wet steam

For the non-technical side of living with Steamboats, videos and general pictures.
wsmcycle
Full Steam Ahead
Full Steam Ahead
Posts: 218
Joined: Sun Mar 13, 2011 5:43 pm
Boat Name: FEARLESS,l'il steamy
Location: Fort Smith Arkansas USA

wet steam

Post by wsmcycle » Tue Feb 02, 2016 6:53 pm

I took out li’l steamy Saturday on a warm 70 deg January day. I rebuilt the Semple boiler recently . New tube sheets and tubes welded in by certified welder. I static tested at 270psi. I did not change the fittings or the outer portion of the boiler. I did remove all the fittings though. I steamed up and headed up the Arkansas River. I started slowly so the pressure would rise from 60 up toward 100. When it achieved 100, I opened up the engine valve more. It sped up but 5 sec later, it slowed down and started blowing very wet steam up the flue. I quickly shut it down but the nice coal fire had been severely retarded by the water dousing. I drifted a bit waiting for the fire to recover. I looked at the water level tube and it was low. Hmmm, if the level was low, how did I blow out wet steam at 100psi. I tied up to a pier in the river and tried to reason this out. My pressure dropped to 50 with the fire dousing. I started the injector and it sounded like it kicked in and was flowing water but I did not see the water rising in the tube so I turned it off. Man I hate to hand pump but I did it. I filled to half way up the glass and waited for the pressure to get to 80 and then I cast off. Since I did not know what had happened, I headed back to the dock. Two thirds of the way there, I opened the throttle and the same thing happened but this time I was quick to throttle it down and open the bypass valve so the water didn’t go up to the flue and douse the fire. Five minutes later, I was blowing out “drier” steam from the exhaust bypass albeit at a slower throttle position.
Here are my theories
1 The level tube was not reporting the actual level in the boiler and I was indeed flooded. This sight glass has a valve at the top and bottom and also a drain at the bottom. Is there a schedule for opening and closing these cocks to get a proper reading? I have tried closing and opening but never found a dependable procedure. My m.o. is to only leave them slightly open. I have opened the drain valve slightly but i don't recall ever having seen a stream of water. I suppose it vaporizes open exposure to atmospheric pressure.
2 Maybe? I placed one of the fire tubes close in front of the steam outlet and the higher flow caused the water to suck up the side of the tube. I gave no consideration to the rotational position of the tube sheets relative to the discharge steam fitting.

More theories?
LIGHT THE FIRE!!
Mike Rometer
Full Steam Ahead
Full Steam Ahead
Posts: 936
Joined: Sat Aug 13, 2011 6:41 pm
Boat Name: B.N.Y.S.
Location: Middle Earth

Re: wet steam

Post by Mike Rometer » Tue Feb 02, 2016 7:24 pm

New boilers tend to prime easily and whilst yours isn't new it has had major surgury including new plates. Could it just be that it is priming also, and will clear with more use?
Retirement is about doing what floats your boat!

A BODGE : - A Bit Of Damn Good Engineering.
wsmcycle
Full Steam Ahead
Full Steam Ahead
Posts: 218
Joined: Sun Mar 13, 2011 5:43 pm
Boat Name: FEARLESS,l'il steamy
Location: Fort Smith Arkansas USA

Re: wet steam

Post by wsmcycle » Tue Feb 02, 2016 7:28 pm

please explain "boiler priming"? I don't know that term. perhaps you meant priming the injector?
LIGHT THE FIRE!!
Mike Rometer
Full Steam Ahead
Full Steam Ahead
Posts: 936
Joined: Sat Aug 13, 2011 6:41 pm
Boat Name: B.N.Y.S.
Location: Middle Earth

Re: wet steam

Post by Mike Rometer » Tue Feb 02, 2016 10:53 pm

wsmcycle wrote:please explain "boiler priming"? I don't know that term. perhaps you meant priming the injector?
Sorry, I thought the term would cross the pond.

Priming in the boiler happens when the water froths when boiling and when the regulator is opened suddenly, or wide, it increases and carries water over into the steam feed.

Condiitions that allow this are usually caused by impurities within the boiler, particularly with new boilers, and also in the some water. The cure is use, and plenty of blowing down, and careful regulator opening 'til it eventually clears.

Hope this helps.
Retirement is about doing what floats your boat!

A BODGE : - A Bit Of Damn Good Engineering.
wsmcycle
Full Steam Ahead
Full Steam Ahead
Posts: 218
Joined: Sun Mar 13, 2011 5:43 pm
Boat Name: FEARLESS,l'il steamy
Location: Fort Smith Arkansas USA

Re: wet steam

Post by wsmcycle » Wed Feb 03, 2016 3:51 am

OK, i understand. however, it doesn't seem that frothing would produce enough water to douse the fire. I would not have figured this one out on my own. I have a natural gas burner which I can use to fire the boiler. I will purge a few times before the next outing. There are probably many others on this side of the pond who understood what you meant but I was certainly ignorant of "priming".
Thanks for responding
LIGHT THE FIRE!!
Mike Rometer
Full Steam Ahead
Full Steam Ahead
Posts: 936
Joined: Sat Aug 13, 2011 6:41 pm
Boat Name: B.N.Y.S.
Location: Middle Earth

Re: wet steam

Post by Mike Rometer » Wed Feb 03, 2016 7:43 am

When bad, priming has been known to pretty much empty a boiler, that water has to go somewhere when it clears the engine and being heavier than air what isn't forced out the spout will likely get back to the fire.
Retirement is about doing what floats your boat!

A BODGE : - A Bit Of Damn Good Engineering.
User avatar
DetroiTug
Full Steam Ahead
Full Steam Ahead
Posts: 1863
Joined: Fri Nov 27, 2009 5:56 pm
Boat Name: Iron Chief
Location: Northwest Detroit

Re: wet steam

Post by DetroiTug » Wed Feb 03, 2016 3:01 pm

Quote: " This sight glass has a valve at the top and bottom and also a drain at the bottom. Is there a schedule for opening and closing these cocks to get a proper reading?"

Easiest way to determine if the sight glass is clear on both ends and reading properly is simply make sure it is fluctuating when the boat rocks. If either end is clogged, the water level will stay in one spot. Water always finds level, sight glasses are very reliable. As a redundancy, trycocks should be in place and opened in succession to verify the sight glass is reading is correctly. Daily or periodically during operation "blowing of the glass" is normal fireman's duty.

It seems logical if there was "priming" or "carry over" happening, the sight glass would display the sudden rise in water level. The semple VFT is typically a very good boiler, good volume, plenty of height to allow for sudden rises in water level. Boiler water above 212 degrees is essentially steam that hasn't expanded. The boiler pressure in correlation to the temperature maintains it as a liquid. Any sudden drop in pressure will cause the water to expand quickly in to steam, the steam gas bubbles in solution cause the water level to rise. It's unlikely the position of a firetube in orientation to the steam outlet is causing carry over. If they both exit at the same height, an easy test would be lay on the whistle, it's going to release as much if not more than the engine uses, if it remains dry then it is something else.

Sounds as though you're exhausting up the stack. I would be looking at feedwater heaters condensing exhaust steam, collecting condensate and belching water up the stack. I have a beautiful exhaust feedwater heater on the tug that I cannot use because of this problem. I didn't want to lose the induced draft, so I found other ways to preheat the feedwater.

-Ron
steamdon-jr
Full Steam Ahead
Full Steam Ahead
Posts: 143
Joined: Thu Apr 05, 2012 10:54 pm
Boat Name: SL Phoebe Snow
Location: Quakertown, PA
Contact:

Re: wet steam

Post by steamdon-jr » Thu Feb 04, 2016 12:59 am

some newer VFT boilers do not come with a placement for tri cocks and are not necessary but nice to have if you actually know how to use them, I have worked with people who don't. I blow down my boiler and my glass at least once a day. A good way to clear the orfices on your gauge glass which can clog with sediment is to;

1. close the bottom valve

2. open drain for a few seconds this will force all pressure thru the top valve and possibly clear debris.

3. close drain

4. open bottom valve

5. close top valve

6. open drain for as few seconds, this will force all prssure thru bottom valve and possibly clear debris

7. close drain.

8. open top valve.
wsmcycle
Full Steam Ahead
Full Steam Ahead
Posts: 218
Joined: Sun Mar 13, 2011 5:43 pm
Boat Name: FEARLESS,l'il steamy
Location: Fort Smith Arkansas USA

Re: wet steam

Post by wsmcycle » Thu Feb 04, 2016 2:11 am

thanks for the site glass blow down procedure. The Semple boiler in "lil Steamy" does not have tri-cocks but my larger boat "Fearless" does. I have used them for reassurance a few times. It looks like we are going to have few weeks of winter here in Arkansas so I won't be able to implement the new procedure yet. I will get the boiler blown a few times during the break to quail this boiler priming problem.
LIGHT THE FIRE!!
User avatar
Lopez Mike
Full Steam Ahead
Full Steam Ahead
Posts: 1903
Joined: Wed Dec 07, 2011 6:41 am
Boat Name: S.L. Spiffy
Location: Lopez Island, Washington State, USA

Re: wet steam

Post by Lopez Mike » Thu Feb 04, 2016 6:18 am

Steamdon=jr,
Thanks for posting that blowdown procedure. I do it at the start of every day on the water. I have seen cases where the only time it got done was at our club's annual inspections. Amazing crud comes out.
One small warning. Some level glasses have a feature to limit flow in the case of a glass breakage. It involves a small ball that is displaced by excess flow. It is possible to get that ball out of place by opening the valve too far. I have not experienced this myself but have been warned about it.
If you think you are too small to make a difference, try sleeping with a mosquito.
Dalai Lama
Post Reply