As pointed out below, I assume they have the same effect as on any
stationary power plant. The use of feedwater heating increases the
efficiency of the steam cycle, thus saving fuel. To further elaborate, the
fuel savings is accomplished because the feedwater to the boiler has been
heated, reducing the amount of heat required in the boiler itself to finish
heating the water to the saturation temperature and then boil it. In a
utility power plant, the steam for feedwater heating is supplied by
extractions from the steam turbine. What was the source of heat to the
various types of FWHs used on a locomotive - exhaust steam?
Like the use of superheaters for the motive steam that also serve to
increase the cycle efficiency, I had assumed that the most modern steam
locomotives (4-8-4s, 2-10-4s, etc.) tended to use both SHs and FWHs. If I
remember correctly, this type of information is listed for all locomotives
in the book Steam Locomotives of the Burlington Route.
> -----Original Message-----
> From: John D. Mitchell, Jr. [SMTP:cbqrr47@y...]
> Sent: Monday, March 11, 2002 2:59 PM
> To: BRHSlist@yahoogroups.com
> Subject: Re: [BRHSlist] Steam engine questions
>
> Jonathan
> You missed it on why the road engines ( in heavy
> and/or fast service) needed feedwater heaters. They
> saved coal or oil and water. This meant less cost for
> fuel and water, plus fewer servicing stops. The
> capital costs and maintanace expense had to be lower
> than the savings.
> John D. Mitchell, Jr.
> --- jonathanharris@e... wrote:
> > Thank you, Mike! Your explanation of injectors is
> > very clear and helpful.
> > Makes me wonder why any railroad would have chosen
> > the "lifting" type.
> > Maybe it had to do with how different roads ran
> > their engines, the profiles
> > of their lines, etc.
> >
> > Regarding feedwater heaters: the Burlington's three
> > Coffin-equipped O-3s
> > (5318, 5325, 5341) all had units that extended out
> > from the smokebox front,
> > sort of like the giant eyebrow of a cyclops, so at
> > least some of the
> > mechanism must have been outside the smokebox. But
> > maybe enough of it was
> > still inside to make it as messy and dirty and
> > troublesome to maintain as
> > you describe. An interesting fact about these
> > engines is that when the
> > Coffins were removed, sometime between 1935 and
> > 1952, they were not
> > replaced with Elesco or Worthington units. The
> > engines reverted to using
> > injectors only. So the Coffins really must have been
> > more trouble than they
> > were worth.
> >
> > That got me to wondering about what kinds of engines
> > were equipped with
> > feedwater heaters and why. A quick perusal of the
> > rosters in Corbin and
> > Kerka shows that many, though not all, of the
> > Burlington's mikados had
> > feedwater heaters. All of the Q's larger engines had
> > them (all 4-8-2s,
> > 4-6-4s, 2-10-2s, 2-10-4s, and 4-8-4s), but almost no
> > smaller engines --
> > with the exception of the Pacifics, almost all of
> > which were so equipped,
> > even the smaller S-1s. What this suggests to me is
> > that the real advantage
> > of having a FWH was its ability to help sustained
> > steaming, especially on
> > heavier trains. Hence its use on mainline passenger
> > engines, some of which
> > produced considerably less tractive effort than the
> > drag-freight 0-3s, some
> > of which used only injectors.
> >
> > In the case of freight engines, the choice of
> > whether to add a FWH probably
> > was determined by a combination of the engines'
> > intended functions and the
> > terrain where they were assigned. Manifest freight
> > engines, for instance,
> > would have benefited from feedwater heaters more
> > than drag freight engines,
> > as would any and all heavy freight engines operating
> > over uneven terrain.
> >
> > Consider the Burlington's USRA O-4 mikados, all 15
> > of which had feedwater
> > heaters, versus the FW&D's corresponding E4A2s,
> > which appear to have only
> > injectors. Presumably the pancake-like topography of
> > central and west Texas
> > diminished the need for FWHs, while the grades of
> > the Q's western
> > divisions, where the 0-4s hung out, made such
> > appliances much more
> > important. It strikes me as significant that
> > feedwater heaters seem not to
> > have been used much on the FW&D, compared to the Q
> > -- or the C&S, where
> > all engines larger than a 2-8-0 had them.
> >
> > Jonathan
> >
> >
> >
>
>
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