Beehive coke oven

A beehive oven is a type of oven in use since the Middle Ages in Europe. It gets its name from its domed shape, which resembles that of an old-fashioned beehive.

Its apex of popularity occurred in the Americas and Europe all the way until the Industrial Revolution, which saw the advent of gas and electric ovens. Beehive ovens were common in households used for baking pies, cakes and meat. These ovens were also used in industry, in such applications as making tiles and pots and turning coal into coke.

A fire brick chamber shaped like a dome is used. It is typically 4 metres (13 ft) wide and 2.5 metres (8 ft 2 in) high. The roof has a hole for charging the coal or other kindling from the top. The discharging hole is provided in the circumference of the lower part of the wall. In a coke oven battery, a number of ovens are built in a row with common walls between neighboring ovens. A battery consisted of a great many ovens, sometimes hundreds of ovens, in a row. Some mines also employed parallel batteries.

With candle wax wrapped in paper, dry kindling (twigs, small sticks, and/or wood chips), and pine cones, a small fire was made toward the front of the oven. As the fire caught, more kindling was added to produce a thick smoke, which coated the oven with black soot. The fire was then pushed back into the middle of the oven with a hoe. More wood would be added until there was a good, hot fire. After all of these steps were taken, the food would be prepared for baking.

The beehive oven typically took two to three hours to heat, occasionally even four hours in the winter. Breads were baked first when the beehive oven was hottest, with other baked items such as cinnamon buns, cakes, and pies. As the oven cooled, muffins and "biscuits" could be baked, along with puddings and custards. After a day's baking there was typically sufficient heat to dry apples and other fruits, vegetables, or herbs. Pots of beans were often placed in the back of the oven to cook slowly overnight.

Coal is introduced from the top to produce an even layer of about 60–90 centimetres (24–35 in) deep. Air is supplied initially to ignite the coal. Carbonization starts and produces volatile matter, which burns inside the partially closed side door. Carbonization proceeds from top to bottom and is completed in two to three days. Heat is supplied by the burning volatile matter so no by-products are recovered. The exhaust gases are allowed to escape to the atmosphere. The hot coke is quenched with water and discharged, manually through the side door. The walls and roof retain enough heat to initiate carbonization of the next charge.

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