THE DIFFUSION PROCESS 



253 



the receptacle h is flat, or nearly so. and the chips are swept out through 

 an opening in the bottom. 



To work up 300 tons of cane in 24 hours, a plant of this nature will be 

 about 5 ft. in diameter. The capacity depends on the number of hoppers, 

 and on the setting of the knives, whether to give thick or thin chips. More 

 cane can be cut when thick chips are allowed, but the efiiciency of the after- 

 process of diffusion is diminished. 



Diffusion Cell. — A section through a cell of a diffusion battery, along 

 with its accompanying juice heater, is shown in Fig. 152. It consists of a 

 cj'lindrical vertical shell, the bottom, being made ^\dth a slight slope, and the 

 top fitted with a head box ; the cell is closed by a door on the top, which is 

 clamped tight by the screw and lever shown at 6 ; by slackening the screw 

 the door can be slung on one side, to allow of a charge of chips being intro- 

 duced. Roimd the bottom 

 part of the cell is fixed a 

 perforated false bottom, 

 d, the object of which is 

 to prevent pieces of cane 

 being carried along the 

 pipe c. In some designs 

 the lower door itself 

 carries the false bottom. 

 The joint in the lower 

 door is a hydraulic one, 

 consisting of a hollow 

 rubber tube provided 

 with a pipe by means of 

 which water is conducted 

 to the tube, which is 

 placed in a circular groove 

 contrived either in the 

 door itself or in the bot- 

 tom of the cell. The 

 water which fills this tube 

 is taken from a tank at a 

 high level, so that in all 



cases the pressure in the tube is greater than the pressure in the cell. In 

 other cases the rubber tube is connected by a pipe with the main steam ; 

 the direct steam becomes condensed in the coil, and pressure is made 

 in the rubber tube by the steam acting on the condensed water. 



Attached to each cell is the juice heater b ; this is of the verti- 

 cal tube type, exhaust steam being admitted at 0, and the condensed water 

 drawn off at h. Communication between diffuser and juice heater may be 

 made either at top or bottom by the pipes k or c. The main juice-circulating 

 pipe is shown at m, the controlling valves or cocks appearing at i. The floor 

 level on which the operator stands is at the fine /, all valves and cocks being 

 within easy reach ; ^ is a small pipe let into the cover of the diffuser to act as 

 an air vent to allow the air to escape when the diffuser is being filled. 



Operation of a Diffusion Battery.- -A diffusion battery generally consists 

 of from twelve to sixteen vessels, of which two are always out of commission, 

 filhng or discharging. In Fig. 153 is represented diagrammatically a six-cell 



Fig. 151 



