BEET SUGAR IDUSTRY.

Marlborough Daily Times, Volume X, Issue 314, 26 May 1888, Page 3

BEET SUGAR IDUSTRY.

By J. Salat.yay. MAitoFACTCEiNO process. —(Continued). Evaporating Apparatus. —Bofore tho juice entered tho evaporating station, it used to undergo a filtration over bone black (animal charcoal). This most expensive operation, however, is nowadays done away with, while more extensive aaturation is substituted, and tho results arc ill every respect equally as good. In nil tho hithorto mentioned apparatus the juice has unavoidably become more and more diluted with water, which requires io be again separated from tho t sugar dissolved in it. This is done by evaporation. Tho quantities of water to be evaporated are enoimous, as will be seen from the following figures, which express the averago dilution of the juice at the various apparatus at per cent of the beet root quantity worked’up : j diffusion battery, 130 ; saturation (milk of lime), 12 ; filter presses and mulaxator, 28; total, 170 per cent; therefore the weight of the juice frem a quantity of 210 tons of roots per diem, will be 210 x 17, equals 357 tors, when entering the evaporating apparatus, whoso object is to concentrate the juico from a density of about 9 to one of 50 per cent. To attain this, a simple calculation will Eihow that the apparatus must have an evaporative capacity of 292-7-1 tons per diem. At, enormous as it may seem, this is accomplished by a comparatively small but complicated apparatus, attended to by pnly one man. The evaporators are constructed on the triple” or “quadruple action” prin-

ciple, i.e., the whole apparatus consists of three or four vessels respectively, which act conjointly in the following manner : The first vessel is heated by exhaust steam from the various engines (partly also by direct steam) and the vapors of the evaporating juice are conducted into a second vessel, where they are employed to evaporate another quantity of juice whose boiling point has been lowered by , producing a certain vacuum within the vessel. The vapours are again conducted into the heating chambers of a third vessel wherein the boiling point of the juice has been reduced to a still lower temperature by an increased vacuum, and so on. At this rate the steam admitted into the first vessel only, produces several heating effects in succession, and in ordinary working there is a continuous circulation through the apparatus, which is so regulated that from tho last vessel the juice is drawn off, having the desired 50 per cent, concentration, when it is called “thick,” in contrast to the “thin” juice supplied into the first j evaporator. I Fourth Saturation.—ln this operation the thick juice is subjected to the same ! treatment as in the first three saturations, * but the addition of lime or atrontia is either limited to exceedingly small quantities, or it is omitted altogether. Tho acid employed here is generally the sulphurous, hut phosphoric or even sulphuric acids have also been used successfully. In any case great care has to be taken that the juice be saturated as near to perfect neutrality as possible, without ever booming acid. Mechanieal Filtration. —lt has been found that for this purpose the ordinary filter press renders the best services; therefore, it has also been adopted, with only slight modifications in its construction. At this stage of the manufacturing process, instead of using the filter press some manufacturers filter the saturated thick juice through layers of gravel and sand, while others use “ Puvrez’s patent filter,” in which fine woollen hags are tho filtering media, &c. It seems, however, that the filter press will not he easily displaced. Vacuum Fan.— This apparatus serves to contiuue and complete the concentration of tho thick juice to a state of supersaturation in which the sugar will crystalize. The vacuum pan is constructed and worked on the same principle as the evaporators, only some new features being introduced required by the different nature of the denser liquid boiled. Tho heating is generally performed by high pressure steam, and as the yacui’m in the vesse is very high, the juice, or syrup (as it is now called), is concentrated very rapidly in this apparatus. It is a well-known fact, that the greater the difference is between sugar and non-sugar substances in the syrup, the more sugar can he obtained in crystalised foim ; and for this reason manufacturers mostly dissolve certain quantities of brown sugar in the juice before it enters the vacuum pan, in order to increaso the yield of No. 1 sugar, and such proceeding is very effective indeed.

Wnen the boiling process is completed the syrup, which is now termed the “boiled” or “ filling mass,” is drawn into a malaxator, and hence charged into centrifugal sugar separators. Such mass as will produce No. 1 sugar is called also No. 1 mass, while those yielding a higher number are named also by tho respective figure—i.e,, mass No. 2or No. 3, which are obtained by boiling over syrups resulting from tho centrifugal separation of qualitatively higher sugar. By repeated increasing the “ purity ” (i.e., the proportion of non-sugar to sugar) of the syrup and reboiling tho same, almost all the sugar produced will be of No 1 quality ; for this purpose a second vacuum pan should always be provided. ANo 3 syrup generally contains such a large pro portion of non saccharine matter that tho secretion of sugar crystals cannot be attained by boiling only, but will take place when the syrup is kept for several weeks in reservoirs at a certain temperature. These ciystals then are again separated in the centrifugal, and the Bugar thus obtained, which is always of a greater “purity” than a No 2 syrup, is dissolved in the latter, thuß producing a higher yield of No 2 sugar, which, as Btated above is added to No 1 syrups, etc. The final residue of the sugar manufacturing process which will secret no more crystals, (although it contains about 40 or 50 per cent of sugar) is called molasses, which iu Europe is either sold to distilleries for alcohol production, or it is subjected to further extensive and complicated processes of sugar extraction, wihoh (the “ Osmosis ” excopted) generally are not connected with sugar factories, hut from separate industrial branches. Centrifugal Separators. — These machines wilt require no lengthy description, as 1 believe they are well known, being in use iu all the cane-sugur mills and sugar refineries. The previous description includes all tho operations which have to be performed in a beet sugar factory of the most modern and improved style, and a factory of this description I would recommend for New Zealand, where, I am confident, the beet sugar industry will prosper exceedingly well. In concluding this chapter, I must not omit to briefly mention the various machines, engines, etc., which, so to speak, form the connecting links between the single apparatus. These are: (1) The various steam engines producing the necessary motive power. (2) The water, juice, carbonic acid, vacuum and air compressing pumps. (3) The various transporters and elevators. (4) The vapour-condensing plant; and (5) the “ heart ” which sets i tho whole factory going: the steam generating plant. It will be seen, that the beet sugar manufacture is a rather complicated process, requiring very intelligent management, under which, however, the whole '“mechanism” works in a wonderfully smooth and harmonious manner.. I trust that the inhabitants of the Wairau will before very long have an opportunity of inspecting a beet sugar factory in their own dislrict.