By-Products of the Apple Industry 351 



are simple in construction and operation and not expensive 

 to build or operate. They have survived the test of time 

 extremely well, although it would seem that for Californian 

 conditions at least, they may be replaced by the more 

 modern air blast types. Some of the natural draft evap- 

 orators are : 



The kiln evaporator is commonly used in California and 

 the East. It is usually constructed in two stories. The 

 upper story houses the drying floor which is usually 20 

 feet by 20 feet and is made of narrow wooden strips with 

 14 or % inch spaces left between them to permit passage 

 of hot air. Over the drying floor is a steep four-sided roof 

 which has at its apex a large ventilator for the escape of 

 the spent air. The prepared fruit is placed on the floor 

 and turned by a fork or scoop shovel during drying, a 

 practice which does not add to the appearance or cleanli- 

 ness of the product. The lower floor contains the heating 

 system. This consists of a wood, coal or oil-burning 

 furnace connected to a number of turns of large heating 

 pipes ; usually the whole lower story is almost filled with 

 these pipes, giving a very large radiating surface with 

 consequent efficient utilization of heat. The heated air 

 rises from the pipes through the floor grating and thus over 

 the fruit. 



The stack or tower evaporator is the most commonly 

 used at Watsonville, California, where it is successful. 

 The trays of fruit are placed on run-ways in cabinets or 

 " stacks " above a fire-pit ; the trays being stacked one 

 above the other. The heated air rises directly through the 

 trays, in this way differing from the tunnel drier. The 

 bottom of each stack or chamber is open, while the top 

 consists of an inverted hopper connecting to the ventilator. 



