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Multiple effects. — In all improved sugar milling the evaporation of the. 

 juice is accomplished by the use generally of double, triple, or quadruple 

 effects specially made for this purpose. These consist of large closed 

 iron bodies with arrangements for heating the contents and fitted with 

 the necessary connections for admitting the juice and steam or hot vapor. 

 The heating device consists of a steam belt placed inside of the body 

 of the effect and resembles in construction a very short steam boiler with 

 the multiple tubes arranged vertically. The steam connections pass 

 through the body of the effect and into the space outside of the tubes 

 in this steam belt. The juice occupies the space above and below the 

 steam belt and inside of the vertical tube so that when the steam or hot 

 vapor is admitted to the inside of the belt it heats the shell and tube and 

 in turn raises the temperature of the juice. The top of the first effect 

 consists of a vapor dome and tube which passes down and connects 

 with the steam or vapor belt in the next effect, and the top of this one 

 is again connected with the third and the third with the fourth in 

 quadruple effects. When there are two bodies in an evaporating set it 

 is known as a double effect, three is a triple effect and four is a quad- 

 ruple effect. The vapor pipe of the last effect is a little more than 10 

 meters in length, is connected with a vacuum pump and the foot of the 

 pipe is immersed in a water tank known as the hot well. Wlien the 

 multiple effect is in operation the vacuum pump is kept constantly run- 

 ning so as to maintain a vacuum of about 710 millimeters in the second, 

 third, or fourth effect, according to the number of bodies used, and 

 decreases in each succeeding effect back to the first one where there may 

 be only a slight vacuum or even a little pressure. The vapor arising 

 from the surface of the boiling sirup in the last effect comes into contact 

 with a stream of cold water passing through the vapor dome at the top 

 of the water-leg, is condensed and passes down the pipe as water. 



These multiple effects are operated by pumping the juice into the body 

 of the first effect and admitting exhaust steam from the engine into the 

 steam belt which heats the juice surrounding it. This effect may be 

 worked with a slight vacuum or pressure depending on fuel supply. 

 As soon as the juice has reached a high enough temperature it begins 

 to give off vapor which passes over through the vapor pipe into the vapor 

 belt of the next effect. The juice or thin sirup which this effect contains 

 is in turn heated by this vapor and boils at a lower temperature than 

 the contents of the first effect because of the higher degree of vacuum. 

 The vapor which it gives off is in turn passed on to the vapor drum of 

 the third effect where there is a still higher vacuum and the heat contents 

 of the vapor are sufficient to boil the sirup in this effect. The vapor 

 again passes over to the fourth body in the quadruple effect where the 



