BOILER PRIMING

[wsmcycle]

Another outing in L'il Steamy with the newly rebuilt boiler. Saturday started off cold but quickly warmed to 55 degrees. I went to get the boat out of the plant and blow down the boiler a few times while I cut and split wood. I love splitting wood nearly as much as burning it in the wood stove. I have natural gas burner I can stick into the ash pan and fire the boiler. I filled the boiler 2/3 full in the sight glass on the first blow. Aside from the steam supply line, I only have ½ pipe fittings into the boiler. When I got to 80# I opened the ½” discharge line at the top of the boiler. When the pressure got down to 40# I opened my lowest valve adding to the blast. When the pressure went to nearly zero, I closed the lowest valve leaving the upper valve open and then opened the inlet water and flooded the boiler for the second purge. At 100#s I followed the same procedure. Then repeated it a third time. On the fourth I simply filled the sight glass 2/3 full and headed for the Arkansas river dock.

I set off up stream when I reached 100#s Some kids nearby so I pulled on the whistle. What I got was a hot shower instead of toot. Didn't think much of it and I was very busy steering, firing and navigating. I wear all three hats on Li'l Steamy. I needed more throttle to move up stream and when I eased it open the engine sped and then slowed. It was perhaps not a bad as the last outing but I think that is because my reactions were honed. I decided to stay out of the flow and go slowly along the edge. Water time came and I slowed to let the pressure build to 100#s before I engaged the Penberthy injector. I found/realized the problem I had with the injector on the previous trip was going to plague me again. Wet steam does not work well but it does work some and I didn't have to hand pump.
The sun was warm and the wind was calm so I Continued on up to the confluence of Lee Creek. I like to turn off the river here and travel up. Under the old train bridge past busy fishermen. I reasoned that the longer I ran the more I would be cleaning out the boiler. Most fellas on this forum blow down the boiler at the end of each day but when I arrive back at the dock, I still have a fire to contend with and I don't blow down because I fear the heat damage to the boiler. I suppose the obvious way is to wait a period of time with the boat in the water until the fire has died and then blow. Mine is a busy ramp and I don’t want to keep it clogged up so I load up and drive home with the steam in the boiler. Somehow when I get back to the plant where the boat stays inside I forget to blow it. I will try and change my habit.
After three outings plus three blow downs. I am still getting wet steam if I open the throttle, pull on the whistle, fire up the injector. Is there some product (like soap) I could put in the boiler to help get over this “boiler Priming”?

[gondolier88]

What has changed on the boiler and what work have you done before this problem started happening?

Unlikely to be oil or impurities after such a rigorous cleaning- you can put a a SINGLE DROP of washing up liquid in and try the blowdown again. However, priming due to oil is usually down to a proper skin of oil on top of the water, not a few oily spots left from fingers after working on a boiler.

My first thought is that the water gauge has a blockage on one of the cocks and could be mis-reading.

Greg

[DetroiTug]

I'm out of suggestions on your water problem, it is definitely strange. It may help find a solution if you made a dimensioned sketch and post it here showing the height of the boiler and where the sight glass is and any changes that may have possibly been made. Maybe a top view showing the tube layout in relation to the threadolets. I doubt this has anything to do with impurities after that many blow downs. I built a new boiler and never had any issues like that. It could have something to do with the water being used/starting out with. Is this well or city water? There may be some mineral like lime in it that is causing foaming?

Have a look at this thread:

http://www.smokstak.com/forum/showthread.php?t=105599

For shut down, I always pull the fire with a set of tongs like those pictured below. I use a 5 gallon bucket with about 2 gallons of water in it. Reach in the fire box, grab the logs one by one, stick them over the side of the boat and plunge them in the water. They are still smoking some and then I put them in the bucket. Then shovel out any hot coals and put them in the bucket to be extinguished. Then shovel out the ash under the grate and put that in the bucket too. It's a mess, but it's all in one bucket that can be dealt with at home. Once home, take a nice walk with the bucket to isolated location and disperse of said remnants. I just pour off the water and then throw the rest in the trash can, then rinse the bucket out for next trip. Once the boiler has cooled a bit, I blow down completely with the boat on the trailer on the ramp and still in the water. It creates much less spectacle than dumping 40 gallons of scalding hot water in the parking lot. Safer too. The fish probably don't care for it. As soon as the pressure is almost gone, I pull the boat up the ramp. Then I open all the valves on the boiler so the heat will dry it out completely.

I also keep a small galvanized garbage can with lid for taking out ashes during the day. Could actually use the 5 gallon plastic bucket with water in it for that as well.



-Ron

[barts]

I would definitely use a healthy dose of TSP in the boiler prior to your next blow-down; that way you know the oil is gone

- Bart

[cyberbadger]

I used the instructions on that smokestak link on my new boiler this fall - Not pressurized - meaning It was open to the atmosphere on a low to very low fire and I let it steam for 1/2 and hour.

2 Lbs per 100 gallons TSP
and
2 Lbs per 100 gallons Soda Ash

I still have 49 pounds of Soda Ash if anyone is driving through Ohio near me. On the house.

I am happy with the results.

Other thoughts...
1)If any pipes or metal is not hot you will get natural wet steam from condensation until steam heats up which ever engine, etc???
2)You can modify one of the jets on a penberthy to make it more pressure tolerant - I haven't done it but I can get the details if you are interested..
3) Sounds like your water level is too high or there is some undesirable chemistry to the water in the boiler?

-CB

[wsmcycle]

I have found a change in the fire tubes. The old tubes were 1.312 OD. The new ones are 1.375 OD. The space between tubes is therefore 0.062" less. The space went from 0.250 to .1875. The kind-of triangle shape between the tubes is 29% less area. The total area comparison (74 tubes in a 17" circle) is 9% less water area. Hind sight!! All i can think of is to add some kind of "steam dome". But the dome would have to be plumbed by 4, 1/2" pipes. It can not just be the top of the boiler. Plus it will just be a heat loss and look stupid up there. Although only a steam guy would know or wonder what or why it is there. But again you steam guys are the only ones whose opinions matter on the subject. Any suggestions?

[Mike Rometer]

Whilst the difference in the tubes is notable I would go with cyberbadger's ploy and try to boil the problem out. It would be a very tight design that was running that close to the limit, even before your tube change. New steel is a known problem, especially in boilers without steam domes. Try looking at a Traction Engine forum and see the numbers on there that report this very problem.

[cyberbadger]

No offence but I question that 9% figure. Not that the calculation is wrong, but that that is the issue.

With handfired boilers - those calculations are a starting point - but there are a lot of variables - not all under your control and not all even practically measurable. 9% to me seems like it wouldn't rock the boat that much as Ron is suggesting.

-CB

[DetroiTug]

Quote: "The old tubes were 1.312 OD. The new ones are 1.375 OD. The space between tubes is therefore 0.062" less. The space went from 0.250 to .1875."

25% less distance between the tubes, I think that may be the problem. I theorize what's happening is the water under high steam demand is rising inside these "triangles" due to the increased restriction between the tubes and is being diffused/sprayed against the upper boiler shell. With no deflector, the water is entering the piping in proximity.

Consider all of these triangular areas from the center to the outer ring, pressure in the center of the bundle is probably exceeding boiler pressure and increasing the velocity of this effect.

I would go through the water regiment and rule that out, but I think it's going to wind up being restriction between the tubes.

-Ron

[wsmcycle]

Detroit Tug, yes is am afraid you are correct. I have an Idea. I could weld at the top in place of the supply discharge, an elbow of perhaps 2.5" pipe and extend it upward a foot or so. Then, plumb the supply, and the whistle port out of it. I don't think it matters that the pressure gauge and the safety valve are moved up.
It will be a bastard look but it will be better than replacing the fire tubes with fewer fire tubes. What do you think?