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Posted by nisikanta pani on November 24, 2009 at 09:31:31:
In Reply to: New Boiler Boil Out Procedure posted by Mike Boyle on November 08, 2005 at 11:05:59:
: I tried to post as a reply to the message dated Nov. 4th with no luck, here's an SOP we found, I'm not sure of the author to give proper credit that being said:
: Any commerical water treatment company rep (i.e. Betz, Nalco, Chem-Aqua, Chem-Treat, Garratt-Callahan) will have their own preferred method and will have a specialty compound. Usually that compound will have caustic, a surfactant (soap), and sometimes sodium silicate. Some simply require you add caustic, phosphate, and sulfite. I prefer using some phosphate due to it leaving a fine corrosion barrier on the tubes.
: We do some boil outs when we install new boilers and the following is an SOP we use:
: ALKALINE BOIL-OUT
: The following procedure can be followed for utility boilers which can be fired.
: Flush loose material out of steam and mud drums.
: Fill the boiler and hydrotest.
: Drain down the boiler to below the steam drum manhole and open the manhole.
: Introduce chemicals through the manhole. The chemicals should first be diluted (at least a drum of water) to prevent local concentration. The following or similar formula can be used (anhydrous chemical in lbs per 1000 gal of water held by the boiler):
: 34 lbs of soda ash
: 34 lbs of trisodium phosphate
: 6.5 lbs of sodium nitrate
: 7 lbs of surfactant
: Replace the manhole and fill the boiler to the normal operating level.
: Open the steam vent (if the boiler has a superheater, the superheater vent should be opened).
: Fire the boiler and run for 12-24 hrs at 25 – 50 psig.
: When the boiler reaches the desired pressure, blow down the mud drum (intermittent blowdown) every 4 hrs (reduce the level about half the guage glass) to remove solids.
: Let the boiler cool, drain, refill, drain, open and inspect.
: Put into service, acid clean, or proceed with layup.
: If the boiler is not fired, and is for example, a kettle design, it is necessary to provide some external source of heat and recirculation. This may be a chemical cleaning truck equipped with a heat exchanger. Water, containing chemicals, is introduced through the BFW inlet and withdrawn through the blowdown and recirculated back (or vice versa). Maintain temperatures at 180 - 200 0F.
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