Hi Chris
On (20 Aug 96) Chris Harper wrote to Alec Cameron...
 AC> There's an operational penalty for using a condenser system- the
 CH> water
 AC> tends to ionise and become increasingly corrosive.
It's due to the use of welds and dis-similar metals in the boiler and
condenser and pipe work- as the very hot water passes thru there is a 
alvanic
action like electrolysis/ electroplating, that strips metal from some spots.
This results in "electrolytes" of various metallic salts forming a nasty
cocktail that further aggravates the problem.
                                             
 CH> First I have heard of this.
Small industrial boilers were dosed with various goos added to the water when
I was an apprentice [1940s].
 CH> I guess I could set up a still for this. I don't know about adding
 CH> chemicals though. I would think that there would be a limit to the 
mount
 CH> of corrosives that could be generated as the agents that produce them 
et
 CH> used up.
Unfortunately, these "agents" are the metallic parts of the boiler, not just
some foreign matter that's inside!
Slow distillation can remove those as well. I would think the
 CH> biggest problem in reguard to corrosion/wear would be the metal from the
 CH> boiler "dissolving into the water/steam, adding friction.
No, not friction. The fouled water is quite mobile.
 The
 CH> demineralization will take care of that. As for ionization, why not just
 CH> find out whether it's positive or negative ions
You got it! A pH recorder is fitted to warn of excessive acidity/ alkalinity.
But the universal remedies, are to chemically dose the water or replace it
with pure water.
 AC>  and be prepared to run at the lowest practical temp and pressure.
 CH> Why?
In a boiler pressure and temp are usually bracketted. Utility boilers run at
about 2400 psi and 1100 deg F. The pressure causes great stress [pipes, 
rums,
welds can rupture]. Stress and temperature, each accelerate corrosion. 
tility
plant stations employ full- time chemists.
 AC> Wear a mask! The vapours of lead and zinc are cumulative poisons. And
 AC> distilling acid seems a health hazard. Maybe take up serious Yoga and
 CH> learn
 AC> to function without breathing! :-)
 CH> With 2/3 of my lungs scar tissue now, I live on anaerobics now ;-)
Well, mebbee you have a chance to delay the evil day!
 CH> Hmmmmm. Now that I think of it, there are LOTS of things one can distill
 CH> in the desert!  ;-)  Maybe I ought to talk to Jack Daniels, eh?
Daniels? Is he a cousin to Johnny Walker?   Cheers..ALEC
... Life is one long process of getting tired
--- PPoint 1.92
---------------