358 



CHAPTER XVIII 



of a horizontal tubular bundle, through which the steam circulates, and over 

 the tubes of which water is allowed to trickle ; the whole combination being 

 exposed to the atmosphere, the cooling effect of which may be increased by 

 fans. This form of condenser is included in Clark's patent (4665, 1822). 

 In the Thiesen condenser a similar idea obtains, but the tubular bundle is 

 immersed in an open tank, from which revolving wheels continuously remove 

 water, letting it fall back in a shower exposed to currents of air propelled by 

 fans. It is easy to see that either of these systems reduces itself to a self- 

 contained combination of surface condenser and of cooling tower. This 

 form of condenser, with juice as the cooling means, was a part of Derosne's 

 patent, and was once largely used in Cuba. 



The condensers almost universally used in sugar-house work are injection 

 condensers, wherein direct contact of the steam and water obtain. The 

 water, condensed steam, and air may be re- 

 moved together by what is correctly called a 

 " wet-air " pump. This adjective is also irration- 

 ally transferred as a distinctive title to the con- 

 denser attached thereto. Otherwise the air 



FIG. 212 



FIG. 213 



and water may be separated in the condenser and removed separately. 

 The pump in this case is called a "dry-air" pump, and the condenser with a 

 singular lack of reason is also called " dry." In this case the condenser is 

 always placed at such an elevation that the water pumped into it can flow 

 away against the atmospheric pressure, and hence this type is frequently 

 called a Torricellian or barometric condenser. The essential differences 

 between the two types will be understood from the diagrams in Figs. 211 

 and 212. The wet system or low level condenser is shown in Fig. 211. 

 The water enters the condenser at a under the influence of atmospheric 

 pressure, and is removed by the pump along with the air and condensed 

 steam. In this system one pump evacuates the vessel, lifts the water and 

 finally removes air, water and condensed steam. In Fig. 212 is shown a dry 

 or high level condenser placed at least 33 feet from the ground level. Water 

 is pumped into the condenser at a ; air and steam from the pan pass through 

 the shower of falling water, the latter being condensed and the former being 



