How do railroads keep coal from freezing together in open cars? For that matter, how did they keep coal from freezing together in the tender of steam locomotives?
The short answer is they didn’t. In many locations, when it was time to unload, the train was pulled under a steam line that “defrosted” the coal in the cars so it would unload.
As far as coal in the tenders, the fireman was constantly removing scoop-fulls from the bottom so the pile was always sloughing off. Then you had a large heat resevoir surrounding that coal in the form of the water. In some cases there were steam heat lines in the water tank to prevent freezing.
I believe that Mike is right on this one. It makes a lot of sense to me.
CANADIANPACIFIC2816
The biggest freezing problem was with coal loaded in hopper cars. As loaded, coal is not that susceptable to freezing in a 100 ton block as there is not usually enough moisture on the surface of the coal particles for the frozen moisture to produce a tight bond between the particles. Further, a carload of coal is a pretty big heat sink.
However, if there was a heavy rain followed by freezing temperatures the water migrating to the bottom of the cars and into the hoppers could freeze into solid blocks. Depending on temperatures and moisture, some coal could freeze to the surface of the sides of the car, but the blocking of the hoppers made it impossible to dump the load through the hopper doors.
In the days before unit trains, almost every coal yard in northern climates would use fire to heat the hoppers and melt the ice. Some facilities may still use that method today, but there are other means of addressing the problem. Rotary dump facilities will empty most of the coal from a car and any frozen coal remaining in the car just moves on the with “empty”. Some terminals have thaw sheds. American Electric Power has (had) a river terminal at Mound City, IL on the Ohio River that had a long shed that used electric radiant heat to thaw the loads.
Spraying a mixture of ethylene glycol and water on the coal is another method of controling the problem. While the water in the load will still freeze, the ice crystal structure is weakened to the point that the car shakers will break everything loose and the unloading can proceed.
I once had to deal with a 50 car consignment of coal in hoppers that because of an unexpected turn in the weather arrived at a power plant with the hoppers blocked solidly. With car detention charges mounting rapidly, I made the decision to call a local construction outfit to bring over a crane with a clam shovel to dig the coal out of the cars. That, and a turn in the weather finally got the
Four seasons ago after gettin’ a load of coal in the trailer it sat outside for a night with 10+ hours of sleet and freezing rain. Had to let it sit in the garage for a day to make it shovelable to get it into the bin.
Adrianspeeder
Now they know why all the scorch marks on the old steel coal hoppers and why the stencilled “no thaw / radiant heat ONLY” warnings on the aluminum hoppers…did they notice the vibrator pockets?
Another question. How do the car ID tags do in an elevated temperature situation?
Do I read this to mean that most coal cars go through a car shaker before unloading?
No. Most don’t. Shakers are a nice-to-have with the old cross-hoppers when they’re hauling coal with a high moisture content especially in freezing weather but are rarely required for rapid-discharge cars and seldom for rotary-dump cars. Ditto with thaw sheds; most users of rapid-discharge do not have them and even fewer for rotary-dump cars. Most of the thaw sheds I’ve visited are in very cold places like Prince Rupert and Superior.
I’ve never heard of issues with melting the insides of AEI tags while heating cars but perhaps it’s possible. Generally the torch heating is confined to the door area, and the AEI tag is up on the carbody side.
Back in the bad old days as jeaton and mudchicken point out, the primary method of getting coal (or whatever) to dump out of a car in cold weather was to beat the tar out of the door area with a sledge, or heat it with a torch, or both. Only the really deluxe car dumper facilities with high throughput required, like Norfolk or Newport News, were equipped with luxuries like shakers or thaw sheds.
S. Hadid
As unloading. Coal doesn’t want to flow out of the hoppers very freely. Think something like damp sand. A car shaker is a rather heavy machine built in an “H” shape, with an electric motor driving an eccentric fly wheel. A winch lowers the shaker onto the top of the car sides, flip on the juice and rattle the “heck” out of the car. The vibration fluidizes the coal and the coal flows out like water. I suspect that left on long enough, the shacker would knock the rivets out of the seams and reduce the car to a pile of sheet metal, but 15-30 seconds of shaking will get the car empty.
I can only imagine what it was like in the era of coal powered furnaces heating nearly every house and Coal Dealers and their delivery men, coal chutes through the basement wall, coal bins…all in the dead of winter…ugh…
You can imagine it - I lived it. [4:-)]
Back in the days of local coal delivery, the dealers built up stockpiles so they didn’t have to do with the thawing issue very much (I remember some cars being pounded, but never torched). Once the coal was loaded off the stockpiles onto delivery trucks, it didn’t really have time to thaw before being deposited in a coal bin (when our old house had a coal bin, I remmber chutes or belts, depending on the truck) being used for unloading.
I think it DID reduce them to a pile of sheet metal – you should have seen some of the old IC and MKT hoppers we used to lease. The side sheets were practically flapping in the breeze on some of them.
S. Hadid
The shaker at the coal unloader where I work shakes surrounding buildings - 100 yards away…
UW Madison’s heating plant uses live steam to thaw out frozen cars, doesn’t take much. I also remember seeing some badly burned cars from places that used torches to thaw the cars.
Wouldn’t it just be easier to use covered hoppers?
A sealable, lightweight plastic cover over the opening wouldn’t be that extra heavy or expensive, not all that much a maintenance hassle, would it?
No.
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Most of the moisture in most coal is already in the coal when it comes out of the ground (PRB coal is ~25% water). The cover would only keep out precipitation and do very little to insulate the coal from freezing temperatures.
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The cover would substantially increase costs for loading, unloading, and transportation. Covered coil cars are a royal pain.
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The cover has capital and replacement costs which might not be much for one cover but multiplied by 1,500-2,000 cars in a typical large power plant’s trainset fleet, adds up to a very large number.
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Freezing just isn’t a factor at most of the plants all of the time, and only matters at the rest of the plants some of the time.
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Freezing is rarely a problem with rotary dump or rapid-discharge cars, ever!
S. Hadid
Didn’t I say to check with me first?[|(]
Actually, that was tried on the East Broad Top (narrow gauge) railroad in the winter of 1932-1933. They fitted 2 of their three bay hoppers with doors on the top that hinged to one side for (I assume) loading. The conclusion: “the desired results were achieved with the coal, but opening those doors was something else!” There’s a photo of one of them on page 136 of East Broad Top by Rainey and Kyper.