THE CARBONATION PROCESSES 



283 



Apparatus employed in Carbonation Processes. The specialized apparatus 

 employed in carbonation are described below. 



Carbonation Tanks. The tanks used in the first carbonation are plain 

 sheet-steel circular or rectangular tanks, of height up to 20 feet, and of dia- 

 meter dependent on the capacity required. At the bottom is arranged a 

 perforated coil or cross where is introduced the gas. A steam coil, or, more 

 usually, a Witcowitz heater (see Fig. 205) is also provided. Other accessories 

 are mechanical stirring gear, including a scraper following the slope of the 

 bottom to remove precipitate settling thereon. The stirring gear may also 

 carry blades to break up the froth that forms during a period in the carbona- 

 tion or otherwise this may be dispelled by a jet of steam or of compressed 

 air. The tanks are often provided with a chimney to carry away the un- 

 absorbed gases. A section through 

 a typical form is shown in 

 Fig. 165. 



The second carbonation tanks 

 are similar to the first, save that 

 the appliances connected with the 

 foam are dispensed with, and that 

 the additional height required for 

 this same purpose is avoided. 



Continuous carbonating tanks 

 are also used to some extent, 

 especially for the second carbon- 

 ation. A type is indicated in 

 Fig. 166. 



For first carbonation tanks it 

 is customary to allow a gross 

 volume of 40-50 cu. ft. per ton- 

 cane-hour divided into four or five 

 units. This refers to the gross 

 capacity of the tanks, a height 

 of 10-12 feet being left above 

 the level of the juice to allow for 

 foam. For second carbonation 

 a capacity of 15 cu. ft. per ton- 

 cane-hour divided into three units 

 is customary, a dead space of 



three feet being sufficient. The FIG. I67 



first carbonation occupies from 

 10 to 15 minutes, from 3 to 5 minutes being required for the second. 



Gas Washer. The carbon dioxide used in this process is, of course, 

 generated on the spot by burning limestone ; after being generated in the 

 kiln, the gas is passed through a gas washer, a form of which is shown in 

 Fig. 167. It consists of an upright cylindrical vessel, in which is placed a 

 series of transverse horizontal partitions e ; in each of these, and projecting 

 a few inches, are fitted the funnels / ; water is pumped into the vessel by 

 the pipe c and flows over the partitions, down through the funnels and out 

 through the pipe d. The gas from the kiln enters by the pipe a, the lower 

 end of which is perforated, and flows upwards in the direction indicated by 

 the arrows. In the passage of the gas the dust carried over is deposited and 



