There are many methods for biodiesel production. Some of them include the batch method, supercritical method, ultrasonic and the latest microwave method.
In the batch process of biodiesel production, catalyst is initially dissolved in the alcohol using a standard agitator. The alcohol catalyst mixture is then charged into a closed reaction vessel and the bio-lipid is added. Here after try to maintain a closed atmosphere to avoid any leakage. The reaction mix is kept just above the boiling point of the alcohol to speed up the reaction. The reactions take a long time then both the resultant biodiesel and by product glycerin are allowed to settle down. Once separated from the glycerin, the biodiesel is sometimes purified by washing gently with warm water to remove residual catalyst or soaps, dried, and sent to storage.
The next method of biodiesel production is the super critical method, which is a continuous catalyst-free process for trans-esterification using supercritical methanol at very high temperatures and pressures. In the supercritical state, the oil and methanol are in a single phase, and reaction occurs almost instantaneously. The process can tolerate water in the feedstock, as the free fatty acids are converted to methyl esters instead of soap, so a wide variety of feed stocks can be used, but energy costs of production are more or less similar to catalytic method.
The other methods include the Ultra Shear and High Shear biodiesel production method, which uses up to three sets of rotor and stator which converts mechanical energy to high tip speed, high shear stress and high shearing frequencies. The droplet size range is expected in the low micrometer until sub-micrometer range after one pass.
These Ultra and High Shear mixers are used for the pre-treatment of crude vegetable oil or animal fats, for the trans-esterification and water wash process such as improved de-gumming, improved refining. They also facilitate faster bleaching, batch Biodiesel conversion, continuous Biodiesel conversion, semi continuous Biodiesel conversion and continuous water wash process.
The ultra shear mixers are used to rapidly and intimately blend the acid or water, allowing a continuous trans-esterification process. The in-line or batch reactors allow production of biodiesel continuously, semi- continuously, and in batch-mode. This drastically reduces production time and increases production volume.
Incase of the ultrasonic reactor biodiesel production method, the ultrasonic waves cause the reaction mixture to produce and collapse bubbles constantly. The cavity simultaneously provides the mixing and heating required to carry out the trans-esterification process. Thus using an ultrasonic reactor for biodiesel production drastically reduces the reaction time, reaction temperatures, and energy input.
Hence the trans-esterification process can be run inline in this method, rather than using the time consuming batch processing. Industrial scale ultrasonic devices permit the industrial scale processing of several thousand barrels per day.
Presently research is being directed into using commercial microwave ovens for biodiesel production to provide the heat needed for the trans-esterification process. The microwaves are capable of providing very high temperatures. A non stop flow process producing 6 liters/minute at a 99% conversion rate has been innovated and proved to consume only 25% of the energy required as incase of batch process.
Although it is still in its development stage, the microwave method has undoubtedly great potential to be a highly efficient, cost effective method for the biodiesel production commercially!
0 Responses to “Biodiesel Production Methods”
Leave a Reply