Steam Engines

Most of the steam turbine ship that I sailed on had a thermal % of around 30%.
This was from 1960-1976, so I with developments is further heat recovery I would think it would be a lot higher.
If you look up the Model Engineer back issues, steaming competions are held each year and will show the load pulled and distace covered for a set amount of fuel used.
 
This, I think, is the engine from Mr Hickey's Elfin.

It's not the Pierrette's engine because that was a 2 cylinder single expansion engine but he did have another steamer as well.

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Maximum power: 108,920 hp at 102 rpm – abot 80 MW at 102 rpm
( A locomotive engine might be 3 Mw at 1500 rpm)
The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine is the most powerful and most
efficient prime-mover in the world today. The Aioi Works of Japan’s Diesel United, Ltd built the first
engines and is where some of these pictures were taken. It is available in 6 through 14 cylinder versions,
all are inline engines. These engines were designed primarily for very large container ships. Ship owners
like a single engine/single propeller design and the new generation of larger container ships needed a
bigger engine to propel them. The cylinder bore is just under 38″ and the stroke is just over 98″. Each
cylinder displaces 111,143 cubic inches (1820 liters) and produces 7780 horsepower. Total displacement
comes out to 1,556,002 cubic inches (25,480 liters) for the fourteen cylinder version.
Some facts on the 14 cylinder version:
Total engine weight: 2300 tons (The crankshaft alone weighs 300 tons.)
Length: 89 feet
Height: 44 feet
Maximum power: 108,920 hp at 102 rpm
Maximum torque: 5,608,312 lb/ft at 102 rpm
Fuel consumption at maximum power is 0.278 lbs per hp per hour (Brake Specific Fuel Consumption).
Fuel consumption at maximum economy is 0.260 lbs/hp/hour. At maximum economy the engine exceeds
50% thermal efficiency. That is, more than 50% of the energy in the fuel in converted to motion.

For comparison, most automotive and small aircraft engines have BSFC figures in the 0.40-0.60 lbs/hp/hr
range and 25-30% thermal efficiency range.

Even at its most efficient power setting, the big 14 consumes 1,660 gallons of heavy fuel oil per hour.
 
Steam Electric

Efficiency is only important if fuel is scarce or expensive. I can get almost unlimited amounts of wood (scrap softwood from old pallets, etc), so a wood fired steam plant would be attractive.

Other major upsides include nice noises, cabin warming, etc.

The downside is time to steam up from lighting, so what about steam electric? A medium size battery bank would get you underway quickly and undertake short journeys. Longer journeys would see you firing up and running a generator tio re charge the batteries. Some sort of duel drive could be fitted (like the EA diesel electric launches) so that you cuold get direct steam drive, for occassions when the batteries were charged and steam being produced.
 
There was a TV programme recently about a new LNG tanker that is propelled by a steam turbine fuelled by its own cargo. One moving part in the engine .. seemed pretty neat.
One of Richard Hammond's series IIRC.
 
maxcampbell said:
Other major upsides include nice noises, cabin warming, etc.
Click to expand...

And don't forget the delicious smell of hot steam oil :)


maxcampbell said:
The downside is time to steam up from lighting, .
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My grandfather was the Chief Engineer at Henry Booth's woollen mill at Morley, near Leeds and, amongst everything else, he was responsible for the steam engine there. ( 350hp cross compound engine by Woodhouse and Mitchell, built 1899. 13"HP, 27"LP X 3ft stroke. 140psi, 86rpm. 14ft flywheel, 11 ropes. Air pump driven by LP crosshead. Proell governor. 11ft rope drum with 6 ropes for drive to 150KVA alternator. )

A house went with the job which meant he was on call at all times.

At midday on Saturday the mill shut down for the weekend and the furnaces were banked. On Monday morning well before 5am he would go into the boiler room and stoke up so as to have steam on the engine by 7am. This saved the company having to pay the boiler man overtime to come in early.

Raising steam from cold would have taken considerably longer, of course. So having a steam engine in a yacht would mean you had to sit there a long time waiting for your machinery to be ready. An alternative might be to have some kind of electric immersion heater to heat the feed water. This could be left plugged into a marina socket and timed to have the water hot by the time you came on board! Another answer would be to have a flash-steam boiler. There used to be a firm in the Isle of Man called Light Steam Power Ltd who sold plans for these and for small steam engines that would power a car.

Incidentally my grandfather kept on working at the mill into his 80s, still stoking up on Monday mornings.

By 'eck! :D
 
agurney said:
There was a TV programme recently about a new LNG tanker that is propelled by a steam turbine fuelled by its own cargo. One moving part in the engine .. seemed pretty neat.
One of Richard Hammond's series IIRC.
Click to expand...

My second ship as a marine engineering cadet with Shell in 1981 was an LNG tanker, she used to burn boil off gas from the cargo rather than fuel oil and there was competition between the watches to see who could burn the least fuel oil, we once got down to 4.7 litres in a 4 hour watch at full steam ahead - not bad for a 22 MW steam turbine - probably didn't deliver much gas to Japan that trip though! :D
 
agurney said:
There was a TV programme recently about a new LNG tanker that is propelled by a steam turbine fuelled by its own cargo. One moving part in the engine .. seemed pretty neat.
One of Richard Hammond's series IIRC.
Click to expand...

Unfortunately you can't believe much of what Richard Hammond says in these Boys Own series. Yes, the turbine rotor is the only moving part inside the engine, but have you ever seen the control oil system that makes it all happen? Many moving parts in there, finely machined, operating steam valves, seal systems, lub oil system, etc.
 
vyv_cox said:
Unfortunately you can't believe much of what Richard Hammond says in these Boys Own series.
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He's a journalist, it's to be expected.

vyv_cox said:
Yes, the turbine rotor is the only moving part inside the engine, but have you ever seen the control oil system that makes it all happen? Many moving parts in there, finely machined, operating steam valves, seal systems, lub oil system, etc.
Click to expand...

I drool over them regularly at the transport/riverside museum.
 
Red Admiral said:
Efficiency of steam engines depend largely on whether or not the exhaust steam goes to a condenser running a high degree of vacuum. James Watt improved the efficiency of Newcomen engines from 1/2% to 2% in this way. Even with a condenser you would be very lucky to get an overall efficiency much greater than 10% with a small modern engine. That's why most merchant ships, even very large ones, are diesel powered.
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One would also have to factor in the boiler efficiency in delivering the steam at required temperature and pressure and heat losses in the system. By way of comparison, a modern diesel engine is expected to consume about 120 gramms per bhp. hour. An "efficient" equivalent steam turbine plant in a ship will be rated at 240 gramms/shp.hr
 
What about Concorde's engines

I remember seeing a TV programme where it was claimed the engines on Concorde at full speed were the most efficient engines ever built :confused:
 
paul.norton said:
I remember seeing a TV programme where it was claimed the engines on Concorde at full speed were the most efficient engines ever built :confused:
Click to expand...

Possibly the most efficient gas turbines ever built? Single shaft GTs have an efficiency not much better than 30%. Latest GT turbofan versions have three concentric shafts, with the LP and IP sections of the compressor section driven at different speeds from the HP end. The result is that such engines by RR and by GE have efficiencies over 40%. A good brochure on the Trent engine is at http://www.rolls-royce.com/Images/gasturbines_tcm92-4977.pdf

AFAIK the most efficient arrangement by far is to burn fuel in an industrial GT, then use the waste heat to generate steam for a steam turbine. This is cogeneration, that is claimed to give efficiencies up to 88%.
 
I love this, looked into small steam plants for a river cruiser. Appealed to my DIY attitude for a fun boat.
Couple of things stood out: One, steam plants require constant fettling, which their owners love doing. Two, efficiency is def not anywhere near the top of the list of their priorities.
It is a labour of love, get used to it. Also the main reason that diesel is the preferred power source.
Concorde was using afterburners, excellent way of reducing your efficiency... Bit like the power needed to get over your hull speed for a displacement boat.
 
The problem with steam is that the whole process (a Rankine process) starts with evaporating water. This costs more than 500 calories per gram (2200 joules). All this energy is than wasted in the condenser or simply in the atmosphere.

In large power plants this energy can be used for a number of useful purposes boosting overall efficiency; not so on small power plants on boats.

Overall efficiency of a steam engine on a boat might not even achieve 10%; a modern diesel engine (yacht sized) will get around 25%.

I do like the principle of steam engines and have enjoyed the photo's; in those applications efficiency is unimportant.

Eric
 
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