The Steamboating Forum

Greetings Steamboaters:

I am nearing a decision to purchase my dream Steamboat. She has a Bryan Water Tube Boiler and is currently fired with Recycled Motor Oil, burns aprox. 4 gal/per hr at cruising speed (5-7 knots). However, I have wholesale access to Propane here where I live; see it as a cleaner, steadier burn and much less hassle to acquire.

My point - Can anyone help me quantify how much Propane can I expect to burn to maintain a working pressure of 150-165 psi when cruising this boat? This boiler has a max pressure rating of 200# and a safety blow off set for 175psi.

This would be a great help to me! Thanks!

diesel = 129,500 btu/gallon

propane has 91,500 btu/gallon

Approximate consumption is 129500 btu/gallon diesel / 91,500 btu/gallon propane * 4 gallons diesel/hr = 5.7 gallons propane/hr.

However, this will vary depending on firebox, controlling excess air, etc.

It's very hard to beat free fuel.

- Bart

1. Propane has a larger Hydrogen fraction than fuel oil, so more of the combustion products are H2O, and that implies lower boiler efficiency. Typically about 5% to 10% worse boiler efficiency with Propane on this point.

2. Beyond that, the oil fire has a very healthy component of radiant heat, whereas Propane does not give radiant heat transfer to the boiler nearly as well as oil. This can be a big factor in any particular boiler, and it is possible to overcome this Propane difficulty with proper boiler design, but many details would be needed to properly quantify this question. I would guess typically about another 5% to 10% worse boiler efficiency due to the radiant heat component.

3. The propane fired boiler can be run for years without any smut or fireside deposits, not so with oil firing. Here the Propane has a clear (no pun intended) advantage. Oil fired boilers often have some buildup of fireside fouling deposits, which impede heat transfer. Oil is not nearly as bad as coal or wood firing in this respect.

In summary, I would expect the Propane consumption to be around 150% to 160% of the oil consumption, with electric driven oil burners. If you have steam atomizing oil burners, then the energy used to generate the steam for the burner, and the lost boiler efficiency via steam flowing on the fireside can bring the oil consumption up considerably, so the Propane might only be 125% - 135% of the oil consumption.

In my view, the cleaner combustion of the Propane is well worth the extra amount required. But then some of us like some smoke and soot!

Thanks Guys. I appreciate your input on this decision. Guess I had this figured all wrong. Yes, Propane would be cleaner on the fireside, but looks like I would be loosing a significant amount of BTU's unless I went through a significant redesign of the existing firebox & burner assembly that is already working quite well on the boat.

Not to mention, if I cordially arrange a partnership with one or more of the local "Oil Change" Garages to take some or all of their used motor oil off their hands at "no cost" to me - then my fuel costs would be negligible. If it's not broke, why fix it just to fix it.

Since you guys have been so kind to offer input. Do you think any Steamboaters have considered using an elongated parabolic mirror device to preheat boiler feed water to lower the energy needed to bring boiler water to the steam flash point...??? Seems a possible "green" angle to the steamboating culture.

If you have any other suggestions, please feel free to offer them.

Thanks!

Actually, firing with downed wood is the greenest solution... Works well, carbon neutral in the long haul, and less annoying exhaust gases.

- Bart

Yep, I'd thought about that. Certainly nuisance Mesquite wood is plentiful here in W. Texas, but getting out in folk's fields and ranches to harvest is VERY labor intensive, costly for tire repairs from cactus thorns and such with a lot of potential exposure to Rattlesnakes in these parts. This boat is set up to fire with wood. However, I plan to do some consistently regular operation of this vessel for hire and I don't really want to take an inordinate amount of time to load wood and off load waste ash.

I'd give some serious thought to converting to a hybrid arrangement if I find a viable application of Oil/Solar firing; we get PLENTY of seriously hot sunshine out here.

Mack

I second the wood option. My particular situation, I do little repair jobs for the tree service across the way and they offer me split seasoned firewood for free. The trees are already cut and were essentially discarded, so no environmental impact. Plus, exhausting up the stack creating forced draft, there is virtually no smoke. Aand, wood is very easy on the boiler. Slow gradual firing reduces stress on steel components that are heated more evenly.

-Ron

Definitely wood is a reliable and predictable fuel source. I believe the owner has told me that he uses wood to initiate warming his boiler for the day's cruising, then switches over to his atomized Oil burner for working up pressure and warming the Engine. This is simple for me to understand and to teach others who will be helping me work this boat. Just about the same way my ol' Coleman Camp Stove works - the initial flame is yellow and sooty, but once is warms up that main feeding tube and the fuel turns to vapor, the flame turns to the clearest blue and makes no soot at all.

Maybe I should run her on Coleman fuel.....????

Mack

By 'atomized' do you mean with steam or a regenerative burner like a Coleman stove? I've not heard of a regenerative burner with crankcase drainings.

Mike

This is more likely the burner and firebox reaching proper operating temp. My burner does this as well.

-Bart