Steam generator with controlled mass flow?

Apr 27, 2000
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#1
I need a steam generator to (hopefully) safely convert a mass flow of water at room temperature into steam, preferably dry steam at a temperature of 300C (or higher). The mass flow is limited (1 gram/second, or 1mL/second if you prefer), but being able to convert that mass flow into steam at such a high temperature over an extended period of time would actually require a fair amount of energy.

Napkin math tells me that I should expect to burn ~3300 j/s, and that ignores the changing heat capacity of water at higher temperatures. So realistically speaking I'm looking at a power source of at least 3.5-4kW to be on the safe side. That far exceeds what can be had from a conventional wall socket.

To provide additional information: the stated temperature is only required for the steam before it exits the heating stage of the generator. It'll be feeding into a controlled flow of ambient air at or below 1 atm, so the steam will increase in volume and lower in temperature as pressure normalizes. The most important thing for me is to control the mass flow (don't want too much water) and to make sure the steam's temperature is suitably high before it leaves the generator.

So, is there anywhere I can buy a device to do something like that? Would I have to build it myself? I'm pretty sure it would be doable with, say, propane. A DiY project of this nature might require skills not in my possession.
 
Jul 20, 2001
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#2
Wouldn't a traditional governor valve do just that? A turbine would have to be introduced into the circuit to drive the governor. Your system would have to over produce and then use the governor to bleed off the excess.

https://en.wikipedia.org/wiki/Centrifugal_governor
 
Apr 27, 2000
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#3
That's a possibility. I would have to hit the books a little to figure that one out (sorry, zombie brain being slow again), and I have considered going that route. But it does look like you're right. Increased steam velocity equals smaller valve aperture, so mass flow should remain relatively constant.

If I have to DiY, it might be easier to control water flow and just run it through a pipe coil over my heat source. I've considered just using a simple pipette-style drip system, where I can predict the flow rate based on gravity and the aperture of the pipette (or whatever it is that I use). It would be suitable for short runs. Or I could buy a water or meth/water injection kit and repurpose it as a metering tool. Snow has some units that would work.
 

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