Why no high pressure steam turbine?

[APOLLO]

The Norfolk & Western built the giant Steam turbine electric loco "Jawn Henry"

 

 

 

http://www.rlhssec.org/pdfs/SEL1006.pdf

 

 

 

 

 

Other Railroads built them also. None were exactly successful, and perhaps the then new Diesel Electrics were better. This explains.

 

https://www.steamlocomotive.com/types/turbine/

 

Still at least they tried !!

 

Brit15

[lather]

I'm surprised that nobody has mentioned the Beyer-Ljungström steam turbine loco that was tested on the Midland Main Line. An unusual beast as the driven wheels were under the tender...

 

(See picture here: https://en.m.wikipedia.org/wiki/Steam_turbine_locomotive#/media/File%3ALjungström_locomotive_(Wonder_Book_of_Engineering_Wonders%2C_1931).jpg )

[keefer]

The 'Loco Locomotives' site has sections for High Pressure and Turbines:

http://www.douglas-self.com/MUSEUM/LOCOLOCO/locoloco.htm

Edited January 7, 2022 by keefer

[peach james]

Having played at the experimental part of model engineering...

 

1:  High pressure steam (>300 PSI) means a water tube boiler.  Tried.  Several times.  See Sentinel for examples.  See Fury, CPR and D&H (US) for examples of multi pass systems running high pressures.  

In conjunction with that is the triple point of steam, which is about 3200 PSI.  There are stationary plants which run above that for efficiency (n) reasons.  ( https://en.wikipedia.org/wiki/Supercritical_steam_generator )

Water tube boilers in railway applications have had a storied history of failure.  Sentinel made at least 6 locos with them, and a series of railcars.  They also appear in Hush-Hush, and the abovementioned Jawn Henry.  

2:  Turbines.  Turbines are less efficient than steam at lower power outputs.  Even the Cofflin CG pumps we had used an "excessive" amount of steam in comparison to the HP generated- they ran about 10 000 lb/hr for 600 hp (or about 17 lb/hr) in comparison to high speed reciprocating steam which could manage as low as 14 lb/hr.  As you get smaller than 600 HP (the CG pumps come quite a bit smaller- they were used on the SAR class 25's for feed pumps), the steam demand doesn't drop that much.

Similarly, dad recounts fitting a Stones lighting dyno onto 8122, and said it was rather a hungry beast for 500w of electricity...small turbines suffer from inherent losses which make them less desirable than you may think.

Traction turbines have to face the same problem as Naval turbines- varying speeds, but with the added horror of varying loads at varying speeds.  

3:  we ran 600 PSI operating pressure, 865 F superheat temperature (full power), on HMCS Protecteur.  This was a GE designed plant, from the 1960's.  The USN ran some steam at 1200 PSI.  (the Leahy  & Belknap classes, and the SL7's) .   Y-100's ran at 550 PSI (RCN, RAN and RN versions).  

---------


Turbines are ill suited to the demand profile of railway operation.  So too are water tube boilers.  Just the wrong tool for the job, like picking up a wrench to use as a hammer.  While open reciprocating steam engines probably were near their limits as per the Standard classes, there isn't a great easy replacement for them.  Steam-Electric combines the worst of just about every world- the book "Rails Remembered Volume 4" is about Jawn Henry, and the tribulations it suffered.  Suffice to say, putting the power plant on the ground and stringing wires makes more sense than trying to move it all around in a 12x12x150' box.

James

[Siberian Snooper]

Our Leanders ran at 550 psi, with triple or quintuple pass superheaters at around 850°F. There was also a big condenser under the turbine, to improve the efficiency.

 

I can't remember the details for the carrier's that I worked on.

 

The OL class tankers had a working pressure somewhat higher than the Leanders, but again the grey cells lacking.

 

 

[johnofwessex]

Given what David Wardale mananed to achieve with a perfectly conventianal locomotive - the SAR Class 26 aka The Red Devil then I suggest that there is plenty of mileage with a conventional steam loco before you try Leader, Hush Hush etc

[62613]

18 hours ago, Siberian Snooper said:

Our Leanders ran at 550 psi, with triple or quintuple pass superheaters at around 850°F. There was also a big condenser under the turbine, to improve the efficiency.

 

I can't remember the details for the carrier's that I worked on.

 

The OL class tankers had a working pressure somewhat higher than the Leanders, but again the grey cells lacking.

 

 

In a merchant ship, the default setting of the main engines was usually as near as dammit flat out, for days or weeks on end, giving fairly steady - state conditions, with no thermal stresses. The 580psi/850F combination was used in a large number of BP tankers. The highest they ever used, IIRC, was 600psi/900F, even on the big tar barges

Edited January 8, 2022 by 62613