downcomer

English

Etymology

down +‎ comer

Noun

downcomer (plural downcomers)

1. A pipe to conduct something downwards.
   1. A large external pipe in a water-tube boiler, carrying unheated water from the steam drum down to the water drum as part of the circulation path.
   2. A pipe for leading the hot gases from the top of a blast furnace downward to the regenerators, boilers, etc.