THE DIFFUSION BATTERY,
as used at the Parkinson factory, consists of twelve iron tanks. (See diagram.) They are arranged in a line, as shown in diagram, Fig. 1. Each has a capacity of seventy-five cubic feet, and by a little packing holds a ton of cane chips. The cells are supported by brackets near the middle, which rest on iron joists. Each cell is provided with a heater, through which the liquid is passed in the operation of the battery. The cells are so connected by pipes and valves that the liquid can be passed into the cells, and from cell to cell, at the pleasure of the operator. The bottom of each cell consists of a door, which closes on an annular rubber hose placed in a groove, and filled with water, under a pressure greater than that ever given to the liquids in the cell. This makes a water tight joint whenever the trap door bottom is drawn up firmly against it. The upper part is of cast iron and is jug shaped, and is covered with a lid which is held with a screw on rubber packing. In the jug neck and near the bottom the sides are double, the inner plates being perforated with small holes to let water in and out. The bottoms are double, the inner plates being perforated like the neighboring sides, and for the same purpose. The cells, of whose appearance a fair idea may be had from diagram, Fig. 2, are connected with a water pipe, a juice pipe, a compressed air pipe, and the heaters, by suitable valves. The heaters are connected with a steam pipe. This, and the compressed air pipe, are not shown in the diagram. The water pipe is fed from an elevated tank, which gives a pressure of twelve pounds per square inch The valve connections enable the operator to pass water into the cells at either the top or the bottom; to pass the liquid from any cell to the next, or to the juice pipe through the heater; to separate any cell from any or all others, and to turn in compressed air.
Now let the reader refer to Fig. 2.
The cutters are started, and cell 1 is filled with chips. This done, the chips from the cutters are turned into cell 2; cell 1 is closed, and cut off from the others, and water is turned into it by opening valve, c, of cell 1 (see Fig. 2) until it is filled with water among the chips. When 2 is filled with chips, its valve, a, is raised to allow the liquid to pass down into the juice pipe. Valve a of 3 is also raised. Now the juice pipe fills, and when it is full the liquid flows through valve, a, of 3, and into the heater between 2 and 3, and into the bottom of 2, until 2 is full of water among the chips. (This may be understood by following the course of the arrows shown in the diagrams of 9 and 10). Valve a of 2 is now screwed down; c is down and b is opened. It will be readily seen by attention to the diagram that this changes the course of the flow so that it will no longer enter at the bottom, but at the top of 2, as shown by the arrows at cell 2.
It is to be observed that the water is continually pressing in at the top of 1, and driving the liquid forward whenever a valve is opened to admit it to another cell, heater, or pipe. When cell 3 is full of chips, its valves are manipulated just as were those of 2. So as each succeeding cell is filled, the manipulation of valves is repeated until cell 6 is filled with liquid. After passing through six cells of fresh chips, this liquid is very sweet, and is drawn off into the measuring tank shown at p in diagram, Fig. 1, and is thence conveyed for subsequent treatment in the factory. To draw this juice from 6, valve a of 7 is raised to connect the heater between 6 and 7 with the juice pipe. A gate valve in the juice pipe is opened into the measuring tank, and the pressure of water into the top of 1 drives the liquid forward through the bottom of 1, through the heater, into the top of 2, out from the bottom of 2, through the heater into the top of 3, out from the bottom of 3, through the heater into the top of 4, out from the bottom of 4, through the heater, into the top of 5, out from the bottom of 5, through the heater, into the top of 6, and now out from the bottom of 6, through the heater, into the juice pipe, and from the juice pipe into the measuring tank. It will be understood that the liquid which is drawn from 6 is chiefly that which was passed into 1 when it was filled with chips. There is doubtless a little mixing as the pressure drives the liquid forward. But the lighter liquid is always pressed in at the top of the cells, so that the mixing is the least possible. The amount of liquid, now called juice, which is drawn from 6 is 1,110 liters, or 291 gallons. When this quantity has been drawn into the measuring tank, the gate valve is closed, and the valves connecting with 7 are manipulated as were those of 6, a measure of juice being drawn in the same way. All this time the water has been passed into the top of 1, and this is continued until the juice has been drawn from 9. Valve c to cell 1 is now closed, and compressed air is turned into the top of 1 to drive the liquid forward into 10. After the water has thus been nearly all expelled from 1, valve a of cell 2 is lowered so as to shut off communication with the juice pipe, and b, of cell 2 is closed. a and b of cell 1 have, it will be observed, been closed or down from the beginning. Cell 1 is now isolated from all others. Its chips have been exhausted of sugar, and are ready to be thrown out. The bottom of 1 is opened, and the chips fall out into the car, o (see diagram, Fig. 1), and are conveyed away. Immediately on closing valves a and b of cell 2, c is opened, and the water presses into the top of 2, as before into the top of 1, and the circulation is precisely similar to that already described, 2 having taken the place of 1, 3 of 2, and so on.
When 2 is emptied, 3 takes the first place in the series and so on. When 12 has been filled, it takes the l3th place. (The juice pipe returns from the termination of the series, and connects with 1, making the circuit complete.) The process is continuous, and the best and most economical results are obtained if there is no intermission.
One cell should be filled and another emptied every eight minutes, so that in twenty-four hours the number of cells diffused should be one hundred and eighty.