Norris, anyone handling large quantities of hydrogen sulfide certainly should have protective gear. I never dealt with more than enough to precipitate cations when I was taking qualitative analysis in college so I could see what cations were present in the unknowns I was given to analyze. Even that little bit was dangerous--and when I think of how little protective gear we had 50+ years ago, I sometimes shudder.
Johnny
jumper- That sounds way too exciting. Do the workers wear any type of protective clothing or masks to do that kind of work?
Thanks to Chris / CopCarSS for my avatar.
I used to work at a chemical plant where we used compressed air to assist in off loading sulphuric or caustic acid tank cars, an air to liquid propane heat exchanger to vaporize the liquid propane thus providing the pressure to offload the tank car and finally a steam powered/heated vapourizer to vapourize liquid hydrogen sulphide providing the motive force to move liquid H2S into storage bullets. All the tank cars had liquid and vapour relief devices which sometimes decided to lift at lower than original/design/spec set pressure. That created some exciting moments while trying to get the tank car depressured and the RV/SV repaired/replaced.
zugmann PZ 1 When I was a kid in the 60's, when the county highway department was paving a road, they would have the tar delivered to a nearby rail yard in a tank car. They had a 1940's Chevrolet truck that had a boiler on it. There were pipes that connected the boiler to the rail car for heating the tar. I assume there were pipes inside the car that the steam flowed through. Then the heated tar would be pumped into the tank of a tar spraying truck, I suppose using steam pressure. I would not think it is done like that anywhere anymore. Strasburg RR has been known to use one of their steam locomotives to heat up tankloads of vegetable oil so it can be transloaded into trucks. But lots of industries still use steam to heat up cars for unloading. Strasburg just has a mobile source...
PZ 1 When I was a kid in the 60's, when the county highway department was paving a road, they would have the tar delivered to a nearby rail yard in a tank car. They had a 1940's Chevrolet truck that had a boiler on it. There were pipes that connected the boiler to the rail car for heating the tar. I assume there were pipes inside the car that the steam flowed through. Then the heated tar would be pumped into the tank of a tar spraying truck, I suppose using steam pressure. I would not think it is done like that anywhere anymore.
When I was a kid in the 60's, when the county highway department was paving a road, they would have the tar delivered to a nearby rail yard in a tank car. They had a 1940's Chevrolet truck that had a boiler on it. There were pipes that connected the boiler to the rail car for heating the tar. I assume there were pipes inside the car that the steam flowed through. Then the heated tar would be pumped into the tank of a tar spraying truck, I suppose using steam pressure.
I would not think it is done like that anywhere anymore.
Strasburg RR has been known to use one of their steam locomotives to heat up tankloads of vegetable oil so it can be transloaded into trucks.
But lots of industries still use steam to heat up cars for unloading. Strasburg just has a mobile source...
What I meant was road paving. When a road is paved (tarred or sealcoated) today, normally a truck delivers the tar directly from the source to the site rather than sending a tank car there and transloading it to a truck. It is possible it is still done, but it would be uncommon today.
Now Conrail Shared Assets did try the swing bridge method of unloading tank cars. Didn't work too well.
Too soon?
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
Asphalt in tankcars is still heated by steam pipes in the car when its time to transfer the asphalt out of the railcar.
The huge storage tanks at the terminal are heated by hot oil that circulates through coils installed in the tank bottoms. Each tank has independent temperature controls enabling different tanks to maintain their contents at different temperatures. Tank cars are heated with steam to raise the temperature of the asphalt and decrease its viscosity so it can be pumped out of the tank cars into the storage tanks.
I used to haul tankers over the road MC707 class stainless steel 7000 gallon capacity hauling foodgrade products and non foodgrade. We never mixed the trailers IE If their first load was foodgrade that was their load for the life of the trailer.
One haul I liked was from Cincinnati, Ohio to Green Bay, Wisconsin, I forget the product name but it was loaded heated and maintained heat by engine coolant built into the trailer. Each trailer was completely cleaned and sterilized before the next load including all safety devices on the trailer. When I arrived in Green Bay with my first load it was suggested to me by the unloader to open the top hatch and fore and aft fittings ( standard two inch thread fittings with sealed caps) and bring a hammer to punch out the solidified product before unloading. You also had to break up all the solidified product from the top hatch as it would plug solid the vent valves, We hadto leave the top hatch sitting on the tie down threaded rod to admit air as I never trusted the vent valves after that first load.
Three months later another driver failed to do as I explained and had to call saftey to explain he wrecked/crushed a brand new MC707 trailer on it's first load. $86,000 gone in an instant.
Over in Revere, Mass were long tracks (4 of em) that I later found out were the primary unloading/loading points for East Coast oil products in WW II The Boston and Albany Railroad had a switcher assigned 24-7 from 1942 to the end of the war. The tracks held 40 cars each and were pulled according to my Engineer back in 1973 every two hours and the average tank car back then was a (for the times) a staggering 8000 gallons per car!! The local delivery tractor trailer tankers back then averaged 4 to 5000 gallons which were considered to be huge.
Soory guys I digress too much but it is interesting to see the difference in size on equipment between a few decades makes.
James Shanks
'TankTrain' cars are regulars in Albany, NY. I'd say they run maybe 5 cars per unit.
With the penchant people and businesses have for circumventing and breaking rules.... I guarantee it.
My guess would be four to five hours for a 30,000 gallon car, based on one hose. I used to drive tanker trucks (6,000-7,500 gallon tanks) and these would take about an hour to unload by gravity.
Paul,
Minor nitpick: For a given flow velocity in a conduit, the pressure drop should decrease with increasing diameter, so you "should" get more than 4X the flow rate with 4X the area. OTOH, there may be gotchas that increase the friction factor to make up for the reduction in L/D (that's Length/diameter, not Lift/Drag for you aviation fans...).
Having said that, good job on the off-the-cuff analysis.
- Erik
Thanks for that data, Brad. A 6" hose has 4 times the area, so about 4+ times the flow rate, hence 4+ times the volume in the same time: 4 x 6,500 = 26,000 gals. in 30 mins., pro-rate to about 35 mins. for 30,000 gals. Pretty good correlation for such an 'off-the-cuff' analysis.
And with a bigger hose, just get bigger (or multiple) pumps to handle larger flows.
- Paul North.
I haul milk in a 6500 gallon smooth-bore tank, it can unload through a 3" hose, 2" thread (on the pump) in about 30 minutes, even with 30+ foot of "head" inside the storage tank. It can gravity unload (four foot drop, 3" hose) in about the same. Pump flow is about 200 gal/minute.
Brad
EMD - Every Model Different
ALCO - Always Leaking Coolant and Oil
CSX - Coal Spilling eXperts
I sure hope you knew I was kidding.
Besides how to unload and implode a rail car, how to unload and explode a rail car.
Concentrated sulfuric acid is nasty commodity. Tank trucks unloaded it using air pressure. Drivers loved the plant's house air. It was higher volume and pressure than their PTO driven compressor could generate.
The problem was bursting the rupture disk required to prevent excessive pressure. One trick drivers knew was to insert a piece of a beer can in place of a rupture disk. This violation expedited unloading.
When unloading was completed, drivers would remove the beer can metal and replace it with a new rupture disk. When they returned to their terminal, or went through a D. O. T. road inspection, nobody was any the wiser.
Is this practice a known problem with rail cars?
Ironeagle2006 Stuff I haul every now and then I might get 2 loads a month has the consistency of 90W Gear Oil when Cold. Compared to the Acid I haul it is a Very and I mean VERY Stable load inside those Smooth Bore Tankers. We use a Standard 4 Inch line to Drain the trailer and no more than 10 PSI otherwise the relief Valve will pop and then you got a Problem. WPG is right around 12 how we haul so much to the Factory is Simple they do not have a Direct Rail Unload Point at their Factory. However my Boss has a Trans Shipment Point less than 20 miles away. So we load up and go with a FULL and I mean FULL tanker load and get it over there when they call for one. Best part is getting the Free Stuff from this Plant every Now and then like Cookies and such.
Stuff I haul every now and then I might get 2 loads a month has the consistency of 90W Gear Oil when Cold. Compared to the Acid I haul it is a Very and I mean VERY Stable load inside those Smooth Bore Tankers. We use a Standard 4 Inch line to Drain the trailer and no more than 10 PSI otherwise the relief Valve will pop and then you got a Problem. WPG is right around 12 how we haul so much to the Factory is Simple they do not have a Direct Rail Unload Point at their Factory. However my Boss has a Trans Shipment Point less than 20 miles away. So we load up and go with a FULL and I mean FULL tanker load and get it over there when they call for one. Best part is getting the Free Stuff from this Plant every Now and then like Cookies and such.
Paul_D_North_JrAssuming corn syrup has roughly the same density as water ...
High Fructose Corn Syrup (HFCS) is actually quite a bit more dense than water. Not all HFCS in commercial use is exactly the same, but generally it is of similar density to honey. Roughly, water is 8 lbs per gallon, honey is 12 lbs per gal. A typical HFCS product is about 11.5 lb per gallon.
(I am also a beekeeper, and honey, sugar, and substitutes are hot topics on beekeeping forums. )
The first photo is the result of a plant worker steam cleaning a tank car, exiting the car and closing the manway hatch, without opening the tank car drain and safety valve.
The video is from Brazil, it is a training tape made for plant workers showing what happens when a non-pressure differential tank car is drained without opening the safety valve.
All US tank cars that carry pressurized gas and liquids have what Mac says, a vacuum breaker valve, which is a one way valve that allows outside air to enter the car.
23 17 46 11
Sparing everyone the math, and ignoring friction, 'head losses', 'edge', orifice, or 'inlet control' effects, etc.:
A 6" diam. outlet has an area of about 0.20 sq. ft.
A 10 ft. diam. tank at half-full (5 ft.) of water at normal temps. will discharge at about 18 ft./ sec. (per Bernoulli's equation).
With various measurement unit conversions, that works out to about 1,600 gals. per minute, if I've done the basic math right this late at night.
So to unload that 30,000 gal. tank car through a single outlet would take about 20 mins., more or less.
Details and refinements, etc. are invited.
Ironeagle2006 Well I can unload 6k gallons of product in a tank trailerin less than 30 mins with 10 psi of air pressure in my trailer and that is hauling corn syrup.
The 10 psi would greatly speed up the process, too. The average pressure of the syrup in an 8 ft. diameter (guess) tank from gravity only would be on the order of 2 psi*, so with the 10 psi added that's 6 times greater.
*Assuming corn syrup has roughly the same density as water - 62.4 lbs. per cubic foot / 144 sq. inches per square foot = 0.43 psi per foot of depth, so under gravity only (no air pressure added) the pressure at the outlet would vary from about 3.5 psi when the 8 ft. diam. / high tank is full to 0 when it is empty. No idea on the viscosity or 'flowability' of the corn syrup, or at what temperature, etc.
Since pressure relief valves are commonly used even on hot water heaters it did seem to me that relieving the vacuum inside a tank car should not be difficult. After all, the problem is excess pressure in the atmosphere.
Most nonpressure cars equipped with bottom outlets have a "vacuum breaker" valve for exactly that reason.
Mac
Semper Vaporothe collapse is often NOT "slow".
I didn't intend to suggest that a tank car which is drained without allowing air to enter would collapse slowly. Rather, in the experiment I describe if the steam filled can is allowed to cool slowly the collapse will be slow because it takes the steam a while to condense. When a tank car is incorrectly drained the vacuum is produced very quickly so I would expect the collapse to be fairly quick.
I am surprised that no fail safe system to prevent such a collapse has been found. Tank cars have been around for a pretty long time now so the problem must not be new.
WHOOPS! posted to the wrong thread! Sorry about that.
Well. I do have something to say here too... the collapse is often NOT "slow". Once the stress reaches a certain point the vessal will start to collapse and once over the starting point, it occurs very rapidly.
Semper Vaporo
Pkgs.
Thanks for the illustration. It sure shows how important admitting air can be. It reminds me of a simple experiment in physics. You take a gallon can with a screw top, put a little water in it and boil the water until the can is filled with steam. Then take the can off the fire and screw on the top. You can run cold water over it or just let it stand and watch the slow collapse as it implodes.
Watch it happen!
watch?v=Ehci9vrvfw
Without being absolutely certain, it looks like that tank car was an empty which imploded when the vapor inside the sealed tank condensed.
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