Without getting too far off track, & in the absence of documentation for HM Iron Duke, we could assume close boiler design similarities to the US BB35 Texas as Google confirms
HM Iron Duke = Built 1914, 25K tons, 18 coal fired boilers, 29K shaft HP
US Texas BB35 = Built 1914, 27K tons, 14 coal fired boilers, 28K shaft HP
If we were to accept the ~~23K cubic feet of free air/minute for each boiler on BB35, to understand this volume of free air at atmospheric pressure
....think of a cube of approx. 30 foot...or say 10 meters approximately
In reality, this is not a big number in volume, the limiting factor was the orifice sizing on the exhaust side of the boiler rooms atmospheric vents...so this may explain the lack of visual images here.....mushroom type vents for the discharge would seem logical
However now we see that Pondweed has some documentation from plans
, would be interesting to see what these look like
....
Derek