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Home grown and processed diesel fuel - Page 5

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Posted by Bruce Richmond on August 23, 2009, 3:58 pm

Again I am just going on theory here.  I haven't actually processed
any SVO.  What I wrote in my last post was that the longer chains
(spaghetti) are what thicken the oil and slow its flow.  With that in
mind I would say that heating the SVO allows some of the lighter parts
to evaporate, leaving the longer chains.  The heat gives some
molocules that would be too big to escape at room temperture the
energy they need to break free.  It might be worth while to pass any
vapor coming off the SVO through a cooling coil to see if you get
anything useful as a fuel.

If you add enough heat the parts of the big molocules that stick out,
which carry most of the hydrogen, can break off forming smaller
molocules.  These can be distilled as they escape the mix.  What is
left has a higher carbon to hydrogen ratio than what you started with
and will be heavier.  The carbon may recombine to form large molocules
with more carbon:carbon double bonds, or not.  Either way it will be
thicker and heavier without the light weight hydrogen to fluff it up.


http://en.wikipedia.org/wiki/Cracking_ (chemistry)


Posted by Irregular on August 25, 2009, 12:36 pm


Paraffins in diesel, just like paraffins in a candle, become softer as
they are warmed up.

Think about which would spray out of a nozzle better, solid wax or
liquid wax. And which will run through a filter as well.

The waxes in regular diesel are what make the issue of cloud point and
pour point.

When you get diesel cold enough, the tank looks like it contains liquid
candle wax. BTDT. About 20 below zero F.

My Cummins N-14E would pump it and inject it, but only because I had a
55 watt electric heater to liquefy the diesel at the fuel filter. And it
would only run at a low idle because the heater could only heat enough
to pass the idle speed draw through the filter. The return from the
engine eventually heated the tank enough for normal operation. (Cummins
dumps a lot of heat in the fuel. The electronic brain boxes are cooled
with fuel coming from the tank.)

Posted by Curbie on August 25, 2009, 9:04 pm

I worked in a receiving department in a mill in Wisconsin as a kid and
used to talk to the truckers all the time, and in the winter there was
a lot of conversation about keeping their trucks running in the Green
Bay winters. Some were independents who owned their own rigs for a
long time and were basically their own mechanics.

Some of the company drivers used to add gasoline to their trucks so
they wouldn't freeze-up and when I'd pass that "tip" along to the
independents they say that info must have come from a company driver,
when I asked one independent who seemed (to me anyway) particularly
knowledgeable and did his own mechanics right down to rebuilds, WHY?,
his explanation was:

Adding a little gasoline to "thin" the fuel was OK and was even in
some of the older diesel manuals, but adding too much was a problem
for combustion, diesels wanted a slow, controlled, and complete
combustion and adding too much gasoline too "thin" fuel changed the
combustion to fast and uncontrolled more like an explosion than a
burn. Which lead to conversations like "why not just pre-cold filter
the wax of the fuel?", to which he replied because the wax serves to
slow and control combustion.

He described a "cold weather" kit much the same way you did and I
don't really know if his description of "cold weather" kits or
combustion was even accurate then or still applicable today, but he
was one of the only driver's that the cold didn't stop, and that's the
basic reason for starting this thread, to test those ideas.


Posted by daestrom on August 23, 2009, 4:11 pm

Curbie wrote:

You've got that reversed.  Heating oil or most any other liquid
*reduces* it's viscosity.  A lower viscosity makes it easier to flow
/pour (molasses has a high viscosity, water has a lower viscosity).

Heating the oil makes it easier to flow, you just got your terminology

Not likely.  Mild heating increases the kinetic energy of the molecules
so they are 'vibrating' more.  As they jostle around faster, they can
slip past each other easier and thus pour/flow more easily.  This
applies to just about all liquids.


Posted by Curbie on August 23, 2009, 5:52 pm


Dont know what I was thinking there, would not have wanted that
misstatement to stand, Thanks for the correction!

Do you know if the same mild heating and its increase in kinetic
energy (DECREASE in viscosity) also increases the fuels

If mild pre-heat is just jostling the molecules around faster,
decreasing the fuels viscosity and the fuels hydrocarbon chain
lengths (volatility) remain the same, it would seem that viscosity and
volatility are NOT tied together under ALL circumstances; this is the
exact point that has me confused???

Bruce, Im tying to prove you wrong here, Im trying to figure this
out, feel free to weight in on this point too.



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