Hey folks,

Recently, I've gone down the rabbit hole researching feedwater heaters. I've read up and become familiar with both the open and closed types, Elesco, Worthington, Coffin, etc.. exhaust steam injectors seem like a nightmare, but that's a different story.

It might be frivolous, but I'm curious... the closed systems all have condensate lines running back to the tender from the heater bundle. How much water does this actually make? I'd imagine a short cut offs at road speeds - not much?

Thanks for any insight,
Joe

I have no idea how much water would be generated from the condensate, but I can tell you something interesting about that system.

In my experience of working on CNR Northerns, the tenders would include small condensate tanks. I've noticed that on engines equipped with exhaust steam injectors, the water capacity for those tenders is 100 gallons more (that would be whatever gallon thingy used in Canada at the time, not whatever gallon thingy the US was using), than those with the Elesco feedwater heater, for the same size tender.

I believe the main reason for these tanks was to separate the oil in the exhaust steam.

CN appeared interested in eliminating these tanks, as during the service life of some engines, an in-line oil separator was fitted on the exhaust steam pipes on top of the smoke box, just before entering the feed water heater bundle.

To accomplish this, those pipes had to moved rearwards to fit the separator. When you see an engine that has been so modified, you will also see all kinds of patches and weld marks covering the old holes in the smokebox course.

I've never seen any documentation on these separators. Basically the oil would trickle down some small pipes on the side of the smokebox, and just drop onto the ground (as far as I can tell).

CNR 6167 received this modification, including the removal of the condensate tank, whereas CNR 6213 did not receive this modification and still has the condensate tank.

Maybe when I have a minute, I'll dig up some photos.

It was not about "how much water it makes". It's more about what to do with the water (and oil) that is a result of cold feed water from the pump(s), running through the heat exchanger tubes and the wet exhaust steam coming in contact with the cold tubes. Did it save some water? Yes, a little, but the goal was to impart as much heat from the exhaust into the cold water. The condensate water, now containing steam cylinder oil, was allowed to flow back to the tender through plumbing with the aid of gravity and eventually flowed into a closed compartment in the tender tank, where at the bottom was a passage back into the water tank. The steam oil (being lighter than oil) separated and was allowed to float up to the top in the closed compartment where it collected and eventually emptied through a funnel connected to a pipe and out through the bottom of the tender every time the tender was filled with water. (Coffin system)

I have a copy of a SP AC-8 Dynamometer test from Colfax to Norden pulling a 1516-ton train water use total 29,444-gals water from tender 24,565-gal exhaust steam condensed by FWH 4501-gals oil used 2,337 gal overall thermal efficiently about 7.5% average track speed 12MPH on ruling grade. Thus, FWH saved both water and heat energy usually figure about advertised was 10%. Studying steam Locomotive Dynamometer reports will open your eyes on just how inefficient the steam locomotive was probably the average runs would have shown poorer results than the tests. I have been always surprised that once diesels came out it took so many years to change over.

Dennis Daugherty

I'm surprised that they didn't just let the condensate drain onto the ballast 80 years ago, it sounds like the water recovered is more trouble than it is worth with the oil in there. It would be an environmental issue now, but back then I doubt it would have raised a peep.

It's an interesting question and I hope someone with experience with a closed FWH can give us a real world answer. My understanding is that it is not an insignificant amount of condensate. Figures I've heard are that about 12-13% of exhaust steam were diverted to the FWH. Accounting for other losses, you might assume maybe 8-10% of the water boiled thus finds it's way back to the tender?

Deep in the dark recesses of my memory, I'm sure I have seen this information somewhere.

Surely the Locomotive Cyclopedia or an Elesco manual will give some figures.

Unfortunately I'm 8000 km away from my collection...

This is what the Asst Mechanical Engineer of the New Haven had to say about feedwater heater performance. Very specific condensate measurements might be found in various test reports from tests conducted at UofI Urbana and the PRR test plant at Altoona. https://www.google.com/books/edition/Ra ... frontcover

At the bottom of page 116, looks like a water savings of 14%, and an endurance of 16% or 32 minutes greater, from reclaiming the condensate?

[quote="PMC"]I'm surprised that they didn't just let the condensate drain onto the ballast 80 years ago, it sounds like the water recovered is more trouble than it is worth with the oil in there. It would be an environmental issue now, but back then I doubt it would have raised a peep.[/quote]

The Santa Fe engines with an SA open type heater had a skimmer and separator. The oily condensate waste indeed drained to the ballast while the separated condensate was shunted back to the tender. The condensate naturally was the exhaust steam used to heat the feedwater, with that the condensate had steam oil entrained which was seperated out.