No idea if anyone is interested, but...

Just for the heck of it, trying to "improve" the steam installation. More for technical entertainment and educational purposes than anything else, not expecting miracles, and it is not going to make the boat any prettier.

The boat, as is right now, has a boiler with a "steamable content" of about 6,5 oz, and a feedwater tank of around 12 oz. Water consumption is about 22~24 oz per hour, so with a safety margin of 2~3 oz there is about 20~25 minutes of operating time, because it is imperative that the feedwater pump does not run dry: When that happens, the boiler needs to be depressurized in order to prime the pump again.

The plan is to pre-heat the feedwater using the spent steam from the engine. This should improve fuel consumption by about 10%, give or take. This saving is relatively unimportant, because the fuel tank is not the limiting factor (suffices for cold start-up plus 50 minutes of operating time), and you have to blow off the unused fuel anyway, so any savings here are moot. It's just a (useless) bonus, but it DOES increase the boilers capacity to maintain pressure under load a bit.

The main reason for this mod is that doing so results in the used steam condensing into reusable water to feed the boiler, which extends operating time.
The pre-heating of the feedwater only results in a condensate flow of about 1/6th of the feedwater consumption, but any heat loss in the condenser (heat dissipation to ambient air) of course increases the return, and I expect to be able to reach about 40% return, extending operating time by the same. Theoretically that would mean 40 minutes of operating time instead of 25.

However, there is a problem with condensate return, and that is in that it can contain traces of engine oil (the engine is lubricated internally by injecting oil into the steam supply. Most of that oil is collected in an oil collector but traces can pass).

So step one is ot build an oil separator in the feed water tank. This has to work first, otherwise the entire project is useless. Oil in the feedwater can cause problems with the boiler fouling internally.

So first step was to build a tiny oil separator in the feedtank, in order to receive and pass the condensate.







it basically consists (just like the real thing on real steamers) of a compartment divided by a bulkhead that forces the water to pass under that bulkhead in order to reach the spillway. Only difference is that in real life installations, these separators usually are a cascade of 3 to 5 bulkheads and overflows.
The idea is that oil, floating on water, will remain in the first compartment, only clean water will pass under the bulkhead and spills over into the feedwater tank.

The oil separation in the first compartment is assisted by (not pictured) a coalescent filter, a fibrous cloth material that has zero affinity with water, but good affinity with oil.
I have tested with a flow of about twice what is expected (appr 0,5 oz/min) and it appears to work well, except for the V-shaped overflow, which seems to be not the best choice WRT shape.

Next week the condenser.