1910.] Picking, Drying, and Packing Hops. 



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The maintenance of a good draught in these hot-air kilns 

 is as difficult as in the open-fire kilns. In order to overcome 

 this difficulty, the more modern hot-air kilns are fitted with 

 some apparatus for improving the draught by artificial means. 

 These are of two sorts :— (i) Reek Dissipators; (ii) Fans. 



Reek Dissipators. — These are contrivances by which hot air 

 is led directly from the stove through a set of pipes, and 

 -delivered just above the hops. The air above the hops during 

 the early part of drying is normally low in temperature, and 

 hence does little to help the draught. The effect of the 

 dissipator is to warm up this air by the admixture of hot air, 

 and so improve the draught. 



Fan Draught. — Fans have been used in hop-drying with 

 the open-fire as well as with the stove kilns. The first to be 

 used were exhaust fans, placed above the hops; these were 

 not found to be perfectly satisfactory, because they caused 

 the fire to come irregularly through the hops, so that the hops 

 were dried unevenly. Blast fans, placed below the hops, are 

 found to be more satisfactory in this respect, and are now 

 generally employed with certain types of stove-kiln. 



Advantages of the Stove-Kiln. — Since in these types of 

 kilns the furnace gases do not pass through the hops, there 

 is no possibility of the latter being contaminated either with 

 the smoke or with arsenic from the fuel, hence the very 

 expensive anthracite coal can be replaced by a cheaper form 

 of fuel, coke or cheap coal, and thus economy is effected in 

 the cost of drying. Against this economy, however, must 

 be set the initial cost of the installation of the stove-kiln ; and 

 since the output of dry hops is not increased, the use of the 

 stove-kilns, unaided by some artificially produced draught, 

 presents no great advantage. 



However, when a blast fan is associated with a stove-kiln, 

 these systems do present considerable advantages. It has been 

 shown previously that, by the use of a thermometer placed 

 just below the hops, the temperature of the hops during drying 

 can be accurately controlled. By the use of a fan the draught 

 in like manner is brought under absolute control, and, there- 

 fore, the risk of reeking is reduced to a minimum. 



Further, owing to the greater draught produced by the 

 fan, much greater quantities of hops can be dried upon the 



