354 



CHAPTER XVIII 



Sandborn Evaporator. — In this apparatus (U.S. patents 1028792, 1912 ; 

 1 143074, 1915) the heating surface, Fig. 206, consists of vertical tubes, a, 

 closed at the upper end and opening at the lower end into a steam chest, b. 

 The removal of the incondensible gases is effected by means of inner tubes, c, 

 passing into the chamber d. This apparatus is referred to as the double 

 tube type, and first appears in Beanes' patent (2898 of 1853). 



Deerr Evaporator. — Patent 16544 of ^9^7 > U.S. patent 1287650, 1918. 

 This apparatus. Figs. 207, 208, 209, adopts a rectangular body, and in other 

 respects is a vertical submerged tube design. The usual central circulating 

 tube is developed into a down-take, a, extending the whole length of a vessel, 

 and on either side are arranged the twin calandrias, c, provided with indi- 

 vidual steam entries, b. The incoming juice enters by the perforated pipes h, 



one to each calandria, and is taken 

 away by the perforated pipe i, lo- 

 cated immediately below the down- 

 take. The incondensible gases are 



Fig, 205 



Fig. 206 



removed by the system of perforated pipes, d, opposite to the steam entry, 

 and arranged in a vertical plane. The condensed water is collected by a 

 system of pipes, /, formed in the lower tube plate, and passing into the 

 header, g. In order to obtain a fall and rapid removal of water, the ap- 

 paratus is erected slightly out of the vertical. 



Regeneration of Low Pressure Steam. — Pelletan (1840), Riltinger (1857), 

 Felix (1871), Robertson (patent 790 of 1872), and Wiebel and Piccard 

 (patents 5143 of 1878 and 1761 of 1883) were pioneers in attempting to 

 introduce schemes whereby low pressure steam as from the first cell of a 

 multiple effect is compressed to the pressure of the steam entering the calan- 

 dria of that effect. 



The four first named experimented with the use of injectors. The 

 Webel-Picard combination depends on the mechanical compression of the 

 steam, and where power is to be had naturally the scheme is practicable. 

 It is, or was, in successful use in a salt factory at Bevieux in Switzerland. 



