CANE SUGAR. 



the pipe g ; a minute air vent is placed in the condensed water box at i. 

 Above the main vessel, and communicating with it by two pipes c, is placed a 

 save-all J, from which passes the vapour pipe to the next effect. Compared 

 with the horizontal apparatus of the Billieux type, the relatively small 

 height of the column of juice, the large vapour space, and the method of steam 

 circulation, are to be noted. This type has been extensively used on the 

 Continent of Europe, and especially so in Austria. 



Swenson Evaporator. This evaporator follows the general form 

 of the Welner-Jelinek, from which it may be regarded as derived ; the tubes 

 are not expanded into the tube plate but a tight joint is made by means of 

 rubber rings. 



FIG. 166. 



Stage Evaporation. In order to minimize the effect of the 

 hydrostatic pressure (of. infra] the heating surface of the horizontal tube 

 evaporators is sometimes divided into stages whereby a low level of juice is 

 obtained : this method is shown in Fig. 165, which represents a section of a 

 Newall horizontal tube apparatus. Each stage has its own juice connections 

 and separate vapour intake ; the vapours from the stages combine, those from 

 the lower stage passing upwards between the shell and the upper stage. In 

 the Welner-Jelinek and Swenson patterns the vapour uptake from the lower 

 stage is arranged through a passage in the centre of the upper stage. 



The Zaremba Evaporator also may be regarded as derived from 

 the Welner-Jelinek : the shell of this apparatus is a vertical cylinder, a 

 calandria of rectangular section being arranged in the lower part. This 

 apparatus is shown diagrammatically in Fig. 166. 



296 



