Steam powered boat why not do it again?

[perchance]

Steam out water in, am I missing something?

[Ti' Punch]

As a former nuc Machinist Mate myself, I will say that I did love the smell in the engine room when we were starting up the plant. All that lagging heating up made a distinctive smell. However, I always had the feeling that the steam plant would loved to have killed us all if we gave it half a chance. Those turbines screamed like banshees. I always felt a little sigh of relief heading back forward when my watch was over. We all took maintenance very seriously. I wouldn't want to deal with that on my pleasure boat.

[ArtM]

Originally Posted by Captain Bill

I agree that once the rods are in the reaction is shut down pretty much instantaneously. The quenching of the fission reaction does not however stop the production of heat associated with decay of the radioactive byproducts of the reaction. If coolant circulation fails the core can still get hot enough to melt down. Even the spent fuel rods which are no longer reacting must be kept covered with water lest they melt, which was the major source of the problem Japan had after the earthquake. While dropping the rods may stop the reaction that does not render a reactor safe.

Thanks Bill, that makes more sense to me. I guess I was considering the decay to be part of "the reaction", but it sounds like the technicians use the term differently.

[sailorboy1]

Originally Posted by Ti' Punch

As a former nuc Machinist Mate myself, I will say that I did love the smell in the engine room when we were starting up the plant. All that lagging heating up made a distinctive smell. However, I always had the feeling that the steam plant would loved to have killed us all if we gave it half a chance. Those turbines screamed like banshees. I always felt a little sigh of relief heading back forward when my watch was over. We all took maintenance very seriously. I wouldn't want to deal with that on my pleasure boat.

I was always WAY more afraid of the steam piping, the electrical cabling and motors, the electrical switch gear, the seawater piping, the high pressure hydraulics, the high pressure air, the torpedo otto fuel, the signal flares (missiles), the battery, the watertight doors when the boat was ventilating or the diesel was running, the other nuts locked in the boat with me ............. than I was of the reactor!

PS - and now that I think of it the sub navigated on chartplotters

[Tony B]

My motto has always been "if the old ways were better we would still be doing it that way". Manufacturers can get an edge on competition by doing things a better way. It's competition that keeps manufacturers from completely raping us. If coal was an all around better source for energy than we would see it used a lot more often.

[Lagoon4us]

Watching with interest the responses to this thread, good coffee topic!

Tony your quote, in a nutshell, sums up a defence for why we don't have these archaic, quaint and very interesting systems anymore. "It's competition that keeps manufacturers from completely raping us.


As another non-forum member once said "Any intelligent fool can make things bigger and more complex... It takes a touch of genius - and a lot of courage to move in the opposite direction.

Cheers

[klem]

To the OP, I assume you are talking about all sizes of boats, not just really large ones?

Taking it from an engineering perspective (I used to work as a designer of steam expanders similar to turbines), steam can do a really good job of taking energy stored in a wide variety of fuels and allowing it to be made into shaft work. However, this process while simple in principle, involves many steps. You need a boiler (with a superheater for a turbine) with fuel pumps, controls, feed water pumps, etc, lots of piping and safety valves, traps, a control valve, an expander, and a condensor. Not only is this a ton of stuff, at each step you loose a little efficiency. In the end, you get shaft work which you need to do something with. Small turbines spin at very high rpms so you either need a big reduction box or you need to spin a high speed generator.

Turbines don't really make sense under about 100 kW because they have to spin too high of an rpm and the parisitics get too large. Carrier sells a nice little radial outflow turbine that is 275 kW if I remember right and it is about the smallest thing out there. There really aren't any other commercially viable technologies for small steam expanders. Also, turbines have really poor startup torque, they really need to be run up to high rpm.

Size is a big issue on this. The turbine itself is usually pretty small but things like control valves add up really quick. Then you get the boiler itself which needs to be massive to have enough surface area. For example a 100 hp boiler (boiler hp is not really comparable to engine hp, look it up if you want to understand it) is typically around 10-15' long by 6' in diameter which is enormous compared to a diesel engine.

Steam systems are usually run at really high pressure (~1000 psi) for efficiency reasons. You can run them at much lower pressures but your efficiency will go way down largely because your condensor efficiency becomes really important.

Then there is the operational stuff. Imagine going to your boat for a cold start and having to wait 2 hours for the boiler to come up to pressure. Then you do all your safety checks before getting underway. Can you imagine the average person blowing down a boiler daily?

Steam is great but not for small boats and not necessarily for big boats. With nuclear powered vessels, it makes sense but just about everything else is phasing it out. It still makes sense in stationary power plants and heating systems because size and weight aren't an issue but it is simply prohibitive on everything but the biggest boats.

[ArtM]

Originally Posted by klem

To the OP, I assume you are talking about all sizes of boats, not just really large ones?


Turbines don't really make sense under about 100 kW because they have to spin too high of an rpm and the parisitics get too large. Carrier sells a nice little radial outflow turbine that is 275 kW if I remember right and it is about the smallest thing out there. There really aren't any other commercially viable technologies for small steam expanders. Also, turbines have really poor startup torque, they really need to be run up to high rpm.

Great post Klem.

I think that the original discussion was about piston-driven steam engines. The article referenced by the OP is about piston operated boats.

The original African Queen is operating today in Key Largo doing day charters. I'm not sure if it is piston or turbine driven, but I think it is piston driven, and I would suspect that the engine is driving the shaft directly.

I believe that the nuclear powered vessels we're talking about are electrically driven, isn't that right? Or are some of them shaft driven from the turbines?

[Ian R]

River Embley and River Boyne retire

The link above is about 2 coal fired ships that recently retired.

[sailorboy1]

Originally Posted by ArtM

I believe that the nuclear powered vessels we're talking about are electrically driven, isn't that right? Or are some of them shaft driven from the turbines?

What would be the point of making the steam then? Turbine driven with electric backup for subs (EPM) that can be via the battery for a while until the ..... wait for it .................... the diesel gets started to supply AC power to the motor generator to make DC to supply the either the battery or the EPM!

Getting close to the "we will have to kill you now" point!

[bobconnie]

Well with all the Nuc boiler men cked in so far !! They have missed one thing !! the story is about Coal! and the one thing you wont get with coal for the heat maker is super heated steam !!! boiling water steam yes! but ya can't run a turbine with hot water steam !!! it takes super heated steam for that !! ya can run piston steam engines with coal or wood power even triple expansion engines! but ya can't run a turbine with a coal or a wood fired steam! just a thought from someone who has run steam engines with coal for heat !!

[ArtM]

Originally Posted by Don Lucas

What would be the point of making the steam then? Turbine driven with electric backup for subs (EPM) that can be via the battery for a while until the ..... wait for it .................... the diesel gets started to supply AC power to the motor generator to make DC to supply the either the battery or the EPM!

Getting close to the "we will have to kill you now" point!

The point of making the steam is to drive the turbine to produce the electricity that drives the shafts. Steam is the only method I know of to convert nuclear energy to any other form. I'm not aware of any direct-conversion method to convert nuclear energy directly into electrical or mechanical energy.

If the sub were diesel powered, then no steam would be necessary.

Wait - how are you going to run a diesel engine on a submarine? For that matter, where does oxygen come from on a submarine? I could look it up I guess....

[ArtM]

Earlier submarines were propelled by diesel engines. They ran when the submarine was on the surface .Under water they used batteries to operate. Such subs were not able to stay under water for a very long time and had to come up for air supplies every few hours. Nuclear submarines do not need air. Special machines turn salt water into drinking water and extract oxygen to make air. They can stay under water for months without surfacing.

But this is off topic.

[Astrid]

Sure you can run turbines off of coal fired boilers. That was done on numerous turbine ships such as RMS Mauretania and Lusitania, virtually all the German WW1 turbine powered dreadnoughts and cruisers used coal since domestic oil supplies were insufficient. The three Olympic class liners used a low pressure steam turbine which was powered by exhaust steam from the two expansion engines, to drive the center prop.

In any event, the boiler itself does not produce superheated steam. Instead the wet or saturated steam produced by the boiler goes through a small tube superheater, which can be coal or oil fired. The superheater dratically raises the temperature and pressure of the steam, turning it into superheated steam. The first superheater units were introduced in the 1880s well before the introduction of oil fired systems and turbines and were applied to most reciprocating steam engines.

[Ian R]

RIVER BOYNE 51,035 gross tons. Lb: 255 x 35.4 metres. on: 8018132 Ore carrier built by Mitsubishi Heavy Industries, Nagasaki for ANL with 'paper owners' being River Boyne Pty Ltd. Single screw, turbine powered, twin boiler design using coal as fuel, fully automatic with UMS certificate. Speed 16 knots. Crew 38. Initially employed bringing ore to Newcastle, New South Wales from the mining ports of Western Australia. Since, with ownership changes being owned by the Australian Government and leased out to Queensland Alumina Ltd. Currently services the Alumina run to Newcastle NSW. Crew as exists August 2009 19 persons. Rio Tinto seems to be the parent owner and look to have an agenda of selling this vessel off in favour of overseas tonnage engaging Australian Coastal work. Both vessels are manned and operated by ASP Ship Management.
Both RIVER BOYNE and her sistership RIVER EMBLEY are are unique in that they are single screw, turbine powered, twin boiler design using coal as fuel
Designed basically as 'new-age' prototype vessels with a view to further construction of this type of ship. Sensible at a time when oil was going to astronomical. The vessels are unique in that they are fully automatic and have UMS certificates.
Due to their high coal consumption and small bunker capacity, they do not have the ability to undertake other runs except for the alumina run to Newcastle, which is done at slow speed.
The vessels have been very reliable over the years, and at the recent dry dockings, considerable work on renewing steelwork and paint systems to extend their life another 10 years was undertaken as well as general repairs.
Over the years many systems have been upgraded or renewed and the vessels are probably more technically advanced now that when built. They are the only vessels as sisterships ever to sail on the coast with twin funnels side by side

A bit more info I found on the SS RIVER BOYNE from the link below.

S.S River Boyne - Australian Merchant Navy