THE EVAPORATION OF THE JUICE TO SYRUP. 



evaporation greater ; the steam or vapour which has induced evaporation flows 

 away, not at the temperature which it possessed when in the form of steam, 

 but at the temperature which prevails in the lower part of the calandria where 

 it is condensed ; however the evaporation on this score is barely appreciable. 



By a system of trial and error, Hausbrand has calculated the actual 

 evaporation in each vessel of a double, triple, and quadruple effect for a large 

 number of differently divided temperatures, for evaporations 90 per cent, and 

 75 per cent, of the original weight of the liquid, and from the results of his 

 calculations he has demonstrated that of the total quantity of water evaporated 

 in any vessel, that portion evaporated by heating (apart from self-evaporation) 

 is very constant, and that the total evaporation in any such vessel is very much 

 of the same order. 



The five conclusions drawn by Hausbrand are : 



1. The smallest amount of heating steam required to produce a certain 

 amount of evaporation is used in all evaporators when the fall in temperature 

 is the same in each vessel. 



2. However the fall in temperature in the separate vessels be arranged, 

 the weight of heating steam to be supplied to the first vessel varies always 

 within very narrow limits. Thus the manner in which the available fall in 

 temperature is distributed amongst the separate vessels has no great influence 

 upon the economy of steam. No considerable saving in stearn can be obtained 

 by any definite division of this fall in temperature. 



3. The quantity of water to be evaporated in the first vessel is on an 

 average of the total evaporation : 



In the double effect ^-^ = 0-466. 



In the triple effect ^ = 0-300. 

 3*333 



In the quadruple effect -rV~ = 0-216. 

 The extreme cases are : 



For the double effect 0-434 - 0-484. 

 For the triple effect 0-2777 - 0-3152. 

 For the quadruple effect 0-1926 0-2335. 



4. The evaporation effected by heating* is in all cases the least in the 

 first body, but the increase in the following vessels is not very great, at most 

 4 per cent. In the mean it may be assumed that this evaporation in the 

 separate vessels is in the 



Double effect 1 : 1'045. 



Triple effect 1 : I'Ol : 1-04. 



Quadruple effect 1 : 1'005 : 1-012 : 1'02. 



* Steam produced by self-evaporation in the second body evaporates water by heating in 

 the third ; these figures do not include water evaporated by heating on this score. 



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