Are water-tube boilers actually easier to build?

[Lopez Mike]

Hmm. I have such a stove on my sailboat. I believe it is rated at 50K BTU. I have an extra burner I can examine carefully. As I remember the flame burns up past a copper disk or some such deviltry. Hard to say whether it would scale up properly. I'd need perhaps three or four times as much output I think.

[Jack Innes]

Mike,

The burner is definitely audible but not annoying. Imagine a cutting torch idling under an insulated bucket.

The alcohol is used in such a small quantity a quart on board will last quite a while. This is a very small setup
& the kerosene on board adds up to 18 litres, the consumption is about 2 liters per hour so the boat has quite a range & the fuel can be carried to the dock from its point of purchase. The locker ahead of the wheel holds the fuel tanks, the locker on the other side has extra cans of fuel & a small make up water tank to use when beaching the boat. The pre-heating could be done with a propane torch but the tray of alcohol, camp fuel, gasoline, Varsol, kerosene or any other combustible liquid is very easy & is augmented by the drips of fuel before the fuel is properly vaporised. You would need the absorbent tray in any case since the transition from liquid to vapor will always involve dripping fuel. In a larger set up I would think diesel fuel would work but might be sooty. I would think too with proper ventilation of the bilge & other precautions gasoline would work well. It does so in most steam cars. The Stanley burner works on the same idea but much more complicated.

The engine is a 2 cylinder 1 3/4 X 2 1/2" calculated (not by myself) at 2 hp at 350 rpm and 120 psig steam. It was built from two Henry Greenly engines on a common base and frame. It also uses a Stephenson link for reverse.

(CB notice the flex line)

[Oilking]

A note on fire pots:
For the old cast iron Neptune, from Washington Stove Works provided a fire pot stove oil conversion. Many of these controled the fuel flow with a needle valve and sight glass drip similar to a drip oiler. Fine until the fuel line warmed up increasing the flow and overflowing the pot. I've seen the remains of several boats the owe there imolation to a stove with a drip valve. A safer option is a regulator valve that has a float like a carbarator. The valve is positioned so that the float will stop the fuel flow well before it overflows the pot. Even this system can be fooled if the boat gets laid over so that the regulator is up hill from the pot. With a a regulator mounted on centerline this should not be a problem with a steam launch.

Dave

[Jack Innes]

I have a "Coleman" brand space heater that uses the float type regulator/carburettor that Dave described. From past home heating experience I have found these heaters are prone to soot up terribly if the fuel is not stove oil or better. They also are finicky if the draft is not right on.

If anyone wants to experiment I have a Coleman space heater with a dim future. The whole thing or just the carburettor and/or the fire pot can easily be available.

Jack

[Lopez Mike]

The Dickinson Antarctic heaters that I have use the float system. But, as I noted, I think they are too small to work in my boiler. I just looked it up and it is only 16K BTU. Would barely hold a spot fire for me.

It's hard for me to keep in mind the amount of energy we consume in our little boats.

[cyberbadger]

Sort of off topic - but related....

A little trick amusement around a campfire...

Warning - do this at your own risk, and I wouldn't advise having any kids around....
Fill a glass beer bottle 1/4-1/2 full with kerosene/coleman fuel(I've even done it with gasoline). Wipe/clean the outside of the bottle, and then Stick it in the fire, carefully, near the edge, not directly in the flames.
The fuel cools the glass beer bottle in much the same way the water in our boilers cool the steel/iron/copper - and prevents the bottle from breaking. After the fuel begins to boil it's vaporized and starts "steaming" out the top of the bottle and eventually catches fire. It's sort of a little mini "flare" that grows up to at least a 6-12" long until the fuel runs out and the bottle breaks and you have to clean it up later.

-CB

[fredrosse]

I have a couple of US Army Tent Heaters. These are the "Vaporizing Pot" type burners, where a float valve maintains a low liquid fuel level in a pot, with a perforated burner chamber where the fuel vapor mixes with combustion air, and the heat of the fire vaporizes the fuel. Rated at 35,000 BTU per hour, not enough for any steamboat except perhaps a steam canoe.

They are rated to burn gasoline, jet fuel, kerosene or Dissel Fuel, and some of them can also burn wood or coal. I always use kerosene. Burning Dissel tends to give some smoke, and a gasoline fire I don't want in my workshop. These burners are simple, made to be operated by soldiers in the field, and perfectly silent. They can be had on the surplus market for $50 to $100 new unused equipment.

A couple of years ago I put high pressure steam heat into the workshop, so the vaporizing burners are waiting till I retire for a very small steamboat project.

[hartleymartin]

Whilst on this topic, I used to amaze many people by boiling water in a paper bowl or cup in the campfire.

[asal0312]

I currently own Alan Amerian's old boat with the kerosene burners that Bart describes. Bart you are correct in your description of the burners. I recently took them apart to rebuild them last week. The burner does consist of 1/2" black iron pipe made with npt pipe fittings, "U" shaped. There is a 4" separation between the tubes. Fuel come into the top tube through a check valve (very important). The top tube is filled with a 1/4" rod wrapped in a copper screen the full length of the tube (about 30" long). The tube bends down with 2 ells to the lower 1/2 tube. This lower tube is filled half way with many small diameter rods, I assume just to take up space. I like the idea of using a smaller diameter tube. In the lower tube, six 0.040" holes are drilled into the tube for the flame to come out. I have two burners like this, one has the holes directly drilled into the iron pipe, the other has small brass (nubs for lack of a better term) brazed onto the tube where the 0.040" hole are drilled into. Both burners work very well, though the one with the brass tends to attract more carbon, cloging the orifices more often. I use the brass one for slow speed operation and the one with the holes directly in the iron pipe for running hard. A small electric fuel pump supplies pressure @ 8psi.

To start vaporizing, simply add a little alcohol to the tray and crack the kerosene and add a little raw fuel to the tray. The alochol lights the raw kerosene. After all the raw fuel burns out of the tube, crack the throttle again and it should vaporize. Alan ran these burners for many years and I intend to do the same, it works very well, and is fairly quiet (soulds like a small gas blow torch even when burning 2.5 gallons/ hr. Initial light-up is sooty however. I will make a diagram and post it when I have time.

alex

[Jack Innes]

Alex,

Thank you for the description of your burners. My set up does not have a check valve but will have one soon. The lack of the check may be the reason for running at 15 psi. It likely needs that to overcome the pressure created by the vaporization process. An 8 psi electric pump is fairly easy to come by & maintain.

Is your check valve before or after the fuel needle valve?

Jack