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 » Sun Oct 15, 2017 2:02 pm

"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. "

Remember that an automobile has loads far different than a boat. My 5100 pound automobile has an accurate MPG gauge, and when cruising at 35 MPH I am getting 40 MPG, but on average with acceleration and hills, I actually get about 16 MPG, with an average speed of about 20 MPH according to the onboard computer.

A boat has full load continuously when cruising. If I was driving a boat of the same weight, and the same average 20 MPH, I would average about 3 MPG.

Because cyberbadger has the Stuart Engine that he can load, and a big existing boiler, he can make a test very easy to get real answers to his "fireless steamboat" questions with regard to sizing his fireless kayak steam reservoir. I would recommend the big boiler be fired up to 150 PSI, then pull the fire., connect to the stuart engine, with 100 watt load.

Time how long it takes for steam pressure to decay to the point where sufficient pressure is about to be lost, say pressure decay till pressure reduces to 40 PSI, and say this takes 50 minutes. If you want similar performance that will last only 10 minutes, then your steam/water reservoir needs to be about 10/50 = 20% the size of the big boiler. Simple test, easy if you already have the big boiler and Stuart engine.
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fredrosse
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Re: What are the concerns/safety of an unfired >100C vessel

Post by fredrosse » Sun Oct 15, 2017 2:22 pm

"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. "

That makes perfect sense, all that energy available from a boiler that is full of hot water, and needs to be drained for maintenance operations.

I think the last use of fireless locomotives was at large electric generating stations, where 1500 to 2500 PSI boilers need close control of boiler water chemistry, and significant blowdown is always needed. Boiler blowdown was sent to a flash tank, and the flash steam was sent into the steam cycle to heat feedwater that was sent to the boiler. The liquid water in the flash tank, at about 450F, with impurities concentrated, could be directed to the fireless locomotive to fill its reservoir.

Fireless locomotives would shunt the coal cars around the plant, which might need to burn a 100 ton coal car full of coal every 20 minutes, more or less. When steam pressure began to get low, the fireless locomotive would dump its water to waste, and hook up to the nearby power plant for a recharge. I always thought this was a great system of energy conservation, but all of the fireless locomotives were taken out of service decades ago.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by DetroiTug » Sun Oct 15, 2017 3:57 pm

Quote: "Remember that an automobile has loads far different than a boat."

Oh absolutely, a boat never coasts and it requires much more power to push a hull through the water than roll a wheel on a flat surface. For a good idea on power requirements and to further expound on your explanation, compare the fuel consumption of a Chevrolet 327 smallblock V-8 in a boat and in a vehicle, I have both and have, the boat drinks fuel by comparison. Something on the order of 1.5 mpg for the boat and around 14 average mpg for the vehicle (heavy 4WD truck, a light 2WD car would get over 20 -30 mpg)

An unfired boiler in a boat, use the above for an estimated steam consumption. It will work, but don't plan on going very far.

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

Post by cyberbadger » Sun Oct 15, 2017 5:33 pm

DetroiTug wrote:An unfired boiler in a boat, use the above for an estimated steam consumption. It will work, but don't plan on going very far.
It's an experiment. Plus I can say that I have a growing steam fleet (Sugar Beet Lines). :mrgreen:

To be honest sometimes I get to the Dock with Nyitra in Chautauqua and I feel it's a shame that I have all of this energy that disappears.

I think I should try just the stuart 4 with a propellor first and see before I make a duck drive.

I'm not seeing great prices on 4" or 6" pipe. Can that be welded schedule 40? Or do I need seamless schedule 40? I may have to try a different source, mcmaster was talking hundreds of dollars just for threaded pipe.

I looked at ASME vessels on ebay and I saw 200PSI stuff in the gallons range but it was all low temp.

Swagelok.Is yorlok ok? I have the remains of a 50ft coil of SS 316 3/8" OD welded tube with 0.319" ID. (Not seamless, but for what I'm doing I don't think that matters much.)

---
Wall Thickness 0.028"
ID 0.319"
Maximum Pressure 2,300 psi @ 72° F
Temperature Range -320° to 1500° F
---

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

Post by cyberbadger » Tue Oct 17, 2017 1:19 am

Found a lot more reasonable prices at a local plumbing distributor.

1) Is schedule 40 seamless 4" suitable for a 200MAWP for this PV?
2) Sched 80 seamless is not really that much more in cost, and it would have double the thermal mass, would this be mater?

Ron - This might be what gets me into your other hobby... My friend pointed out that if I had such a PV it would be equally useable for a steam golf cart! :P (And actually that would be easier to test at home because I have no pond in Ohio)

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

Post by fredrosse » Tue Oct 17, 2017 5:29 am

"1) Is schedule 40 seamless 4" suitable for a 200MAWP for this PV?

ANS: Yes, even A-53 ERW steel pipe would be fine for 200 PSI/400F please use butt welded fittings, many small shops can do this welding for low nominal cost.

2) Sched 80 seamless is not really that much more in cost, and it would have double the thermal mass, would this be mater?

ANS Pound per pound, water has a specific heat that is ten times that of steel, 1.0 BTU per poundmass per Fahrenheit Degree vs 0.1 for steel. In other words, if you have a pound of water that gives up heat from changing temperature from, say 375F down to 275F, that is 100 BTU of energy. A pound of steel traversing the same temperature range would only give out 10 BTU of energy.

Steel is much more dense than water, but it is not ten times as dense, so water still has an advantage in terms of stored energy holding capacity. A vessel 4.5 inches OD x 0.125 wall thickness, filled with water has a higher "thermal mass" than a 4.5 inch OD x .250 wall condition, etc...
Last edited by fredrosse on Tue Oct 17, 2017 6:08 am, edited 1 time in total.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by fredrosse » Tue Oct 17, 2017 6:05 am

I would recommend you get a WELDBEND catalogue from the internet, it has much technical data that would be of interest to you.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by DetroiTug » Tue Oct 17, 2017 2:07 pm

Quote: "Ron - This might be what gets me into your other hobby... My friend pointed out that if I had such a PV it would be equally useable for a steam golf cart! :P (And actually that would be easier to test at home because I have no pond in Ohio)"

Well, I'm not doing it with an unfired vessel. To imagine what you're suggesting would be a very frustrating fruitless endeavor. It's going to be an involved time consuming filling procedure fraught with thermal losses resulting in a drive of a very short distance. About the time everything starts getting up to temperature (condensate cleared, and everything up to temperature which can be a mile er so down the road), you'll need to recharge. When I shut my Kerosene burner off, besides the stored steam, there is also stored latent heat that continues to generate steam for a short bit. The inverse is lag in cutting the burner back in and the time it takes to get the heat back to the water again. Also, my car is very light and has very little rolling resistance to the road surface, Golf carts, go carts etc, don't. I'm already rolling when the burner is cut, so the energy required to accelerate up to speed which is significant is not in that short drive I'm able to make.

The rail lines did it on a much larger scale, and many steam things don't scale down well. And too, they likely didn't care how efficient it was, as it was waste boiler water anyway. If it would move a few cars around the yard, it was worth it. I'll bet there were many times it got stuck out away from the shed and had to be retrieved.

If you want to do that hobby, just build or buy a boiler for it and an appropriate burner, it will be more enjoyable.

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

Post by cyberbadger » Tue Oct 17, 2017 3:41 pm

Fred,

Got it. Thicker steel would increase the thermal mass, but water will store much more thermal energy.

The weldbend catalog is interesting, but I'm not comfortable welding a PV myself.

So what I'm leaning towards is the 40 seamless 4in pipe threaded - and probably it will have a 90 elbow and 4" pipe "steam dome".

I was even thinkening for that - if I strategically bend and cut some mild steel sheet I could make an insert inside the PV steam dome to be a baffle. It would just float inside in the PV - and not super tight It's just supposed to help retard carry-over.

Ron. No, it is not practical for most and the run times will be short. But I already have a working boiler. This is going to be a small few hundred $ rig for testing and fun. Because it is limited and simple you don't have to commit to a full project and you don't have to worry about all things you must have for a boiler. As part of the insulation I can make it so I can just carry it to the vehicle/project if I need to. And if gets me hooked to steam land propulsion I'll talk to you about an olfelt.

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

Post by cyberbadger » Wed Oct 18, 2017 11:58 pm

Order was placed today, I have some of it already. It was about $360 from a local distributor.
2x 36" 4" ERW Pipe (3.92Gallons)
2x Malleble 4" Elbow
1x 4" Close
2x Reducing/Bushing pairs to get it to 1"

Should be around 5gallons with all the fittings.
Image

-CB
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