Beehive oven

Documented efforts at cokemaking date from 1584 (34), and have seen various adaptations of conventional wood-charring methods to the production of coke including the eventual evolution of the beehive oven, which by the mid-nineteenth century had become the most common vessel for the coking of coal (2). The heat for the process was suppHed by burning the volatile matter released from the coal and, consequently, the carbonization would progress from the top of the bed to the base of the bed and the coke was retrieved from the side of the oven at process completion. 

Some beehive ovens, having various improvements and additions of waste heat boilers, thereby allowing heat recovery from the combustion products, may stiU be in operation. Generally, however, the beehive oven has been replaced by waH-heated, horizontal chamber, ie, slot, ovens in which higher temperatures can be achieved as well as a better control over the quality of the coke. Modem slot-type coke ovens are approximately 15 m long, approximately 6 m high, and the width is chosen to suit the carbonization behavior of the coal to be processed. For example, the most common widths are ca 0.5 m, but some ovens may be as narrow as 0.3 m, or as wide as 0.6 m. 

Table 1.30 Merits and demerits of beehive oven practice.

Figure 1.29 Coke production processes. (A) Beehive oven (B) by-product coke oven.

Coke is also produced from coal in the by-product ovens in which the coal charge is heated on both sides so that heat travels toward the center and thus produces shorter and more solid pieces of coke than are made in the beehive oven. Air is excluded so that no burning takes place within the oven, the heat being supplied completely from the flues on the sides. About 40 percent of the oven gas, after being stripped of its by-products, is returned and burned for the underfiring of the battery of ovens, and some is used for fuel gas locally. 

In all designs involving "acid brick," provision must be made for the irreversible growth of North American brick which takes place over an extended period. This growth or "swelling" was not much noted in "acid brick" prior to about 1954, when manufacturers stopped using "beehive" ovens and started using continuous kilns. 

Evidence indicates that the ancient people of India from as early as 4000 BC were well acquainted with the production of building materials such as lime and plaster. By using crude equipment they fashioned the materials they needed, some of which have lasted until the present day. Present-day methods used in India probably resemble those used in ancient times. In the production of bricks, it is still not uncommon to find that sun-dried bricks are heaped or stacked in piles alternating with coal and arranged in the form of a beehive oven for firing. 

Coke making has seen various adaptations of conventional wood-charring methods to the production of coke with the eventual evolution of the beehive oven, which by the mid-nineteenth century had become the most common vessel for the coking of coal. 

The beehive oven (Figure 16.5) is actually a simple brick structure into which coal can be introduced through an opening at the apex of the dome. Beehive ovens are charged as soon as practicable... 

Beehive oven A dome-shaped oven not equipped to recover the by-product gas and liquids evolved during the coking process. 

Beehive oven means a coke oven in which the products of carbonization other than coke are not recovered, but are released into the ambient air. 

For decades this was an unwanted by-product of coking, as all gases from inefficient beehive ovens, which had been used since the substitution of coke for charcoal began in the United Kingdom after 1750, were simply released into the atmosphere. ... 

Abraham Darby produced pig iron with coke in 1709, but widespread replacement of charcoal came only after 1750 see Harris, J. R. 1988. The British Iron Industry 1700-1850. London Macmillan. Beehive ovens are described in detail in Porter (27), pp. 106-110. Byproduct recovery ovens are rectangular chambers built in rows and interspersed with heating flues (coke-oven gas is the most convenient heat source). Coal is charged through their tops, ovens are sealed, and the processed fuel is pushed out after sixteen to twenty hours of coking. Tar and phenols are other usable by-products. 

Munroe (23), p. 235. The abundance of excellent coking coals and cheapness of the beehive ovens are the best explanations of the late introduction of by-product coking ovens in the United States. 

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