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Biodiesel Production Process

There are a number of steps that the biodiesel production process follows.

1) Sourcing a suitable biodiesel oil or fat.

The biodiesel production process starts with finding the correct raw materials. The first of these is an oil or fat which is a triglyceride. Old motor oil or mineral oils are not suitable as the molecular structure is different - the oil must be able to be converted using transesterfication. You should visit all the local restaurants in your area and try establish a working relationship with the manager. All restaurants have to change their oils frequently. You will find that the restaurant is quite used to selling their oil and you just need to convince them that they should sell it to you.

2) Homogenizing the oil

Once the oil is back at the production facility it should be blended together to form a homogenous batch. This is pretty simple to do and often is done in the biodiesel processor.

3) Filter the oil

The oil should be filtered to remove all the big particles. A 1mm mesh will do just fine, removing the large particles removes a source of water contamination as well as chips and fish heads which may get stuck in the impeller of the pump. Filtering down to micron levels is not necessary but some people do it anyway.

4) Test the oil for water

This is optional but if you live in a wet country where the oil is stored outside it is a pretty good idea to test the oil for water first. Any water in the oil will result in soap formation and this can wreck the whole batch of biodiesel. Please have a look at our water test video to see how to do a water test.

5) Heat the oil

In the biodiesel production process the oil should be heated to around 55 deg C (130 deg F), going above 60 deg C (140 deg F) is dangerous as it is close to methanol's boiling point.

6) Test the oil with a titration

The oil should be titrated to test its Free Fatty Acid content. It is very important to get this right as adding too much catalyst will result in yield loss while adding too little will result in poorly converted, substandard fuel.

7) Mix up the methoxide

Methoxide is made by mixing methanol and sodium or potassium hydroxide. The amount of hydroxide to add is worked out in your titration process, we have some titration worksheets which simplify the process. Please read methoxide mixing for some important safety information.

8) Add the methoxide to the oil

The methoxide should be added to he oil slowly so that it is evenly distributed throughout the batch of oil.

9) Mix for 1-2 hours

The batch should be mixed for enough time to allow the chemical reaction to occur. This is typically 1-2 hours. Mixing can be done by circulating the batch with a pump or by means of a mechanical mixer. Typically smaller systems will use a pump as appropriate chemical mixers are expensive.

10) Settle

The mixing process is stopped and the glycerine which used to be in the oil will separate out of the biodiesel, falling to the bottom. Settling takes a few hours to days, the longer you settle the glycerine the more will settle out. In large commercial processes a biodiesel centrifuge can be used to separate the biodiesel and glycerine and this is then a quick process. If dry washing chemicals are used it is important to get all the glycerine out.

11) Remove any remaining methanol.

Raw biodiesel has suspended methanol in it and if a dry wash is to be used then it needs to be removed.

12) Remove the remaining soaps/impurities

Raw biodiesel has soaps and free glycerin in it, these need to be removed before it is suitable for an engine. These can be removed easily with a water wash or dry wash process.

13) FInal filter

In the last stage of the biodiesel production process the finished biodiesel should be filtered or polished through a biodiesel filter system before being used in an engine.


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