See BEET SUGAR.
Of recent years there has been added to the ordinary defecating process a super-heating apparatus generally known by the name of the Deming Super-heater. It is claimed that the principle of the Deming system is in converting some of the soluble into in soluble material at a temperature of from 110° to 115° C. To apply this principle three ves sels, cylindrical in form, are connected with each other by a system of tubes, two of these vessels being termed absorbers and the other digester. The juice enters one of the absorb ers and is pumped through it into the second. In these it is heated by exhaust steam and passes thence into the digester where it is heated with live steam to the high temperature above mentioned. As it passes out from the digester it is surrounded by an inflow of the juice on its way to the absorbers which heats it up to about C. The super-heated juice, limed before being heated, is conveyed to spe cially constructed settling tanks that permit of a continuous inflow and outflow of juice, the impurities being collected in the conical bot tom of the settling tank. This tank carries within it a large cone, the top part of which is on a level with the top of the tank, the bottom part ending at the top of the conical portion of the tank The cone, both ends of which are open, is suspended within the tank. The lower end of the cone is of a very large diameter while the upper end has a small diameter. The principle of this contrivance consists in a down ward current of juice from its entrance into the tank and an upward flow through the cone, the particles of solid matter having a greater density than the liquid and to go downward, but the upward current causes a portion of them to rise, though in their ascent they strike the sides of the cone and are returned to the bot tom.
Evaporation and The evaporation of sugar solutions or cane juice has for its object the concentration of the liquid to such a density as will cause the sugar to crys tallize out. To accomplish this there are two methods, the "open kettle' and the vacuum pan. The open-kettle process consists in boiling the juices in open pan's, either of circular or rect angular form, provided with steam coils. The heat is continued until the density indicates suf ficient cooking. When a density of 22 to 36 Baume is reached, the liquid is termed a syrup, and when the syrup is cooked to a stiff mass, a masse cuite. After allowing crystallization to take place in wood or iron vats, the masse suite is thrown into a hogshead and the mo lasses percolates through a perforated bottom, or the sugar and molasses may be separated in a centrifugal machine. The sugar thus made is termed open kettle and the process is not used in the up-to-date factory.
The vacuum apparatus, a dome-shaped•ves sel, 5 to 10 feet in diameter, 8 to 15 feet high, provided with steam coils, is the most economi cal for evaporating sugar solutions, requiring only about one-third the fuel of the open ket tle process and reducing to the minimum the loss by burning or inversion. This apparatus
may be arranged in °multiple effect"— two or more pans connected — or consist of one pan. More than three pans have not been found ad vantageous. These vessels are so controlled that the vacuum in the first is about 5, in the second 15 and in the third 25 to 27 inches, 30 representing a perfect vacuum. They are con nected with a system of valves so that the juice discharging of the pan is termed a °strike," and the product discharged, mite?) This is conveyed to a mixer provided with a shaft carrying paddles or fingers that keep the sugar and adhering molasses mixed. The well mixed masse suite is next conveyed to a cen trifugal machine, made to revolve 1,000 to 1,200 times per minute, and in its rapid motion the sugar and molasses are separated, the latter may be drawn from the first to the second and from this to the third, from which it is drawn into a syrup tank. Exhaust steam is usually utilized for concentrating the juice, though it becomes necessary at times to use live steam. The steam enters the first and causes it to boil, and the steam generated in this is sufficient to boil the second and so on. The concentration is carried to a density of 22 to 26 Baume or about 50 per cent water.
The syrup is drawn from the syrup tank into the vacuum strike pan until one, two or three coils are covered, and this definite quan tity is heated until grains of sugar may be seen on withdrawing, with a proof stick, a sample and spreading it on a piece of glass. The for mation of grain is sometimes brought about by permitting a little cold juice to enter the pan and suddenly cool it. The object here is to form a crop of °seed crystals," and the re mainder of the process has for its purpose the developing or growing to a desired size. This is accomplished by continuing the boiling and adding, from time to time, small quantities of the syrup, taking care that no more grains or crystals are formed. In three to four hours the pan will be as full as is convenient to cook it and the sugar crystals as large as desired. If very large crystals are wanted, as is sometimes the case with confectioners, a "cut" strike is made, that is, one-third or half the sugar in the pan is dropped out through the bottom and the remaining portion, say one-half, is built up in the same manner as already described. On completing the boiling the second time there are not so many crystals, but they are twice as large. This process may be repeated, but it is very expensive. The principle of the strike pan is similar to that of the effects already de scribed. The vacuum in the pan is usually 25 to 28 inches and the temperature to 160' F. The cooking is continued until the concentrated mass contains 6 to 8 per cent of water. The being thrown through very small perforations in a copper gauze basket, while the sugar re mains in the basket. The product thus obtained is termed °first sugar," also °raw sugar," and usually of test.