Okay, So I've seen a strange old system, and I'm looking for some explanation. It's from 1951, and has got three of these massive old Birchfield boilers. It's a classic two pipe steam system from that era. This I understand. However, the boilers have old Ray rotary burners. Can anyone explain these things? They look incredibly inefficient. They burn crude oil, (not no.6) and require air atomization. However, the combustion atomizing air is derived from the building's pneumatic controls. (???) that doesn't seem right. Any thoughts?
Sorry for the delay Smith, I have been on the road working for a few weeks.
These rotary cup burners were the common method of burning heavy oil from the late 30's till the mid 60's. The pump pressure required to atomize heavy oil is huge. Like 250-300 psi. The oil pumps of the era were not capable of producing this pressure reliably (still aren't really), so external atomizing air was the preferred method. This method is still employed on occasion with Tar Sands burners. Quite often, there would be a compressed air plant within the boiler plant. The secret and often problematic issue is that the air had to be dry. Very dry.
These old burner setups were not very efficient, but remember that oil was dirt cheap at that the time. Reliability was the name of the game.