|Home||Open Account||Help||153 users online|
Eastern Railroad Discussion > TVA eliminating rotary coal dumpers?
Date: 02/09/04 08:55
TVA eliminating rotary coal dumpers?
During my last trip down south, I visited a TVA fossil power plant which apparently has switched from rotary dump unloading to bottom dump rapid discharge unloading.
Prior to this change, coal was delivered using NS Top Gon and ex-Conrail bathtub steel cars which, in the winter months, had to be flame-thawed prior to being shoved into the rotary dumper. Since Top Gons are not rotary cars, each car had to be uncoupled at both ends prior to the rotary dumper doing its thing.
After the change, the steel bathtubs have been replaced with TVAX and leased CEFX aluminum bottom discharge cars which cannot be flame-thawed. Apparently they use this air-powered jackhammer-like shaker thingy which gets raised and lowered from above to break frozen loads loose at the top during the winter months. They also may be applying some radiant heat too, but each car essentially got dumped in less than a minute, and thats not much time for radiant heat to thaw a coal load. The jackhammer thingy was raised and lowered using a mobile crane. Since the need to shake-n-break the load only happens when the temps get below freezing, there is no need for anything more permanent than a mobile crane to perform the task. What I could not tell is whether the shaker device was lowered down onto the top of the car sides, or down onto the load itself (not touching the car sides at all). I did note that the rotary dumper cage was up and out of its hole, and was sitting alone off to the side.
For as much as the car rebodying/rebuilding programs are taunted as progressive by the carriers, the railroads essentially created a car design which required a hell of alot of unnecessary "handling" at the unloading end - too much handling apparently in those instances where utilities find it more expedient to eliminate their rotary dumpers and switch to rapid discharge bottom dump cars which are purchased or leased by the utilities themselves. From my observations, the unloading process certainly was alot quicker using the bottom discharge/shaker method than flame thawing and rotary dumping the bathtubs.
Are other utilities 'shifting gears' towards elimination of rotary dumpers? Granted, this was 'down south' where continuous freezing temps and snow are less frequent than, say, in Ohio or Pennsylvania.
Are these rebodying programs worth the money/effort when the resulting car is too cumbersome for most customers to work with - to the extent the customer re-designs their unloading process? These Top Gon type cars may be okay for export coal where equipment cycle times are less critical and cars are used essentially as an equivalent for ground storage, but the prevalence of privately-owned cars in the domestic utility area imples that the railroad-owned rebodied cars are less than acceptable wherever equipment cycle times are more critical.
Do the portable shakers which are used to break up the frozen loads actually make contact with the cars in any way, or do they only shake the loads themselves? Is an aluminum car durable enough to be shaken gently in an attempt to break up a frozen load? Who makes these devices?
It would appear to me the biggest setback to efficient rotary dumping is the inability of railroads to keep rotary cars properly oriented so they don't have to perform any uncessary uncoupling during the unloading process. How often do you see a train of rotary cars where all the cars are properly oriented? Railroads seem willing to accept the penalty of uncoupling any improperly oriented cars rather than orienting them correctly and keeping them that way, to the extent that rotary dumping becomes less efficient than bottom dumping.
Date: 02/09/04 09:08
Re: TVA eliminating rotary coal dumpers?
As to the vibratory appliance itself. I am sure there are more than one brand out there but I have seen an FMC Syntron type be lowered to the top edges of a coal hopper to shake it out, even to loads that were not frozen. I believe it was air powered.
For NS to rebody the old hoppers to the Topgon body had to be cost affective OR it kept some people employeed rebuilding cars at a critical time.
Date: 02/09/04 11:02
Re: TVA eliminating rotary coal dumpers?
Kevin, I think that TVA is making a mistake and will regret it later. The Rapid Disharge Bottom Dump hoppers have a higher initial cost, and will have a higher maintenance cost for the doors later. Of course this is somewhat balanced by the cost of the Dumper. The Dumper however is stationary and is available for repairs most of the time. A big problem with hoppers the impact of the coal entering the car from the tipple. The mines, if they care, will try to slide some of the coal down the end sheets onto the doors which will cushion the doors during the rest of the loading process, Most of the Rapid Discharge type hoppers have steep slope sheets which stress the doors during loading. From the what you said the TVA plant had the worst possible arrangement where they have to uncouple the cars for the dumper. There is no good reason to have rotary discharge gondolas get turned around in the consist if they are fixed consist types cycling for one powerplant. Common user types serving many power plants can be a different story. IF you look at the trains running out of the Powder River Basin you will find that they are 90% or better rotary dump gondolas. The largest utility owned fleet belongs to Detroit Edison with over 5,000 cars and every one is a Rotary Dump Gondola.
Date: 02/09/04 11:13
Re: TVA eliminating rotary coal dumpers?
Minor correction, and a comment:
Detroit Edison does own some modern aluminum hoppers, but they are not of the quick-discharge variety. (Which begs the new question: why?)
As for rotary-dump gons being mis-oriented: if a dumper were capable of unloading two gons simultaneously, the orientation of the rotary end would not be a problem. There would be times when only one car could be unloaded, but two adjacent cars could always be rotated.
Date: 02/09/04 11:48
...on an interesting topic. Wish that I had something to add, but have enjoyed reading this thread. Thanks for starting it.
Date: 02/09/04 14:02
NS Rebody Program vs. Rapid Discharge
NS' TopGon program was started when rotary dump operations were becoming vogue, in the late 80's and early 90's. NS' Rebody program started with replacing the body of H11 and H12 class coal cars built by the N&W in '60's and '70's, some 27,700+ all told. There were roughly 8,000 that were rebuilt with a 3 bay dump bottom, (H11_R's, insert A-E, i.e. H11BR). Between 1992 and 1998, there were 13,800+ TopGons built from old H11's and H12's(G84R-G86R and G88R-G93R). Since 1998, there were another 3,000+ TopGons (G98R-G101R) that were rebuilt from Southern's former coal car fleet, until the program ended ~2000.
After the TopGon program ended NS built a small fleet of 100T 4 Bay Coke Cars called "High Tops", and also built a reather sizable fleet of 4 bay coal cars (H62R's) similar to Conrail's H2(?) fleet.
NS bought ~550 rotary dump aluminum hoppers (BethGons and "Dolly Partons", wher the tubs run the width of the car) and ~400 rapid discharge hoppers in the 1990's. So there was interest on NS' part in the new aluminum car phenomenon.
Point being, NS had the expertise (in Roanoke, VA) to rebuild their fleet, as they built most of it to begin with. The cause for the program was sulfur attack on the steel bodies. The center sill, trucks and draft gear were all re-used during the rebuild program. Keep in mind that when the cars were originally built rotary couplers didn't exist.
Pier 6 in Norfolk was built to handle two 100 ton cars at a time, and rotate them both, while bypassing the door latches, in an age were export "met" coal was a large portion of what N&W and later NS shipped.
A fair number of utilities in the southeast and leasing companies, have rapid discharge cars that have a rotary end on them, in order to run through various plant locations.
Is TVA eliminating their rotary dumps, I don't know, but they are expensive whether you are looking at adding one or removing it.
Hope this info. helps.
Date: 02/09/04 15:52
Re: Good post...
Yes ... This is a good post ... esp for us coal foamers!
Regarding freezing weather coal dump operations ...
Coal loadouts (at mines, prep plants or wayside operations) have the option of spraying a coal car's insides with antifreeze prior to loading coal to keep the coal from freezing to the car's surfaces. If that works (mainly if the antifreeze application has been thorough) the car shakers have an edge. They shake the car and -- with the coal not attached to the car surfaces -- the coal more readily bounces around and breaks into small enough glomps to drop or flow through the bottom car doors.
I should add, the shakers are not just feeezing weather devices as they are needed to help empty certain coal cars even in nice weather.
Missing coal country life ... Bob Loehne
Date: 02/09/04 17:11
Re: Good post...
I think TVA has just made a wise $$$ decision.
TVA's Bull Run plant has always used bottom dumps and is on what CSX calls it's Rapid Cycle System. Basically a train can load on the CV Sub in 4 hours, get to Corbin in two hours, be recrewed and get to Bull Run in 3-4 hours and dump in about an hour without ever stopping on the loop track. I've shot loaded TVAX hoppers on the CV in the morning and caught the same set again running mty in the evening. How long does it take an ice tray to freeze in your freezer? How long would it take 100 tons of coal to freeze solid? Think of all that mass! This has never been a major problem for Bull Run trains since the facility opened unless the train was delayed by CSX during sub-zero temps. The bottom doors opening in-route during the L&N days is another story.
Now at Kingston, things are much different since they are not Rapid Cycle trains. CSX and NS have a complex series of charges that apply when the end customer has a problem unloading. CSX Harriman trains (bound for Kingston) can sit at Hazard, Ravenna or Corbin for a day or more then sit in TN awaiting the dumping process. Same for NS trains, they pause at Weller, they pause in Middlesboro, etc. PRB coal can freeze coming across the midwest and NS is responsible for getting the cars back to the connecting roads on time. Coal can and does freeze. If the coal freezes, the railroad considers itself not responsible. Here's what TVA gets ticked about:
If coal is frozen upon arrival causing the mtys to miss a TLD (Target load date): $50.00 per car per day, that's $4,500 a day.
Recrew charge: $1,637 every 12 hours the hoppers sit at the PP.
Holding charge: $2,500 per day per train.
So right now, one frozen train that misses it's next TLD can cost TVA $12,274.
Now if the mtys miss a CLD (Confirmed Load Date), CSX tags another $1,637 per day on the bill up to a $5,000 max. Now TVA could be out almost $14,000 on day one.
TVA does get off on the charge for turning a rotary dump since they uncouple anyway. Otherwise, it's $189 per car to rotate it.
One other point to ponder, TVA does not itself operate any rotary dumps that's I've seen. Correct me if I'm wrong. They do own rapid discharge bottom dumps and they are long proven in Bull Run service. From what I understand, rapid discharge bottom dumps are less prone to freeze up problems than rotary dumps. The problem is not that the coal will not fall out, the problem is the coal comes out all at once. A rotary dump, when rotated frozen, runs the risk of one solid 100 ton block smashing into the hopper bin and damaging equipment. Bottom dumps tend to break the block up when the doors are forced open and gravity further breaks the block into smaller chunks as they fall across the door supports. The vibrators, which do contact the car bodies, then do a good job shaking the remaining coal free. Augers in the dumper can then manage the smaller chunks.
Frozen cars are only one problem that can cause delays and induce the above charges. Rotary dumpers fail, look at what they are exposed to. TVA switchers can fail, TVA personnel actually uncouple and move the cars so if something goes wrong, it's TVA's fault again.
Then there are car usage fees which are in affect for using TopGon and CSX tubs, they could be seeking lower charges by leasing bottom dumps from the various lease companies out there. Now they save the NS/CSX car usage charges (or get a credit-same thing), they save the maintenance on the rotary dumper and they don't need to worry about wear on the hopper fleet since that's up to the leasing company. Somebody in TN is getting an atta boy.
Date: 02/09/04 17:24
Re: Good post...
Re: TopHat's comments
I too noticed that most rapid discharge cars seem to be common with southeast utilities. Florida, Carolina, Alabama, and Georgia utilities all seem to focus on rapid discharge cars as opposed to bathtubs, which are more common up north. Anyone venture a guess as to why? Most of these southeast utilities use rapid discharge aluminum cars built since 1998-99 (or later), and essentially represent 'the latest design'.
BNSF Powder River coal thru the Memphis gateway via the Thayer Sub corridor, including the Scherer trains, feature rapid discharge-type cars as well.
Does coal consistancy (lumpy vs. dirt-like) come into play? I can see where the finer, dirt-like coal, once it gets wet by rain, would also have to be shaken even in the summer months. The lumpier stuff would seem to flow, even wet, in the summer months and would only need to be shaken in the winter.
Do any other carriers (besides NS) or any utilities utilize the unique "Dolly Parton" cars? (seen in the photo below). I seem to recall the builders sticker for these cars stated they were built by Trinity in Greenville PA (before that facility closed)
And no, Robby, I've never seen any TVAX rotary bathtubs either, so I doubt they own any.
Date: 02/09/04 19:12
Re: Apprpriately named.....
looking at the cars on the last post - Dolly Partons - they are appropriately named!
Date: 02/09/04 21:52
Re: Good post...
When I worked at a power plant as a temporary, the rotary dumper was almost 40 years old, sized for the old style short eighty ton cars with with bottom doors.
You had to walk onto the platform and into the cage next to the car to uncouple it while it was moving-it always scared the hell out of me-no where to go if something happened. The worst thing was that if the cars coupler did not line right you ended up derailing the empty coal car because the rotary dumper was on a curve. they had to bring in a wheeled crane to lift the car up and line it back up. We had, and I assume it still has radiant electric heat to heat the coal cars before they enter on the dumper floor.
The dump hopper had a sections of stainless steel welded together like the card board separators used in beer cases. This in turn helped break up the coal before it dropped into the apron feeder which fed the 48 inch conveyor to the coal stack where it was pushed back and stacked by a small earth mover. If the coal was still frozen you had to walk down into the hopper
and use a jack hammer it to break it up- all this time wearing a life line. The biggest thing that always bothered me was they did not use lock outs to de-energize the conveyor system or the primary crusher under the coal pile, they employed a tag only system to tell you that a conveyor or crusher was not to be started-I was not happy about that at all- I have seen to many times where a conveyor was energised and something happened or a conveyor would start by itself. The underpile draw system relied on a small secondary crusher mounted above the tail pulley in the concrete ceiling of the receiving pit for the 48 inch conveyor which feeds the coal pile to this day. Oh yes, before I forget we had to make sure that the air powered diverter gate to switch from the north pile to the south pile was working-every coal crew shift had to check it this way- you had to climb up on top of the tail pulley and take a 12 foot cheater pipe and slide it over the handle that was welded to the bottom of the air powered diverter gate and in the process hope you did not fall off the tail pulley and break your neck or anything else in the process. I made the mistake of asking for a ladder or small platform to be installed near the diverter plate and I got the usual- well we have never had a problem before, so why should we change it now speech. From what I have seen of the new dumpers they have no provision for a third man to stay on the tipper and disconnect the cars which makes much more sense safety wise. The thing that always sticks in my mind and probably will till I die is how
that young boy died there when he was crushed between the couplers of two empty coal cars, the lead man was not paying attention to where the crewman was and did not see him as he was lining up the couplers so they would not derail the cars. I do not know what is worse-
having it happen or the fact that he was related to a family friend. This is why I do not like the old dumpers as they were not designed for the newer heavier and longer cars and you had to shovel the spillover back into the hopper when it became unmanageable/fire hazard.
I am sorry for taking up so much space mt.ararat
Date: 02/10/04 09:59
Re: Rotary Couplers
Related to this: On cars such as the Top Gons, without rotary couplers, once they are rotated, doesn't the drawhead swing over to one side? Does the conductor then have to realign each drawhead when they put the train back together?
Date: 02/10/04 14:55
Re: Good post...
To my knowledge there are no other "Dolly Partons" in existance, other than a demonstrator that was built. Not sure if it wound up in the NS fleet.
Date: 02/11/04 07:25
Re: Rotary Couplers
It probably does swing over, but aligning drawheads comes with the territory. Often in such unloading situations there are barney men to ride the empties out of the dump shed, and part of the process would be checking the knuckles and drawheads, something every trainman does automatically anyway. Most unloading facilities are not owned by the RR and the plant would have its own barney men. That is if they also do car tipping to unload. Some plants like Virgina Power's Wheelwright plant can take any type car, they tip or open the doors or whatever, but they use up a train a day, so it's to their benefit, since sometimes the the railroad can't cough up a specific car type.