What are the concerns/safety of an unfired >100C vessel

A special section just for steam engines and boilers, as without these you may as well fit a sail.
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cyberbadger
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What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sat Oct 14, 2017 1:12 am

One of the things that I didn't expect from steaming in chautauqua with nyitra was refinding my love of kayaking. I had this interesting idea ... what if I could have a "scout" boat in the form of a steam powered kayak with no boiler, but a vessel to hold some water from Nyitra's boiler. Enough to run a small model engine for say - up to 10 minutes?

What are the engineering concerns to this? Could a pipe say 3+ inches in pipe size be schedule 40 be used? I'd like to keep it as simple as possible. Is there a reason that only one connection couldn't be used using a gravity feed and sanitary ss steam hose fittings? Do I really need a sight glass - it's going to be used until there is no more pressure? Do I need a pressure relief device - it's not going to gain any heat?

-CB
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Re: What are the concerns/safety of an unfired >100C vessel

Post by DetroiTug » Sat Oct 14, 2017 1:01 pm

Some rail lines ran switcher Locomotives like that in the yards. Just a small engine with a big insulated pressure vessel.

-Ron
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sat Oct 14, 2017 5:42 pm

https://en.wikipedia.org/wiki/Fireless_locomotive
Interesting, still made into the 1980s, still at least one active as late as 2016.

So I think the pressure gauge and some sort of safety relief should be installed.

And then I need to insulate the heck out of the vessel and make sure the filling operation is reasonably safe. I think filling would be best below Nyitra's Deck - and have the pressure vessel be in the bow kayak compartment.

Wonder if Fred could let me peak at any drawings of his John Fitch duck paddle mechanism? 8-)

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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sat Oct 14, 2017 5:55 pm

This is to give ideas. Nyitra's Deck is very convenient for a lot of things. Two of these are for Dogs(it's at a great level for them to hop on board) and Having a Kayak on the side for tendering or excursioning.

We have a few kayaks, but perfering larger seagoing kayaks this is a reasonable candidate...

-CB
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Re: What are the concerns/safety of an unfired >100C vessel

Post by fredrosse » Sat Oct 14, 2017 11:22 pm

"Wonder if Fred could let me peak at any drawings of his John Fitch duck paddle mechanism?"

Some good video of the paddle mechanism on youtube, look up " John Fitch Steamboat". I just copied John Fitch's original drawing from 1788.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by fredrosse » Sun Oct 15, 2017 12:10 am

Fitch Model Drawing, showing layout of stern paddles and Watt engine.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by fredrosse » Sun Oct 15, 2017 12:32 am

An unfired pressure vessel for the service you want simply needs to be rated for at least the maximum operating pressure of your boiler. ASME rules require a relief valve on a pressure vessel IFF it can potentially be charged above its design pressure, so just design for, say 250 psig, and have three connections:

Top steam off-take to the small engine.
Try cock which assures no overfilling to a water level too high
Bottom connection to receive steam from your big boiler, and to drain the vessel when desired.
I would do all these connections in 1/4 inch OD tubing if powering a kayak.

I would guess about 1 cubic ft of vessel water volume would give several minutes driving a Stuart Double 10 engine under load, initially charged to 150 PSI, with pressure decaying to about 50 PSI before recharging. This is just a guess, calculations would be needed for an accurate assessment.

Does anyone have any experience with this condition?
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Re: What are the concerns/safety of an unfired >100C vessel

Post by DetroiTug » Sun Oct 15, 2017 1:03 am

Experience with an unfired boiler at pressure? When I shut my car burner off it can travel close to a mile without having to cut the burner in again. The rail lines probably implemented these types of switchers to use up the water on boilers at temperature that came in to the shed for wash out, which was pretty often.

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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sun Oct 15, 2017 1:47 am

Fred, thanks. You did give these images to me in the past, they look familiar. The ratios/lengths of the rods is what I was looking for.

1 cubic ft is 7.48 gallons! For reference Nyitras boiler holds Aprox 25-30 gallons. 5 gallons worth is roughly the range viewed on the sight glass of her boiler.

I could run an injector while transferring to get something in the range of 5-10 gallons for a fill and stay on Nyitra's boiler glass. . This to me represents the amount that would be reasonable in Nyitra's configuration to transfer - somewhere between 5-10 gallons.

I was thinking this for transfer connection:

High-Polish Quick-Clamp Sanitary Tube Fitting
304 Stainless Steel Adapter for 3/4" Tube OD x 3/4 NPT Male
https://www.mcmaster.com/#4322k418/=19td0rs
Mcmaster item 4322k418
and
High-Polish 304 Stainless Steel Sanitary Quick-Clamp
with Wing Nut, Spring Loaded for 1/2" and 3/4" Tube OD
https://www.mcmaster.com/#9155k12/=19td3h7
9155K12?
with a braided steam hose with this quick connect and the appropriate gasket - which is going to fall straight into the water. :evil:

I have really so far never found anything that I liked for a "quick" disconnect flexible hose solution. NPT is a great seal - but the heating expansion can make the mating surfaces operationally inseparable. Not to mention twisted hose... So then you try to prebend it a few turns in the opposite direction - but then it never is quite right.

I need a connection that is:
1) Orientation Ambivalent
2) Tolerant of big heat changes without binding shut because of expansion/contraction.
3) Have a good seal
4) Tolerant of mild to moderate impacts/vibration while holding pressure during transfer (the accidental hit from a paddle)
5) Easily Connectible in less than 1 minute

I have never tried pipe unions - do they bind from thermal cycling?

I like the idea of avoiding scalding, I had a several burn that required mutliple hospital procedures when a pot of water on a campfire emptied onto my foot (as a child), but lets arbitrarily say the filling shouldn't take much more then 1min. I think that is going to take 1/2" to 3/4" to complete in fast enough time.

-----------
Probably the closest ballpark engine I have is a Stuart 4(or 4a) 1.5"x1.5". (I had it powering a 100W incandescent via a PMA)
It has a slip eccentric. I'm trying to think if there is an easy way to reverse that remotely (I'm thinking if the engine is behind me)

To do the concept justice though maybe a custom cylinder(engine) to really let take full advantage of the expansion. What about something with a really long stroke

-CB
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Re: What are the concerns/safety of an unfired >100C vessel

Post by fredrosse » Sun Oct 15, 2017 1:40 pm

"I need a connection that is:
1) Orientation Ambivalent
2) Tolerant of big heat changes without binding shut because of expansion/contraction.
3) Have a good seal
4) Tolerant of mild to moderate impacts/vibration while holding pressure during transfer (the accidental hit from a paddle)
5) Easily Connectible in less than 1 minute"

A correct answer in one word------ Swagelok

"I think that is going to take 1/2" to 3/4" to complete in fast enough time"

Too big in my view, 1/2 inch OD tubing would be plenty big enough.

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"Probably the closest ballpark engine I have is a Stuart 4(or 4a) 1.5"x1.5". (I had it powering a 100W........"

This engine will be more than enough for a kayak with one or two persons.

"It has a slip eccentric. I'm trying to think if there is an easy way to reverse that remotely (I'm thinking if the engine is behind me)"

Why a reverse? This is complication that is not necessary when you have a paddle in your hands for maneuvering. Just a steam on/off valve for the engine is needed. But a single cylinder engine will not generally be self starting, so I would recommend you put the engine in front of you.

"To do the concept justice though maybe a custom cylinder(engine) to really let take full advantage of the expansion. What about something with a really long stroke."

Long stroke or short stroke has nothing to do with taking advantage of steam expansion. It is the valve gear and steam passages that matter here. An engine with 1.414" bore and 2 inch stroke, vs an engine with 1 inch bore and 4 inch stroke will show no difference with respect to this. Note that the long stroke engine here is at a disadvantage with respect to surface exposed to initial condensation, as well as piston speed issue.
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