Monotube Javelin

[TahoeSteam]

Are SNAP generators about the size of a coke can?

[fredrosse]

SNAP = Systems for Nuclear Auxiliary Power
there is a good summary from Wikipedia, the free encyclopedia. Sizes ranged from about 2.5 watts to several kilowatts, with weights (and size) ranging from a few pounds to thousands of pounds, however the safety issues eventually led to development of solar electric generation, and Hydrogen/Oxygen fuel cells for space based electric generation

[TahoeSteam]

I ask because my uncle told stories of small nuclear power cells the size of a coke can that him and some of his coworkers would sometimes hold in their pockets to warm their hands... He was an electrical engineer for Sandia working on defense projects like the NKC-135 aerial laser laboratory, amongst other things...

[Elver1]

fredrosse, do you have a steam safety valve in your system? I imagine you do. I ask mainly because I haven't seen many flash steam models, etc described as having safety valves, while with any other type of model boiler it's always a major part of the equipment description.

[fredrosse]

The ASME (American Society of Mechanical Engineers) publishes the basic code book for boiler design and construction. Virtually all boilers as well as pressure vessels are governed by the rules here, and most USA States, as well as the majority of countries follow these rules. While many steamboats and hobby boilers do not strictly follow the ASME Code, its rules are generally followed to a certain extent.

The ASME Code requires a spring loaded safety valve on every boiler, with absolutely no intervening valve, with piping short and directly to the safety valve. There is no compromising on this rule, and every steamboat event will require the safety valve or the boat will be prohibited from participating in the steamboat meet. This rule is for any boiler or steam generator type, without exception.

[Elver1]

Thanks Fred Rosse, I was planning on it for my plant. I was just wondering why safety valves are so seldom shown in diagrams in the model monotube world. Maybe just diagrammatic over-simplification? Seems to me that besides the safety function, it is valuable for pressure regulation -- which itself is a frequent topic in flash steam. I was just wondering why it isn't often even mentioned.

[fredrosse]

Working as a Professional Engineer for over 50 years in the steam power industry, I have never seen a diagram produced professionally that did NOT have the safety valve shown, if there was one in the system.

"just wondering why safety valves are so seldom shown in diagrams in the model monotube world?" I do not know why, many people make diagrams without rules or conventions.

"Seems to me that besides the safety function, it is valuable for pressure regulation-" The safety valve should NEVER be used except to protect systems from over-pressure. Pressure regulating valves are entirely different types of valve.

"I was just wondering why it isn't often even mentioned." I think, either people talking about steam generators are assuming "of course, everybody knows that a safety valve is required", or they may not know this at all. Trusting statements on the internet easily can go either way.

[Elver1]

I appreciate that Fred Rosse. Most of the information I've found on flash steam power over the years wasn't found on the Internet though, so I can't blame the digital world for any misapprehension on my part. Most of the model engineering information I was thinking of above was gleaned from books and periodicals, although the little that has appeared online re. SL Alba, and Terry Williams Sprite was greatly appreciated. (Both did mention safety valves, btw.)

The reason I asked in the first place was not to avoid including a safety valve, but wondering if there had been some difficulty in building them for the very high temperatures and pressures that have been mentioned particularly in the model hydroplane racing world. I'm not interested building something to those extremes, myself, and I know your plant is at the other end of the scale with wet steam. I had just wondered if the reason they weren't present in those discussions and drawings of auxiliary flash steam plant equipment was that they might be impractical to actually design or build because of materials limitations for that level competitive model.

[TahoeSteam]

Fred,
Quick question about your steam separator;
Is it considered part of your boiler pressure vessel or considered 'plumbing'?

[Lopez Mike]

Fred,

Reading about all of the stuff under your foredeck, I am reminded of this:
http://southlopez.net/Mill/marblemill.htm

Mind bending.

Mike