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Steam Generator take me off grid.

  1. Aug 14, 2008 #1
    I have made a Solar collector out of a 10' diameter satelight dish and lexan mirrors. I have a collector that converts water to steam ( 20lb propane tank) at a rather frightening rate I must add. Now i have a dilema. Where can I buy a turbine that i can bolt onto this scary steam source.

    The output of this device is a 1/2 copper pipe. I just need to make my generator spin. tyhen off grid I go. I was thinking of making one however i would not be able to make one with any great efficiency.


    If I can maintain even a 40% eff, this thing should make 3000w of power.
  2. jcsd
  3. Aug 15, 2008 #2
    Ok, well the laws of physics is going to stop you from obtaining that efficiency, and 3,000w certainly isn't going to take you off the grid.

    Anyway, your going to have a lot of trouble finding a steam turbine for that size and less then $30k. Your better off looking at some other positive displacement device like a gerotor or a vein type rotor.
  4. Aug 15, 2008 #3
    All i'm looking for is a way to convert the steam to rotational motion.. You say gerotor (I never heard of it) or a vein type rotor.. Where do i find these? do you have a web site I can stydy them? specs? Any info would be appreciated..
  5. Aug 15, 2008 #4
    A gerotor is a very simple positive displacement device that is used as a pump or a hydraulic type motor. They are used as oil pumps in some Ford engines and as coolant pumps in turbine engines. A vein type displacement device is commonly used for power steering pumps, its rather popular and reliable.

    Heres a link to some gerotor information: http://en.wikipedia.org/wiki/Gerotor

    What quality, pressure, and temperature is the steam that would be entering this device?
  6. Aug 15, 2008 #5


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    We need a disclaimer here: Be extremely careful. What you are doing is extremely dangerous. YOU MUST ATTACH A PRESSURE RELIEF VALVE TO THIS SYSTEM TO PREVENT EXPLOSION.

    Next, you're going to need to learn a little about steam cycles here. You need a condenser and a pump, otherwise you have an open system that is extremely inefficient and uses tons of water.
  7. Aug 17, 2008 #6
    Looked into doing something similar to this myself. Your best bet would be either a scroll compressor used as an expander, or a compound piston steam engine. Unless you are willing to spend a lot of money on destroying things during your R&D this may not be for you. Also, although commercial steam power plants get up to 40% efficiency you are gonna be running much lower. 15-20% is doing pretty good.

    Also look at this:

    I ended up giving up on the idea for now, and turning instead to solar powered cooling. The efficiency is much better, you can use the solar heat directly, and it's the biggest part of the electric bill around here.

    But if you really want to spend 10 times what the finished project will cost on R&D to get there, be my guest just post pictures/plans/results.

    Oh and if you have never worked with steam systems before, give up now. Steam is dangerous. In my work in nuclear power I have rarely been afraid of the radiation/contamination around me, but high pressure steam scares the #%$ out of me.
  8. Aug 20, 2008 #7
    I have yet to aquire meters to tell me what I am getting out of this.. Right now it's an open system.. I'm just trying to figure out what type of energy I am dealing with. I have some reading to do so I can answer in terms of steam quality and such. I've just picked up a roasting thermometer, and i'll be getting a reading the next time I try it out.. Right now I'm working on a way to change to black pipe. the solder thing just won't work anymore. ( Need and entrance and exit out of a single 3/4 threaded hole. I was using a 1/2 copper inside a 3/4 copper, but the boiler is hitting 1200F so the solder melts.). It'll be a week or so before i can try again..

    How do I tell the "quality" of the steam? Temp and pressure are easy.. Quality? how do i measure that?

    BTW, for the Pressure relief valve, for now that is the 1/2 copper that is open to atmosphere. 46 inches long, so it's not a closed system.. But I'll be sure to put one in once i close loop it.. and the pressure doesn't rise fast enought to be a danger for now. it's a steady rise until the steam turns to a "jet st(r)eam"
  9. Aug 20, 2008 #8


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    Gold Member

    As soon as you put a restriction on the end of that "jet stream", you'll potentially create enough pressure to kill yourself.

    Please read Russ' post again. It sounds to me as though you don't know enough about what you're doing to understand the potential dangers involved.
  10. Aug 20, 2008 #9


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    I'm somewhat skeptical of 1200F. I'd believe 600°F, if the pressure was about 1500 psia, and that's pretty high. Many high pressure steam turbines run at around 1000 psia inlet.

    Critical point for water/steam is 705.4°F at 3200 psia. Temperatures above that are supercritical.

    How did one measure temperature?
  11. Aug 20, 2008 #10
    Since you posted that you were already building one of these things I assumed you knew all about what you were doing. But since you apparently do not, I would suggest that you giving solar or wind power a go instead. As stated before steam power is extremely dangerous even if you are an expert. +1 for what Russ said or better yet consider another way to generate power. No one here wants to see you on the 10 o'clock news tonight.
  12. Aug 20, 2008 #11
    Sounds like extremely superheated steam if your readings are right. Not something to mess with unless you know what you are doing. You obviously do not. It can and will kill you, and superheated steam is invisible until it desuperheats. Stay away!
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