THE EXTRACTION OF JUICE BY MILLS. 



1 Ib. in the pans ; for heating the extra juice each ton is regarded as requiring 

 016 ton coal. The expenses of evaporation are thus obtained. On reference 

 to the tables below it will be seen that these expenses are practically 

 constant for the different types of cane and crushing when the added water 

 is the same, and that one ton of coal will, with the data adopted, account 

 for twenty tons added water. If w tons water be added, the expenses are then 

 'w per 100 tons canes for heating and evaporation of extra juice. 



The total amount of sugar washed out of the megass as the result of the 

 maceration is calculated before the amount of marketed sugar is obtained ; the 

 sugar is valued as fuel at 1 per ton, with coal at 2 per ton, and to the values 

 so obtained 10 per cent, is added to express the fuel value of other organic 

 combustible removed. With the data adopted the value of the sugar, &c., as 

 fuel is '144 of the sugar markets. The other expenses, packages, handling, 

 transport to port, &c., are estimated at 10s. per ton or *055 of the value of the 

 sugar marketed ; the sum total of these last two sources of expenditure is then 

 almost exactly '2 of the value of the sugar marketed. The general expression 

 then to give the value of maceration with the data adopted is : Net profit =- 

 7'2$ -w per 100 tons of cane, S being the tons of sugar marketed, and w 

 the tons of water added. 



When only two mills are used, very different results are obtained; the 

 method of calculation employed is then somewhat different. After the canes 

 have been crushed to 30 per cent, of fibre, water is supposed to be added, and the 

 megass crushed to 45 per cent, of fibre ; the sugar obtained is calculated on the 

 supposition of complete admixture ; the excess over that obtained by simple 

 dry crushing to the same fibre content has already been given, and 85 per cent, 

 of this excess is taken as the extra sugar brought into the juice as the result 

 of maceration. The other calculations are made as detailed above. 



The results of these calculations just indicated are given in the appended 

 tables, and are also expressed as curves in Figs. 131 and 182. The curve 

 marked 'gross' represents the value of the extra product obtained at 9 per ton, 

 and the curve marked ' expenses ' gives the expenditure, and that marked 

 * economic ' the profits. 



Three points bearing on the subject have not been included in the above 

 calculations. Firstly, no allowance has been made for decreased purity of 

 the juice ; in the writer's experience this is not serious. Secondly, no 

 allowance has been made for increased consumption of steam to drive 

 the third mill. With a modern engine, and where the exhaust is used in 

 evaporation, this is a small item. And, thirdly, there is the question of in- 

 creased initial cost for enlarged boilers and evaporating plant. Referring to the 

 4 economic ' curves it will be seen that as the curves approach the maximum, 

 the increase in the profits is very slow. In designing a new plant, this might 

 well indicate the financial economy of arranging for a dilution of from 5 per cent, 

 to 10 per cent, less than the indicated maximum. 



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