Compare and contrast an oil refinery and a bucket-based biodiesel processor.?

Question

Compare and contrast an oil refinery and a bucket-based biodiesel processor.?

Answer 1

A bio-diesel refinery is really not a refinery, but basically a bucket processor that uses great big huge buckets.  Refiners also typically get their stock as freshly produced vegetable oils.  Smaller "bucket" processors may obtain their raw materials from various sources.

A bio-diesel manufacturer may also deal in such a huge volume that they can use a continuous process.

Now, there is also something known a vegetable oil refining.  This is the same as oil refining, except that they use vegetable oil along with crude oil.  The results are the same petrol-based products we are already familiar with (eg. gasoline, propane, plastics).

I compared a bio-diesel "refinery" to a bucket processor here because they are the most similar, but maybe you are talking about an actual petrol-chemicals refinery?  

Refineries are basically great big chemistry labs which perform all sorts of chemical reactions, but on a massive scale.  Crude oil is a mixture  of many different organic compounds.  Mostly long-chain hydrocarbons between 6 and 20 carbon atoms in length.  One of the first steps at a refinery is to sort the oil into similar lengths by using what is basically a still.  Once the oil is separated into batches of uniform molecular weight, it can undergo further processing.  For example, long chains (12+ carbon atoms) might be sent through a hydrogen cracker, which turns the long chains into shorter ones.

The fatty acids that make up plant oils are also hydrocarbon chains of 3 to 21 carbon atoms long; however, they come with extra bits on one end.  Bio-diesel processors basically remove these bits, and then cap the chains.  They do no sorting, cracking, or other alterations.... although they could.  In fact, if bio-diesel was distilled, you could make bio-gasoline out of the shorter chains,  and keep the longer chains for bio-diesel and bio-kerosene.  This is basically what is done in the afore mentioned vegetable oil refining.