Condensate collection tank

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cyberbadger
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Condensate collection tank

Post by cyberbadger » Tue May 18, 2021 5:41 pm

If you connect the engine exhaust with a tee fitting to a puffer exhaust and at the lowest point of the tee to a steam trap which is connected to a tank. Can a tank like below be used to collect the condensate? Is a 75psi or lower safety valve on that tank necessary?

https://www.mcmaster.com/3667K1/
Gray-Painted Steel Expansion Tank for Water
8 Gallon Capacity
Maximum Temperature: 450° F
Maximum Pressure: 75 psi
Wall Thickness Gauge:14 gauge

I don't understand if the tank needs to be rated for the full MAWP of the boiler. If that is true it seems it is probably made of unobtanium.

-CB
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Re: Condensate collection tank

Post by barts » Tue May 18, 2021 5:55 pm

If the tank is vented in such a way that it cannot be pressurized, no. If any combination of valves opened/closed can pressurize the tank, then yes.

- Bart
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Bart Smaalders http://smaalders.net/barts Lopez Island, WA
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Re: Condensate collection tank

Post by cyberbadger » Tue May 18, 2021 6:31 pm

barts wrote:
Tue May 18, 2021 5:55 pm
If the tank is vented in such a way that it cannot be pressurized, no. If any combination of valves opened/closed can pressurize the tank, then yes.
I am trying to #1 not pollute steam oil into the water I am floating on.

A tank like this would have to be under my deck because that is where the low point of the exhaust line is.

Both venting and a safety valve below the deck seem like they have a high potential to drop steam oil into the water I am floating on.

The intent would be initially to pump this condensate into a portable container land at a dock and filter/dispose of it on land.

The steam trap I'm going to try is supposed to typically fail in a closed position, but failing closed is not a 100% certainty.

-CB

P.S. I'm leaning towards not getting a tank and having the steam trap lead to 15 feet of 250swp steamhose, that holds 0.1gallons. I don't think it will actually be that great nor particularly safe, but according to the specs the steamhose is fully rated, I am unwilling to commission a special tank or vent steam oil into the water.
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Re: Condensate collection tank

Post by TahoeSteam » Thu May 20, 2021 1:55 am

Could run a 1/4" copper line to a open tub , tank, whatever... If you have an open top on it that is greater cross section than the 1/4" tubing, you'll be fine.
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Re: Condensate collection tank

Post by cyberbadger » Thu May 27, 2021 10:08 pm

Thank you Bart and Wes.

I ended up getting the tank.

I welded two 1/4" npt tank fittings to the bottom so I can drain the darned thing.

Just hydroed it to 2xMAWP (60psi) successfully.

I got a 30psi safety.

I'm going to either have a long pipe leading to a open bucket on deck or the safety leading to a open bucket on deck.

If it doesn't seem to work as I'd like I'm going to convert it into a kerosene fuel tank at the same location.

-CB
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Re: Condensate collection tank

Post by cyberbadger » Sun Jul 04, 2021 12:16 am

I installed the condensate collection tank below deck between the center and starboard pontoons fore of the boiler by a few feet.
The exhaust from the engine is configurable by a series of ball valves and a few tees.

Engine Exhaust -> Ball Valve -> Armstrong Inverted Bucket Steam Trap -> Swing Check Valve -> Condensate Collection Tank
Engine Exhaust -> Ball Valve -> Puffer, ~0.4" Orifice
Engine Exhaust -> Ball Valve -> Engine Exhaust above deck
(These three are in parallel)

I steamed up two days in a row. Both times the puffer and steam trap ball valves were open the whole time.
The tank has a compound vacuum-60psi gauge and a 30psi safety that pokes up out of the deck (passenger suppression system?).

It's a little hard to read the gauge from the back of the boat, but it didn't seem to vary from 0psi.
Both times at the end I opened the 30psi safety valve and there was a slight snort, so I think it is helping to remove condensate from spraying into the puffer. I do think the tank maybe getting the occasional wave hit the underside.

I have also added insulation to the exhaust line that runs from the engine to the boiler, below the deck - that probably helps minimize condensate generation.

Temporarily I may try to use my electric transfer pump to drain the tank to a bucket above deck when the tank is cold. If I just leave it I'd imagine it would fill with condensate if it's not already full. The tank holds 8 gallons, luckily It's in a perfect location for ballast. I am curious how quickly the condensate actually accumulates. Unfortunately the only way to measure it right now would be to pump it into a bucket above deck.

In the future I am considering trying to use my gem steam pump to see if I can pump this back into the boiler. The takeoff would be at bottom of the tank, and hopefully oil floats on water?

-CB
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Re: Condensate collection tank

Post by fredrosse » Mon Jul 05, 2021 6:59 am

Repeating a previous post that is relevant here:

Having investigated ordinary motor oils, and the great majority of them cannot be separated from condensate. I thought that "Non-Detergent" motor oils would separate from water, but they do not. Spoke to Gulf Refinery engineers, and they told me that real non-detergent mineral oils will separate from water. However the motor oils labeled "Non-Detergent" are not actually non-detergent, but they are various motor oils that miss their specification numbers in some respect, so they are just labeled "non-detergent" and sold at lower prices. As far as years of study have indicated, the only oils that can be separated from water are pure mineral oils, otherwise known as "straight mineral oil".

The compounded steam oils, containing a few percent tallow, will never separate from hotwell water. The result will always be oil in the feedwater. Oil in the feedwater runs the serious risk of baking oil onto the water side of boiler tubes, which can form an insulating layer on the tube, and result in overheating of the boiler metal.

The other side of the story is that compounded steam cylinder oils are very effective in cylinder lubrication, compared to straight mineral oils which are more easily washed from cylinder surfaces by wet steam. If you use mineral oil for cylinder lubrication, then you need to inject much more oil to get effective lubrication. The oil can however be caught in the hotwell filter material, and can be precluded from entering the boiler.

Green Velvet Steam Cylinder Oil comes as "Compounded" or "Straight Mineral Oil". The compounded oil is virtually impossible to "un-mix" with water, the only way to separate the oil from the water is to boil away the water, the oil remains, but we cannot do that on a steamboat. Check your oil by mixing it with some hot boiling water, put it into the blender, then see if it can be separated from the water with your poly material. This is a good test to see it separation can be obtained. However it may cause separation from your wife if you use her blender or her stove/kitchen for that matter! If the oil separates, the water will be clear, oil floating on top of the water. This water is OK to feed the boiler. If the water stays milky, the separation does not work.

The only other place I know where one can find real, unadulterated mineral oil, is at veterinary supply stores. It is however somewhat expensive, being for animal treatment.
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Re: Condensate collection tank

Post by cyberbadger » Mon Jul 05, 2021 2:39 pm

I wish there were more diagrams of the complete piping and instrumentation of how steamboats and steamships close the loop.

I do not have a hotwell, it is a ballast tank.

Call it what it is.

P.S. m not really interested in some nebulous unobtainable oil that sounds somewhat inappropriate for the job. I have a 5 gallon bucket of compounded oil and Im going to use that. If It can't be separated then it doesn't sound like an appropriate fluid to reuse.

-CB
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