Steam powered sternwheeler ( first boat build ever )

[apointofview]

I'm hoping to run it next month sometime and it doesn't get too cold to freeze over here and cold air should show the steam off nicely. It's going to depend on getting a calm day and plenty of time to finish the details

[apointofview]

More progress, all the lights are mounted, but the interconnecting wiring still has to be figured out.  I would like to make it so the connections are made just by placing the levels on each other.  Some sort of brass plate and springs that would make contact as the levels come together.

Pete

[DamienG]

Outstanding Pete.   

[apointofview]

Thanks Damien !

Derek, I measured the water capacity of the boiler and supply tanks and its just at a 1/2 gallon ( just under 2 liters ) so I need to adjust my bow ballast with the full water load on board because it is enough weight to change the trim. Here is a question, since the trim of the boat will change as I use water should I start out with the bow a little low so that the boat doesn't shift the paddle to low in the water by the end of the water supply ?

A bench run on steam and with the r/c system on is going to happen maybe as soon as tomorrow.  I'm sure there will be a few unforeseen problems that will come up but that's why we test stuff right ?

I'll have pictures/video of that event for everyone,

Pete

[derekwarner_decoy]

Well Pete.....you have progress well, however thinking more about bench tests ..... you could consider the following

1. substitute home water tank tests for bench test
2. fill the boiler & on board supply tanks to the correct draft [without the superstructure] , fill the gas tank...[measure the weight of gas].
3. place the vessel in the test tank, secure lines fore & aft, steam up & set every thing to about 1/2 to 3/4 throttle...synchronize watches....camera at the ready
4. sit back & have a  ......monitor your water levels [plastic straw & thumb over the filling point in the tanks]....
5. occasionally increase/decrease engine RPM, and also do a little astern time
6. sit back & have a  .......eventually the system will shut down due to no gas
7. check the new draft, check the remaining volume/weight of water.....then calculate a nominal/optimal running time on the river water
8. sit back & have a  .......& take a few photographs for us here 

Remember square root of scale x model steaming minutes = real life running time ...so a 30 minute run is really equivalent to about 2 1/2 hour steaming trip.......I hope that makes scence

Derek

[DamienG]

Too many of these    however may have a detrimental effect on the outcome of the test and the ability to write the results down legibly or take photo's 

[apointofview]

Well it has run on steam with the r/c gear in control but only on the bench.  I wanted to use the water tank, but everything was in the garage and there is still work to be done.  Moving this big bugger around is no easy task so this run was on dry land.  When its ready it will go in the tank before it goes to the lake.

Every thing went fine except for the FIRE 
What happened was that my burner was turned up too high and the ceramic heated up to the point that the underside of the ceramic got hot enough to light the gas on the inside of the burner, which shot out the air holes next to the gas jet.  That burned some of the insulation on the manifold but nothing else.  The remote emergency fuel shutoff worked perfectly and killed the fire.

After that fun it became real obvious that a change to the burner is needed.

Other than a bit of a hot spot everything else went pretty well.  I am going to change the orientation of the pressure relief valve.  it dumps water all over the bow and makes a mess, especially on its first blow off when its cold.  Later when its up to temp it cycles better and the steam is dryer. I need to get the hang of balancing the heat and steam use.  The relief valve wastes a lot of water just dropping 5psi.

I timed the warm up of the boiler. From stone cold to 5psi was 5 minutes, 6min to 20psi and 9min to 40psi and the primary relief valve venting.  The engine was warm enough to turn in 11min from the lighting of the burner. 

I didn't measure gas consumption or water use, that will have to be in the next run.  I seem to be fairly busy tinkering with the system so documenting every thing that happens is hard to do.

I took a video of a little bit of the run and posted it here - https://youtu.be/y3eVxcSsl3Q

Well I guess it took Edison more than one try to get the light bulb right so this will go smoothly eventually.   At least the hull and superstructure ( which was on at the time ) didnt get any damage.

Pete

( good thing I didnt have any of these    or the reaction time of the fuel shutoff might have been a bit slower and I would have a lot more repair work to do !!! )

[Hankwilliams]

very interesting the american valve geared engine! Until now I`d never seen a functionating model of this kind of engine in steam meetings in Germany or Austria. What are bore and stroke?
The problem with the burner seems not very big, may be a normal brass burner for soldering will be the better choice,
in my two sternwheelers I used this kind of burner with none problems.

Greetings

Thomas

[apointofview]

Thomas,
From what I understand these engines didnt see much use other than in the western American rivers. So I guess people build what they see around them is why the shows around you dont have any examples of my engines.

My bore is 5/8" with a stroke of 3 1/2"

Could you tell me more detail ( maybe a picture or two ) about the burner you use ?

Pete

[Hankwilliams]

Hi Pete,

my "Ville de Bruges" Congo steamer. You see the quite normal burner for silver soldering in front of the boiler. Diameter is 20 mm, here you can buy such burners in every tool market. It cant`t be overheated, if the gas pressure would became too high, the flame will be extinguish.

Thomas

[apointofview]

Ok, I see what you mean, thanks for the picture that made it clear.  A burner like that gives you a bit of a roar noise correct ?  One of the things I like about my ceramic burners is that it is very quiet.  Most of the noise my setup makes is the steam exhaust and the valve cam movement.
Pete

[apointofview]

Well another bit of a setback. 
This was to be the last bench run today and off to the lake tomorrow.  I changed the jet orifice diameter of my second burner to a #80 drill bit hole ( .0135in or .3429mm ) and opened up the air bleed holes to lean out the burner.  It works great especially when the steam blower in the stack is running which pulls even more air into the burner making it hotter with less gas consumption. The problem is that there was a 45% silver solder joint in the super-heater line just above that now hotter burner.  There was enough heat in the new setup to melt that joint and start a leak.  It sounds minor and it is in comparison to melting a boiler joint, but to fix the damage it means pulling the boiler box apart ( which disturbs every fitting ) and putting a compression fitting in where the solder joint was. 

I am also going to take the opportunity to try to fix my water level glass setup since everything is tore apart.  Right now it taps the bottom of the boiler and the top.  That setup worked fine until I built the box around the boiler and turned it into more of a pot boiler with flues.  The lower water glass fittings now are exposed to the heat from the burners and therefore the water in the fittings boils and makes reading the level really hard.  I am going to punch a new hole in the boiler shell and add a fitting out of the burner area.

Gotta just keep plugging along, i'll get it right sooner or later.

Pete

[derekwarner_decoy]

Hullo Pete.....I too had a tube failure a few days ago........however with a cold boiler feed tube which had previously been tested to 5.5 Bar TP

When attempting a boiler static water pressure test @ 1.5 x WP [4.5 Bar], I continued to experience decay.......so yes the failed joint was found under the bulging insulation

Your issue it is more curious......45% [Ag] silver solder has a melting point range between 680 to 800 degrees C.... so I cannot understand or see you boiler burner flame creating a temperature high enough to refluidise the soldered joint even at your maximum boiler pressure..............you would need an internal boiler heat/temperature which equates to approx. 400 PSI steam pressure

Having said this, the consideration of installing a brass/copper compression union for this joint is absolutely fraught with danger

The heat/cooling gradient that the copper tube being exposed to will anneal and soften the tube......the initial sealing characteristic [torque/circumferential force] created  will be lost after the first boiler steam up...... Derek

[apointofview]

Well that gives me another reson to worry about this boat.  The design of the boiler has many problem, one of which is the routing of the steam line.  Where the faiure happened is directly over the ceramic burner which at the time was nice and hot and it cant be moved.  I can melt the silver solder on small parts with propane which is listed at 1980 degrees C not sure my burner is there but it is hot.  Another factor could have been fatigue.  It was in a coil that must be moving as thing heat up and cool so it could have been a mechanical failure.

As far as the compression fitting goes, I have one under there in the fire box already and it been there since the box was built around the boiler.  What you are saying about the copper getting soft and letting go of the crimped fitting does sound right, but I am usually at 25-30 psi and the relief happens at 42psi so the forces on the inside of that little line aren't that high.  The best thing about this whole situation is that the line and its fitting are in the stainless steel fire box so the loss of the line and the venting of steam wont do anything but maybe blow the fire out.  Its kind of a safety relief ? 

I do appreciate the input though, it helps me think this stuff out

Sorry to hear about your boiler, I hope your repair goes well.



Pete

[derekwarner_decoy]

Pete......if we go back a few steps

a. 99.9% oxygen free copper has a MP of ~~1080 degrees C
b. 45% [Ag] silver solder has a MP point range between 680 to 800 degrees C [depending on the balance metals x %]
c. the tip of your propane build torch flame may be listed at 1980 degrees C...I suggest that the flame available here would just heat the tube components to say ~~1000 degrees C max
d. what is the actual temperature that your boiler burner produces?

A hand held digital laser pyrometer cannot measure the temperature of the flame, but certainly will provide an accurate confirmation of the temperature effect on the parts directly in line or direct proximity of the radiant heat from the flame

[I paid $1,000 for a Ray-O-Tek digital laser pyrometer for work ten years ago, a few months ago I spent $18 AUD for similar device including air parcel post from China.........the best $18.00 ever spent]

You mention a silver soldered joint in the direct path of the burner gas flame....this essentially is not good

e. the 45% silver solder may have a lower melting point over copper, but the solder is harder
f. continual heating and cooling of the joint will create the failure point, however not the actual mechanical joint between the mating components, but the heat affected zone in the parent material [ie., the copper tube]

Spend the $18.00.....you won't be sorry .........it will give you confirmation of actuals......& not just guesses.....

The pyrometer [-50 to +380C] is on the left, the tachometer [1.0 to 9999 RPM]  on the right & the strain gauge [0 to 40 kg] in the middle....yes all ~~$18.00 each landed in OZ..............Derek