View Full Version : Low tech oil shale processing

02-25-2014, 10:33 PM
Say I have plenty of oil shale and I want to make gasoline out of it using relatively low tech methods, say circa 1915. From my superficial research, mainly on wikipedia, I gather the following steps have to be taken:

1) Prepare the shale, presumably grinding it to gravel. Along the way you might be able to recover some "tight oil" directly from the shale, not sure if this would be a substantial amount or if a special process is required for that.

2) Pyrolyze the shale. Ie, roast it in a retort in the absence of air, and extract the vapor and any fluid this yields. I suppose ordinary coal would be fine for the fuel for the retort, (or possibly the left-over combustible shale once you're done with pyrolysis?)

3) Condense the vapor.

4) Refine the resulting fluid as if it was ordinary petroleum. This is basically fractional distillation in a tower. You can presumably skip desalting beforehand (?), but I don't know if any other chemical procedures would be required such as removing sulphur (is there sulphur in oil shale?).

All this seems conceptually straightforward, just a "simple matter of engineering". Have I missed any important steps along the way? The resulting gasoline doesn't have to be super-pure or super-high-octane, just the sort of petrol you would expect to be able to obtain commercially for vehicle fuel during the period.

03-08-2015, 11:49 AM
Ok, I have worked for about 2 years as a fuel lab quality assurance rep. I can tell you about the petroleum to gasoline, you have it exactly right with the fractional distillation(moonshine is also made this way). Desalting may need to occur somewhere along the way for long term refinery as the salt crystallization may bog down your refinery. However since you are getting a very precise liquid with only one specific gravity no other chemical should effect your gasoline.

Hope this helps!

03-08-2015, 12:09 PM
The process of extracting oil from shale is pretty simple in principle. You grind it up, cook it and the locked in kerogen turns to liquid and oozes out as oil. The problem is it takes a lot of heat for long periods of time. Charcoal fires with bellows were used - as were coal fired furnaces - in the earliest attempts to do this commercially. Lots of fuel was burned however, making shale oil not particularly economical.

One of the things that was very common in early distilling methods for kerosene regardless of the source of the crude oil, was the need to run it through the process several times in attempts to remove as many impurities as possible.

Using a much taller and fatter tower for the more volatile gasoline distillation would be needed, but it would also likely benefit from multiple passes through the process as well. Atmospheric pressure plays a role in the "cracking" process, and tower dimensions have a lot to do with the ability to extract the desired product.

The multiple distillation passes remove many of the impurities, however they foul the distillation chambers and as such the "salts" will need to be scrubbed out regularly.

Poor quality fuels - whether they are kerosene or gasoline - burn inefficiently and are very dirty. For kerosene lamps, the lower quality, dirty kerosene would result in large soot deposits and a very smelly lamp. Higher quality, more expensive kerosene burns very clean, much brighter and with less odor (think jet fuel).

Your biggest issue with low quality gasoline is likely to be clogging and gumming up of fuel delivery systems - filters, pump elements, carburetor jets, etc.