# Uni-flow electricity making steam engine



## bedgen (Nov 25, 2011)

Hi to all!
I'm planing to make steam engine to get electricity in outdoor
what kind of engine will be best? (I'm planning to make uni-flow engine)
what more relevant for this? shaft torque or high rev/min?
what kind of valve is better?

and i want to make it in most simplest way

tnx for any advices

and any links for h.p. and boiler calculations?


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## steamer (Nov 25, 2011)

Hang on a minute son.

Welcome to HMEM! We're a good bunch of people who build model engines and a variety of other things.  We're a big group, and as such we like to know who we're dealing with and welcoming into our home.  That's a reasonable expectation I think anyone would understand, wouldn't you? 

If you could please, Please put a welcome post in the welcome section and tell us about yourself, where are you from, what do you want to build, what do you have for a shop ect.

and Welcome to HMEM! ;D

Dave


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## Rocket Man (Nov 25, 2011)

According to the law if your boiler is smaller than 5 cubic feet or 5 gallons I don't remember which you are not required to have the boiler inspected.

The best boiler has the fire box in the center of the water jacket there is less heat lost. Do the math to calculate the outside diameter, fire box size, number of boiler tubes to make it legal.

The fire box needs to be no smaller than a 12" diameter pipe about 18 to 20" long. Put that inside of a larger pipe maybe 24" diameter. Weld on both ends then put in enough tubes to get the size slightly below 5 so it is legal.


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## steamer (Nov 25, 2011)

Rocketman,

Considering he's from the Ukraine, I would just bet the laws are different.

Hell here they vary wildly by state.....

Dave


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## bedgen (Nov 25, 2011)

Rocket Man,
Tnx! but im looking for math fomulas to fit heating square to make the engine work in nominal power( dependence between preasure revs/min diameter of piston and stroke)


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## seagar (Nov 25, 2011)

Steamer.Do you have to be so rude to a newby who may not understand the protocol of this forum?This attitude noes not promote good will & friendship. :rant:

Ian.


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## jonesie (Nov 25, 2011)

i do not think steamer was rude i seen the word" please"'used twice in his post.jonesie


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## bedgen (Nov 25, 2011)

it was ok, and understandable 
but guys, i still need advices


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## tattoomike68 (Nov 25, 2011)

Im not sure how muck power you want to make. A machinist friend wanted the price on 15 HP steam engine to make power. the plans were $150, buy one done for under $2,000 it looked like a motorcycle v twin and not hard to make.

The big kicker was the boiler, it was $10,000+

It all depends on how much power you want.


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## Tin Falcon (Nov 25, 2011)

Bedgen:
 Steam is old technology as such there are Manny many books out there on steam engines and there design. 
there is lots of stuff on http://www.archive.org/index.php type in "steam engine design " in the search block. 
And as an engineering student get yourself a copy of machinery handbook. 
The KN Harris books introductions talk a lot about sizing boilers to engines and scaling. it is directed to model engineers but a good start.

Rocketman brings up an interesting point . Check local boiler codes this could help you size your boiler without getting into a lot of red tape or government inspection requirements. there are many considerations to a design. 

Tin


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## steamer (Nov 25, 2011)

Bedgen,

For what your doing, how much power do you want to generate?

A flashlight or a city block?

1 kw or 100000 kw?

Start there and we can talk...hope you have deep pockets ($$$$)  ;D

This steam hobby is never cheap...I can tell you that.

Dave


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## Tin Falcon (Nov 25, 2011)

1 HP =33,000 ft/lbs/min = 746 watts or 746 joules/sec
IIRC the formula is P.L.A.N.
              33,000

P is pressure in PSI at the piston 
L the length of stoke in feet
A area of the piston in square feet
N number of strokes per minute 
Going by memory here so if someone has the book in front of you feel free to elaborate. 
tin


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## steamer (Nov 25, 2011)

YUP...Thats right Tin

but thats brake horsepower. Thats the power at the engine shaft

 There will be losses in the generator too.

You might get 5% efficiency from a steam plant in the 10000 watts range.

With that said, if you get 80% at the generator....and I think I'm being VERY optimistic, 

10000/.8 =12500 watts in to the generator to get 10000 watts output

12500/.05 = 250000 watts of fuel into the boiler to get 10000 watts return....round numbers.

I hope you have one of those endlessly producing oil fields handy.... ;D

Dave


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## steamer (Nov 25, 2011)

As far as heating surface. There are some general rules that work.

For a watertube boiler, you need 5 square feet of heating surface for every 1 indicated horsepower

For a firetube boiler, you need 10 square feet of heating surface for every 1 indicated horsepower.

Dave


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## Tin Falcon (Nov 25, 2011)

the area where i live boilers need to have less than 10 square feet of area and less than 10 kw/hr of heat input bigger than that it has to be registered inspected etc. 
tin


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## steamer (Nov 25, 2011)

In Massachusetts, its over 100 pounds of steam per hour produced....

I have no idea what is required in the Ukraine Bedgen....you will have to figure that one out for yourself.

Dave


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## dwentz (Nov 25, 2011)

In Illinois the limit is 1.5 square fee, and the inside diameter may not exceed a foot!

Dale


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## bedgen (Nov 26, 2011)

I dont think that Ukraine have laws like that
but still, my engine will be little one
its like 0,2hp


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## Niels Abildgaard (Nov 26, 2011)

Try to Google Flash steam Bamford and tell us what You think?

Regards

Niels


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## Dan Rowe (Nov 26, 2011)

Dale,
There is a thread for US State Boiler Codes. I just updated the list for Illinois.
http://www.homemodelenginemachinist.com/index.php?topic=8846.0

The exact wording of the exemption for Illinois is:
Sec. 5 (430ILCS 75/5) Exemptions
(7) Steam boilers of a miniature model locomotive, boat, tractor, or stationary engine constructed and maintained as a hobby and not for commercial use, that have an inside diameter not exceeding 12 inches and a grate area not exceeding 1 1/2 square feet, provided they are constantly attended while in operation and are equipped with a water level indicator, pressure gauge, and a safety valve of adequate capacity.

Dan


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