THE EVAPORATION OF THE JUICE TO SYRUP. 



Instead of taking steam from the first vessel of an evaporator it may be 

 taken from a later one, and a still greater economy effected ; let steam be 

 taken for use in the pan from the second vessel of a triple ; thus if a be the 

 evaporation in the last vessel of the triple, 



3a -f -1165 + -1165 = -7272 

 whence a = '1647 



that is to say, the evaporation in the first and second vessel is 16-47 + 11-65 

 = 28-12, and this quantity is the equivalent evaporation at single effect; 

 other combinations might be the taking of extra steam from both first and 

 second vessels of a triple or quadruple, but as in the second vessel the 

 temperature of the steam is already low, it does not seem there would ever be 

 much opportunity in a cane sugar factory to take steam other than from the 

 first vessel ; in a beet sugar factory opportunity arises at the diffusion and 

 carbonation stations. 



FIG. 178. 



This method of evaporation is shown diagram matically in Fig. 178 , 

 where a l a 2 a 3 is the triple, the first vessel having an enlarged heating 

 surface, so as to provide steam for the pan b and the heater c. Any scheme 

 as the above requires an entire redistribution of the heating surfaces in the 

 evaporative plant. Suppose in a certain factory there is a triple with 2000 

 square feet heating surface in each vessel and it is desired to alter the arrange- 

 ments and boil the pan with steam from the first vessel, the output of the 

 factory remaining unaltered ; then using the data established above, the 



O (\ *^ A 



heating surface in either the second or third vessel will be 2000 X 



or 1680 square feet, and in the first vessel it will be 1680 x 

 square feet. 



317 



32-01 

 20-36 



24-24 

 = 2140 



