After years of using the batch reactor processor to create bio-diesel, Soul Ecology was unsatisfied with the slow and tedious steps used to create bio-diesel. In 2003, Soul Ecology initiated a research project to find a more efficient processor to create bio-diesel. We read numerous papers on different bio-diesel processing techniques. We were impressed with several technique and we narrowed are research scope to those techniques.
The techniques were as followed:
- Microwave Irradiation - Microwave irradiation is a well-established methodology to improve extraction and to accelerate chemical reactions such as those of hydrolysis and esterification. Microwaves act as high frequency electric fields and will generally heat anything with a mobile electric charge. Polar solvents are heated as their component molecules are forced to rotate with the field and lose energy in collisions. Semiconducting and conducting samples heat when ions or electrons within them form an electric current and energy is lost due to the electrical resistance of the material.
- Ultrasonic Waves - Ultrasonic waves, like all sound waves, consist of alternating cycles of positive and negative pressure. The waves of positive pressure will increase local density in a gas or liquid by compressing molecules together. The negative pressure waves will decrease local density by pulling molecules further apart. For cavities to form, the negative pressure within the liquid during the expansion cycle of the sound must exceed the attractive forces between molecules.
- Oscillatory Flow Mixing - Oscillatory Flow Mixing occurs when fluid is oscillated between 0.5 and 15 Hz - at amplitude of typically 1 to 100 mm - in a baffled tube. The oscillating fluid motion interacts with each baffle to form vortices, and the resulting fluid motion gives efficient and uniform mixing in the space between two baffles.
We were able to eliminate the Microwave Irradiation technique early in our project, but the other two techniques excelled in different ways. The Oscillatory technique was the most efficient the energy required to create a reaction was very low. The Ultrasonic technique was the most effective; it took less time to complete the reaction.
We decided to physically buy, create and evaluate both the Oscillatory flow mixing processor and the Ultrasonic Waves processor along with a Centrifuge for both processes. We would first implement the Ultrasonic waves because the parts are currently for sale. Some metal fabrication is necessary for the oscillatory method to work.