CIRCULAR 4 4 3, U. S. DEPARTMENT OF AGRICULTURE 



Furnace manifold 



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l^J Motor 

 PLAN 



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M Fan ' 



SECTION 



N, S Apron \ 



Apron ret 



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Furnace 

 manifold 



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% Op 



i-Ul 



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at fans I and 4 



at fans 3 and 6 



at fans 2 and 5 

 CROSS SECTIONS 

 Figure 5. — Apron-conveyor drier used in forage-drying experiments at Iberia 

 Livestock Experiment Station. Drying air enters fan 1 from furnace manifold 

 and is discharged above apron, is drawn through apron by fan 2 and released 

 above it in second compartment, and then is drawn again through apron by 

 fan 3 and released outside the drier. Circulation through fans 4, 5, and 6 

 is similar. 



In all the experimental driers at Jeanerette discussed herein, electric 

 power was used for operating the machinery and fuel oil was used for 

 heat, because of the ease of measuring the quantities used and ease of 

 control. 



After the conveyor-type drier had been used for a few years, a 

 revolving-drum drier was installed. This machine consisted of a sin- 

 gle shell 6 feet in diameter and 24 feet in length, mounted horizontally. 

 Flights or flanges were attached to the inside of the shell, for picking 

 up and dropping the chopped forage as the drum revolved. A furnace 

 was connected to one end of the drum and an exhaust fan to the other. 

 The dried forage passed from the drum through the fan and was blown 

 into a cyclone. This machine was inefficient because of the short dry- 

 ing zone, or length of travel, and period of exposure of the material in 

 the drier. 



In order to increase the efficiency of this machine a cylinder 2 feet 

 in diameter and 20 feet long was installed inside and concentrical 

 with the large drum (fig. 6) . This cylinder was connected to the fur- 

 nace and to the feeder for the undried material at the furnace end of 

 the drier. At the opposite end the 2-foot cylinder was open and ended 



