Table Of Contents
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.
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.
Centrifuge performance refers to the cleaning ability of the centrifuge on waste oil. In this section, we answer the question:
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 Centrifuge | After Centrifuge |
| Sediment by Extraction | 0.42 % Wt. | 0.06 % Wt. |
| Water by Distillation | 38.0 % Vol. | 1.2 % Vol. |
| Metals: | ||
| Vanadium | 28 ppm | 31 |
| Aluminum | 495 ppm | 85 ppm |
| Silicon | 386 ppm | 132 ppm |
| Ash Content | 1.17 % Wt. | 0.09 % Wt. |
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.
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 in lube or hydraulic oil, self-cleaning centrifuges are required for waste oil processing.
For example, consider our medium capacity, self-cleaning Alfa Laval centrifuge, widely used for waste oil recovery. Notice the reduction in capacity at reduced oil temperature in the specifications below.
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.
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.
Yes, our waste oil centrifuges are 3-phase; high G-force separators that simultaneously separate sludge and water/antifreeze from the oil.
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.
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.
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.
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.
The smallest capacity waste oil centrifuge from Alfa Laval process up to 5 GPM or 300 Gallons per Hour.
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.
The following table highlights the specifications of our most popular large-scale waste oil processing disc-stack centrifuges.
| Centrifuge Model | Alfa Laval MOPX207 Self-Cleaning, Disc Stack | Alfa Laval MOPX 210 Self-Cleaning, Disc Stack |
| Separation Efficiency @ 200 F | 1 µ Particle Size; All Free Water | 1 µ Particle Size; All Free Water |
| Rated Capacity | 32 GPM | 72 GPM |
| Waste Oil Capacity @ 70 F (Ambient) | 5 ~ 7 GPM | 12 ~ 15 GPM |
| Waste Oil Capacity @ 140 F | 10 ~ 12 GPM | 20 ~ 24 GPM |
| Waste Oil Capacity @ 200 F | 20 + GPM | 45+ GPM |
| Drive Motor | 7.5 HP | 15 HP |
| Operating Voltage | 230 / 460 V - 3 Phase | 230 / 460 V - 3 Phase |
| Bowl Speed | 7,200 RPM | 5,100 RPM |
| Centrifugal Force | 7,200 Gs | 6,800 Gs |
| Material of Construction (MOC) | 316L Stainless Steel (Bowl Parts); Nickel Plates non-SS Bowl Parts | 316L Stainless Steel (Bowl Parts); Nickel Plates non-SS Bowl Parts |
| Skid Size | 4' x 5' x 6' (H) | 6' x 7' x8' (H) |
| System Weight | 2,800 Lbs | 4,000 Lbs |
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.
Read our new article: 6MGY Used Oil Centrifuge Plant Layout
A typical waste oil centrifuge installation requires certain auxiliary equipment and site features for the optimum and durable operation of the centrifuge system. The following photograph shows a typical installation of an Alfa Laval self-cleaning centrifuge (manufactured by Dolphin Centrifuge) in Panama.
The recommended ancillary equipment to augment the centrifuge installation are:
The Alfa Laval disc-stack centrifuge shown in the installation photograph above was supplied as shown below.
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.
Our industrial waste oil centrifuges generate up to 8,000 g's. Separating microscopic solid particles from the contaminated oil requires 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.
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 continuously handles high levels of sludge (up to 40%).
Alfa Laval decanters replace belt presses and screw presses in many demanding high-sludge applications.
This section will delve into commercial aspects of waste oil recycling using filters versus centrifuges.
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 daily. 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, this method still does not remove all free water.
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 labor-intensive. Replacing and disposing of filter media adds to cost and time. Cleaner oil requires small mesh filters, which means frequent media replacement and 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.
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 waste oil purification. 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.
The following models show 3 Alfa Laval centrifuges of different capacities for processing Used Engine Oil. Hover on each model for technical specifications.
| 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 |
| 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 |
| 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 |