TrainsOfDisney
Well-Known Member
N
Some of the exhaust steam will condense into the feedwater heater and flow back into the boiler.
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Feedwater heaters on the WDWRR locomotives
- Thread starter disneytrain2001
- Start date
flynnibus
Premium Member
Turbines spin? Sir, this is steam train, not a generator@TrainsOfDisney almost certainly knows more than I do about this, but I believe that at least a portion of the saved water can be placed on this. I don’t know very much about Disney’s steam engines, but what I believe from my limited knowledge is that the hotter input water would also likely result in hotter steam (assuming a similar amount of energy is being applied). The water, theoretically, is only a medium to store energy, and therefore hotter steam results in more energy being exerted on the engine of the train. This reduces the amount of freshwater that the train needs to be fed because the train's turbines are being spun more efficiently. In other words, hotter water is doing the same amount of work with less water and greater energy. TrainsofDisney can certainly correct me, and I may be completely wrong, but I believe this to be the cause.
(This is more of a guess than an actual answer, I might be completely wrong)
TrainsOfDisney
Well-Known Member
The fun thing about steam locomotives is they are actually even more simple than that! They don’t have turbines, the steam pushes the pistons back and forth which move the driving rods which are connected to the driving wheels of the locomotive.
flynnibus
Premium Member
@TrainsOfDisney almost certainly knows more than I do about this, but I believe that at least a portion of the saved water can be placed on this. I don’t know very much about Disney’s steam engines, but what I believe from my limited knowledge is that the hotter input water would also likely result in hotter steam (assuming a similar amount of energy is being applied). The water, theoretically, is only a medium to store energy, and therefore hotter steam results in more energy being exerted on the engine of the train. This reduces the amount of freshwater that the train needs to be fed because the train's turbines are being spun more efficiently. In other words, hotter water is doing the same amount of work with less water and greater energy. TrainsofDisney can certainly correct me, and I may be completely wrong, but I believe this to be the cause.
(This is more of a guess than an actual answer, I might be completely wrong
The steam doesn't get hotter due to a pre-heat system like this... the good gas laws will regulate the steam's properties. They need higher pressure to get higher temp.
The pre-heat system reduces the amount of energy needed to reach the intended operating point... so it's more fuel efficient. Feedwater going into the system needs to be brought up to the operating temp using fuel. This simply reduces the amount of work the fuel needs to do to reach that operating point. You can use those savings to either reduce fuel spent.. or use that gained efficency to push your system harder for the same amount of fuel spent.
The 'saved water' has got to be about the discussion if it's an open or closed loop system. If it's an open system, the condensate from the steam that results from the heat exchanger could be recycled into the feed system. But supposedly that has it's own contamination issues (oil) - so it must be treated or other systems were closed loop so they don't regain any of the water from the exhaust steam... just their heat.
flynnibus
Premium Member
Open loop system. The steam used to heat the feedwater is cooled - a percentage of that steam condenses back to water... and can be fed back into the feedwater.
Basically you get to reclaim some of your steam exhaust as water due to the cooling work it did. But this water is not clean and systems had to be made to get the oil out of it.
DisneyFanatic12
Well-Known Member
Meant to say pistons, sorry... haha. Thank you for your explanations, it's fun to learn about!Turbines spin? Sir, this is steam train, not a generator
DisAl
Well-Known Member
99% sure that is not how it works. The "used" steam exhausts to the atmosphere after passing through the preheater. On steamships, generating plants, and nuclear submarines the steam is run through a condenser after it exits the turbine to cool it and convert it back to liquid which is then fed back into the boiler. On the WDW locos the steam exhausting from the small turbine generator was run through the preheater to warm the water coming from the tender before it entered the boiler. So no water saved, just fuel.
Another issue is that if the water is too warm before it gets to the steam injector it won't work. The water must be cool enough to condense the steam from the boiler in the injector. I have seen them have to pour cold water on the injector to get it to start the water injection process. The preheater must have been in the water line past the injector.
REGARDLESS of differing viewpoints on the subject, I still hate to see authentic technology removed from the locomotives. I'm sure the electronic boiler ignition is safer, but how are you going to be able to tell the difference between the engineer and the fireman if the fireman doesn't have the hair singed off his (or her) arm?
TrainsOfDisney
Well-Known Member
I’m 100% sure that’s how it works on some locomotives - I can’t say for sure about the former Feedwaters on the WDW locomotives though.
TrainsOfDisney
Well-Known Member
Yes. Traditionally, locomotives with a Feedwater heater required a pump.
If the water is still cool enough that the injector won’t work, I’m not sure how much of a difference the Feedwater is making? So maybe the Feedwaters on WDW were somewhat useless haha.
flynnibus
Premium Member
Thats a closed loop system. Trains are open loop because the steam is vented through open valves due to the piston action (instead of a turbine)…. And why trains go through so much water!
DisAl
Well-Known Member
Correct. Having enough water was a much greater challenge than having enough fuel for steam locomotives travelling across the country. I was told that the water at WDW used in the locos is purer than the drinking water to help reduce scale in the boilers. If I remember correctly the WDW locos use about 200 gallons of water to 50 gallons of fuel.
To me there is no sweeter music at WDW than the sound of the whistles on the trains and the riverboat.
Long live steam trains! (And riverboats too.)
Rinx
Well-Known Member
Thank you for teaching me the value of PROOFREADING! Yes, I meant FUEL. Oh my goodness the mayhem I have caused on this thread and the subsequent posts. I apologize everyone. I am a menace and a shame to my avatar
I really should've checked back on this a couple days ago...
TrainsOfDisney
Well-Known Member
Indeed… let’s argue about what kind of Feedwater the Strasburg 90 has!!!! Haha
DisAl
Well-Known Member
Just blame it on spell checker! That's what I do...Thank you for teaching me the value of PROOFREADING! Yes, I meant FUEL. Oh my goodness the mayhem I have caused on this thread and the subsequent posts. I apologize everyone. I am a menace and a shame to my avatar
FYI I could use a preheater here is southeast Alabama.
Low of 16 degrees tonight. I know that doesn't compare to what some of you are experiencing but for us that is COLD!
DisAl
Well-Known Member
Let's throw superheaters in the mix and we can really have some fun here.Indeed… let’s argue about what kind of Feedwater the Strasburg 90 has!!!! Haha
DisAl
Well-Known Member
The locomotives at WDW have both pumps which are driven by the piston rods and steam injectors. The problem with the pumps is that they only work when the locomotive is in motion. If the loco is stationary for very long and they need to add water to the boiler they have to use the steam injector.
All things considered a steam locomotive is an absolutely fascinating piece of technology. I will admit that the guy who invented the steam injector was a whole lot smarter than I am.
TrainsOfDisney
Well-Known Member
Are you saying this is how it was with the Feedwater or how it is now? You don’t need the pumps if you don’t use the Feedwater although I guess you could just for fun? Haha.
Or perhaps Disney doesn’t want excess steam / water releasing when they open up the injectors?
DisAl
Well-Known Member
They had the pumps available regardless of whether they were using feedwater preheaters. The pumps are much easier to use - just open a valve if the train is in motion. When the trains are in service the pumps provide plenty of water.
They often have to use the injectors first thing in the morning to add water while getting ready and doing the safety check of the pop off (over pressure valve) and boiler blowdown. (Another bit of trivia - the boilers are rated at 300 psi and the safety valves are set at just over 150 psi.)
The steam injector has to be "tuned" by adjusting the feed valve with the water coming from the tender and another valve regulating the steam coming from the boiler. There is a "sweet spot" where both valves are set just right to achieve water injection into the boiler. And the warmer the water coming from the tender the more cantankerous it is to get it running.
When they hit the sweet spot no steam or water is lost. The steam condenses in the injector and that condensed steam goes back into the boiler along with the water drawn from the tender.
For those of you who may be as much of an engineering nerd as I am here is a link to a video on how steam injectors work.
For those of you who have already heard much more of this than you ever wanted to know, sorry....
I don't know if they still do this, but during the night time fireworks show the train would park in the woods on northwest side of the MK on fire watch and they would have to use the injectors to add water.
Finally, if I lived close enough to WDW to be a cast member my dream job would be on a locomotive!
TrainsOfDisney
Well-Known Member
Historically, a locomotive wouldn’t have a pump if it didn’t have a Feedwater heater, there would be no need. But it’s easier for the crew so that makes sense.