Methoxide mixer

An important part of any biodiesel processor is the Methoxide mixer. It needs to efficiently and most importantly, safely mix the Methanol and catalyst so the catalyst is completely dissolved in the Methanol.

The two main design criteria are:

Safety, ensure that the mixer is air tight and vented safely.
Materials compatibility, ensure all materials used are compatible with Methanol, the catalyst used and the resulting Methoxide mixture.

The following designs are offered as examples; however you should satisfy yourself on the above points before starting construction.

Methoxide mixer design 1

This design is intended for use with a GL type processor which employs a venturi to create a vacuum. I might be possible to connect it via a T piece on a pump suction, but this arrangement has not been tested.

Depending on how extensive your scrap bin or collection of “bits that might come in useful” is, most likely you will need to buy the barrel and the flange bearing. Some items were turned on a lathe but with a bit of ingenuity these could be fabricated. Silver soldering or possibly soldering will be required and welding equipment might be useful.

The barrel is a 25 litre fermenter from an online homebrew beer company. The beauty of this fermenter is that you can buy spare lids separately, with or without holes.

The bearing is readily available from online auction sites or any bearing specialist. Ensure the one you buy has a sealed bearing so there is no leakage of fumes.

This design has two minor draw backs. It won't pick up every last drop of methoxide and due to the size of tubing employed it’s a little slow on delivering Methoxide to the processor, about 1 litre/min with a good vacuum from the venturi. Neither is a major problem and both are far outweighed by its safety and ease of use.

Methoxide mixer design 1, suitable for a processor with venturi
Complete unit. The vent and Methoxide pickup pipes are blanked off with short tubes blocked at one end with silicone when not in use.
Top view of the lid. The pipe on the right is the vent connected to the processor vent by flexible tube which runs to outside. Pipe on the handle is the Methoxide pick-up which is connected to the venturi suction again by flexible tube.
View underneath the lid. The spindle is drilled down its centre to form a section of pipe then cross drilled to solder the copper tube in place as seen in this photo. For the vent, one of the bolts holding the bearing to the lid was centre drilled (just in view above the copper tube).
This is the business end. The height of the paddles can be adjusted up and down the studding to suit the height of the fermenter. The flexible tube is positioned to get as close to the bottom of the fermenter as possible.
The paddles have to fold up to fit through the lid of the fermenter. Once inside they are unfolded.