Hoffmann kiln

The Hoffmann's ring furnace is a device for effective continuous burning of bricks, lime and gypsum. It is named after the engineer Friedrich Eduard Hoffmann (1818-1900), who had signed him up in 1859 for a patent. The test pattern was in Scholwin near Stettin. It was invented in 1839 in the furnace Fiirstenwalde.

Principle of operation

The ring oven consists of a large circular or oval with about 14 to 20 chambers in which, independently, a fire can be entertained, that burns the also present in the chamber adobe blanks. After the burning process is allowed to extinguish the fire in a chamber, and the next chamber is fed with fuel. This emigrated in about one to two weeks the fire once to the oval. Through ingenious ventilation of the chambers, the fired bricks heat the supply air for the fire, what makes this cool turn faster as the hot exhaust gases to dry and preheated the blanks. Compared to the heated are the coolest respective chambers. Here is the finished bricks are removed and filled the chamber again.

Plan view of a circular ring furnace


1859 was the architect Friedrich Eduard Hoffmann in Prussia and Austria a patent for " the invention of an annular furnace for continuous burning of all types of bricks, pottery, lime, gypsum and the like ." The patent was denied him later, after it could be proven that the master mason Arnold had in 1839 invented from Fürstenwalde the ring stove, but no patent filed. In 1873 he was made an honorary citizen of Fiirstenwalde for his invention.

The ring oven revolutionized the tile industry of the 19th century. The continuous fire delivered for the first time a consistent quality of the bricks, while the result in the previously conventional furnaces after each fire looked different. In addition, the kilns were burning the first time continuously day and night, which swelled the demand for labor by leaps and bounds, but at the same time also allowed for a previously unprecedented increase in brick production.

Since 1859, the image of the houses of gray ( reed and thatch, shrub, timber, clay walls ) changed to red ( roof tiles, brick house, less fire hazard). Brick pipes enabled sewerage, underground drainage and drainage of fields.

Today, the brick-making is done by machine. A few kilns were preserved - as in Ziegeleimuseum Cathrinesminde as well as in the brick location - and be protected as industrial monuments. In developing countries, but they are still being used. Thus, for example, in the Kathmandu Valley in Nepal in 2009 more than 90 kilns in operation.

Ring oven in Wiesenburg - Reetz

Ring oven in Großtreben

The Eisenach Brickyard Sältzer with the Hoffmann's ring furnace, copper engraving from 1875