Wet Steam Carryover

islandfrank

A relatively small fluid milk dairy has 2 old HRTs, 250 hp ea, operating at 12 psi. Steam headers from both boilers drop into a distribution main in the boiler room. Condensate return is pumped back to a heated feedwater (soft makeup and condensate) tank. Severe water hammer and boiler water carryover have been experienced periodically. We decided to get to the bottom of the issue and had the drip leg steam traps replaced and boiler level controls (McDonnel Miller Pots) repiped and replaced. The steam pressure gauges on both boilers hold relatively steady( between 8 & 12 psi) and the boiler sight glasses do not overfill or modulate much. After the mods we can still blow boiler water from the main steam header for over 30 minutes and actual "clean steam" may never materialize. There are no non return valves on the boilers and the steam header is approximately 1 foot above the boiler water level. Any ideas on easy troubleshooting steps to determine why we don't have relatively "pure" steam and boiler water is in the main? The conductivity of the boiler water is kept between 2500 and 3500 umhos.

Jamie Hall

Never worked on a boiler that size -- but I'll bet that @Steamhead has, and maybe he'll see this and be actually helpful, unlike me.

That said, what I do know (operating purely on book knowledge here, which is a very dangerous thing!) suggests to me that that clearance to the header is inadequate. What is the header? Is there any possibility that you could replace it -- or add to it -- with a proper, large diameter, steam drum arrangement? I'm envisioning two or however many rather large lines coming up from your existing header and going into a large diameter drum or pipe (the one on the boiler I care for, which is much much smaller, is 8 inches in inside diameter) with the steam mains coming off the top, and a drip return to your condensate system off the bottom at the other end...

JUGHNE

Is there a factory applied water level mark on the boiler somewhere? Could have the water level been simply adjusted/set too high. Pictures would be interesting. We seldom see any of the big boys here.

aircooled81

is there anyway to determine if you are putting all the heat into the tubes at the boiler? lets say the heat exchange has gotten poor over the years, might not be boiling off the water well enough to create the 'dry' steam you are looking for.
i am interested to see what boiler models these are, so I can find an iom on line. I have no time infront of fire tube boilers and you have made me wonder how they can 'wring' out the water from entering the header at such a low height from the water level.