AS devotees of Steamboatin', we tend to
look disapprovingly at other prime movers such as diesel and gasoline
engines. Noisy, disagreeably smelly, uninteresting, and the like,
while we boast about the fine attributes of our finely handcrafted
is Inefficient: Unfortunately
steam, with all its beauty, mechanical ingenuity, traditional and
nostalgic appeal has been replaced for a very good
reason--efficiency. A generally accepted figure is that steam
machinery is about 8% efficient. That is, of the heat (energy)
produced by the burning of the fuel, only 8% produces work at the drive
A steam plant is a heat engine, thus it follows that inefficiency
results either from heat loss or from heat transfer. The biggest
heat loss occurs at the boiler via the stack; minor heat losses occur
from the engine, associated piping, and accessories.
Heat transfer problems occur mainly within the boiler and within the
various heat exchangers used in the particular system. Rather
than accept these inefficiencies as inherent to our steam plant, let us
look at the great increases in efficiency that can be achieved
A brief look at the arithmetic involved: If we can, by our
corrective action, measure increases efficiency by 2%, say from 5% to
7%, or from 6% to 8%, then the horsepower at the drive shaft can be
increased by 1/4 to 1/3. Quite a large improvement!
Stack Heat: Obviously
our prime effort must be to do some thing about the tremendous waste of
heat going up the boiler stack. Insulate the stack to keep the
waste heat in place, also a cool stack has many comfort and safety
advantages. Metalbestos double wall insulated stainless steel
stacks, lagged with sheet brass, if desired, performs this task
conveniently and economically
now let us add preheater and super heater coils to he interior of the
stack thus partially recovering the stack heat. If one can be
certain that the feed water lines can always be full of water (a rare
circumstance) copper tubing may be used. Otherwise this and the
superheater should be made of stainless steel tubing which, when dry,
will tolerate the stack heat.
2. We must
second effort should be insulating. Adding one to two inches of
glass insulation to the exterior of the boiler covered with wood or
metal lagging is a good start.
Then insulate the steam lines: main steam line boiler to engine, cross
over from HP exhaust to LP steam chest, the engine cylinders
themselves, engine exhaust, exhaust/feed water preheater, Feedwater
line to stack preheater, and then from stack preheater to boiler.
Keep the whistle feed line inside the stack.