Question Regarding "A" Type Water Tube Boilers
Question Regarding "A" Type Water Tube Boilers
(OP)
The "A" Type boiler consists of a steam drum and two mud drums; my question is regarding the flow of water between the three drums...Is the flow produced by natural draft(natural flow)? If so, is this natural draft occuring due to different temperatures at different locations within the tubes which produces differential pressure causing a flow?
Thanks for the help.
Thanks for the help.





RE: Question Regarding "A" Type Water Tube Boilers
Your boiler is a natural circulation type. Circulation occurs due to differing density of water in the hotter generating tubes and the cooler downcomer tubes. It's the product of uneven heating between the generating tubes and the downcomer tubes. Tube location in the boiler determines which absorb more heat. Cooler water is heavier. Hotter water is lighter. The differance in density/weight by volume causes the hotter water to rise and the cooler water to fall.
If your generating tubes slant sharply upwards, you can describe your boiler as an accelerated natural circulation boiler. This design is best for boilers that operate at high rates of steam production.
RE: Question Regarding "A" Type Water Tube Boilers
The process is also called thermosyphon, and as stated is due to differences in the water density in the downcomers and the density of the water/vapor mixture in the risers. A full explanation of this and a simply JavaScript calculator can be found at the site for Waste Heat Boiler and HRSG design at http://www.HRSGdesign.com
Thanks,
Jack Hardie
RE: Question Regarding "A" Type Water Tube Boilers
RE: Question Regarding "A" Type Water Tube Boilers
on the net they are too expensive???
RE: Question Regarding "A" Type Water Tube Boilers
Dave Furey
BTCM USN
RE: Question Regarding "A" Type Water Tube Boilers
You can go to the National Board web Site and order them. They are expensive anywhere you go.
Rex