Talk:Boiler blowdown

Additions.

I'd suggest some expansion of blow-down to cover other sorts of impurity, not just mud & scale:

• Brine. An issue for early steamships, where seawater feed was used. This is also discussed under evaporator (marine), which could usefully be linked.
• Oil scum. Many early lubricants were a problem for encouraging foam and priming, so surface blowdown was used to remove them.

Thanks for starting the article though, it has been missing for a while. Andy Dingley (talk) 09:28, 18 September 2012 (UTC)

Thank you for the suggestions. I have looked through my references and find comparatively little mention of either. I suspect they are issues of historical interest with relatively little applicability to modern boiler practice. It might be preferable to cover the brine issue within the article of early ships or boilers using salt water. During my time aboard United States Navy steam warships I had some experience with brine scale in evaporators used to distill fresh water from seawater. Brine scale formation isn't significantly different from the divalent cation scales conventionally encountered with fresh water supplies, although it has a higher concentration equilibrium which makes it easier to remove.

I added mention of foaming problems from preservative and lubricant residues, but this is one of several issues which might be better covered in an article on boiler water treatment. During experience with steam boilers ashore and at sea, I was surprised to discover dramatic boiler water chemistry differences as working pressures increase from domestic units used in residential heating, through the moderate pressures used in early ships and railway locomotives, and the 600 psi naval installations of the early 20th century, to the higher pressure municipal utility power plants used to maximize thermodynamic efficiency. Each step is different enough to require at least a separate section, and perhaps a separate article.

I was unfortunate enough to serve in the United States Navy when most senior boiler technicians had learned their craft on 600 psi boilers and were running 1200 psi boilers of ships built during the cold war. Water chemistry procedures intended for the earlier boilers destroyed the more modern boilers; and the cold war ships were worn out before their older 2nd world war predecessors. Concepts like blowdown may be generally applicable, but attempts to include too much specificity may be potentially confusing because of the variation between boilers operating at different pressures and temperatures.Thewellman (talk) 20:35, 18 September 2012 (UTC)

Seawater feed is about a 25 year issue from 1840-1865 (and later, as old ships didn't just stop) from the beginning of seagoing steamships to the development of useful condensers that allowed feedwater recycling. Rippon's book, cited in the evaporator article, is a good history, albeit mainly for the period a bit later than this.

Marine water-tube boilers are a big topic and we could certainly use help with them. I started a bit of this myself with Yarrow and three-drum boilers. The later marine boilers really need work though. Andy Dingley (talk) 20:49, 18 September 2012 (UTC)