Technically perhaps, the first primitive open hearth furnace was the Catalan forge, invented in Spain in the 8th century, but it is usual to confine the term to certain 19th century and later steelmaking processes, thus excluding bloomeries (including the Catalan forge), finery forges, and puddling furnaces from its application.
The regenerators are the distinctive feature of the furnace and consist of fire-brick flues filled with bricks set on edge and arranged in such a way as to have a great number of small passages between them. The bricks absorb most of the heat from the outgoing waste gases and return it later to the incoming cold gases for combustion.
In 1865, the french engineer Pierre-Emile Martin took out a licence from Siemens and first applied his furnace for making steel. Their process was known as the Siemens-Martin process, and the furnace as an "open-hearth" furnace. The most appealing characteristic of the Siemens regenerative furnace is the rapid production of large quantities of basic steel, used for example to construct high-rise buildings. The usual size of furnaces is 50 to 100 tons, but for some special processes they may have a capacity of 250 or even 500 tons. The Siemens-Martin process complemented rather than replaced the Bessemer process. It is slower and thus easier to control.
Basic oxygen steelmaking or LD process replaced the open hearth furnace. In the US, steel production using the inefficient open hearth furnaces had stopped by 1992. The nation with the highest share of steel produced with open hearth furnaces (almost 50%) remains Ukraine. (http://www.energystar.gov/ia/business/industry/41724.pdf).