[Rhodes22-list] What's The Difference Between #1, #2, #3, ... ,
#6 Fuel Oil?
Roger Pihlaja
cen09402 at centurytel.net
Wed Dec 10 09:14:21 EST 2003
Hi Everybody,
The 1st thing you need to know is that crude oil is a very complex mixture
of literally thousands of different organic, inorganic, and organo-metallic
compounds & the specific composition varies greatly between crude oils from
different fields. One of the first processing steps in an oil refinery is
to send the crude oil thru a distillation tower. In the distillation tower,
the components in the crude oil mixture are separated into fractions by
their boiling point ranges. The components with the lowest boiling points
come out the top of the distillation tower as vapor. These would include
compounds like methane, ethane, ethylene, propane, and butane. These so
called "light components" are sent to another distillation tower which
operates at cryogenic temperature for further separation. Going down the
crude oil distillation tower, fractions with greater & greater boiling point
ranges are removed as liquid side streams. From the top of the tower down,
these fractions are: gasoline or naphtha, JP-4, kerosene or #1 fuel oil, #2
fuel oil, #4 fuel oil, #5 light, #5 heavy, & #6 fuel oil. #3 fuel oil is
not an official API crude oil fraction designation because it would have to
be removed from the distillation tower very near the feed port. Removal of
this #3 fuel oil side stream in the vicinity of the feed port would tend to
upset the operation of the distillation tower. Believe me, achieving stable
on-spec operation of a distillation tower with 9 or 10 product streams & a
variable feed stock is one of the most difficult process control problems in
all of chemical engineering, even without screwing up the column operation
by removing a side stream near the feed port! Sometimes refineries will cut
a deal with a local business & sell them a product called #3 fuel oil with a
boiling point range intermediate between #2 fuel oil & #4 fuel oil. But,
it's always made by blending #2 fuel oil & #4 fuel oil. Remember, all these
products are not pure compounds. They are complex mixtures that meet a
boiling point range specification.
OK, so what happens if you feed a diesel engine a fuel oil that's too light?
The fuel injection system in a diesel engine has a number of very precisely
machined, highly polished components that meter & atomize the fuel. These
pieces/parts depend upon the lubricating qualities of the fuel oil to
lubricate & cool them as they operate. A fuel oil that's too light will not
have the oil film strength (basically viscosity) to prevent metal-to-metal
contact in the fuel injection system. The fuel injection system will
self-destruct in short order. In addition, a fuel oil that's too light will
have a boiling point range outside of the design range of the fuel injection
system. Remember, the fuel injection system is located right next to a hot
engine. If the light fuel oil starts vaporizing inside the injection pump
&/or injectors, the system will stop working. There will be instant
catastrophic metal-to-metal contact & the system will seize up. Finally,
smooth operation of the diesel engine depends upon the atomized droplets of
fuel in the combustion chamber behaving in a predictable manner. Basically,
what's supposed to happen is that in the microseconds immediately following
fuel injection, the light components of the diesel oil mixture start boiling
out of each droplet. These light components mix as a vapor with the air in
the combustion chamber, eventually forming a mixture with a composition
within the flammable range. Somewhere in this vapor space, the flammable
mixture lights off due to the adiabatic heat of compression (remember it's a
diesel - no spark plugs). The flame front rapidly consumes all the fuel
present as a vapor & ends up burning at the surface of the remaining
droplets of fuel. These droplets of fuel progressively boil up their
remaining lightest components & the remaining droplet gets enriched in heavy
boiling components. Under heavy load, there isn't enough time available
during the 4-cycle engine's power stroke to completely combust the heaviest
components. These heavy components get ejected with the exhaust gases & we
see them as diesel smoke & soot. If there are too much light boiling
components in the diesel fuel; then, too much of the droplet vaporizes
in-between fuel injection & ignition. Two things can happen. Ignition can
actually occur while the fuel injectors are still atomizing fuel. The fuel
injectors were not designed to have a high temperature flame impinging on
them while they are in operation atomizing fuel & they can be damaged. The
other thing that can happen is that a relatively large amount of light
boiling components end up in the vapor space prior to ignition. When this
big fuel charge lights off, combustion is too rapid & the
pressure/temperature in the combustion chamber exceeds design limits. This
can cause problems like blown head gaskets, holes in pistons, burnt valve
seats, etc. It's sort of like having the spark timing set incorrectly on a
gasoline engine &/or using a fuel with too low an octane number for the
spark ignited engine's compression ratio. In fact, diesel fuels actually
have a "cetane number", which is the opposite of an "octane number". A high
cetane number means the fuel will preignite very readily. Diesel fuels have
a low octane number and a high cetane number. The optimum injection timing
in a diesel engine strongly depends upon the lag time between fuel
atomization & initial light off & this lag time is mostly controlled by the
boiling point range of the diesel fuel.
So what happens if you feed a diesel engine a fuel oil that's too heavy?
The viscosity of the fuel oil goes up along with the boiling point range. A
heavy fuel oil may be too viscous for the fuel system to pump from the fuel
tank to fuel injection metering system, especially at low temperatures. In
addition, all fuel oils have a specification called the "cloud point".
Basically that's the temperature at which the fuel oil becomes visibly
cloudy or scatters transmitted light. Physically, what's happening is that
the heaviest boiling components in the fuel oil have solidified into micron
sized particles of a waxy material. Remember all those very precise, highly
polished pieces/parts in the fuel injection system? The diesel engine's
fuel system has a system of very fine mesh filters & oil/water separators
designed to filter out abrasive particles & water in order to protect those
parts. These waxy particles will clog up the fuel filters in a diesel
engine very quickly. Winter diesel fuel additives increase the solubility
of these waxy materials so they stay dissolved. The higher viscosity fuel
oil may not atomize properly in the fuel injectors, resulting in the
atomized droplets being too big in the combustion chamber. Bigger droplets
result in less surface area for the light boiling components to evaporate
from. In addition, the heavy fuel oil has relatively less of the lighter
boiling components in it to begin with. So, there are less of the low
boiling components present to vaporize off the droplets & those that are
there vaporize more slowly because of the bigger droplets to mix with the
air in the combustion chamber to light the fire. In other words, especially
at low temperature, the engine may not even run on this fuel. That's why
diesel engines have glow plugs (combustion chamber preheaters) for winter
operation. Even if the diesel engine does run on this fuel, a much larger %
of the combustion will be of the slower, less efficient variety wherein
burning occurs at the surface of the droplets. I would expect the engine
would be down on power & the exhaust would be very smoky & sooty.
So, although diesel engines can theoretically burn a wide range of fuels; in
reality, they are pretty finicky about what they will reliably run on.
There, that's probably much more than you ever wanted to know re fuel oil
specifications & how diesel engines work. Hopefully, I answered your
question.
Roger Pihlaja
S/V Dynamic Equilibrium
----- Original Message -----
From: "Kroposki" <kroposki at innova.net>
To: "'The Rhodes 22 mail list'" <rhodes22-list at rhodes22.org>
Sent: Tuesday, December 09, 2003 9:31 AM
Subject: [Rhodes22-list] Michael's Diesel #1 and #2
> Dan, Rik and Rummy,
> Dan thank you for the latest on Ford's diesels, and for your
> inputs on diesel fuel and additives.
> Maybe we can get Roger to explain the chemical differences
> during the Christmas holidays, if he gets them.
> As for #3, it was used in big locomotive engines during the
> transition from coal to diesel. It was used to generate steam.
> Ed K
> -----Original Message-----
> From: rhodes22-list-bounces at rhodes22.org
> [mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Michael Meltzer
> Sent: Monday, December 08, 2003 11:28 PM
> To: The Rhodes 22 mail list
> Subject: Re: [Rhodes22-list] RE: Michael's Diesel #1 and #2
>
> thanks, I will watch it and take it easly on the centen booster, BTW
> mine might be a early one 3/2003(did not know it until I picked
> it up), is their anything I should watch out for or bitch to the dealer
> about?(reflash the chip)
>
> MJM
> ----- Original Message -----
> From: "Dan Bodnar" <dsbodnar at earthlink.net>
> To: "'The Rhodes 22 mail list'" <rhodes22-list at rhodes22.org>
> Sent: Monday, December 08, 2003 11:23 PM
> Subject: RE: [Rhodes22-list] RE: Michael's Diesel #1 and #2
>
>
> > Michael,
> > I've had several of the old 7.3L Diesels in E350 Vans. The last one I
> owned
> > was in 2001 and it had glow plugs and a fuel heater and I'm fairly
> certain
> > that the new 6.0L still has the fuel heater. I'm in the Metro Detroit
> area
> > and we rarely have nights much colder than -10 degrees. I learned
> that I
> > did not need to plug it in unless it was going to be colder than 10
> below
> > 'cause the diesel started fine. I did plug it in when I knew it would
> be
> > colder than 10 below at night just to be safe. But, having forgotten
> to do
> > it a few times, taught me that they would start using just the
> recommended
> > start procedure.
> >
> > Anyway, fresh winter grade fuel, or some Premium diesel (which I think
> is
> > really #1) and your diesel should do fine. Also make sure that the
> water
> > separator really does get drained with every oil change. I never had a
> > diesel not start. They were a little smoky sometimes when it was zero
> or
> > colder, but they always started. I only used a diesel fuel
> conditioner on
> > one trip into Michigan's Upper Peninsula where I knew I was going to
> have
> > 20+ below-zero weather. I don't remember the gel point of diesel
> either,
> > but I'm pretty sure it is lower than 15 below... now that I think
> about it,
> > if the numbers aren't in the diesel supplement to your owner's manual,
> then
> > the gel point is printed on the back of some of the bottles of fuel
> > conditioner. Oh, and with the new 6.0L electronically controlled
> diesel, if
> > you decide to use a fuel conditioner, "more is NOT better". Raising
> the
> > flash point of the fuel too far will play havoc with proper
> combustion.
> > We had some initial growing pains with the new 6.0L Diesel, but the
> reports
> > I'm seeing lately say that the late 2003 and 2004 units are top
> drawer.
> >
> > Dan Bodnar
> > SV QOL
> >
> >
> > -----Original Message-----From: rhodes22-list-bounces at rhodes22.org
> > [mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Michael
> Meltzer
> > Sent: Monday, December 08, 2003 9:46 PM
> > To: sanderico at earthlink.net; The Rhodes 22 mail list
> > Subject: Re: [Rhodes22-list] RE: Michael's Diesel #1 and #2
> >
> > That nice to know, under a little knowage is dangerous I heard that
> use
> > Kerosene can be use up to 20% in the winter, also almost
> > anything can go into a disel engine, like bio-disel, made from used
> frechfry
> > oil :-)
> >
> > MJM
> >
> > ----- Original Message -----
> > From: "Rik Sandberg" <sanderico at earthlink.net>
> > To: <kroposki at innova.net>; "The Rhodes 22 mail list"
> > <rhodes22-list at rhodes22.org>
> > Sent: Monday, December 08, 2003 9:54 PM
> > Subject: Re: [Rhodes22-list] RE: Michael's Diesel #1 and #2
> >
> >
> > > Ed,
> > >
> > > #1 fuel oil and kerosene are not the same thing. Kerosene is more
> > "refined"
> > > than #1 oil. #3 fuel oil is an even heavier oil than #2. I think
> they use
> > it
> > > for firing funaces (like asphalt plants) and things, industrial
> stuff more
> > > down south than up around here. It's heavy enough that you have to
> warm it
> > up
> > > before it will light easily. Not an expert on this though :-)
> > >
> > > I did run across a guy from down south a few years ago that claimed
> to be
> > > using #3 oil in the truck he was driving. It was about -20 F that
> night
> > and I
> > > stopped to help him as his truck was froze up (fuel gelled) on the
> side of
> > > I-94. Poor bastard was out in that shit in nothing but a light
> jacket and
> > a
> > > t-shirt. He was, to say the least, happy to see me. I would imagine
> that
> > they
> > > had to drain whatever fuel was in that truck and start over with all
> new,
> > > lighter fuel before that truck would ever go anywhere again before
> spring.
> > I
> > > think he learned that some of the things you can get away with down
> south,
> > > won't get you very far up here when it gets cold. Up here, we've got
> real
> > > honest to God.......COLD!!!!!
> > >
> > > Rik
> > >
> > >
> > > On 12/08/2003 08:16 pm, you wrote:
> > > > KEROSENE! What is # 3 used for? and yes there is a #3. Hey guys
> help
> > > > Rummy.
> > > >
> > > > Ed K
> > > >
> > > >
> > > >
> > > > Subject: Re: Michael's Diesel #1 and #2
> > > >
> > > >
> > > >
> > > > I've always just known it as #1.
> > > >
> > > > __________________________________________________
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> >
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