a "Plug and Play" container or skid including:

The Decanter Centrifuge.

The Feed Pump (Screw pump).

The Polymer Dosing Unit.

The Cake Conveyor (Shaftless screw conveyor).

The Control Panel.

This ensures all components communicate perfectly with each other.

Q22: What is the typical delivery time?

Standard Models: 6 – 8 weeks.

Custom Alloys/High Complexity: 10 – 14 weeks.

All units undergo rigorous Dynamic Balancin* and factory testing before shipment.

Q23: Why choose DAGYEE over European or American brands?

Cost-Efficiency: We offer top-tier technology (Duplex steel, VFDs, Tungsten Carbide) at a significantly more competitive price point.
Customization: We are willing to modify the L/D ratio (Length to Diameter) and internal geometry to fit unique niche applications that big brands often refuse to touch.
Speed: Our manufacturing lead times are typically 30-40% faster.

Summary: The DAGYEE Advantage

The Decanter Centrifuge is the workhorse of modern separation. Whether you are performing Sludge Dewatering in a municipal plant, recovering oil in a refinery, or clarifying juice in a food factory, the physics remain the same, but the engineering details matter.

At DAGYEE, we combine high Centrifugal Force, precise Torque Control, and robust Wear Protection to build machines that last. We don't just sell you a machine; we sell you a guaranteed process result.

Ready to Separate with Precision?

Do not settle for a standard catalog model that is "close enough." Get a centrifuge engineered for your specific slurry.

Contact DAGYEE today for a technical consultation and proposal.