also: へいろ
noun
open-hearth furnace
Technical term in metallurgy; a type of furnace used for steelmaking.
平炉はかつて製鋼の主要な設備だった。
The open-hearth furnace was once a major facility for steelmaking.
Compound of 平 (flat) and 炉 (furnace), describing the shallow hearth design.