Posted by Shannon on November 15, 2001 at 01:54:57:
In Reply to: Re: Thanks tony, more....... posted by Tony Conner on October 24, 2001 at 06:37:20:
: With a straight heating plant, you'll probably get close to 100% of your condensate returned. If this is the case, the water treatment requirements will be close to zero, as long as there are no steam to water heat exchangers somewhere leaking hard/oxygen filled water into the steam side.
: Normal operating levels of sulphite in DA tanks is usually 30 - 50 PPM. If they really want you to keep the boiler full of water, you'll need something like this, with the boiler overfilled (right to the non-return valve) because the corrosion will happen at the water line. Blow down valves can leak slightly, etc, and you can lose water and chemical, so things have to be checked at least once a week. You can leave the level lower, and fire the boiler a few times a week, and that will drive off the dissolved oxygen as well. Laying a boiler up like this requires some looking after. It's easy to forget/neglect it, especially if the guy who normally looks after it goes on vacation for a couple of weeks. If there's no need to get this boiler on-line quickly (like in a process plant), then I think dry lay-up is the way to go, because there's not very much to go wrong.
We try to achieve 200 ppm's of sulphite (oxygen scavenger) in the boiler on a wet lay-up. A low ph level can also be corrosive to iron. Keep that in mind.