Dolphin Centrifuge

Waste Oil Centrifuge

waste oil centrifuge

Table Of Contents

Operation

A waste oil centrifuge works by exerting gravitational forces up to 12,000 Gs to separate sediment and water from waste oil. This force separates particles as small as 1-micron from the waste oil. The centrifuge has a flow-through design that enables the continuous flow of the separated contaminants through separate outlets.

Industrial waste oil centrifuges offer a large processing capacity. Continuous three-phase separation is the key to the efficient separation of waste oils.

Alfa Laval Waste Oil Centrifuge P-615
Alfa Laval Waste Oil Centrifuge (10 GPM)

Three-phase separation means the separation of the three phases in contaminated oil. The 3 phases are the light phase – oil, heavy phase – water, and sludge.

A waste oil centrifuge is a heavy-duty, industrial-grade machine. It has the added capacity to self-eject the separated solids. It also discharges the separated water continuously through a discrete heavy phase outlet.

Pilot-scale Waste Oil Centrifuge Testing Video

Performance Results

Centrifuge performance refers to the cleaning ability of the centrifuge on waste oil. In this section, we answer the question:

How well does a disc centrifuge clean waste oil?

The following is a real-world example of our centrifuge performance results on waste oil. The table shows the contaminant levels in waste oil before and after an Alfa Laval MOPX 207 Centrifuge.

Centrifuge Type Alfa Laval MOPX-207 3-Phase, Self-Cleaning, Disc Stack Centrifuge
Contaminant ↓Before CentrifugeAfter Centrifuge
Sediment by Extraction0.42 % Wt.0.06 % Wt.
Water by Distillation38.0 % Vol.1.2 % Vol.
Metals:
Vanadium28 ppm31
Aluminum495 ppm85 ppm
Silicon386 ppm132 ppm
Ash Content1.17 % Wt.0.09 % Wt.

Factors Affecting Centrifuge Performance

Temperature: Processing temperature is a key consideration while sizing waste oil centrifuges. Higher process temperature reduces the oil viscosity, which enables higher throughput.

Conversely, lower temperature oil leads to lower capacity through the same centrifuge.

Flow-Rate: Lower flow rates give higher retention time in the centrifuge bowl. This time enables longer exposure to the high centrifugal forces leading to better separation.

Inversely, higher flow rates lead to less effective separation.

Sizing

Industrial centrifuges used for waste oil purification are sized based on their throughput of processing capacity. Centrifuges with processing capacities from 3 Gallons per Minute to over 100 Gallons per Minute are available for sale.

Due to the higher sludge levels in waste oil than lube or hydraulic oil, self-cleaning centrifuges are required for waste oil processing.

As an example, consider our medium capacity, self-cleaning, Alfa Laval centrifuge, which is widely used for waste oil recovery. Notice the reduction in capacity at reduced oil temperature in the specifications below.

Advantages of Centrifuges Over Filters

Waste Oil Centrifuge FAQ

Can a disc centrifuge separate emulsified waste oil?

A disc centrifuge can break some types of emulsified waste oils especially simple physical emulsion of waste oil can be split at a high temperature (200 F). A longer residence time i.e. low flow rate is helpful in breaking emulsions.

Can a waste oil centrifuge remove fine metal contaminants from the oil?

A disc stack centrifuge exerts over 7,000 Gs of centrifugal force which is adequate to pull metal particles down to 0.5 micron level. Our field testing has shown remarkable reduction but not the total elimination of metal particles from waste oil. So, yes, a disc stack centrifuge can remove fine metal particles from waste oil to a certain degree.

Can your waste oil centrifuge separate antifreeze or glycol from the oil?

Yes, our waste oil centrifuges are 3-phase; high G-force separators that simultaneously separate sludge and water/antifreeze from the oil.

What happens to the separated sludge in a waste oil centrifuge?

Our self-cleaning disc centrifuge automatically eject out the separated sludge periodically during the process. The centrifuge does not need to stop for the sludge ejection cycle.

Can we use a waste oil centrifuge for other applications such as diesel purification?

Yes, a waste oil centrifuge is multi functional and can be used for other applications such as diesel/water/sludge separation, lube oil conditioning, industrial oil recovery, etc. The centrifuge needs a small internal adjustment to adapt to a different separation application.

How does a disc stack centrifuge differ from other open bowl waste oil centrifuges?

A disc stack centrifuge is an industrial centrifuge that exerts an extremely high centrifugal force compared to open bowl centrifuges. Also open bowl centrifuges only separates some of the sludge from waste oil whereas a disc stack centrifuge removes all the sludge AND water from waste oil.

Is a waste oil centrifuge a flow-through type separator?

A waste oil centrifuge is a flow-through or continuous separator. The contaminated waste oil enters the centrifuge, and clean oil, water, and sludge are discharged from the centrifuge. This is a concurrent process that does not need the centrifuge stoppage for cleaning.

What is the smallest capacity Alfa Laval waste oil centrifuge?

The smallest capacity waste oil centrifuge from Alfa Laval process up to 5 GPM or 300 Gallons per Hour.

Can a waste oil centrifuge remove the black color from waste oil?

Though a disc stack type centrifuge removes most of the metal particles and some ash from waste oil, it does not remove sub-micron carbon particles that make the waste oil appear black. Therefore, a waste oil centrifuge cannot change the color of the oil.

Specifications

The following table highlights the specifications of our most popular large-scale waste oil processing disc-stack centrifuges.

Centrifuge ModelAlfa Laval MOPX207 Self-Cleaning, Disc StackAlfa Laval MOPX 210 Self-Cleaning, Disc Stack
Separation Efficiency @ 200 F1 µ Particle Size; All Free Water1 µ Particle Size; All Free Water
Rated Capacity32 GPM72 GPM
Waste Oil Capacity @ 70 F (Ambient)5 ~ 7 GPM12 ~ 15 GPM
Waste Oil Capacity @ 140 F10 ~ 12 GPM20 ~ 24 GPM
Waste Oil Capacity @ 200 F20 + GPM45+ GPM
Drive Motor7.5 HP15 HP
Operating Voltage230 / 460 V - 3 Phase230 / 460 V - 3 Phase
Bowl Speed7,200 RPM5,100 RPM
Centrifugal Force7,200 Gs6,800 Gs
Material of Construction (MOC)316L Stainless Steel (Bowl Parts); Nickel Plates non-SS Bowl Parts316L Stainless Steel (Bowl Parts); Nickel Plates non-SS Bowl Parts
Skid Size4' x 5' x 6' (H)6' x 7' x8' (H)
System Weight2,800 Lbs4,000 Lbs

Black Diesel

Black diesel is a term used to describe used engines and other used mineral oils that are repurposed as fuel for diesel engines and diesel generators. Read more about our black diesel centrifuges.

Industrial Scale Waste Oil Processing

Small scale centrifuges (open, top-loading type) produce approximately 2,500 g force. This force is enough to separate bulk sludge from the waste oil but not separate the small particles.

Alfa Laval Disc Centrifuge

Waste Oil Recovery

Our industrial waste oil centrifuges generate up to 8,000 g's. Separation of microscopic solid particles from the contaminated oil needs a higher g-force. Industrial centrifuges best handle the commercial processing of waste oil. Alfa Laval disc stack centrifuges have a continuous flow-through design and are perfect for this application.

Industrial-scale waste oil centrifuges are NOT cost-competitive for DIY or small-scale WVO separation. These waste oil centrifuges are workable for large-scale or commercial processors.

Our turn-key waste oil purification systems range from 500 Gal/Day to over 10,000 Gal/Day.

Decanters For High Sludge Waste-Oil

Waste oil decanters are well suited for de-sludging of high sludge waste oil. Refinery waste slop and tank bottom sludge are typical examples. This process is also known as sludge thickening. A decanter centrifuge handles high levels of sludge (up to 40%) continuously.

Alfa Laval decanters replace belt-presses and screw presses in many demanding high-sludge applications.

Waste Oil Filter versus Centrifuge

In this section, we will delve into commercial aspects of waste oil recycling using filters versus centrifuges.

Using Filters for Waste Oil Recycling

Filtration is not suitable for large-scale processing of used engine oil due to the ongoing cost of labor and material involved.

Consider a large-scale used oil collector who wants to process 10,000 gallons per day. Their collection consists of WVO, UCO, Waste Oil, Yellow Grease, and any other used oil. The first step involves heating and settling to remove the free water.

This process requires significant tank volume with heat for the 'heating and settling' routine. Despite the time and heating cost, all free water is still not removed by this method.


If you have simple, routine questions: We have condensed our 40+ years of disc-stack centrifuge experience into 101 Frequently Asked Questions about Disc Stack Centrifuges!


Let's not forget about the sludge left in the settling tanks! That sludge contains significant amounts of oil, which means lost revenue. Also, the tank bottoms need cleaning.

Next, filtering the decanted waste oil through bag filters is a labor-intensive process. Replacing and disposing of filter media adds to cost and time. Cleaner oil requires small mesh filters, which means frequent media replacement, which means more material and labor costs.

The 'finished product' contains water. Water removal requires adsorption or 'boiling off,' which adds extra cost to the process. Water removal by settling adds time to the process.

The capital expense of centrifuge equipment is more compared to decanting and filtration. The payback period of a centrifuge system is short, considering all costs. It is often in months, depending on the volume of oil processed.

Waste Oil Separation Using Industrial Centrifuge

Waste Oil Processing - Industrial Scale

Waste Oil Centrifuge Operation - Process Flow Diagram for Industrial Scale Processing.

A decanter centrifuge is a heavy-duty continuous de-sludging machine. It generates approximately 3,100 times the force of gravity by centrifugal force. The decanter centrifuge processes incoming crude oil to remove all solids from 1/2" down to 50 micron level in a single pass.

The de-sludged oil and water are then pre-heated. A high-efficiency inline electric heater heats the fluid. An inline electric heater is energy efficient because it heats only the in-process liquid. Heating the entire tank volume is wasteful.

The heated waste oil is now processed through a self-cleaning, high-speed disc centrifuge. These industrial centrifuges generate up to 12,000 times the force of gravity. This g-force is enough to separate all free water and solid particles down to the 0.5-micron level.

This centrifuge machine continuously separates the water and intermittently ejects the separated solids. A PLC in the local centrifuge control panel controls the entire process. It also controls the sludge ejection system.

The process illustrated and described above is ideal for commercial-scale purification of waste oil. This separation is a continuous process without media and labor costs.

Have you considered a centrifuge for Pyrolysis Oil separation? Please read our article using Industrial Centrifuges for Pyrolysis Oil production.

Used / Remanufactured Alfa Laval Centrifuges for Waste Oil Recovery

The following models show 3 Alfa Laval centrifuges of different capacities on processing Used Engine Oil. Hover on each model for technical specifications.

Alfa Laval WHPX 405 Waste Oil Centrifuge

Alfa Laval MOPX205 Waste Oil Centrifuge
Type: Three-Phase; Self-Cleaning
Bowl RPM: 8,500 (8,000 Gs RCF)
Capacity: 5 GPM @ 180 F
Drive Motor: 4 HP
Power Req.: 460 V; 20 Amp (Without Heater)
Size: 4' x 5' x 5' (H)
Weight: 1,800 Lbs

Alfa Laval MOPX 213 Self-Cleaning Centrifuge

Waste Motor Oil Centrifuge System
Type: Three-Phase; Self-Cleaning
Bowl RPM: 4,500 (8,000 Gs RCF)
Capacity: 40 GPM @ 180 F
Drive Motor: 10 HP
Power Req.: 460 V; 50 Amp (Without Heater)
Size: 5' x 6' x 7' (H)
Weight: 3,500 Lbs

Alfa Laval WHPX 513 Self-Cleaning Centrifuge

Alfa-Laval-WHPX-513-Used-Engine-Oil-Centrifuge
Type: Three-Phase; Self-Cleaning
Bowl RPM: 4,500 (8,000 Gs RCF)
Capacity: 60 GPM @ 180 F
Drive Motor: 15 HP
Power Req.: 460 V; 60 Amp (Without Heater)
Size: 6' x 7' x 7' (H)
Weight: 4,500 Lbs
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