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Steam & Excursion > Coal vs. Oil Smoke

Date: 02/21/24 08:24
Coal vs. Oil Smoke
Author: jdw3460

I have read a few posts on the subject of converting coal burners to oil burners, primarily to reduce the risk of forest fires in the west.  The nostalgic whines about missing the smell of coal smoke is most certainly not a complaint of mine.  I lived in southern Kansas and my town enjoyed the frequent sounds (and smoke) of the Santa Fe, Frisco, and Mo Pac steam engines.   Both Santa Fe and Frisco were all oil burners and the MoP burned coal.  I learned very early that the Mop spread cinders with their smoke and I became prejudiced against being near the Mop trains.  But the MoP's engines didn't have the market cornered on smoke.  The oil burners supplied plenty of that also.  I have attached a photo of two double-headed Santa Fe Mikes belching oil smoke in California in the WWII era.  I am hoping Wes Camp might give us a treatise on the training and practice of the two firemen involved here.  Perhaps one engine was working harder than the other??  Maybe one fireman was asleep?  There was no EPA back then and the miles per gallon was not maximized by management.  Anyway, an ancient photo like this almost reminds me of the smell in the air when a hard-working steam engine climbed the hill out of my home town.

Date: 02/21/24 08:39
Re: Coal vs. Oil Smoke
Author: wingomann

Actually fuel usage was monitored back then.  My dad worked for SP as a fireman and said that a real dirty stack like the second locomotive could get you a talking to.  He always disliked when a locomotive would smoke it up for a runby.  His comment was always "They're wasting fuel!"  
But that being said, another possible reason for the dark smoke on the second loco could be that they are sanding the flues.  Don't be downwind of them when they do it.    

Edited 1 time(s). Last edit at 02/21/24 08:40 by wingomann.

Date: 02/21/24 09:01
Re: Coal vs. Oil Smoke
Author: Txhighballer

My guess is that both locomotives are wide open with a heavy train ( thinking the hoppers behind the locomotives are loaded) the firemen are fighting wide open throttles and running water pumps trying to get a roll on the tonnage. Once they get rolling, the smoke plume will lessen to a slight haze, at least hopefully it will.

Date: 02/21/24 09:39
Re: Coal vs. Oil Smoke
Author: Lackawanna484

That's a fine picture, thank you.

I hope no housewives were hanging out their white laundry  that day...

Date: 02/21/24 10:01
Re: Coal vs. Oil Smoke
Author: wcamp1472

Many years ago, when I first became deeply intrigued by sream engines,
I was encouraged by George Hart.  George owned several locomotives 
for excursions he operated out of York, Pa.

He was about 55 years old, and had been photographing trains from before WW2.
And later, he was an advisor to Reading Co., when they decided to re-introduce
the Reading Rambles, in 1960.

 George was very knowledgeable of railroading in Pennsylvania.  I had many 
discussions with him about his recollections .... I was a rapt student.
During one conversation, he was telling me about the common observation 
that with double-heading, it was common that the second engine would be 
smoking profusely, while the lead engines were relatively cleaner at the stack.
He told me that he observed that many times, but he had not actually asked 
engineers why that was.  We discussed possibilities, but made no firm conclusions.

In my observations, most smoking observations occurred in conditions of 
level track, or downhill.  Up hills, where train weights are heaviest, strong drafts 
in both engines made for both stacks to be clear and fires were strongly drafted.

So, remember that the burning of carbon ( solid or liquid) requires the proper 
weight ratio be maintained at 16:1.  16 parts Oxygen ( by weight), to 1 part carbon.
So, oxygen makes-up only 20%, by volume of the earth's air, 80% of air is 
Nitrogen.  The 'by weight' modifier is needed because of matching the requisite
fuel/oxygen ratios.  The thing to remember is that it takes many cubic
feet of air through the firebed, to get enough oxygen to match the released
carbon gasses.

Remember that "air"  is gasses... thus, you're matching molecules to make 
new gases:  CO2, CO, and H2O.  Air being gasses has immense spaces between 
individual molecules ... especially when compared to liquids and solids.

So to burn carbon, you've got to heat it to get to get the former states to 
be in the gaseous state.  New molecules must both be in the gaseous 
state.  So, when you're adding fuel, add it slowly enough---that you don't add 
cold fuel at too great a feed-rate .  The black smoke you see is free carbon
molecules --- all looking free oxygen molecules to partner-with...
What's needed is HEAT!  As soon as you cool-off the gasses, they wil
not combine.

If more carbon is added, the excess is un-burned carbon: black smoke.
Such observations tell you that firebox conditions are 'cold',  with low flame 
temps, adding more fuel further cools the combustion temperatures ---
in order to get carbon to burn, it must be heated to get the gaseous state.
Where does that heat come from?

Getting carbon to be a gas, from either a solid or liquid, it robs heat 
from the flames ---- cold fireboxes are due to trying to heat up, way too
much carbon.  When you see black smoke it indicates firebox temperatures 
between 1100F and 1800F, hottest carbon fires are about 3,000F!

The lead engine in this photo is running a little too rich, but that's OK..
The lead engine is pulling the whole train, and has a good draft.
The poor second engine has virtually 'no load' to create a strong draft.
So, the fireman is adding more carbon to try to keep-up boiler pressures.

On flat track, for the second engine to have a decent draft, they'd be over
70mph!   So, the engineer of the second engine can only add enough steam to 
keep #2 moving...any more power that he could add, and the train accelerates!

Boiler pressure drops, the fireman panics, adds more carbon, that cools-off the
flame temps even further ( cold, fresh fuel) and smoke gets darker.
Add more than enough fuel, and you can extinguish the flames!

The best practice is for the two engineers to meet & coordinate,
ahead of time, so that they together, balance the "drafting-load"
between the two locos.  The lead engine needs to be lighter on the throttle,
let #2 do some of the work.

In order to keep a clear stack on engine 2, ( with #1 doing 90% of the pulling),
the crew of #2 has to coordinate, across the cab,  on maintaining a fire at a
low draft condition.  You're gonna carry the boiler water a little higher level,
and let the firebox temperatures moderate.

At times when double-headed on fan trips, my stoker firebed was mostly
fine-stuff that burned-out quickly.  To keep a brighter fire, I'd build a big 
coal-bank, or 'heel' at the back 30% of the grate --- that increased the 
oxygen flow through the rest of the grate, and I'd use the scoop to throw 
larger coal lumps, strategically, across the flat firebed --- to keep flames 
active, over a mostly 'dead' grate.

So, my scoop rhythm was "3 scoops across the far front, 3 scoops across
the middle, and 3 scoops across the back". My scoops were about 1/3 full,
for better control ( targeting), and refresh scoops were added about 5 minutes 

So, that when we eventually reached the steep grade, and had the need, I'd add
the stoker feed. Stokers deliver large amounts of fuel very well; however,
at low firing rates they're very poor ---- the coal they deliver is crushed and
intended to be burned very rapidly!

At low firing rates I'd use the scoop so I could get the larger lumps to burn 
for a longer duration.  In such conditions, strategic placement is more important 
than quantity.  It worked best if I had a cab rider that wanted some of the "action".

I'd tell them about the 1/3-scoop Rule, and the 3-'Threes', across the grate.
It took them several tries, but soon they got better at it.  And I got to relax, and 
open the firedoors, when needed!

Firing a low draft sutuation requires more care and attention.
When 759 was hauling 80-car freights on the WM, 1972, the
Big Berk was right at home...a fierce draft, good coal and a wide 
throttle was a sight to BEHOLD!  On fan trips, we never got to properjy
'load' the engine, so with a train heavy-enough the to make a strong draft,
it was a pleasure to observe.


Not proofed, yet

Edited 3 time(s). Last edit at 02/23/24 14:17 by wcamp1472.

Date: 02/21/24 10:39
Re: Coal vs. Oil Smoke
Author: jdw3460

Thanks, Wes.  I knew you would cover the subject well.  And I'm sure there are a bunch of "modern" excursion firemen out there reading your post over and over.  8-)

Date: 02/21/24 10:48
Re: Coal vs. Oil Smoke
Author: HotWater

Remember that back in the old days of steam power, those railroads with "oil burning" locomotives used Bunker C fuel, which was so thick that it had to be heated to at least 150 degrees F, just to get it to move. That stuff smoked a LOT, when forcing the fire.

Date: 02/21/24 10:54
Re: Coal vs. Oil Smoke
Author: wcamp1472

The practice of a 'heavy-heel' across the back came 
from several NKP firemen that were assigned various segments
of the 1969, Golden Spike train, as we were on the former NKP tracks.
Without exception, the various "700's-experienced" men ALL, buit and
maintained the 'heavy heel" technique.  It worked very well on the 
flat track-profiles of most of the old NKP, but was also very useful
on the hills and undulating territories.

I was a slow-learner, but eventually it 'took-hold'...

As I've said, one old-timer gave me the BEST stoker advice:
He said: " Build your firebed so it resembles a coal-scoop:
high in the back and rear corners, and level and flat across the rest 
of the grate" ...

Best firing advice I'd ever gotten..


With oil-burners, follow what HotWater says.... I've never fired an oil burner..
    But the same fuel/air mixtures rules still apply; however,  being a liquid,
     the oil fuels have greater carbon-density, & they smoke, way-easier ....)

Edited 2 time(s). Last edit at 02/21/24 11:01 by wcamp1472.

Date: 02/21/24 11:57
Re: Coal vs. Oil Smoke
Author: Frisco1522

Second engine could be sanding the flues.   That produces one of those clouds you could walk on.
If the double header is lead engine=helper, 2nd engine=road engine, standard practice on some roads was to let the road engine work until it needed help than open up the helper and get up to speed.  To me that sounds kinda backward.  The helper should be working hard and then open up the road engine to lessen the water consumption.
Some firemen believe with an oil burner "You gotta make smoke to make steam".  BS, smoke is unburned fuel.  Jack's point about heating the oil is dead on.  Also some oil firemen frowned upon turning up the atomizer.  I don't know where that theory came from but its also BS.
I've only fired a stoker engine about 30 miles on a main line, so can't compare the two.  At least I didn't embarrass myself.
Lotta times it would have helped to have my Dad up in the cab tutoring the finer points of running. (and firing)
When we fired up 1522 for the first time, a retired Frisco engineer who fired back in the 40s came out and gave us some advice.  Was handy.
Ideal situation is to know your engine, your engineer and the railroad you're running over.  Or have a good pilot engineer who talked to you and told you what's coming up.  Can make you look good just as a pilot who doesn't want to be there or help.  I've had both and the fireman gains from a good one.

Date: 02/21/24 17:03
Re: Coal vs. Oil Smoke
Author: SR2

Lackawanna484 Wrote:
> That's a fine picture, thank you.
> I hope no housewives were hanging out their white
> laundry  that day...
Right you are!
Before 1956, my mother scheduled her laundry to hang outside between the C&NW wayfreight
and the CGW (on trackage rights) local it roughly gave her four hours.  We also had inside 
lines in the basement, sometimes an "extra" would mean at least a re-rinse if not a re-do.  The
"400" (518 and 519) runs were dieselized in 1951.

Date: 03/04/24 07:41
Re: Coal vs. Oil Smoke
Author: filmteknik

I’ve never been a fan of big smoke. And it has nothing to do with pollution. A fairly clean stack means hot, efficient combustion. For still photos, a bit of haze so you know it’s alive is ideal.

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