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Steam generation for an experiment

  1. Dec 19, 2015 #1
    What would be the best, cheapest way to generate steam intended for introduction to a device for testing? I would use a standard American 110v three-prong outlet as a power source for the steam generator. All I really need is a steam source with an absolute pressure of 2 atm/202650 Pa/29.39 psi. The intended mass flow out of the generator would be 20-28g.

    I've looked at commercial/industrial boilers, but they generally operate at much higher power than the limits imposed by using a standard 3-prong outlet. They're also hauled on the back of trucks and produce much greater quantities of steam than indicated by my needs. I've examined the possibility of using dental sterilization equipment, but such would need modification to serve as a steam source, since they don't generally have any kind of outlet or blow-off valve (that I can tell). There's also the question of whether or not any of them can serve as a steam source for any non-trivial amount of time.

    All I'd really need is a reservoir with a blow-off valve to maintain maximum internal pressure of 2 atm, a pressure gauge, and an outlet. I could tailor a throttle plate to control flow through the outlet. Something as simple as a hot plate could provide heat for the reservoir. Maybe I should take a stovetop presure cooker to a shop and have them modify it or something? I know typical pressure cookers have at least one blow-off valve to maintain pressure, though the valve might need to be replaced unless it's designed to maintain an absolute pressure of 2 atm.
     
  2. jcsd
  3. Dec 20, 2015 #2
    Mass flow of 20-28 gram per what time?
    (needed to estimate the electrical power)
     
  4. Dec 20, 2015 #3
    Let's see here. Steam at 30 psig will be about 275F. To heat an ounce of 70F water (29g) to 30 psig steam in a minute will require 35 kW or about 300 amps of 117 V AC power (I am doing this from the top of my head - I may not have the correct power numbers). The volume of one ounce of 30 psig steam is about 0.56 cubic feet. Do you need steam or will compressed air work in your experiment?

    Small steam generators are available commercially, but more information is needed regarding requirements.
     
  5. Dec 27, 2015 #4
    Sorry I meant to specify, 20-28g per second.

    And the gauge pressure (assuming standard 1 atm barometric pressure) would only need to be ~15 psi. That would be ~30 psi absolute pressure. 29.7 psi actually . . .

    It would need to be steam. Your numbers look okay to me, though the pressure would be lower than that. 300 amps is more than I could pull off a standard 3-prong outlet. I would have to build steam in advance, I suppose, and that complicates things.

    Or I'm going to have to settle on lower steam pressure.

    What other information would you need?
     
  6. Dec 27, 2015 #5
    Oh my, that is just not possible with a standard outlet. It would need 60 times the power and the current that Vedward calculated.

    Two liters of water per minute into 30 psi steam! Just compare with your ordinary tea water cooker. How long does it take to boil away one liter of water at atmospheric pressure? And those things are the appliances that have the highest power ratings in homes.
     
    Last edited: Dec 27, 2015
  7. Dec 27, 2015 #6
    OK - your demand is about 100 kg/hr (220 lbs/hr) of 30 psig steam. If you don't want to use a gas-fired boiler, you will need to use a 480 V 3-phase power source. These are available but you will also need water treatment and other support systems.
     
  8. Dec 27, 2015 #7
    Sorry, I meant 15 psig steam. I'll have to pull out my data sheets to confirm the boiler capacity, but this is not a small, tea kettle requirement. This will be a $7,000 US installation.
     
  9. Dec 28, 2015 #8

    jim hardy

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    Back of napkin estimate... i'm old and still use English units
    is 28 grams still about an ounce?
    Rule of thumb : one BTU per second is within ~5% of a kilowatt ; 3412.7 BTU/kwh / 3600sec/h = 0.948 BTU/kw⋅sec
    ~1200 btu/lb X 1/16 lb/sec = 75 BTU/sec / 0.948 BTU/kw⋅sec = ~79 kw

    is that about what the SI guys estimated?

    79 kw at 120 volts is 658 amps.

    Water is amazing stuff isn't it?

    old jim
     
  10. Jan 2, 2016 #9

    rbelli1

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    Do you have a natural gas hookup? It would probably be cheaper and easier to get a gas furnace installed than try to upgrade your electrical system. Even if you have to build a chimney.

    BoB
     
  11. Jan 2, 2016 #10

    CWatters

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    I'm curious about the device that needs all this steam?
     
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