Biodiesel Centrifuge | Separating Biodiesel from Glycerin

30 Second Summary Takeaway

A biodiesel centrifuge is an industrial disc-stack centrifuge used in biodiesel production to separate biodiesel from glycerin, remove wash water, purify WVO feedstock, polish finished biodiesel, and clarify glycerin. In the biodiesel separation step, the centrifuge uses about 8,000 Gs and a rotating bowl to push denser glycerin out through the heavy-phase outlet while lighter biodiesel exits through the biodiesel chamber outlet. Because biodiesel plants often use methanol, biodiesel centrifuge systems may require hazardous-area electrical design, VITON seals, special plating, Teflon-covered collecting covers, and a biodiesel kit.

What is Biodiesel?

Biodiesel is an organic, renewable alternative to conventional diesel fuel. It is environmentally friendly due to lower emissions and is usable in current engines designed to operate on diesel fuel.

Biodiesel is not to be confused with black diesel, which is also an alternative fuel but is made from used oils.

How is Biodiesel Produced?

The transesterification process converts organic fats and oils into biodiesel. In other words, transesterification is the process of converting fats into biodiesel and glycerin. Methanol and lye are the catalysts in the process. The lipids are animal fat or used vegetable oil.

Large-scale biodiesel production utilizes Alfa Laval biodiesel centrifuges for high volume, continuous processing of feedstock, and separation of biodiesel from glycerin.

Also, read our Alfa Laval Centrifuge Selection Guide.

Biodiesel Centrifuge

A biodiesel centrifuge uses a high g-force of 8,000 Gs to separate biodiesel from glycerin. The centrifuge bowl rotates at 7,000 RPM. The centrifugal force spins out the denser glycerin to discharge out the heavy-phase outlet. The lighter biodiesel discharges through the biodiesel chamber outlet.

A small 'self-cleaning' centrifuge can separate 10 GPM of biodiesel and 5 GPM of hot WVO.

Advantages

The following are key advantages of centrifuges in biodiesel production.

• A continuous process with the least operating costs.
• Mechanical separation extracts the most amount of biodiesel.
• Simultaneous separation of fine sediment.
• Fast separation under the high centrifugal force.
• The automatic process saves labor costs.
• Removal of small particles without filters (filters tend to plug up).
• Wash water removal to produce 100% clear biodiesel.
• Breaking emulsions (if any).

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!

Specifications

Biodiesel Centrifuge Design

Biodiesel production requires the use of methanol. This requirement, in turn, needs unique manufacturing specifications. Biodiesel centrifuge systems manufactured by Dolphin Centrifuge have the following features. We refer to these features as the `Biodiesel Kit.'

• VITON seals in all fluid contact areas.
• Direct-drive (frictionless) design for hazardous area installation.
• Teflon-covered collecting covers.
• Electrical design for hazardous areas. (Class 1 Div 2 or Div 1)

Centrifuge Applications in Biodiesel Processing

The commercial biodiesel production process uses industrial centrifuges in most of the production steps. The list below explains each step with the corresponding centrifuge application.

WVO Purification

The WVO (Waste Vegetable Oil) feedstock contains water and food particles that need separation before the biodiesel conversion process. The three-phase disc stack centrifuge separates all free water and sediment down to the 1-micron level from WVO. This separation is a continuous (flow-through) process.

See our case study on using Alfa Laval centrifugal separators for large-scale WVO purification.

Biodiesel Glycerol Separation

Post reaction is essential to separate the two immiscible liquid phases (biodiesel and glycerol) to get pure biodiesel. Removing all traces of glycerol and any sediment is critical to reducing the load on the next process step.

Industrial centrifuges are a proven way to separate the two liquids at this stage. Alfa Laval industrial centrifuges (disc-stack type) generate a high centrifugal force on the fluid. This force separates the glycerol from the biodiesel to produce ASTM-grade biodiesel. Especially in cases where virgin vegetable oils are the feedstock.

Biodiesel Wash Water Separation

Biodiesel produced using WVO or animal fat needs a further step to remove any remaining impurities. A simple water wash polishes the biodiesel to the ASTM purity level.

An industrial centrifuge is the best fit for separating wash water from biodiesel. High centrifugal force in the disc stack centrifuge separates the water from biodiesel. This separation is, again, a continuous, efficient process.

Biodiesel Final Polishing

Polishing the biodiesel removes tiny particulate matter from the finished biodiesel. In the case of water wash, trace amounts of water may still be present in biodiesel. The Alfa Laval centrifuge removes the water from the biodiesel at this polishing stage.

Glycerin Clarification

Distilling separated glycerol recovers the methanol and produces glycerin. Pure glycerin has good resale value and is in demand in the food and cosmetics industries.

Clarification of glycerin to remove small impurities makes it usable. A disc stack centrifuge requires g-force to remove the finest trace particles from glycerin.

The advantages of using industrial centrifuges (listed above) are also applicable for glycerin purification.

FAQ

Biodiesel Centrifuge Photo-Gallery

Alfa Laval MAB-205

Capacity	15 GPM on Biodiesel Glycerin
Motor Power	5 HP
Voltages	230 / 460 3-Phase
Size	4' x 5'
Weight	2,000 Lbs
Options	Teflon Coated Covers

Alfa Laval MAB-206

Capacity	25 GPM on Biodiesel Glycerin
Motor Power	7.5 HP
Voltages	230 / 460 3-Phase
Size	4' x 6'
Weight	2,500 Lbs
Options	Teflon Coated Covers

Alfa Laval MAB-207

Capacity	50 GPM on Biodiesel Wash Water
Motor Power	15 HP
Voltages	230 / 460 3-Phase
Size	5' x 5'
Weight	2,800 Lbs
Options	VITON O-Rings

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