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

Post by fredrosse » Fri Nov 17, 2017 8:03 am

?? I would have connections as delineated on my post just after the pictures of the John Fitch paddles.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Fri Nov 17, 2017 8:31 am

So the top has
Safety(no restriction),
Swagelok connection (1/4 pipe restriction)
Pressure gauge
Trycock(Should Nominally show Steam)

The bottom is:
Swagelok connection(1/4 pipe)
Trycock(Should Nominally show water)

Plan for first steam test:
1) I think first I should bulk transfer hot water from the bottom of the boiler to the bottom of the PV, Initally with the top PV trycock and top PV swagelock connection open slightly to wheeze until it is full till the water line.
Boiler bottom->PV bottom (Assuming Boiler >= PV pressure)
2) If it's already has some water that is hot, then you could run steam into the PV bottom until the relief on the PV trips.
Boiler bottom->PV bottom (Assuming Boiler >= PV pressure)

Part of question is, Can I assume that the relief valve (unrestricted) can prevent pressure from spiking on the other end of the PV. Or since I have the relief valve and the two swagelok connections restricted to 1/4" npt that Nyitra's Boiler water or steam does not pose a risk because of this arrangement.

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

Post by fredrosse » Fri Nov 17, 2017 7:21 pm

"1) I think first I should bulk transfer hot water from the bottom of the boiler to the bottom of the PV, Initally with the top PV trycock and top PV swagelock connection open slightly to wheeze until it is full till the water line.

ANS: In general that is OK, but be sure the big boiler feeding the PV is at a pressure lower than the PV safety valve. A PV relief opening here could give much hot two phase steam water release, and must not impinge on people. I think your setup may be prone to priming when the PV safety lifts, spewing out much of the stored hot water as a two phase mixture.

"2) If it's already has some water that is hot, then you could run steam into the PV bottom until the relief on the PV trips. "

ANS: I thought you were not going to charge the new unfired pressure vessel if the big boiler was at a pressure above the relief valve setting on the unfired pressure vessel. That is the way things should be done, avoid having a relief valve operate unless you are testing its function, never during normal operations if you can avoid it.

To test the PV relief valve, I would recommend that it be very low on contained water, then charged with the big boiler (steam only), which is at about 150 PSI, and the PV relief valve should lift at 125 PSI.

In general, I would always charge the PV with steam at the bottom connection, with water already in the PV , hot or cold.

".....Initally with the top PV trycock and top PV Swagelock connection open slightly to wheeze until it is full till the water line."

ANS: That practice should always be followed. Even if there is too much water in the PV, having the top vent open slightly will allow charging without getting excessive liquid in the PV, bleeding off the liquid till the liquid level is correct.

Did you ever comply with my recommendation to have 1/4 inch OD tube Swagelok connections maximum size on the connecting line? I think this will be plenty fast enough for your purposes?

"Part of question is, Can I assume that the relief valve (unrestricted) can prevent pressure from spiking on the other end of the PV. Or since I have the relief valve and the two swagelok connections restricted to 1/4" npt that Nyitra's Boiler water or steam does not pose a risk because of this arrangement."

ANS: I believe I recommended 1/4 inch inside diameter maximum connection size, with a further recommendation of 1/4 inch OD tube connections as adequate. Also you should have 200 psi rating on any valves that could be exposed to the big boiler fluid with its 200 psi MAWP, if those valves could be exposed without the protection of the PV relief valve. That rule should not be dependent on using procedures, in other words, an "idiot proof" arrangement. Simple and obvious logic here. Look back over my posts, I don't have good access to review this.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Fri Nov 17, 2017 7:59 pm

fredrosse wrote:"1) I think first I should bulk transfer hot water from the bottom of the boiler to the bottom of the PV, Initally with the top PV trycock and top PV swagelock connection open slightly to wheeze until it is full till the water line.
ANS: In general that is OK, but be sure the big boiler feeding the PV is at a pressure lower than the PV safety valve. A PV relief opening here could give much hot two phase steam water release, and must not impinge on people. I think your setup may be prone to priming when the PV safety lifts, spewing out much of the stored hot water as a two phase mixture.
This is the part that I have to carefully play with at home until I experience it and get a feel for it. With a nice bucket of cold water nearby to relieve accidental burns.
fredrosse wrote: "2) If it's already has some water that is hot, then you could run steam into the PV bottom until the relief on the PV trips. "

ANS: I thought you were not going to charge the new unfired pressure vessel if the big boiler was at a pressure above the relief valve setting on the unfired pressure vessel. That is the way things should be done, avoid having a relief valve operate unless you are testing its function, never during normal operations if you can avoid it.
That is the plan. But My MAWP for the PV is 150, but the safety is set for 125. I still feel though that water at the bottom of Nyitras boiler could potentially be slightly hoter because it only has natural internal circulation, and this is drawing from the firebox area. So I'm expecting it to be a messy...

I'll try to build up to it. I think I'll try the initial fill at roughly 100 PSIG Nyitra Boiler. I won't try to fill if it's above 150PSIG.

When I fill the PV, I'm going to run the stuart generator and see how many seconds (hopefully minutes and seconds) it can run making a 100Watt Incadenscent 12V light glow. This should give me a baseline that makes sense to me.

Or I could find that cold water is not the same as hot water and need to stop, vent the PV, and tighen up PV weepage.
fredrosse wrote: Did you ever comply with my recommendation to have 1/4 inch OD tube Swagelok connections maximum size on the connecting line? I think this will be plenty fast enough for your purposes.
Not exactly. I made it so the pipe size must go down to 1/4 npt before the swagelok connection.

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

Post by fredrosse » Fri Nov 17, 2017 8:25 pm

The Steam Engine, by Holmes, 1895, one of many that will educate you about valves, valve diagrams, adjustments, etc.

A free PDF here: https://www.pdfdrive.net/the-steam-engi ... 56206.html
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Re: What are the concerns/safety of an unfired >100C vessel

Post by fredrosse » Sat Nov 18, 2017 2:43 pm

Previous post should have gone on another thread, my apologies.

From CB: ".... I still feel though that water at the bottom of Nyitras boiler could potentially be slightly hoter because it only has natural internal circulation, and this is drawing from the firebox area. "

Actually natural circulation will favor the opposite. Hotter water will tend toward the top of the liquid, cooler water will go downward.

However in a proper functioning boiler the entire liquid space should receive general circulation, and all of the liquid would be at virtually the same temperature. If the boiler is not fired, lower temperature water will seek the low elevations of the boiler. As a VFT slowly cools down, either with or without a wet furnace, the lower temperature water will prevail at the lower elevations.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by Oilking » Sat Nov 18, 2017 6:51 pm

CB,
I haven't followed every post on this thread so forgive me if this is ground already covered.
Back to the steam catapult accumulator where the steam is used to heat and reheat a the water equal to about half the volume of the vessel. My thought is that it may be easier to partially fill the accumulator with ambient temp water, and then position it so that the steam is admitted at the low end under the water while venting the high end. When steam starts to flow from the vent throttle it back until it's at pressure and you should be there. One problem you'll have in transferring water from the boiler is that it is going to flash to steam until the pressure and temperature are the same as the boiler or until equilibrium between the two phases with in the accumulator is established.

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

Post by fredrosse » Sat Nov 18, 2017 8:20 pm

Dave, what you are suggesting is already in this thread, and is the recommended method of charging the pressure vessel.

"My thought is that it may be easier to partially fill the accumulator with ambient temp water, and then position it so that the steam is admitted at the low end under the water while venting the high end. When steam starts to flow from the vent throttle it back until it's at pressure and you should be there. "

Yes, that works, it will also work if the water is hot or cold. The small vent opening should be at the desired final water level, and excess water will be blown out here until the vessel is fully charged.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sat Nov 18, 2017 8:32 pm

I'm close to trying this (within the next few days), and I will put up a video. I think it's a great idea to video something new as you try it, so you can go back and see what exactly happened and how you could have done better (esp if a problem occurs).

Thanks fred, I got that book. The link is correct on this page.

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

Post by Lionel Connell » Mon Nov 20, 2017 6:05 am

Too True, get the person with the video camera to stand well back in case you need to see which way the parts went.:-)
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