from the GNU version of the Collaborative International Dictionary of English
- n. A pipe for leading the hot gases from the top of a blast furnace downward to the regenerators, boilers, etc.
- n. In some water-tube boilers, a tube larger in diameter than the water tubes to conduct the water from each top drum to a bottom drum, thus completing the circulation.
from The Century Dictionary and Cyclopedia
- n. Any tube or passage for leading solids or fluids downward.
- n. A downtake.
- n. The descending element of a sectional boiler, through which the cooler or heavier water descends in the process of circulation.
- n. In a blast-furnace for smelting iron from the ore, a large pipe which takes combustible gas from the top of the furnace-shaft and brings it down to boilers, stoves, engines, etc., in which it is burned as a source of heat.
Sorry, no etymologies found.
The gases produced by the combustion of the fuel and the reduction of the ore, together with the nitrogen of the air forced in through the tuyers, escape through pipes D, called downcomer pipes, which leave the furnace near the top.
Solar collector tube, steam separator, riser and downcomer tubes, air well, siphon tubes, and immersion heater together make up a closed circuit, partly filled with water.
A siphon tube evacuates the condensate via the downcomer back to the collector tube.
I dreaded to be found eating, alone in that vast room, by the first downcomer.
This video shows the steel mill blast furnace downcomer piping to the dust collector/pot.