Energy, fuels, and chemicals 



3215 



Figure 26-30. — One-haif-cord sheet metal beehive kiln. Fully portable, these kilns were 

 developed in the 1930's and were still in wide use through the 1960's. The kiln shown 

 here is in the coaling phase. (Photo from Page and Wyman 1969.) 



In the past, small-scale charcoal production was accomplished with a variety 

 of kilns. As any relatively air-tight structure with properly placed smoke and 

 draft vents can be used to produce charcoal, small kilns with capacities of Vi cord 

 to 10 cords or more were popular through the late 1950's (fig. 26-30). Such kilns 

 varied considerably in construction and size; building materials commonly were 

 cinder blocks, bricks, stone, metal, and reinforced concrete. Yields of charcoal 

 varied greatly in the kilns, even under optimal operating conditions. In cinder 

 block kilns typical yields for seasoned hardwoods averaged around 900 lb of 

 charcoal per cord and slightly less for unseasoned hardwoods (Witherow 1956; 

 Witherow and Smith 1957; Peter 1957; Page and Wyman 1969; U.S. Depart- 

 ment of Agriculture, Forest Service 1961). 



Today, over half of the Nation's wood charcoal is produced in Missouri-type 

 kilns (Baker 1977), from roundwood or sawmill slabs (fig. 26-31). Typically the 

 kilns arc made of poured concrete and have an average capacity of 50 cords. 

 Some, however, hold up to 100 cords. White oak and hickory are the two major 

 species of wood used. 



HERRESHOFF MULTIPLE-HEARTH FURNACE 



The Herreshoff multiple-hearth furnace uses hogged wood or bark to produce 

 charcoal in a continuous process (fig. 26-32). Production rates range from 1 to 4 

 tons per hour. As the units operate continuously, they must be fed a steady 



