Big Bad John Locomotive

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  • Member since
    December, 2004
  • 602 posts
Posted by tdmidget on Wednesday, January 10, 2018 10:21 PM

NWP SWP

Well the NWP-SWP System runs from New Orleans to the west coast all the way to the top then on to Chicago...

Could theoretically jet turbines be used in the locomotive? Being fueled by aviation fuel?

Overmod, I really appreciate your help, but some of the stuff your saying is going over my head could you try to explain your ideas in layman's terms?

 

NWP SWP

Well the NWP-SWP System runs from New Orleans to the west coast all the way to the top then on to Chicago...

Could theoretically jet turbines be used in the locomotive? Being fueled by aviation fuel?

Overmod, I really appreciate your help, but some of the stuff your saying is going over my head could you try to explain your ideas in layman's terms?

 

"jet turbines"? grow up. This is not the fifties with the love affair with the word "jet". here is a "jet turbine locomotive":

https://www.pinterest.com/pin/383650461988036101/

It it is driven by a shaft , it is not a jet in any shape or form. It is a "combustion turbine" in the common usage of "gas turbined". Steam is a gas so all steam turbines are "gas" turbines. Combustion turbines do not require aviation fuels. Such fuels are spec'd with such factors as extreme cold and ability to start under extreme conditions. If you were paying attention you would know that such locomotives have been tried by Union Pacific. They did not require aviation fuels. They were not "jet turbines".

  • Member since
    December, 2017
  • 127 posts
Posted by SD70Dude on Wednesday, January 10, 2018 10:35 PM

NWP SWP

Could theoretically jet turbines be used in the locomotive? Being fueled by aviation fuel?

Jet fuel is indeed very similar to kerosene but turbines can easily run on pretty much any liquid fuel (and there have been experiments with pulverized coal or coal slurry), historically the most common turbine locomotive fuel has been heavy residual oil (thick tar-like Bunker C grade).  The reason for this is simple:  It was dirt cheap, to the point of being almost free, and this made up for the turbine's monstrous appetite (the UP turbines consumed roughly DOUBLE the fuel volume that diesels of equivalent power would burn).

As I said this did not matter at first but eventually became the turbines' downfall, as refineries found new markets for residual oils (especially in the plastics industry) their price went up, and turbine locomotives became uneconomical to operate.

But this would not have been an issue in the 1950s, and there is plenty of room in your boxcab for both a turbine and an auxiliary diesel engine, which is very useful in both starting the turbine and moving the locomotive around shops & yards (UP once got to replace all the windows in a roundhouse after someone started one of the turbines inside).

UP also investigated using propane as a fuel, carried in a pressurized tender.  The turbine actually ran better on propane (clean burning, no soot or ash like with heavy oil) but refueling was difficult and time-consuming, and there were safety concerns about carrying that much propane right next to the locomotive (I wonder how that would play out in today's world of LNG tenders?).

Coal-fired turbines never did get around the problem of ash destroying the blades.

An additional problem is that turbines are incredibly inefficient at idle, burning nearly the same amount of fuel as they do at full throttle.  This is why the auxiliary diesel engine was used to move the locomotive when it was running by itself.

I can boil my ramblings down to this:  A turbine powerplant makes sense if your #1 priority is raw horsepower, and/or your railroad wishes to use a fuel other than diesel.  Otherwise a multi-engined diesel makes more sense.

Greetings from Alberta

-an Articulate Malcontent

  • Member since
    September, 2003
  • 4,516 posts
Posted by Overmod on Thursday, January 11, 2018 2:27 PM

SD70Dude
I can boil my ramblings down to this: A turbine powerplant makes sense if your #1 priority is raw horsepower, and/or your railroad wishes to use a fuel other than diesel. Otherwise a multi-engined diesel makes more sense.

Steven: note tdmidget's comments carefully (he is knowledgeable about power turbines).  The correct term for what you're using is turboSHAFT engines, and there are much more 'likely' designs today than there were in the era you're wanting to model, with a host of issues including the ones already mentioned.

One great promise of relatively small turboshaft engines was that their relatively small size and light weight  would allow them to be packaged in lightweight passenger trains -- that is NOT your concern here.  Neither is the idea of using alternative crap fuel like #5/#6 in an expensive and finely machined Brayton-cycle device, without effective regeneration or even cost-effective applicability of combined-cycle equipment.  One important priority of railroad economics is to keep the cost of fuel down; another is to minimize the absolute fuel consumption (by extension in modern practice with SCR, 'fluids consumption'); yet another is to have fuel that is relatively immune to fires or accidents in handling.  I have never thought of any of these things applying to gas turbines burning some weather-tolerant version of Jet A.  Unless you arrange your turbines to burn diesel, you'll have to arrange ... and staff ... and maintain ... alternative fueling facilities, including emergency response capability, for the alternate fuel, and it is likely only a matter of time before the wrong fuel makes its way into a consist of the other kind of engine.  This may not be catastrophic in the YouTube video sense, but a consist that may require a full purge of what may be gelled fuel is not a happy thing, even once.

I tinkered around with the idea of stuffing an E-unit shell with a bunch of PT6 gensets in modular frames, with the idea I could start and stop some of them to approximate the output of Essl's locomotive (and use the additional power in something like MATEs with fuel bunkers).  This was pretty well given the kibosh after the oil-price shenanigans in 1973, similar to what shut down effective development of gas turbine power in rail applications almost anywhere else.  There are other reasons not to use them 'on the ground' in a high-vibration environment subject to over 180g of instantaneous shock, but we don't need to take them up if the idea is already a non-starter economically.

One thing that at least in theory favors a combustion turbine over a compression-ignition engine is that the fuel they use can be less refined with lower need for additives.  Modern diesel injectors involve close tolerances and special coatings; if you have experience with light diesel trucks you will already know about stuff like Stanadyne and reasons for its use.  Turbines can be made to run on just about anything that can be run through simple injectors with adequate heat release and reaction time characteristics ... the Chrysler turbine-car development program made the interesting comment that the engine would happily run on Chanel #5, which if nothing else proves some engineers have a good sense of warped humor.  This is common to light-oil firing in steam locomotives: you can cut quite a few steps out of the production process otherwise needed for diesel fuel or 'biodiesel' and still have something that works quite nicely and reliably.  Of course, you then need a production and distribution infrastructure for the lower-cost fuel -- a point upon which many alternative-fuel schemes have foundered.

See the earlier discussions (related to restoring a UP 8500 turbine set) concerning gas fuel.  Personally I don't think much of LPG or CNG, and while it is possible to inject LNG into engines it is NOT something that typical lowest-cost railroad power is likely to find valuable (as tdmidget indicated, most of the working schemes to burn it involve vaporization of the liquid, ideally with 'regeneration' heat, before combustion).  I could tell you a reasonable alternative to free-piston generation of the 'typical' 1950s sorts ... but it is likely to produce even more problems for the neighbors than 'hot starts' of the UP turbines did Wink

(erikem: do you think he might get more benefit than he would out of the Oxford catalytic cycle if he tried this as fuel for a high-horsepower engine?)

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