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CHAPTER XVIII 



evaporator work, are on the market. With these it is possible to really clean 

 three tubes a minute, and, as four labourers can easily work in one cell, an appar- 

 atus can be very rapidly brushed. These apparatus are, of course, only applic- 

 able to the vertical submerged tube type, and it is the latter's amenability to 

 mechanical cleaning that the writer regards as its one great advantage over all 

 other types. This remark is equally applicable as between coil and calandria 

 vacuum pans, the former of which can only be cleaned satisfactorily after 

 dismantling. 



.A deposit of another nature forms on the steam side of the tubes in the 

 first cell, and has its origin in oil volatilized in the back pressure steam. This 

 deposit can be reduced to a minimum by the use of an efficient oil separator, 

 of which there are many types on the market. Even with these some oil will 

 find its way to the tubular bundle, and it will always be serviceable to remove 

 this in the dead season. This can be done efficiently by filling the calandria 

 with water, on the surface of which one or two inches of kerosene is floated. The 

 water is allowed to drain out slowly, occupying four or five months in doing 

 so. The fermentation of molasses and water will also effect the removal of 

 this grease. A deposit of fats may also sometimes be found on the steam side 

 of the tubes in the other cells. This probably has its origin from the vegetable 

 fats and lecithins present in the juice. In the dead season it may be advisable 

 to examine these bodies also. In the absence of fats a considerable amount 

 of rust may likewise be found in them. This rust is readily soluble in very 

 dilute acids, and its removal at the end of every season will tend towards 

 maintaining the efficiency of the apparatus. Whenever an excessive fall in 

 temperature is noticed in the first body, oil on the steam side may be suspected, 

 and this oil may go on accumulating till the capacity of the apparatus is 

 notably diminished. Oil will also be found on the interior of the coils in the 

 vacuum pans which are used for exhaust steam, and these may be cleaned in 

 the dead season by swabbing with kerosene. 



PROPERTIES OF SATURATED STEAM. 

 (After Peabody.) 

 ENGLISH UNITS. 



