GB1220415A - Process and apparatus for treating sucrose bearing materials - Google Patents

Abstract

1,220,415. Extracting sugar. FRENCH OIL MILL MACHINERY CO. June 26, 1968 [June 26, 1967], No.30577/68. Heading C6B. In a process for extracting sugar from sugar cane or other sucrose bearing material which comprises the steps of mechanically working the cane to rupture substantially all the cells of the material, adding maceration liquid during the final stage of working and collection of the bagasse in a hopper so that the material is steeped in the maceration liquid, elevating the material from the hopper by a conveyer and at the same time heating it, and delivering the material to one or more mechanical presses which include a pressing surface having a substantial number of drainage openings for releasing juice combined with maceration liquid immediately as the material is compressed, at least a portion of the juice is recirculated directly back into the material being conveyed from the hopper. In the arrangement of Fig. 1, the cane C passes into the hopper 50 by way of a rotary chopper 12, crushing rollers 24, pressing rollers 32, and a rotary shredder 40. Maceration liquid, which may be water is introduced in small amounts into the crushing and shredding stages. The bagasse thus delivered to the hopper is allowed to build up to the level indicated so that it is steeped in maceration liquid both from the previous stages and also from a pipe 70 suppled with juice extracted from a screw press 75 which the bagasse is fed from the hopper by an elevator 55, the elevator comprising drag slats 56 which slide over a wall 62 and are carried by a pair of endless chains. Immediately below the upper rim of the elevator there are disposed conduits 68 feeding steam or hot water through openings in the wall 62 to the bagasse to assist in the release of the juice. In addition, juice produced by the press 75 is fed to a chamber 72 from whence it is sprayed on to the layer of bagasse being elevated, this layer being trimmed by rotary kickers 65 to a desired thickness. The press is of a known type which includes a cage 76 lined with screw bars 77 which form an inner pressing surface having a substantial number of drainage slots, and a screw 78 having interrupted flights 79. Alternatively, a cone-type disc press may be used. The crushing and pressing stages may be omitted, in which case a second shredder or/and hopper 50 may follow the press 75 and a second elevator 55 may deliver the bagasse to a second press 75. In Fig. 2, such an arrangement is shown but modified in that the crushing rollers 24 are retained, smaller hoppers 89 replace the hoppers 50, and recycling of juice is not effected directly into the hoppers 89 but via two chambers 100 on each of the elevators 90 which convey the bagasse from each hopper 89 to the associated press 75. Collecting pans 108 are arranged below perforated portions of the walls 96 over which the elevator slats 94 slide and deliver collected juice to an earlier part of the apparatus. The complete recycling system for providing maceration fluid at desired points in the apparatus, which is indicated by the arrowed lines, is so designed that the most concentrated juice is collected at the first collecting pan 108 for delivery to the boiling house, the juice collected for recycling at other points being progressively weaker, fresh water being used as maceration fluid only in the last chamber 100 to assist the final extraction via the second press 75. Lime is preferably added at a suitable point in both arrangements to reduce corrosion effects and power requirements.