Author Topic: Feedwater, to heat or not to heat? (Read 292 times)

KNO3 · « **on:** July 08, 2019, 03:23:31 pm »

Hello all,
Being in the middle of a steam plant build, I have come to the point in which I should decide how to best feed the boiler with water from the pump. I thought of drawing upon the forum knowledge, as I am sure others have tried this before. Is it worth the trouble heating the boiler feed water in a model steam plant? I am thinking of perhaps building a coil in the condenser, so the feed water gets heated by the spent steam. An alternative would be to place the coil in the chimney, to heat it with the exhaust gases.
What are your recommendations?

St Paul Steam · « **Reply #1 on:** July 08, 2019, 03:31:40 pm »

I think a pre-heater condenser looks cool and all , but honestly I've never had the need for such things as I don't run my engines long enough or often enough to get the full benefit from it.

Stoker · « **Reply #2 on:** July 08, 2019, 03:41:30 pm »

Depends entirely upon the level of efficiency that your operational paradigm requires, or conversely what features you want your steam plant to represent and display.

I would use some care if you choose to preheat in the chimney, as the temperatures found there may well create steam in the feedwater pipe, which would be a most undesirable occurrence.

KNO3 · « **Reply #3 on:** July 08, 2019, 04:14:00 pm »

Thanks for the answers. I want the steam plant to run efficiently and to avoid the cold feedwater reducing boiler performance. That's why I asked if preheating feed water is advisable in our small scales. I am yet undecided, as it adds a level of complexity to an already very small and rather complicated steam plant.

Jim · « **Reply #4 on:** July 08, 2019, 05:59:39 pm »

I made one and it made a big difference in boiler efficiency for thirsty engines and stopped the boiler 'going off the boil' so to speak when hand pumping a lot of replacement cold water into the boiler.

KNO3 · « **Reply #5 on:** July 09, 2019, 06:57:20 am »

Thanks, this sounds very interesting. What type of feed water heater did you make? Could your share some pictures of the steam plant please ?

CBWho · « **Reply #6 on:** July 09, 2019, 01:28:29 pm »

If using a pump, I suspect preheating based on the condenser would work best but if using an injector, I would avoid a preheater.

Is there a reliable manner to separate the water and the oil from the condensate? Perhaps always maintain some water level, so the oil floats?

KNO3 · « **Reply #7 on:** July 10, 2019, 10:44:02 am »

I am using a pump. No experience with injectors.
Anyway, I think it would be hard separate the oil from the water in model size condensers. The exhaust of my steam engines looks like an emulsion and it takes a while for the oil to separate from the water.

Belugawhaleman · « **Reply #8 on:** July 10, 2019, 12:23:36 pm »

I simply heat my feed water on the stove before filling my feed water tank and continue to add hot water during
the run

KNO3 · « **Reply #9 on:** July 10, 2019, 12:43:56 pm »

That won't work in a r/c ship though, unless I build a mini stove and hire a crew of mice

St Paul Steam · « **Reply #10 on:** July 10, 2019, 12:56:18 pm »

Quote from: Belugawhaleman on July 10, 2019, 12:23:36 pm

I simply heat my feed water on the stove before filling my feed water tank and continue to add hot water during
the run

simple and effective 😉👍

Stoker · « **Reply #11 on:** July 10, 2019, 01:04:48 pm »

Quote from: St Paul Steam on July 10, 2019, 12:56:18 pm

simple and effective 😉👍

Not so simple and effective if it is a boat out on the water however!

frazer heslop · « **Reply #12 on:** July 10, 2019, 02:51:40 pm »

Have a look on the john=tom site for the Clayton Wagon drawings as it has a feed water heater
I fitted one to my Clayton and it made a difference
In the book Steam and Stirling Engines you can build is a full plant that has a single acting V4 wobbler and a feed water heater fitted
It maybe book 1 not sure

KNO3 · « **Reply #13 on:** July 10, 2019, 04:20:24 pm »

Thanks for the suggestion. I have found the Clayton Wagon plans and they show a feed water heater using exhaust steam. I could build one along those lines.

CBWho · « **Reply #14 on:** July 10, 2019, 09:04:34 pm »

> ...a crew of mice...
I’d like to see that!

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Author Topic: Feedwater, to heat or not to heat? (Read 292 times)

KNO3

Feedwater, to heat or not to heat?

St Paul Steam

Re: Feedwater, to heat or not to heat?

Stoker

Re: Feedwater, to heat or not to heat?

KNO3

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Jim

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KNO3

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CBWho

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KNO3

Re: Feedwater, to heat or not to heat?

Belugawhaleman

Re: Feedwater, to heat or not to heat?

KNO3

Re: Feedwater, to heat or not to heat?

St Paul Steam

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Stoker

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frazer heslop

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KNO3

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CBWho

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