CANE SUGAR. 



A similar calculation for the quadruple gives the total fall as divided in 

 the ratio 



1736 : -1919 : -2569 : -3776 



and if, as before, the total fall is 90 F., there occurs in the 

 First vessel, 90 X '1736 = 15-6 F., 

 Second vessel, 90 x "1919 = 17'3F., 

 Third vessel, 90 X '2569 = 23-1 F., 

 Fourth vessel, 90 x '3776 =: 34-0 F., 



and the temperatures prevailing will be 



First vessel. Second vessel. Third vessel. Fourth vessel. 



204-4 F. 187-1 F. 164 F. 130 F. 



Extra Steam. By this term is meant an arrangement in which 

 steam is taken from an earlier vessel of the evaporator to perform evaporation 

 or heating in some other part of the factory ; this scheme is also due to 

 Billieux and has been developed almost exclusively in the beet sugar industry, 

 where indeed the opportunities for its use are more numerous than in the cane 

 sugar factory, and where, owing to all the fuel being purchased, every 

 economy in this department means a direct source of profit. 



To demonstrate the economy of this scheme, let there be 100 parts of 

 juice at 15 Brix, which are to be evaporated to 55 Brix in a triple effect, 

 and finally to 96 Brix at single effect; then there are removed in all 



- X 100 = 84-37 parts water, and in the triple alone - x 100 

 96 55 



= 72-72 parts water, so that in the pan there are removed 11-65 parts water; 

 the evaporation in the triple is equivalent to the removal of 24'24 parts 

 water at single effect, so that the total consumption of steam is proportional 

 to 24-24 + 11-65 = 35-89 parts water per 100 of juice. 



Now let the arrangements be changed so that the steam necessary for pan 

 evaporation is taken from the first vessel of the triple ; thus evidently both 

 the heating surface of and the evaporators in the first vessel must be increased 

 since this vessel has to supply steam for the second vessel and for the pan. 

 Let the evaporation in either of the last two vessels be a ; then in the first 

 vessel the evaporator is a -\- '1165*; whence it follows that 



30 + -1165 -7272 

 a -2036 



i.e., the first vessel must evaporate 11 '65 + 20-36 = 32-01 parts water per 

 100 of juice, and of this quantity 20-36 parts go on to the second vessel and 

 11*65 parts go on to the pan ; this quantity is the equivalent evaporation at 

 single effect, where as previously it was 35-89. 



* This assumes equal evaporation in each vessel, a result which does not happen, but 

 the differences do not affect the present reasoning. 



316 



