GB1252749A - - Google Patents

Abstract

1,252,749. Extracting sugar by diffusion. BRAUNSCHWEIGISCHE MASCHINENBAUANSTALT. Dec.12, 1968 [Dec .13, 1967], No.59201/68. Heading C6B. In a method of extracting sugar from bagasse by passing it through a diffusion trough 11 wherein it is subjected to the action of sprays 21 which are supplied with extraction liquid from containers 18 beneath the trough on the countercurrent principle, the trough comprises at least two zones including an entry zone 12, where thermal treatment is given to the bagasse by hot liquor sprays 33, and a diffusion zone 14, between which zones there is disposed a roller 23 which exerts a downwards force on the bagasse in excess of its own weight. Preferably the peripheral speed of the roller 23 is faster than the speed of movement of the bagasse in the diffusion zone. In the embodiment of Fig.1, the floor of the inlet zone is formed by a conveyer band 22 travelling at a speed faster than the peripheral speed of the roller 23 and an intermediate zone 13 is formed beneath the roller wherein the bagasse is supported either by a fixed plate 25 or by an endless plate conveyer (26), Fig.3 (not shown). The bagasse is conveyed in the diffusion zone by a succession of driven rollers 17a which are driven in batches by reciprocating mechanism consisting of cylinders 42 which are coupled through linkages and radial arms to freewheel devices at the individual rollers, the drive mechanism preferably being duplicated on the other side of the apparatus and out of phase so as to provide for a substantially continuous drive to the rollers 17a. In the spaces between the rollers 17a either small idler rollers 17b, or adjustable plates 49, or a combination of the two, are provided to prevent the bagasse falling between the rollers 17a. At the outlet end of the diffusion trough a compression roller 37 carried on pivoted arms 36 is provided, followed by a bladed wheel 38 to break up the bagasse as it is fed to a final press (not shown). The bagasse is supplied to the entry zone 12 by a shoot 29 which can be slewed about the axis of a vertical shaft 30, with its outer end running on an arcuate rail 31, to distribute the bagasse across the width of the trough. The trough is preferably of trapezoidal section, having inwardly and upwardly sloping sides to reduce the tendency of the bagasse to stick to these sides. In a modification, Fig.4 (not shown), only an entry zone and a diffusion zone are provided, the floor of the entry zone being formed by a conveyer band travelling more slowly than the bagasse in the diffusion zone, so that the bagasse builds up to a greater depth in the entry zone to provide a maceration stage following the thermal treatment.