Table Of Contents
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.
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 production of biodiesel utilizes Alfa Laval biodiesel centrifuges for high volume, continuous processing of feedstock, and separation of biodiesel from glycerin.
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 is able to separate 10 GPM of biodiesel and 5 GPM of hot WVO.
The following are key advantages of centrifuges in biodiesel production.
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!
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.
The WVO (Waste Vegetable Oil) feedstock contains water and food particles that need separation prior to 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 the use of Alfa Laval centrifugal separators for large-scale WVO purification.
Post reaction is essential to separate the two immiscible liquid phases (biodiesel and glycerol) to get pure biodiesel. It is critical to remove all traces of glycerol and any sediment to reduce 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 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 the separation of 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.
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 the biodiesel. The Alfa Laval centrifuge removes the water from the biodiesel at this polishing stage.
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 has the required g-force to remove the finest trace particles from glycerin.
The advantages of using industrial centrifuges (listed above) are applicable for glycerin purification as well.
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.’
A biodiesel centrifuge needs to be rated for operating in hazardous areas. This rating is essential because methanol (flammable liquid) is often present in biodiesel production facilities. It is a requirement to use hazardous area certified equipment in area with flammable fluids present.
The smallest biodiesel centrifuge is an Alfa Laval MAB 103 that can process approximately 1 gallon per minute of a biodiesel glycerol mix.
Biodiesel centrifuges are standard centrifuges that are specially modified to process biodiesel. Some of the modifications include the use of special elastomers (instead of nitrile), electrical components suitable for hazardous areas, protective coating for parts affected by biodiesel, etc.
Biodiesel and glycerin separate quickly under gravity. However, the complete separation to produce 100% pure biodiesel can take a long period. A biodiesel centrifuge speeds up the separation by exerting up to 10,000 times the force for gravity to quickly produce 100% pure biodiesel without the need for decanting.
The largest biodiesel centrifuge processes over 200 gallons per minute of a biodiesel glycerin mix. This centrifuge is an Alfa Laval, 3-phase, disc stack type centrifuge.
A biodiesel centrifuge of the self-cleaning type is useful to separate water and sludge from WVO. The same centrifuge is also suitable to separate wash water from biodiesel in the wash process. Glycerin purification is another application for biodiesel centrifuges.
A properly set up and tuned biodiesel centrifuge can produce biodiesel to meet or exceed ASTM biodiesel standards.
The only operation-related expense of a biodiesel centrifuge is the cost of electricity. As an example, the cost to produce 1,200 gallons of biodiesel with a centrifuge is less than $1.00 based on electricity cost.
| Centrifuge Type | Alfa Laval Disc Stack Centrifuge with Biodiesel Kit | ||
| Model | BDB 104 | BDPX 207 | BDB 209 |
| Sludge Handling | Manual Clean | Self-Cleaning | Manual Clean |
| Biodiesel Kit Features | Compatible Elastomer, Corrosion Resistant Top-coat, Friction Clutch Replacement, Motor Suitable for Hazardous Applications | ||
| Capacity | |||
| Titrated WVO Stock | 3 GPM | 10 GPM | 35 GPM |
| Glycerin Separation | 6 GPM | 18 GPM | 60 GPM |
| Wash-Water | 3 GPM | 10 GPM | 35 GPM |
| Glycerin Clarification | 5 GPM | Not Suitable | 40 GPM |
| Motor | 2 HP | 10 HP | 15 HP |
| Bowl Speed | 7,500 RPM | 6,400 RPM | 6,700 RPM |
| Sludge Space | 0.325 Gal | 1.3 Gal | 2.0 Gal |
| Technical Specifications | |
| 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 |
| Technical Specifications | |
| 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 |
| Technical Specifications | |
| 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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